# Home Foundry



## GreenTwin (Jul 2, 2021)

I built my first furnace back in 2012, and have experimented with oil and propane burners ever since.

I melted aluminum first, and that was pretty easy.  You can melt aluminum as easily as Zamak (in my opinion) using the same propane burner and just slightly more heat.
Zamak has more mass to it.

I really wanted to master pouring gray iron, and that took a figure out.
If you know what you are doing, casting gray iron is not much more difficult than casting aluminum, although there is a lot more radiant heat that has to be carefully controlled to protect body and eyes.
The slag has to be carefully handled with iron, but that is really no problem.
Gray iron does not have to be degassed, but you do have to let it cool in the mold overnight to prevent hard spots, and add a very small amount of ferrosilicon.

The burner and furnace must be built to withstand iron temperatures, and the crucible needs to be a high-quality clay-graphite unit that is ferrous-metal-rated (I use Morgan exclusively).

I use a siphon nozzle style burner, and diesel for a fuel, with a flow rate of about 2.6 gal/hr.
Variable speed Toro leaf blower for combustion air.
I will be converting to a gear-pump style pressure nozzle soon, which looks just like a siphon-nozzle but does not use compressed air for atomization, but rather a small gear pump instead.

I had to learn pattern making with machining allowances, shrinkage, draft angle, etc., and now I use a lot of 3D printed patterns.


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## GreenTwin (Jul 2, 2021)

There is an art to gating, runners, risers, spruing, pour basins, etc.
I use a variant of some of John Campbell's methods these days, and am getting consistent results with no defects in gray iron.

Gating/risering/spruing/pour basins is a hot topic (no pun intended), and discussing methods in the backyard community is like discussing whether you think a Ford, Chevy, or Chrysler (Hemi) makes the best racing engine.

What I have done is to find a method that works consistently, and stick with that until I find something better.

All of the iron pour events I was aware of were cancelled due to COVID, and so I got very bored, and decided to make a jumbo-belt buckle, or plaque, or whatever you want to call the thing.   The intent was to cast something/anything, and the symbolism of the Phoenix was to show that one day the iron pour events would occur again, and the casting community would rise up out of its fear of COVID and start the group casting shows again.

Here is the pattern, which was designed in Solidworks from a hand sketch, and then printed on a Prusa.




















.


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## GreenTwin (Jul 2, 2021)

Here is the 3D print, and the front of the print is convex, to get away from just a flat-front look.
I used dual-colors for kicks, to see if that would work, and it did.
I just cut the filament in mid-print, and then fed in another color.


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## GreenTwin (Jul 2, 2021)

Here is the pattern filled with a bit of spackling compound, and then painted.
Filling the pattern was easier than getting Solidworks to insert a fillet around such a complex shape.


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## GreenTwin (Jul 2, 2021)

The pour went without a hitch.
The molds were made using resin-bound sand, which is the cat's meow of molding sand.
The molds were sprayed with ceramic mold coat to give a superb finish.

A simple open-face pour was used, but normally I use a cope/drag closed mold arrangement.































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## GreenTwin (Jul 2, 2021)

These are the castings immediately after I flipped them out of the mold, and before I did any cleanup work on them.
With the ceramic mold coat, there is only very light sand adhesion to the casting, and that can be cleaned off with a few light strokes using a dry paintbrush.


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## GreenTwin (Jul 2, 2021)

Here are the Phoenix castings after brushing them off with a paintbrush.
It was a very fun day at backyard casting, and a nice relief to the pandemic stuff going on.

With a slight amount of ferrosilicon, machinability is excellent, and there are no hard spots or chills in the iron.

It took me about 8 years to completely figure out the iron process, but I have seen people pick it up in a month when provided with the right information about how to do it.  I had to learn mainly by trial and error.


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## SmithDoor (Jul 2, 2021)

I like 3D printing 
That will save a lot time.

FYI: The make sheet wax for making cores. 

Dave 



GreenTwin said:


> I built my first furnace back in 2012, and have experimented with oil and propane burners ever since.
> 
> I melted aluminum first, and that was pretty easy.  You can melt aluminum as easily as Zamak (in my opinion) using the same propane burner and just slightly more heat.
> Zamak has more mass to it.
> ...


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## GreenTwin (Jul 2, 2021)

For round cores, I have a variety of sizes of schedule 40 PVC pipe, and I cut a piece to the correct length, using a diameter that is slightly smaller than the rough cast cylinder bore.
I slit the PVC down one side with a thin slitter saw, and make a short slot at the center of the slit.
I fill the PVC with either sodium silicate or resin bound sand, and when the binder sets, I put a screwdriver flat blade in the slot and pry slightly.
A near perfect core drops out.

Most people will cut their PVC in half, which means you have to clamp the two parts back together, and then the corebox halves are prone to getting separated/lost.

Below is an example of cores made using a one-piece PVC corebox.
You can see the coreboxes in the background.
I make multiple cores at the same time.
The cores are vented using an 1/8" or 1/4" wood down in the center, which is removed once the sand sets.
The cores are vented to the top of the cope.


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## GreenTwin (Jul 2, 2021)

Some examples of 3D printed parts that were derived from a 3D model are shown below:


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## GreenTwin (Jul 2, 2021)

This was the first item I cast in gray iron, in 2012, for the green twin oscillator.
I was pretty clueless about how to do iron at the time, and sort of stumbled my way through it.
All things considered, it turned out pretty well, and I used this on the green twin.

Its one of those things, if you don't get in there and try it, then you will never figure it out.

I built my furnace way too heavy, and it took 30 minutes to heat up enough to start melting the iron.
I thought bigger (heavier) was better with furnaces, but later learned the opposite is actually true.

The sand I used is called (tradename) Petrobond, and while it works pretty well with aluminum, it does not work very well with iron.


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## GreenTwin (Jul 2, 2021)

For the next flywheel (this was a group build with two builders, myself and woodguy) I upgraded to OK85 sand and a resin binder that sets the sand into a hard block.

The resin bound sand is the best I have seen for mold making, and is extremely versatile.
The art-iron folks use it a lot.
Resin-bound sand is not easily reusable, unfortunately, but I have not seen a better finish than can be produced with a resin-sand mold, and ceramic mold coat.


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## GreenTwin (Jul 2, 2021)

Here was a test run of the furnace and burner, and I poured some ingots.
Pouring ingots from scrap is ok for aluminum (if you degass), but for iron, it is best to leave the iron in the rough scrap form, and not make ingots.
Since this was just a test of the equipment, I did make ingots, and they were usable, but a lot of time and fuel is wasted if you convert iron to ingots.

I cut one of the ingots, and broke another, and it was good clean iron.

The amount of ferrosilicon that needs to be added to an iron melt is ever so slight.
Any more than a very small amount and you get a lot of shrinkage and bad parts.
The ferrosilicon is not absolutely necessary unless the parts are thinner than about 3/4".

Some folks will insist that you have to use clean scrap iron, but that is not true.
I have seen some people use scrap iron that looked like it had been on the bottom of the ocean for 20 years, and it melted no problem, and created perfect castings.

I use plain gray iron scrap, and scrap that breaks cleanly with a sledge hammer.
I don't use scrap that has phosphorus in it, such as many thin iron castings like radiators, since I have heard this makes for weak engine parts.


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## GreenTwin (Jul 3, 2021)

Here is an oversized Cretor's style flywheel, in 356 aluminum.
I carved one spoke from wood using a dremel tool, cast six of them, added those to a wood rim and hub, and then cast an overall flywheel.
At the time, I was still learning how to do iron consistently, and so I did not attempt this piece in iron, but I will go back and re-pour it in iron one day.

I found a little stainless steel sauce pot on sale at a nearby store for cheap.
The lady asked me "Are you going to do some cooking with this little pot?".
Best I could do was give her a simple "Yes.......cooking."   LOL, how do you explain pouring molten metal out of a cook pot?

I now use clay-graphite crucibles exclusively, but in a pinch, for a one-time use thing, you can use a metal crucible, but beware since they sometimes fail in mid-melt.


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## GreenTwin (Jul 3, 2021)

Here is the assembled flywheel pattern, and the mold making setup.
I used sodium-silicate-bound sand for this flywheel, and it turned out ok (this was a proof-of-concept piece), but I prefer the resin-bound sand.
I used a simple naturally aspirating propane burner for this melt, since it is easier to use with small melts.

You can melt iron with propane, but it takes a lot of pressure and the tank tends to get too cold, and the pressure drops too low, so I use diesel exclusively for melting iron.


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## GreenTwin (Jul 3, 2021)

This is how the pattern was assembled.


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## GreenTwin (Jul 3, 2021)

And a comparison between my flywheel and a Cretors No.02 flywheel.
The concept was proven.
You can make a pretty realistic Cretors-style flywheel using just one hand-carved spoke.


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## GreenTwin (Jul 3, 2021)

Here is a straight edge that I cast for a buddy of mine.
He made the pattern.
This piece turned out pretty well.
I was starting to get the process figured out, and was getting consistent pours with my 2nd iron furnace, which is infinitely lighter than my first iron furnace.

I started using snap flasks, and I remove the flask from the sand before I pour the iron.
The two mold halves are adhered together with a ceramic glue.
This prevents any damage to flasks due to heat/spills, etc., and so they last indefinitely.

I don't use hardware on the sides of the flasks for registration, but instead just drill holes with a long drill bit through the cope and into the drag, and then insert rods for cope/drag alignment.  The pin method works perfectly.
I normally bend an L-shape on the end of my pins, but these were of hard material and would not bend.
I misplaced my L-shape pins, but later found them.


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## GreenTwin (Jul 3, 2021)

These straight edges turned out pretty well.
I think this was the first time I used ceramic mold coat, and that prevents most of the sand from adhering to the casting.


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## GreenTwin (Jul 3, 2021)

I sent these castings off to my buddy (the one who made the patterns), and he final machined them.
Turned out pretty well for a first-time straight edge attempt I think.

Machined easily with no hard spots.


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## GreenTwin (Jul 3, 2021)

I ran across another individual who had a broken bearing cap, and so I decide to practice my pattern and mold making skills on that, and see if I could cast it without defects.

I had to build up the original cap a bit using wood tongue depressors.
The owner wanted the numbers retained, otherwise I would have just made a new pattern from wood.


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## GreenTwin (Jul 3, 2021)

I was running out of time and used some tape on the top of the bearing to fill in a few low spots.
Normally I would continue filling the pattern and sanding it, and would only use the blue painter's tape on surfaces such as the round bore, to prevent the pattern from sticking to the sand.


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## GreenTwin (Jul 3, 2021)

I did not need a core for this pattern, but rather just used the bottom of the pattern itself for the round interior.
I used the ceramic mold coat again, and burned it off.
Don't burn your shop down with the alcohol-based ceramic mold coat if you happen to use it.

You can use rotary rasps and such to machine the sand after it sets, to add runners, etc.
You can cut gates into the sand using a small knife with a straight end.


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## GreenTwin (Jul 3, 2021)

The pour went flawlessly, and this is the result.
Iron castings must be left overnight in the mold, so that they cool very slowly, else you will have hard spots (chills) in the castings.
The best way to ruin a good iron casting is to pull it out of the sand mold as soon as the metal solidifies, but when the metal is still very hot (ask me how I know this).

I was very pleased with the surface finish and how I was able to retain the original letters/numbers.

You can see the mold was poured with no flask around it, but with some heavy weights on top the mold, to prevent the cope and drag from separating due to hydraulic forces.


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## GreenTwin (Jul 3, 2021)

Here is the casting with the gates/runner/sprue cut off.

I sent this part to the owner, and he machined it, poured new babbitt, and installed it on his machine.
He was a happy camper to get a new bearing cap.

I was glad to use this as a verification that I had finally got the new furnace and iron process to a point were it could make consistent defect-free and easily machinable parts.

Edit:
You can see how the bound sand mimics the blue tape exactly.
I normally fill and sand the pattern, and don't use tape, but was running out of time.
I was going to buff out the tape lines, but did not have time for that either, so I just mailed the casting as-is.


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## GreenTwin (Jul 3, 2021)

Large gray iron electric motor end bells make very good scrap iron material.
The paint and rust does not need to be removed prior to melting the scrap; it all comes out in slag.
The difference in the amount of slag between melting a perfectly clean piece of iron and a rusty piece of iron with paint on it is very little.

I was initially told that the scrap iron had to be very clean, but I found out that is a myth.
As long as the metal inside is a good grade of gray iron, it will make a good casting, regardless of what is on the surface.

The furnace interior was clean since I had just coated it with a reflective ceramic coating (ITC100).
The coating is not necessary, and since ITC prices have skyrocketed in the last few years, I don't use it anymore, and I can't tell any difference in melt times.


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## GreenTwin (Jul 3, 2021)

These are the typical Morgan clay-graphite "Salamander-Super" crucibles that I use.
They are ferrous-metal rated, and work well with iron.
Other crucibles that I have seen others use that are probably not ferrous-metal-rated, and perhaps not rated for 2,900 F, often appear to fail quickly, and at the worst possible time.

I use Morgan clay-graphite crucibles for all metals, but do not mix metals and crucibles (one crucible for each metal type).
These crucibles can be purchased in a range from very small to extremely large.
I use a #10 a lot, but have also used a #30.
I have seen several backyard casters using a #70.

For capacity, these crucibles will generally pour about 2.5 times the crucible number, ie: a #10 will pour about 25 lbs. of iron.
You need some space at the top of the crucible to be able to pour the iron without spilling, so you don't fill them brim-full.


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## GreenTwin (Jul 3, 2021)

My workload has been extremely heavy for the last year, and will continue to be that way for a while, but when I get caught up, I plan on casting a 60% scale model of this engine, which I found in Oregon.
These engines seem to be rather difficult to find, and this was one of those miracle finds that I stumbled across by chance.

Edit:
That is the seller' Ford, not mine.
People look at that photo and say "Great auto.  Is there a steam engine in the photo with that great auto?".  LOL


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## GreenTwin (Jul 3, 2021)

And after the O-S engine build, I am going to cast a 60% scale Frisco Standard marine engine.
JasonB and friends made the helical gear patterns for this engine (many thanks Jason and friends; could not have done this gear without you folks from across the pond).
Jason nailed the 3D model for these gears to give an exact 2:1 speed ratio with a perfect mesh, and I must say this is not an easy design, at least not for me.

The 3D model for this engine was developed from photos that were found online of a 4hp engine.

Being able to create a 3D model from photos, 3D print the patterns, and then cast the parts in gray iron is I must say a fabulous experience, and I really never dreamed I would get this far with the process, but here we are, with help from JasonB.


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## stragenmitsuko (Jul 3, 2021)

casting grey iron , now that is impressive .
thx for sharing


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## MRA (Jul 3, 2021)

The O&S engine looks like the one Dave Richards used to use in his 'Old steam Powered Shop' youtube series.  There are about 60 videos, and he moves to a larger engine about half way through.  Thanks for posting your pictures here - I have got as 'hot' as brass and bronze, but not iron yet (I can see diesel working better than old engine oil there).  I especially enjoyed seeing you build-up that bearing cap for shrinkage - I replicated my home setup at a small museum where I volunteer, and it looks likely we'll need to replicate parts for machines there (mostly pre-war diesel and gas engines) in the not-too distant future.  I had been thinking about shrinkage and I'm glad to see your approach is practical.

When you use an oil pump, do you plan to use a smaller jet in the end of your fuel tube in the burner - and is this expected to give a 'better' flame?  I'd not thought of this - my burner is like a very, very simple carb - the air tube is reduced in diameter a little for more velocity, and the gravity-fed fuel tube (1/4" or so copper pipe) just terminates somewhere near the end, in the middle of the air tube, and the air flow drags oil out in blobs and strings!  Well, it burns, but I could imagine screw-in jets perhaps, especially with pressurised, clean (!) fuel.
cheers
Mark


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## GreenTwin (Jul 3, 2021)

_casting grey iron , now that is impressive .
thx for sharing _

Thanks.
I noticed today that the member here "sawyer Massey" is also pouring iron, and making steam engine parts.
He appears to be making some nice castings, and so I have to guess he has been at it a while, or is a quick learner.

I know a handful of people who melt gray iron in a backyard setting, but there are not too many who make parts regularly that I am aware of.

Casting aluminum is very easy.
I have done it (as shown above) with a stainless sauce pot, a propane burner, and some sodium-silicate-bound sand (it could be greensand also).
Aluminum melts in the 1200 (+) F range, and as long as you don't have any dampness, moisture, water, etc. in the mold, or in the ingot mold, then it is easy to melt and pour.
Any water anywhere, and you can have a face full of molten aluminum, since the even a tiny drop of water will flash to many times it size, and blow the aluminum right back out of the mold and onto the person pouring (another one of those don't ask me how I know this).
Full face shield and eye protection are critical, as well as some leather all over for personal protection.

It took me on and off about 7 years to learn how to get consistent gray iron castings.
Work kept interrupting me for long periods of time, and so the real amount of time from first iron pour to consistent iron pour was probably 4 or 5 years.

Without understanding the entire process, ie: the burner operation, the furnace operation, how and when to handle the slag, the ferrosilicon additive for machinability, and getting set up to safely handle the every intense radiant heat, then one can have on and off successes, which is what I did for about 5 years.
One casting would turn out well, and the next one would not be usable, but I can finally consistently make a good machinable casting basically first time, every time.

Pattern making, shrinkage, draft angle, etc. are things that have to be understood.
Pour basins, sprues, runners, gates, risers, etc. are sort of an art to lay out so that they work every time.
Nobody agrees on how to do pour basins, sprues, runners, gates, risers, but I have a method that works well for a variety of pattern shapes and sizes.

I got a little help from some folks online who do iron castings, but sometimes people will not share all of their iron secrets, and sometimes people are simply not good as describing in fine detail exactly what the iron process is.

I finally did a lot of experimentation on my own, and established what the fuel and combustion airflow should be to get a fast iron melt (fast being about 1 hour).
I build a somewhat lightweight iron furnace, with about 120 lbs of refractory, and it heats up relatively quickly using an oil burner.

I also experimented with many burner types, fuel types, sand types, etc.
I am not really aware of a good book for backyard folks about how exactly to consistently melt and pour quality gray iron castings; at least I could never find such a book.  The Navy Foundry Manual was somewhat helpful, but so dated that it was not very much help.

.


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## GreenTwin (Jul 3, 2021)

MRA said:


> The O&S engine looks like the one Dave Richards used to use in his 'Old steam Powered Shop' youtube series.


It is the same engine that Dave Richards uses, and as I recall he said his flywheel was fabricated, and he noted that my engine has an original flywheel.
Its a very nice engine to say the least; classic styling, and simple.

If you can melt brass and bronze, then with a little more learning, you can also pour gray iron (*assuming you get set up correctly to melt iron).
I know of one individual who went from brass/bronze to iron this year, without too much trouble.
Don't expect your first iron pour to be perfect.

 .


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## dazz (Jul 3, 2021)

Hi 
What ceramic coating do you use for the moulds?
Is it available in powder form to avoid the cost of shipping it as dangerous goods (adding alcohol before use)?


Dazz


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## GreenTwin (Jul 3, 2021)

MRA said:


> When you use an oil pump, do you plan to use a smaller jet in the end of your fuel tube in the burner - and is this expected to give a 'better' flame? I'd not thought of this - my burner is like a very, very simple carb - the air tube is reduced in diameter a little for more velocity, and the gravity-fed fuel tube (1/4" or so copper pipe) just terminates somewhere near the end, in the middle of the air tube, and the air flow drags oil out in blobs and strings! Well, it burns, but I could imagine screw-in jets perhaps, especially with pressurised, clean (!) fuel.


At the moment, I am using a Delavan siphon nozzle, which is a spray nozzle very similar to a paint sprayer in that it uses compressed air to atomize the liquid (diesel in my case) and spray it in a fine mist.
The problem with a siphon nozzle burner is that it requires a somewhat decent air compressor, and over time, the air compressor tends to wear out.
If the air compressor fails in mid-melt, then you have a problem if you don't have a backup.

The latest burner I am using looks identical to a siphon-nozzle burner, except that it uses a gear pump to pump diesel to the nozzle at 100 psi, and no air compressor is required, since the 100 psi does the atomization work.
The gear pumps are readily available from the commercial heating-oil furnace market, as are the siphon and pressure nozzles.
The siphon and pressure nozzles can be used with the same brass adapter, but they operate differently, and are not interchangeable.

Gear pumps can be driven by a fractional horsepower motor, and are quite efficient.
It is much easier to carry a small gear pump/motor combination around, than an air compressor, and a gear pump motor may draw 3 amps or less at 120 volts, whereas some air compressors can draw 12 amps or more at 120 volts.

.


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## GreenTwin (Jul 3, 2021)

dazz said:


> What ceramic coating do you use for the moulds?
> Is it available in powder form to avoid the cost of shipping it as dangerous goods (adding alcohol before use)?


I think the product that I found is called "VelaCoat", and it is alcohol-based.
I am not aware of a dry product, but I have never asked anyone if they sold that either, and that would be a good idea, and cheaper to ship.
I am not sure if ceramic mold coat would work on green sand (greensand being clay and sand mixture).
I use resin-bound sand, and so the mold sets and becomes hard, thus making it impervious to spraying on the ceramic mold coat and burner off the alcohol.

I tried alcohol and graphite many years ago with petrobond (tm) sand, and that was an absolute disaster.
I have not tried ceramic mold coat with greensand, and I don't use greensand.

.


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## GreenTwin (Jul 3, 2021)

MRA said:


> When you use an oil pump, do you plan to use a smaller jet in the end of your fuel tube in the burner - and is this expected to give a 'better' flame? I'd not thought of this - my burner is like a very, very simple carb - the air tube is reduced in diameter a little for more velocity, and the gravity-fed fuel tube (1/4" or so copper pipe) just terminates somewhere near the end, in the middle of the air tube, and the air flow drags oil


I will have to detail how I set up my siphon nozzle burner and pressure nozzle burner.
Below are the internals of a Delavan siphon nozzle tip.

Basically, with a siphon-nozzle burner, you feed compressed air in the center pipe, and fuel in the side of the adapter via an elbow fitting.
There are two parts to a nozzle, which is the adapter body, and the actual burner tip.


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## GreenTwin (Jul 3, 2021)

A few more siphon-nozzle photos.
You can see there are small spin vanes built into the burner tip that spin the fuel, and the compressed air comes out the hole in the center of the tip.


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## GreenTwin (Jul 3, 2021)

This is the schematic for a Delavan siphon nozzle burner.

I use 10 psi compressed air pressure on the fuel tank with a 30 psi safety valve, in order to get a consistent diesel fuel flow at all times.
I use an automotive inline fuel filter in the fuel line just before the burner.

I use about 30 psi compressed air to the siphon nozzle.
Some folks use slightly less compressed air.

I use a #30609-11 nozzle, and a #17147 adapter with the siphon nozzle burner.
The chart below lists the #30609-11 at a nominal 1 gal/hr fuel flow rate, but it actually operates over a wide range of fuel flows, depending on your compressed air pressure, and fuel tank pressure if you are using a pressurized fuel tank.

People that use waste oil for fuel often use a drip-style oil burner, since waste oil is often not clean, and can be prone to clogging.
There are no fine passages in a drip-style burner to clog.
I don't use a drip-style burner because they don't have the fine control I want in a burner.

Generally people who use waste oil thin it perhaps 15-20% with diesel to make it flow better.
Handling waste oil and trying to filter it is not worth my time and effort, so I use diesel only.
Diesel burns cleanly with no concerns about the heavy metals that are in waste oil.

I have seen folks melt iron with diesel, kerosene, cooking oil, waste oil, etc., and they all seem to work well.

Some hydraulic oils are reported to be toxic when burned, so don't just use any waste oil; use caution.
Waste oil is notorious for being contaminated with sludge, water, antifreeze, etc., which is another reason I avoid using it.


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## GreenTwin (Jul 3, 2021)

Here is the pressure nozzle arrangement.

I think the connect can be simplified.

I plan on using a needle valve in the return line, instead of the pressure-regulating-valve PRV.
Closing the needle valve forces 100% of the fuel flow out the nozzle tip, and no fuel flows in the bypass.

Opening the needle valve allows fuel flow in the bypass line, back to the fuel tank, and so the fuel output of the nozzle can be varied from very little up to its maximum rated amount.

Note that siphon and pressure nozzles both use the same adapter, but the nozzle types are not interchangeable due to the differences in how they operate.


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## GreenTwin (Jul 3, 2021)

I tried several drip-style burners, and experimented with them for several years.
I could never get consistent operation out of any of them, and finally gave up trying to use drip-style burners.

There are those who use drip-style burners to melt iron routinely, and they love them.
Drip-style burners just don't have good fine control, and their operation seems to fluctuate much more than a siphon or pressure nozzle burner.

.


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## GreenTwin (Jul 3, 2021)

This is the gear pump rig I am building to use with the pressure nozzle burner.

I am not sure exactly where that fuel filter will end up, and I am still playing around with the gear pump support, but you get the idea.

The motor is larger than it needs to be.
I oversized it, to keep the load on it very low (for long life).
The motor is 1/3 horsepower.


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## GreenTwin (Jul 3, 2021)

This is the gear pump from a commercial fuel-oil burnering heating unit.

It will operate at 1725 rpm, 100 psi, 7 gal/hr maximum output.
I will use it at 2.6 gal/hr, and return the balance of the 7 gal/hr to the fuel tank.


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## dazz (Jul 3, 2021)

Hi
I have never cast iron or aluminium but I am planning to.  I looked at compressed air and decided it was not a practical option for me.  I don't have the money or space for a compressor.   I will be trying an electric pump, of the type used on domestic furnaces.    I purchased mine from Aliexpress, but there are probably other sources. 

I have attached the pump data sheet.

For air, I plan to try a small centrifugal fan.   

I have also purchased a pressure nozzle,  swirler and electric igniter.  

Basically I aim to build a version of a standard domestic diesel heating burner.   I did look at the option of buying a complete assembly,  but liquid fuel burners are not used in this country and it was much cheaper to import the parts than import a complete burner.

I am a long way from completing a furnace so I can't report the results of this system.   I think it should work but I really have no idea.

Dazz


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## awake (Jul 3, 2021)

GreenTwin said:


> A few more siphon-nozzle photos.
> You can see there are small spin vanes built into the burner tip that spin the fuel, and the compressed air comes out the hole in the center of the tip.
> 
> View attachment 127039
> ...





GreenTwin said:


> Here is the pressure nozzle arrangement.
> 
> I think the connect can be simplified.
> 
> ...



Thanks so much for sharing all of this! I am slowly working my way towards making a forge. I'd be interested in any details on how you made yours.

One thing that I think might be backwards - as I am understanding the diagram, it looks like it is the air that is swirling in the "vanes," and the fuel is coming out of the center hole. (I may just be reading the diagram incorrectly ...)


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## GreenTwin (Jul 3, 2021)

awake said:


> Thanks so much for sharing all of this! I am slowly working my way towards making a forge. I'd be interested in any details on how you made yours.
> 
> One thing that I think might be backwards - as I am understanding the diagram, it looks like it is the air that is swirling in the "vanes," and the fuel is coming out of the center hole. (I may just be reading the diagram incorrectly ...)


Edit:  I think you are correct on the air swirling in the vanes.  I get confused sometimes with all those passages in the adapter and nozzle.

You are welcome.
Some people make a forge, generally for heating steel that can then be hammered into shape, like blacksmithing, and a forge is generally a horizontal thing like a bread oven, open on one end.
For melting meltal, I use a crucible furnace, where the metal is melted in a container (crucible) inside the furnace, and when molten, the crucible is lifted out of the furnace and poured into a mold of some type.
Some people mix and match their equipment, and use their furnace as a forge, and use their forge as a horizontal furnace, so the terminology can get a bit confusing, LOL, but I have a furnace.

This was my second furnace build, and I wanted it to be able to handle multiple crucible sizes, and use a minimum of dense refractory.
This furnace uses 120 lbs of dense refractory on the hot face and lid, and then has a layer of insulating fire bricks, followed by two 1" layers of ceramic blanket.
I guess that two or three layers of ceramic blanket could be used instead of the insulating fire brick, but I used the fire bricks to give a bit more support to the 1" thick hot face.
The hot face is a product called Mizzou, and it has held up well.
Hot face does crack, but that can easily be repaired.
My hot face cracked into 4 pieces, but they were patched (with high temperature plastic refractory), and the 4 pieces remain solid and still work perfectly.  Don't panic if your hot face cracks; this is normal.
If your hot face crumbles, then you should have used Mizzou, since some refractories don't hold up to iron temperatures well like Mizzou does, and do not have the temperature rating of Mizzou.  I think Mizzou is rated at 3,000 F.

There is a layer of insulating fire bricks under the hot face, with a 1/2" layer of ceramic blanket on top of the fire bricks.

They also make non-insulating fire bricks, which are very hard and dense like cast refractory, and some just use a circle of standing hard fire bricks, sometimes two tall, as a hot face, and this actually works pretty well if you have some good hard fire bricks, but cutting the tuyere can be a bit tricky.
Some use hard fire bricks and leave out a half brick at the tuyere, and cast the tuyere in castable refractory, which is also a good option.

The stainless exterior remains cool to the touch at the end of the melt, except for around the tuyere and lid.

The tuyere is the hole that is near the bottom of the furnace, about level with the bottom of the crucible, where the burner enters the furnace.

Interior dimensions are 13" diameter, and 14" in height.
The crucible sits on a platform called a plinth (not shown below), and I use several of them of various heights depending on the crucible size.
The plinth is cast from dense refractory.
Two layers of heavy cardboard are needed under the crucible when you start a melt, so that the crucible does not adhere to the plinth.
The cardboard carbonizes and prevents sticking.


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## GreenTwin (Jul 3, 2021)

dazz said:


> Basically I aim to build a version of a standard domestic diesel heating burner. I did look at the option of buying a complete assembly, but liquid fuel burners are not used in this country and it was much cheaper to import the parts than import a complete burner.
> 
> I am a long way from completing a furnace so I can't report the results of this system. I think it should work but I really have no idea.


I have seem people use commercial heating units as a package on a furnace, but the packaged unit is a bit bulky, and the burner tube on it is really too large for most furnaces (perhaps a 4" burner tube, which could impinge flame on the side of the crucible and cause it to fail).

The components you have will definitely melt iron, but I will have to read that fuel pump spec, to see what pressure it produces.
I don't use an ignitor, since they protrude beyond the end of the burner tube.
Anything protruding beyond the end of the burner tube in an iron furnace will generally melt off.

Edit:
I use a paper towel with a little diesel on it placed lit in the cold furnace, and then I turn on my fuel and compressed air at the same time, with the leaf blower dump valve open, and the leaf blower not running.
If you start with the combustion air on (combustion air is produced by the fan or in my case leaf blower), then you will generally flame out the burner when you first start it.
Once I have a flame going, I slowly close my combustion air dump valve, make sure the burner is running in a stable fashion, and then close the lid.
Never start a burner with the lid closed.  One guy did that and he launched his lid over the top of his house (he was not an experienced person with burners).

I don't leave the burner running when I am not standing in the vicinity, and so I don't need an automatic flame-out protection (I am the flame-out protection).
What happens if the burner flames out while it is running?
Immediately turn off the fuel and compressed air ball valves that should be in a location that is easy to access quickly.
The only flame-outs I have had with my burner is when I was learning how to run it, and tried to start it with full combustion air.

I did have a flame out in one of my recent videos during start up, due to an excessively large piece of cardboard under the crucible disrupting the flame pattern, but I just turned off the compressed air and fuel, dropped another piece of lit paper towel in the furnace, and reopened the ball valves.
No big deal if you quickly turn off the air/fuel ball valves, but he have to do that immediately after a flame-out.

The end of the nozzle should be about 1/2" inside the end of the burner tube, and the burner tube should not protrude in any way into the furnace, else the burner tube will overheat.
The burner tube should be as far into the tuyere as you can get it without the tube actually protruding into the furnace, else you will spray fuel onto the walls of the tuyere and it will puddle in the bottom of the furnace, which is a dangerous situation.

The burner tube should be relatively tight in the tuyere, and if there is combustion air blowing past the burner tube and out of the furnace at the tuyere, this must be sealed, else you will overheat the burner tube and nozzle.

.


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## GreenTwin (Jul 3, 2021)

I moved my videos over to Vimeo, and I use a fake name for privacy (thus the Raphael Mantegna name; I can tell immediately if I get spam where spam is coming from with that odd name).

Everyone should be able to access these Vimeo videos.  Let me know if that is not the case.

Here is a video that shows a flame out of the burner at startup, due to the cardboard under the pinth protruding out too much.
I just turn off the air/fuel, and start over.



			https://vimeo.com/user82094693
		


And here is a normal burner start, which only takes a few seconds.
Some recommend ramping up the burner slowly, but I go to full power immediately, and this has not caused any apparent problems with crucible life, etc.
Be sure to wear a full face shield; don't get lazy like I did and wear glasses only.
And note that the paper towel flies out of the furnace, and comes floating down dangerously close to the fuel line.
Keep any eye on the paper towel and don't let it catch something on fire as it flies out.

I leave my furnace outdoors all the time, and my cover is not as good as it should be, so the ceramic blanket at the burner tube tends to get wet, which can cause the smoking which can be seen in some of the videos (the smoke is actually steam).



			https://vimeo.com/user82094693
		


.


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## GreenTwin (Jul 3, 2021)

dazz said:


> Basically I aim to build a version of a standard domestic diesel heating burner.


For a foundry burner, I use separate ball valves for compressed air and diesel, and then I use a needle valve for fine fuel adjustment.
I calibrate the fuel flow with the burner off using a measuring cup and a stopwatch, and use about 2.6 gal/hr for my furnace size.

I adjust the combustion air flow to match this 2.6 gal/hr fuel flow rate, to give the approximate flame out the furnace lid that you see in my videos, using the variable speed on the leaf blower.  I also use the large PVC dump valve on the leaf blower output to allow me to turn on the combustion air slowly while the leaf blower is running.
It just so happens that a Toro leaf blower on its lowest speed is the exact amount of combustion air I need for my 2.6 gal/hr, and so I operate with my dump valve closed.
I have used burners with a combustion air damper (sometimes on the intake of the combustion air fan, and sometimes on the output in a 3-way configuration), and you can run a blower at 100% and control the combustion air via the damper.

Once I set up my 2.6 gal/hr fuel flow, I never adjust my needle valve again, unless I happen to bump it out of position or something.
I never adjust my burner during a melt, ever, and that is why I like this burner/pressurized fuel tank arrangement.

A pressure nozzle arrangement will be sightly different than a siphon nozzle setup, in that I guess at startup you just turn on the gear pump.
It may require a slight amount of combustion air flowing with a pressure nozzle, since the compressed air that the siphon nozzle burner used to initially start and run will not be present.

For my pressure nozzle burner, I will probably use two ball valves in the return line, and have have one ball valve with a series needle valve preconfigured to give me 2.6 gal/hr, and other ball valve with needle valve to give me some small amount of fuel flow for when I start the burner, perhaps 1 gal/hr.

I have not run a pressure nozzle yet, but it is a well established technology, and I have no doubt it will work well, and thus I can retire my air compressor.

Another benefit of diesel is that it will easily light and burn at a wide range of temperatures, and I have lit diesel with a siphon nozzle down to about 36 F with no problems.  If it gets too cold, some sort of fuel warming arrangement may be needed, but at the temperatures I see, I can light straight diesel easily.

I have heard that 100% waste oil may not light easily, and so some mix in 15-20% diesel, and sometimes heat the waste oil a bit (I don't heat fuel for any reason, but some do).
.


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## GreenTwin (Jul 3, 2021)

When I think back on how I figured out how to do iron, several things come to mind.

1. There are a lot of opinions on how to build the best burner and furnace for a hobby setting.

2. There are "burner" folks, "ingot" folks, professional talkers, book writers, professional video makers, etc.
Many/most have their own pet favorite methods and materials, and things/methods that work best for their situation, based on exactly what it is they are trying to achieve.
Some folks just want to have fun doing whatever, and that is what it is all about in life in general I think, but for me, I make small steam engines, and so that is my focus.

3. While there is some general agreement in the hobby crowd these days about what works and what does not work, there are still gray areas where there is not a consensus about what works best.

4. Success with a foundry often depends on whether you can source the special materials that are required for a foundry.
It is easy to find good clay-graphite crucibles for sale (Morgan Salamander are my prefrence).
It is more difficult to find castable refractory, and the trend these days is to make furnaces using ceramic blanket coated with a high temperature material.

5. Since I wanted to cast steam engine parts, I started watching various people online who were doing a lot of cast iron work.
One individual was in Texas, and he was routinely pouring a #70 crucible full of iron, with what appeared to be a very high success rate.
The Texas individual used a Delavan siphon-nozzle burner with waste oil, and some sort of combustion air blower (leaf blower perhaps?).

The other individual was and still is in Australia, and he uses a coated ceramic blanket furnace design, with a drip-style waste oil burner.

Both individuals cast a lot of iron successfully, using different burner and furnace styles.

6. I used the Texas-style furnace and burner style for a few reasons; I consider a rigid cast refractory furnace hot face more durable in the long term than a coated ceramic blanket style furnace, and I could never get a drip-style burner to control properly, so I selected a siphon-nozzle type burner.

7. I started with Petrobond (tm) style oil-based sand, and used that for a while.
I was getting too much sand failure when I tried to use Petrobond with iron, and I noticed that the "art-iron" community (the folks who use cupolas to create iron sculptures) used bound sand, which was often resin-bound sand.
I tried resin-bound sand, and a commercial (very dry) foundry sand (OK85), and I I would never use anything else.

Resin-binder is not easy to source, not cheap if you can find it, and a good industrial respirator is required to filter out the fumes that it creates.
Many of the professional foundries use resin-bound sand, and it will provide consistent and quality castings if you do your molds correctly.
With a ceramic mold coat sprayed onto resin-bound sand, the surface finish is superb, and a bright clean shiny surface finish can be obtained with a light swipe of a dry paintbrush.

8. For every good burner design I have seen "good being it functions well over a long period of time with little or no problems", there are other burner designs that are either a very poor design, or downright dangerous, with "poor design" being defined as a burner that needs constant adjustment during the melt, burners that won't hold a constant setting and surge a lot, burners that impinge a lot of heat on the burner tube, which will cause a number of problems, burners that require multiple fuels to operate (generally oil and propane), etc.

Drip burners are the simplest burners of all, and have a proven track record, but I could never get any of my drip designs to work.
I opted to use a siphon-nozzle burner with an increase in complexity, with the benefit that it did not need a propane start/warmup, if set up correctly it never needs adjustment either before, after or during a melt, and the control of a siphon nozzle is immediate and precise.
I can use a siphon nozzle over a wide range of heats, but generally always operate mine at 2.6 gal/hr on diesel, regardless of the metal type.

9. The final hurdle was to find individuals who produces iron castings that not only looked very good, but were also easily machinable, with no voids, gas holes, inclusions, hard spots (called chills), etc.
I discovered ferrosilicon, and a tiny amount of that added after the final skim, and just before pouring the iron makes for some very fluid iron that machines like a dream.  Note that iron castings must be left in the mold overnight to cool slowly, to prevent chills and hard spots.
Any more than a slight amount of ferrosilicon and your will have excessive shrinkage, which is prone to hot tears in the metal, and unusable castings.

10. I built a modular furnace, ie: the 1" cast refractory hotface shell is not physically bonded to anything else, and so it can be replaced without having to replace any other part of the furnace.  Most folks I see cast their refractory right up against insulating fire bricks or other material, and when the hot face is replaced, the entire furnace has to be chiseled out.

11. And one more iron secret it the material called "plastic refractory".
Plastic refractory is basically a pre-mixed refractory that has the consistency of stiff putty.
A high-temperature (I use 3,800 F plastic refractory) plastic refractory is worth its weight in gold when it comes time to repair a hot face, or when repairing a domed furnace lid.  I use a domed furnace lid so that when the refractory cracks (all refractory cracks), it will still be self-supporting, like a Roman arch.
Plastic refractory is also not easy to source.
If I had to do over, I would roll out a thin layer of 1/2" thick 3,800 F plastic refractory into a sheet, and roll it into a cylinder, to use as a hot face.

So in summary, if you want to cast metal, I would recommend finding someone who is casting the things you intend to cast, in the metal that you intend to use, and someone who is having a high success rate with their castings, and copy their materials, methods and techniques.
I often use a hybrid of methods and materials, and there are many ways to accomplish casting metal.

Generally I use the simplest methods and equipment I can find that will produce consistent high-quality casting results.
The cheapest initial cost materials and equipment are often not the least expensive in the long run, so you have to decide if you want to just dabble a bit in metal casting on a casual hobby level, or get in the hobby for the long term with some ambitious and repeatable casting designs.

Making professional-grade gray iron castings in the backyard is entirely possible; not necessarily cheap, and there is a learning curve, but the castings can easily rival professionally made iron parts if you do your homework and use the right materials.

.


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## dazz (Jul 3, 2021)

Hi
"My" swirler is about 7.5cm diameter so I think it should be OK.  I will make the burner tube longer than a commercial unit.
The igniter is part of the swirler so well away from the flame. 
My blower runs at a constant speed so the plan is to have a tube valve sliding over the exterior of the burner tube.  The tube valve would regulate air flow by how much it covers holes in the burner tube.    Surplus air would bleed to atmosphere before it reaches the fuel.
I plan to regulate fuel flow by selecting a nozzle with the right flow rate. 
If I have problems with fuel/air ratio, the plan is to fit an automotive Lamda sensor to the exhaust.  The Chinese versions are cheap as.
I have no plans to burn waste oil.  Diesel only for consistency and ease of handling.
I have seen problems with cracking cast refractory lining.  I am going to use my 3D printer to produce molds of shaped interlocked bricks about 100mm long, 50mm high, 25mm deep.    This will reduce the weight and cost.  The bricks will create controlled cracks that will allow for thermal expansion.   I will be able to modify/repair the lining without building a new furnace.
The lining will be backed with suitable fibre insulation.  I also plan to include layers of reflective aluminium foil type insulation to reduce infra-red radiant heat loss.
I am aiming to reduce the exterior temperature of the furnace to make it touch safe, where practical.

I am trying to figure out how to use the furnace exhaust to pre-heat iron before it goes into top up the crucible.

I think broken down cast iron engine blocks would be a good source of high quality machinable material, but I have not seen this source mentioned on the web. 

The best quality industry casting facilities use crucibles with a bottom feed to avoid pouring the slag floating on the top.  Completely impractical for the home foundry.   I have been wondering if a stainless steel guide could be slipped down inside the pouring side of the crucible to draw flow from the bottom of the crucible while holding back the slag on the surface.   Easy to make, easy to try.    I have never seen such a device, so maybe it is a really bad idea.

Just my thoughts backed by nil practical experience.

Dazz


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## Larry G. (Jul 3, 2021)

GreenTwin said:


> I think the product that I found is called "VelaCoat", and it is alcohol-based.
> I am not aware of a dry product, but I have never asked anyone if they sold that either, and that would be a good idea, and cheaper to ship.
> I am not sure if ceramic mold coat would work on green sand (greensand being clay and sand mixture).
> I use resin-bound sand, and so the mold sets and becomes hard, thus making it impervious to spraying on the ceramic mold coat and burner off the alcohol.
> ...



VelvaCoat from ASK Chemicals LP
495 Metro Place South 
Suite 250 Dublin, OH 43017 
Phone: +1 800 848 7485 
Fax: +1 614 761 1741 
[email protected] 
www.ask-chemicals.com

Download their PDF catalog which includes water-based products;
https://www.ask-chemicals.com/filea...oundry_products_brochures/US/Coatings_USA.pdf 

Good luck,
Larry


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## awake (Jul 3, 2021)

Sorry, somehow got a duplicate post. Can't delete it, so edited out the content.


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## awake (Jul 3, 2021)

GreenTwin said:


> When I think back on how I figured out how to do iron, several things come to mind.
> 
> 1. There are a lot of opinions on how to build the best burner and furnace for a hobby setting.
> 
> ...


Again many thanks - all very helpful posts. You mention that some materials are hard to source; can you share where you have found the hot face refractory (I could not find anything with a brand name Mizzou?) or the ferrosilicate? (I did find a couple of on-line sources for plastic refractory.)


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## GreenTwin (Jul 3, 2021)

Larry G. said:


> VelvaCoat from ASK Chemicals LP
> 495 Metro Place South
> Suite 250 Dublin, OH 43017
> Phone: +1 800 848 7485
> ...


Thanks for the info.
ASK Chemical also makes the brand of resin-binder that I use, which is LINOCURE.
It is a 3-part product, with a resin, hardener, and catalyst, and it is very popular in the art-iron communities because once it sets, it can be carved into an infinite number of shapes to create artwork in iron.
It does require an industrial/chemical-rated respirator when you are mixing and ramming it.

And the sand must be very dry, which is why I use OK85, which is a fine grain sand made for foundry use that has a very low moisture content.
If you use sand with any appreciable moisture in it with resin-binder, the binder will not work.

.


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## Foketry (Jul 4, 2021)

GreenTwin said:


> I sent these castings off to my buddy (the one who made the patterns), and he final machined them.
> Turned out pretty well for a first-time straight edge attempt I think.
> 
> Machined easily with no hard spots.
> ...



I am following your foundry work with a lot of interest and great appreciation. I started casting aluminum a couple of years ago for my engine models which you can see here. Porsche 917  flat 12 engine
I would like to cast iron but my gas furnace does not reach the required temperature. I kindly take advantage of your experience to ask you for some advice : how did you make the Diesel burner, nozzle size, pressure, air blowing, etc?
What  coating did you use in your furnace to withstand the temperatures needed to melt cast iron?  . For my furnace I used ceramic fiber, but over 900/1000 degrees centigrade it starts burn.
Last  3 question, what% of sodium silicate do you use in the sand ?
I have a sticking and breaking problems to the molds, is there a release agent to avoid this?
Ceramic mold coating, can you tell me some brand of this product?
thank you very much


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## GreenTwin (Jul 4, 2021)

dazz said:


> Hi
> "My" swirler is about 7.5cm diameter so I think it should be OK.  I will make the burner tube longer than a commercial unit.
> The igniter is part of the swirler so well away from the flame.
> My blower runs at a constant speed so the plan is to have a tube valve sliding over the exterior of the burner tube.  The tube valve would regulate air flow by how much it covers holes in the burner tube.    Surplus air would bleed to atmosphere before it reaches the fuel.
> ...


1. Some folks use a very short burner tube, such as 12" long, and often put gauges and such right on the burner tube.
If the tuyere ever leaks hot gasses, then anything near the tuyere, such as gauges or anything else, will melt.
The tuyere will leak sooner or later; that is a given.
I use a 2.5" diameter burner tube either in stainless steel, or sometimes muffler pipe, which works pretty well too.
It is difficult to fit the adapter with its fuel elbow on the side into a pipe that is smaller than 2.5" diameter.

2. Some use spin vanes near the end of their burner tube, and some do not.
I have tried both, and can't tell any difference, so generally I do not use spin vanes in the burner tube.
A commercial heating unit burner is discharging into a large combustion chamber, but for a foundry furnace, you are discharging into a space that immediately swirls around  a round chamber, and so probably the reason a spin vane may not have an effect when used with a furnace.

3. It is easy to use a constant speed blower, and your idea sounds like it would work.
And it does not take a very large blower either.  My leaf blower is really overkill, and I run it on its lowest speed.
I have seen large hair dryers melt iron too, when used for combustion air, but they many not last very long.
The leaf blower is pretty rugged, which is why I use it.
I would guess you could use 100% of the output of that blower, without having to damper it, depending on your exact furnace size.

4. Anything that I have seen inserted into the exhaust of an iron furnace gets melted off, including steel, which will eventually melt off.
I tried a temperature sensor on the outside of my hot face, and those thermocouples burned up.  They were rated maybe 2100 F.
Don't underestimate how hot the exhaust stream will be.
When you first bend over (with a full face shield and glasses) and try to look into the furnace lid opening, when melting iron, you will see what I am talking about (your plastic face shield will start melting in a few seconds.
I use a piece of tempered glass (old refrigerator shelf) as a shield, holding it in front of my face shield at an angle, to give me maybe 30 seconds of looking into the furnace.

5. The way I figured out fuel-air flow is to operate the furnace at night in total darkness, and try various fuel flows, each time adjusting the combustion air to get a 6" flame out the furnace lid.  The fuel/air setting that produced the brightest luminance inside the furnace was about 2.6 gal/hr., and after I discovered that flow level, I compared notes with others doing iron work, and found that for the same size furnace, they were using an almost identical fuel flow level.

6. All refractory cracks, and that is normal.
As long as it does not crumble, then it can easily be patched.
I fill in small cracks every time I run my furnace, and if you fill in the cracks immediately after they occur, then that seems to slow down the propagation of the cracks.
Cracks that are not filled will let a high temperature stream of hot gas get behind the hot face, and that can cause a lot of damage to the ceramic blanket.
Some commercial furnaces use modular curved pieces like you are talking about making, and so that is a valid design it would seem.
If you have plastic refractory to use for repair, then the whole crack thin is very minor regardless of how the hot face it built.

I have seen one furnace build from leggo-style individually cast refractory curved blocks, but they made the blocks about 4" thick, which is way too much mass for a furnace.

You may have to back up individually cast pieces with something rigid, such as insulating fire brick, since the joints can be a point of failure.
Staggering the joints would probably solve this problem.

7. The aluminum foil is not a bad idea, but be aware, the back of my hot face is probably not much cooler than the face of my hotface, and so the foil would have to be behind enough layers of ceramic blanket to prevent melting the foil.
Iron furnaces run extremely hot.


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## GreenTwin (Jul 4, 2021)

8. I like to keep the exterior of the furnace (I use a stainless sheet metal shell) cool to the touch.
It is as much about preventing contact burns as it is about efficiency.
A furnace that is cool to the touch on the exterior is not wasting energy.
The idea is to keep the heat inside the furnace, not radiate it off the exterior wall.

9. There are two schools of thought on preheating the scrap iron in the exhaust of a furnace.
Initially I preheated my scrap by setting the iron on the lid and letting it protrude into the exhaust opening.
A few years ago, I ran across the MIFCO furnace manual, and it mentioned never preheating iron scrap in the exhaust stream, due to the excessive oxidation it causes.
So I no longer put scrap iron on the lid of the furnace to preheat it.
I hold each piece of scrap iron (using tongs) in the exhaust stream for perhaps 30 seconds (depending on the size of the scrap piece), and then drop it into the crucible.
The added scrap must be pushed under the surface of the molten pool of iron in the crucible, to break up the slag, else the slag will get very dense and hard, and will become unmanageable.
MIFCO also mentions that scrap with any moisture on it will cause an explosion when it drops into the crucible.
All scrap iron and steel has moisture on its surface, but you cannot see it.
A dry steel ingot mold is not dry, and if you pour hot iron into an ingot mold without first heating it to perhaps 500 F, it will eject the iron right back into your face (I have 3rd degree burn scars on my hands from doing this, where molten iron splashed back onto my leather jacket, and then rolled down inside my gloves.  You can't get gloves off fast enough when you have molten iron in them.

https://mifco.com/wp-content/uploads/2019/12/B-C-furnace-manual-revised-12-19.pdf

There is a section in the MIFCO manual listed above titled "Melting Gray Cast Iron", and several things mentioned in there I do not agree with, and I have proven this information to be false for me, perhaps because I am using an oil burner, not the MIFCO natural gas burner.
MIFCO says cast iron engine blocks and other iron machinery should not be used, but I have used many types of iron machinery scrap including machinery, and it makes excellent defect-free castings.
I have also used pure Class 40 gray iron, and it worked very well too, but no better than scrap machinery iron.
What I have heard is to not use any iron that has phosphorus in it, such as thin castings like bathtubs, radiators, etc. I think due to mechanical weakness of the castings.
Window sash weights in the US are junk metal and should not be used.
If I can break a piece of gray cast iron with a sledge hammer and get a nice clean consistent rough gray surface, I use it for scrap.

MIFCO also says that either clay graphite or silicon carbide crucibles can be used with iron, but the Morgan information sheets only list the clay-graphite "Salamander-Super" for ferrous metal, rated for iron temperatures.
The Morgan silicon carbide crucibles are not iron rated, and have a much lower operating temperature that would not necessarily be usable at iron temperatures.

And I don't add carbon to my melt, and have never had a problem with not adding that.

Don't confuse the MIFCO burner diagrams for an oil burner.
Natural gas and propane burners are not the same as oil burners (similar, but not the same).

I don't use drains in the bottom of my furnace.
I have never broken a crucible inside my furnace, but if I did, I would just turn the furnace on its side and operate it with the burner until the metal melted and ran out.
If you use good quality crucibles and don't use them beyond their life, then you should not see a broken crucible.
People break crucibles when they jam metal into them cold, and the metal expands and cracks the crucible, or they force too much scrap into a crucible, and crack it.

10. If your furnace and burner are operating correctly, then a 5/16" diameter steel rod used to stir iron when it is at pour temperature (perhaps 2,500-2,600 F, or maybe a little higher; I can't measure it since it melts the end off of a submersion pyrometer) will melt its submersed end off after about 30 seconds of stiring.
Anything you insert into the molten metal must be preheated to at least 500 F or more, else you could eject the metal from the crucible.

The only way I am aware of to handle the slag is to skim it off with a skimmer that has a heat shield on it.
Some have mentioned using vermiculite to get the slag to gather into a ball, but I don't use that, since if you did not get all the vermiculite out of the crucible, then that can cause inclusion defects in the casting.

Everyone I know who does iron just skims the slag at the last moment before the pour.
I skim slag, add ferrosilicon, stir, quickly skim any remaining slag, and then immediately pour.
I leave the crucible in the furnace during the slagging and adding ferrosilicon, since the metal will drop below pour temperature extremely rapidly after the crucible is removed from the furnace.

I am told that sooting the end of the skimmer will help prevent slag buildup on the end of the skimmer.
I just strike my skimmer on a piece of metal to clear it after each scoop of slag, and between melts I break the slag off the skimmer with a hammer.

.


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## GreenTwin (Jul 4, 2021)

Foketry said:


> I am following your foundry work with a lot of interest and great appreciation. I started casting aluminum a couple of years ago for my engine models which you can see here. Porsche 917  flat 12 engine


Wow, that is a fantastic build thread, and it is going to take me a while to read that (I am new here), but rest assured I will read every word of it.
I will answer your questions, but it will take a bit to do that.

My current siphon nozzle burner that uses diesel is similar to this one, except I don't use propane, and I don't need propane to light the burner with diesel.
I tried propane on the very first burner I made, and the propane accumulated in the burner tube, backfired, and burned my hand.
Since then I have never tried to mix an oil burner with propane, and I don't consider that arrangement as safe as I would want it to be (burned hand as an example).
I angle my combustion air entry tube into the main burner tube.
I don't use a spin vane.



I will post a few photos of one of my burners, in a minute, and try to get to your other questions.
There is much to do and read here.

Edit:
I am trying to learn how to make ductile iron, so I can make crankshafts.
Regular gray iron is not suppose to be strong enough for a crankshaft.

.


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## GreenTwin (Jul 4, 2021)

There are free programs online which will plot a template for mating two burner tubes at an angle, and this is what I used to make my latest burner tube.
I have used both stainless tubes, and muffler pipe, all at 2.5" diameter, and either works well if you can well thin metal (I can using the lowest setting on my stick welder).


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## GreenTwin (Jul 4, 2021)

I  have used several methods for the cap on the back of the burner tube, where the air and oil lines enter.
The latest method I used was to weld up a cap, and use a piece of thin plumbing joint stainless steel wrapped around the joint to secure it.

This was actually a drip-burner test, not a siphon nozzle, but the burner tube and cap construction are the same/similar as I would use on a siphon nozzle or pressure nozzle.


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## GreenTwin (Jul 4, 2021)

Here is an earlier siphon-nozzle design that I tried, with spin vanes cut into the end of the burner tube.
The spin vanes did not have any effect on the melt, and I ended up cutting them off.

One think I liked about this burner tube was the three nuts that I welded at 120 degrees from each other, after drilling holes through the burner tube under each nut.  I added a screw in each nut, and do a fine adjustment to center the nozzle in the burner tube.
I like this method of supporting the nozzle in the tube best of the several methods I have tried.

Be sure the nuts you use are well outside the tuyere, else the nuts and screws will not allow the burner to be inserted into the tuyere.

The nozzle tip is always about 1/2" inwards from the end of the burner tube.


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## GreenTwin (Jul 4, 2021)

Here is an early version of a siphon nozzle burner.
You can see I added a section onto the burner tube to make it longer.
I think now days I generally make the burner tube 18" long, but I will have to check that.

And I used a rubber plumbing coupling to seat the cap to the end of the burner tube, which can melt due to the heat, so now I use a sheet of stainless wrapped around the tube and clamped twice to secure the end cap to the burner tube.

For my latest burner, I moved the PVC air valve to a remote location, again to prevent heat damage.

For the top photo, diesel enters the clear line, goes through quick disconnect, a ball valve, transitions to a black rubber fuel line, goes through an inline automotive fuel filter, goes into a needle valve, transitions to a piece of 1/4" copper tubing which goes through a hole in the end cap and runs down the burner tube to the elbow on the side of the nozzle adapter.
The copper tube is not fit airtight in the hole in the cap, since the combustion air pressure in the burner tube is low, and the small leakage at this joint does not affect the burner operation.
Some use steel brake lines, but I have more fittings that I can use with copper tube, so I use it.

The compressed air enters via the red hose, and is feed from the pressure regulator set at 30 psi.
The compressed air hose has a quick release, then a ball valve, then it goes into a piece of steel pipe that threads into the end of the siphon nozzle adapter.
The steel compressed air pipe is welded to the end cap.  This pipe according to Delavan is a 1/4 NPTF, and its outside diameter is about 0.54".

The second pressure regulator feeds 10 psi air pressure to the fuel tank, and the fuel tank has a 30 psi safety valve, in case the pressure regulator fails.
One guy had his pressure regulator fail, and did not have a safety valve, so he blew open a fuel line fitting, spewed fuel everywhere, and started an inferno.  This is why you don't use oil burners near houses, cars, or anything else valuable, and this is why you need a safety valve if you pressurize your fuel tank.

Other features of this burner which I like are the quick-adjust height support, which has a short hand lever which can screw or unscrew the burner from the vertical support, to adjust the burner height.

Another feature on this burner is a quick release to separate the burner internals from the burner tube, by unclamping the rather crude clamp.
This allows the burner nozzle to be withdrawn from the furnace at the end of a melt to prevent o-ring damage.
The rubber seal at the end of the burner tube is a slip fit, and there is no appreciable pressure on this joint, so it does not have to be very tight at all.

A better way to prevent overheating a siphon nozzle tip when the burner is turned off at the end of a melt is to leave the combustion air blower operating after you turn off the fuel ball valve.

Pressure nozzle burners do not have an o-ring, but I will still leave my blower on at the end of the melt with my pressure nozzle burner, to prevent cooking diesel onto the burner tip, which makes a varnish-like buildup.

Comments I have seen regarding a siphon nozzle burner are generally "Boy, that sure is complicated compared to a drip-style burner".
Yes, I agree, but if you have ever used a drip-style burner, and compared its operation to a siphon-nozzle burner, you would see why I go to the trouble of making a siphon nozzle burner.
The siphon nozzle burner is instantly controllable, with rock solid consistent operation.
Building a siphon nozzel burner requires a certain amount of technical expertise, and I have seen some who build them, but can't quite master it.
For those who are use to working on machinery, engines, and such, a siphon nozzle burner is not complicated.


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## GreenTwin (Jul 4, 2021)

I have also used a gland arrangement to seal the compressed air pipe to the end cap, but generally I just weld the compressed air pipe to the end cap.

A gland arrangement allows complete disassembly of the various burner parts, and also gives you adjustment of the position of the burner tip relative to the end of the burner tube.

The fuel line needs a ball valve and a needle valve, so if you have a flame-out, you can immediately turn off the fuel using the ball valve.
You don't want to try and quickly shut off the fuel using a needle valve, and if you get the needle valve set correctly, you want to leave it in the same place, and use the ball valve for fuel on-off.

Edit:
Some things I learned about oil burners, after much experimentation.

1. Bigger is not better.
An oversized burner and combustion air blower actually run much cooler than a smaller properly sized burner and blower.

2. A higher fuel flow will operate cooler than a lower fuel flow.
For my furnace, fuel flows above or below 2.6 gal/hr run cooler than 2.6 gal/hr.

The idea is to introduce the maximum amount of fuel and combustion air into the furnace that the interior surface area can completely combust inside the furnace.  There is a scientific term for this fuel/air ratio which I forget, but this ratio is critical if you are trying to achieve iron temperatures, minimum melt times, and the correct pour temperature for iron.
.


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## GreenTwin (Jul 4, 2021)

As far as foundry suppliers, they don't take small orders generally, and they often sell in bulk.
So foundry suppliers generally will not talk to hobby folks (on rare occasions sometimes they will if they are having a good day).

I buy foundry materials in bulk, with "bulk" being defined as an order large enough so that the supplier does not hang up the phone in my face.

I have purchased from some foundry suppliers, and the second time I try to place an order, they don't respond because they don't want to waste their time on little orders when they could be making a large profit on a large order.
I can't blame them for what they do (ignore the hobby folks).

I normally don't reveal the regional suppliers that I use because I have to beg them to sell me materials, and if they were flooded with calls for small orders, they would probably stop talking to me.

The way I found suppliers is to do a web search for "Foundry Suppliers"; found some that were in the US, and started calling them.
I basically said "I am a hobby guy who needs a small quantity of (fill in the blank, ie: refractory, etc); do you have time to talk to me?".
The would either say "sure" or hang up the phone.
I purchased some things from the ones who wanted to sell small quantities, with small quantities perhaps being 75 lbs of ferrosilicate, 200 lbs of castable refractory, or 100 lbs of plastic refractory.

As I mentioned, I use Morgan Salamander-Super crucibles exclusively, and there are a number of sellers of these on ebay, which is where I purchase mine.

I fabricate my own pouring shank, lifting tongs, furnace, burner, and pretty much anything else I need for the foundry.
I make my own wood patterns, or 3D print patterns.
Sometimes I make patterns out of steel.
.


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## GreenTwin (Jul 4, 2021)

This is the castable refractory that I use, which is called Mizzou.

I think the MSDS sheet goes with the Mizzou pdf file, but I am not certain.

It should be noted that the amount of water that you mix with castable refractory is tiny, which makes hand-mixing difficult but not impossible.
If you decide to add more water, you can easily ruin the refractory.
And as with all foundry material handling, one should wear a good respirator/industrial dust mask, to prevent inhalation of refractory dust, ceramic blanket fibers, sand particles, fumes, etc.

.


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## GreenTwin (Jul 4, 2021)

An internet search for Mizzou turned up the following:






						Mizzou Plus Refractory Castable in 55 pound bag
					

Conventional  Refractory Castable



					refwest.com
				









						High Temperature Tools & Refractory | Castable Refractory
					

High Temperature Tools & Refractory is your source for refractory and other knifemaking supplies. We specialize in high temperature tools and refractory for forges, kilns, and heat treating applications. We have been serving the needs of industry, small business, and the individual craftsman...



					hightemptools.com
				




I have no idea if either of these companies are reputable, so use at your own risk.
They are both in the US.
Shipping can be pretty extreme for refractory, so be sure to check on that before you purchase.

If the bag(s) get wet during shipping, or if you store them in a damp spot, then the refractory will set and will not be usable.
If you breath refractory dust, you will not be usable.

Don't purchase the refractory until you are ready to use it.
If you don't waterproof your cardboard forms, then the water in the refractory will cause the form to collapse, and you will have lost everything (I saw someone lose several hundred dollars of refractory this way on ytube a few years ago).

This is a very dense refractory, but it stands up to iron slag well.
Since it is very dense, it should probably only be used in thin hot face applications, such as a 1" thick hot face.
If you cast Mizzou 3" thick, your furnace will heat very slowly.
.


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## GreenTwin (Jul 4, 2021)

When I make sodium silicate molds or cores (normally I use resin-bound sand for everything, but I have used sodium silicate bound sand for both molds and cores), I use 3%.
The secret to making strong sodium silicate cores is to not over-gas them.

Like many foundry things, I originally thought that more is better.
When making sodium silicate cores, using more than 3% makes the core very difficult to remove after casting, and they do not permeate the CO2 very well.

When gassing sodium silicate cores, gas for 5 seconds with CO2, and then immediately stop.
Any gassing over 5 seconds will ruin the core, and it will crumble within hours.

A 3% sodium silicate core gassed for 5 seconds works perfectly, and I have left unsealed on the shelf in the unconditioned shop for a year, and they were still usable.

Never put a sodium silicate core in a plastic bag filled with CO2.
The is the fastest way to ruin I core that I am aware of.

.


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## GreenTwin (Jul 4, 2021)

Foketry said:


> I am following your foundry work with a lot of interest and great appreciation. I started casting aluminum a couple of years ago for my engine models which you can see here. Porsche 917  flat 12 engine
> I would like to cast iron but my gas furnace does not reach the required temperature. I kindly take advantage of your experience to ask you for some advice : how did you make the Diesel burner, nozzle size, pressure, air blowing, etc?
> What  coating did you use in your furnace to withstand the temperatures needed to melt cast iron?  . For my furnace I used ceramic fiber, but over 900/1000 degrees centigrade it starts burn.
> Last  3 question, what% of sodium silicate do you use in the sand ?
> ...


1. See info above for how I make diesel burners using Delavan siphon nozzles.
2. I use a 1" thick refractory called Mizzou, and it easily withstands iron temperatures, and is highly slag resistant too (see info above).
3. For sodium silicate, I use 3%, see my post on sodium silicate.
4. Sodium silicate is very sticky material, and it sticks to patterns worse than resin-bound sand.
I wax my molds to prevent most sticking.
Some use various pattern coatings that are silver in color, and I have tried this once, but don't know enough about it to say if it works well.
5. The ceramic mold coat that I use is called Velacoat (manufacturer info was posted by someone above, see ASK Chemical).
Sodium silicate begins to break down in water, especially at 3%, and so alchohol-based ceramic mold coat may also break down a sodium silicate mold or core.
I have never used a mold coat with sodium silicate, and am not sure if it would work.
If I had a bit of time, I would try it, but I am too busy with work for now.

.


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## dazz (Jul 5, 2021)

GreenTwin said:


> 2. Some use spin vanes near the end of their burner tube, and some do not.
> I have tried both, and can't tell any difference, so generally I do not use spin vanes in the burner tube.
> A commercial heating unit burner is discharging into a large combustion chamber, but for a foundry furnace, you are discharging into a space that immediately swirls around  a round chamber, and so probably the reason a spin vane may not have an effect when used with a furnace.


I will try using spin vanes only because it is the easiest way to hold the burner nozzle.



GreenTwin said:


> 3. It is easy to use a constant speed blower, and your idea sounds like it would work.


I have no idea how big the blower motor/fan should be.  Trial and error required.




GreenTwin said:


> The fuel/air setting that produced the brightest luminance inside the furnace was about 2.6 gal/hr., and after I discovered that flow level, I compared notes with others doing iron work, and found that for the same size furnace, they were using an almost identical fuel flow level.


There seems to be an upper limit on the fuel combustion rate for a given size (volume) of furnace.  



GreenTwin said:


> Cracks that are not filled will let a high temperature stream of hot gas get behind the hot face, and that can cause a lot of damage to the ceramic blanket.


I have thought about slightly pressurizing the space where the fibre insulation is to ensure there is air flow through any cracks into the furnace.    Rather than cool the furnace hot face, the added oxygen may increase combustion.




GreenTwin said:


> I have seen one furnace build from lego-style individually cast refractory curved blocks, but they made the blocks about 4" thick, which is way too much mass for a furnace.


A concept drawing is attached.  The actual bricks would be shaped to fit the allocated position.   With CAD and a 3D printer, it will be easy to made bricks with complex shapes.  



GreenTwin said:


> 7. The aluminum foil is not a bad idea, but be aware, the back of my hot face is probably not much cooler than the face of my hotface, and so the foil would have to be behind enough layers of ceramic blanket to prevent melting the foil.
> Iron furnaces run extremely hot.


Aluminium insulation is only good to about 200 deg C, so it would only survive if separated from the hot face with ceramic blanket.  
Really thin stainless steel would work OK until the surface oxide changed colour and it stopped being such a good mirror.
I plan to use stainless steel for the furnace outer casing.


Dazz


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## TSutrina (Jul 5, 2021)

I am just someone that view this site so I am only suggesting something.   Lots of hobby people exist and they do need material.  They could form a co-op to purchase material.  The group could purchase in bulk and repackage it a local warehouse.  Ideally be a corner of a small business builing with multiple small businesses so that they could rent/borrow fork lift truck owned by other tenant and maybe have use of their dock.  The building is more likely to have the proper environment to keep the product dry.  I visited a semiconductor manufacture in England that had space in a very old building that didn't have the environment needed.  They built a plastic sheet enclosure within the building with the proper environment.  So example humidity can be reduced within such an enclosure.  Some equipment will be needed to do the repackaging and maybe sufficient co-op members live close enough to get together one or two Saturdays a month to do the repackaging.  And need a person that does the receiving and shipping.  This could be done by the small business that has the fork lift truck for a fee per order and a monthly retainer.


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## GreenTwin (Jul 5, 2021)

TSutrina said:


> I am just someone that view this site so I am only suggesting something. Lots of hobby people exist and they do need material. They could form a co-op to purchase material.


The problem is that some of the materials used in a foundry can be hazardous if the proper precautions are not used, such as commercial respirators, etc.
Every foundry product should come with a MSDS sheet (material safety data sheet), and the product should not be used without reading that sheet and adhering to its recommendations.
I think the safety aspects are what prevent many/most from creating a coop-type arrangement.

Some backyard casting folks take a casual approach to safety and material data sheets when casting things, but safety is priority #1.
If you are not doing things safely, you should not be doing them; that is the bottom line.

I like the idea of a coop, but not sure if the logistics of that could be worked out.
.


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## GreenTwin (Jul 5, 2021)

dazz said:


> There seems to be an upper limit on the fuel combustion rate for a given size (volume) of furnace.


I was told by someone who worked on commercial oil heaters for many years that the method of determining the maximum fuel rate for any give furnace is to begin with some low nominal fuel flow value, and adjust the oil and air to give about 4" of flame out the lid opening.
The combustion air flow is then increased until the flame is drawn back into the furnace.

The fuel is then increased again to give 4" of flame out the lid opening, and then more combustion air to draw the flame back into the furnace.

At some point, when the combustion air is increased, instead of drawing the flame back into the furnace, it will increase the flame size coming out the lid opening.  This is the maximum fuel flow rate for the furnace.
I have not tried this method, and only learned it not too long ago, but next time I run my furnace, I am going to try it.
.


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## GreenTwin (Jul 5, 2021)

dazz said:


> A concept drawing is attached. The actual bricks would be shaped to fit the allocated position. With CAD and a 3D printer, it will be easy to made bricks with complex shapes.


One thing I have learned from my own furnace, and observing other's iron furnaces, is that melting iron is a brutal business, as far as the heat generated, the effect that iron-level temperatures have on the furnace hot face and crucible, the splattering slag, the very extreme expansion/contraction that all the components are exposed to, etc.
I have seen some folks transition from doing brass/bronze work into doing iron work, and the temperature difference between brass/bronze and iron is not that great (in my opinion), but the infrared energy coming out of a furnace at iron temperature, and the infrared coming off of the crucible required that shaded welding goggles, or some sort of shaded lens be used, else you will get sunburn in the eyes.
And with that much IR coming out of the furnace, you need full leathers, leather boots, heavy leather gloves, head cover, full face shield, etc.

And another common mistake I see when people try to pour iron is they do not use heat shields on their skimmer handles, pouring shank, etc.
Without a heat shield to protect the gloved hand, you will overheat the glove and burn your hand within perhaps 15 seconds, if your gloved hand is within 30" of a hot furnace or crucible.

As I mentioned, don't underestimate the IR coming out of an iron furnace.
I have had the black body of cameras 10 feet away start to get hot and smell when the furnace is opened.

And avoiding any moisture anywhere, such as in the scrap metal, the ingot molds, or anywhere else is essential.
The slightest microscopic amount of moisture on any surface, such as the dry surface of an ingot mold, can eject the molten iron right into your face/facemask.
I have 3rd had degree burns on my hands that prove this point.
I will link a video one person posted to highlight the moisture thing around iron pours.

But the point I was trying to make (I drifted off-topic a bit) was that spending a lot of time making custom fire bricks may or may not be productive.
If all the fire bricks crack after the second iron pour, then you are right back to patching with plastic refractory, and the question becomes why not just make the hot face from plastic or cast refractory in a thin sheet, or a thin cast refractory hotface?

.


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## GreenTwin (Jul 5, 2021)

Here is an extreme case of a backyard guy I watched before I built my furnace, and he poured a lot of iron in his furnace.
He re-built his furnace perhaps three times, during the time I was following him, and learned a lot about what to do and not do with furnaces by watching his builds.
I will post a photo of the interior of my newest furnace, and you can see it is not nearly as bad as this one, but I don't have the large number of iron melts on my furnace either.

The material on the sides of the furnace is slag that has been splattered out of the crucible during the melt.
The crucible in the photo below is rather thin at the top, and that is ok as long as it is only thin at the top but otherwise still thick and solid elsewhere.


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## GreenTwin (Jul 5, 2021)

This is my badly cracked hot face after about four iron pours.
This may look like a total disaster, but it is actually completely repairable/serviceable, since the Mizzou is still very solid, but just cracked.

I still use this hot face, and just patch any slight cracks with 3,800 F plastic refractory.


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## GreenTwin (Jul 5, 2021)

Here is the rebuild I did on the hot face above, and it only took about 30 minutes to rebuild/patch.
With plastic refractory, I don't have long dry-out times, but rather just fire the burner on low for about 15 minutes, then 1/2 power for about 5 minutes, and then full power.

I have seen more than a few backyard folks go to great lengths to build a pristine furnace/hot face, and baby it, and obsess about a tiny spot of slag that shows up on the hot face.  These folks generally never do iron work.
As long as the refractory has a high temperature rating and does not begin to crumble, then you can just patch it.


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## GreenTwin (Jul 5, 2021)

Here are the insulating fire bricks installed around the hot face, after the rebuild.
I used a grinder (with a very good dust mask) to cut a convex surface on the bricks where they meet the hot face.
Insulating fire bricks are very soft, and easy to cut by hand if necessary, but they won't stand up to iron temperatures unless they are 3,000 F rated.

These are about 2,500 F rated.  The price of insulating fire bricks goes up exponentially with temperature rating.
If you have to ask how much a 3,000 F insulating fire brick costs, you can't afford them, and I certainly can't (perhaps $10 per brick for the 3,000F was one quote I got).

The insulating fire bricks are lightly banded (not tight, since everything will expand when heated) using stainless bands.

I use a cast refractory extended tuyere, and am not entirely happy with it, but it does work.
I think an extended tuyere made from insulating fire bricks would be better, and let the bricks sit on the furnace steel base.

Two layers of ceramic fire brick are wrapped over this, and then a stainless steel shell.
The stainless shell ended up being the diameter of a 55 gallon drum, and if I had to do over, I would have just bought a stainless steel drum, instead of piecing together the sheet metal as I did.

The insulating fire bricks are not adhered to the hot face, to allow for rebuilds.


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## GreenTwin (Jul 5, 2021)

This is what the interior of my rebuilt furnace looks like after seven iron pours, and I consider this to be a pristine and clean look, with no visible cracks.
I fill any cracks with plastic refractory prior to using the furnace each time, and if you do this, then you generally only have to fill a few very small cracks, and this seems to minimize crack propagation.

Even after the rebuild, I consider this hot face to be repairable and serviceable for many years.

I discovered that the art-iron foks use plastic refractory to patch their cupolas, and they generally never rebuild a cupola, but rather just pack new plastic refractory into the low spots before every use.
If I ever get to the point where I have to replace this hot face, I will add a layer of tap to the inside of the insulating fire bricks, and just pack on 1" of 3,800 F plastic refractory, so that I don't have to build forms, mix refractory with water, cast it, etc.

Plastic refractory is like very thick putty, and you don't add water, but rather just hand-pack it into place.
You could probably roll out a 1" thick sheet of plastic refractory (like cookie dough), and then put wrap it around the furnace interior sides and floor.
That would give a more consistent thickness to the hot face.

I used the same plastic refractory to fill out the L-shape that I used in my lid, and cover the stainless metal, and that is the only modification I have had to do to the lid shown below.

The plinth below the crucible is cast from Mizzou, and I have several of these, at different heights, depending on which crucible size I am using.

When I have finished pouring the iron, I empty any remaining iron into a preheated (to perhaps 500 F) ingot mold, but I don't try and clean out what remains in the crucible.   Crucibles are somewhat delicate, and they should not be stacked, dropped, or roughly handled in any way.
The slightest crack in a crucible will cause it to fail during a melt.

If you tap lightly on a crucible, it should have a ring to it if it is not damaged.
If the tapping caused a dull thud sound, the crucible should probably not be reused.
A crucible should be retired when it begins to get too thin.


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## GreenTwin (Jul 5, 2021)

One thing to note is that when I first built this 2nd furnace, I installed a 4" wide stainless steel band around the hot face, near the top.
I think this was a mistake, and I think the steel band exacerbated the cracking of this hot face.

One thing that using a hot face made of sections would to is give controlled cracking joints.
If you have access to a good plastic refractory, cracking is a non-issue regardless of how you build the hot face, as long as you use a good refractory that does not crumble at iron temperatures.

.


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## GreenTwin (Jul 5, 2021)

I used a domed lid, so that if the refractory cracked, it would not fall into the furnace (self-supporting Roman-arch thing), and I had inner and outer domed forms to create the 1" shape with Mizzou.

I used a chimney on top of the lid to try and retain the heat in the furnace just a bit longer.

The formwork for this lid did work and it turned out nicely, but it was all far more complex than it needed to be ( used an upper and lower domed form).

If I had to do over, I would have made the outer shell, found a dome of some type (generally the end of some air compressor tank or any domed shape of any material), and just packed 1" of plastic refractory on it, which would only take about 15 minutes, instead of the days it took me to make this lid.

It is best to work smarter, not harder, when building foundry equipment, and I often find myself using the "harder" methods, when I look back in retrospect.


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## GreenTwin (Jul 5, 2021)

I carefully rammed the refractory before I added the upper domed form, but there was no way to ram the top of the refractory (the upper form was just pushed down into place on top of the refractory).

So there are few air bubbles inside the lid, which is good, but a number of air bubbles on the top of the lid refractory.
The air bubbles on the top of the lid refractory are cosmetic, and are covered by insulating fire bricks or ceramic blanket anyway.

Some folks obsess about air bubbles in their refractory, and get upset at the slightest sign of a void in the hot face.
I did carefully ram my hot face refractory in 4" layers, to get rid of the air bubbles, and got a good surface finish.

There is one school of thought that says cast refractory should be vibrated into place.
I do not prescribe to vibrating refractory, and prefer to hand pack it, because you can settle out the aggregate particles from the fine particles when you vibrate it, which is not what you want.  And the cast refractory instructions specifically mention to not trowel the refractory, which I think also separates out the aggregate.

If the air bubbles bother you, just patch them with plastic refractory.
After a few iron pours, the bubbles in the refractory will be the least of your concerns.


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## GreenTwin (Jul 5, 2021)

I added a layer of 1" ceramic blanket on top of the lid refractory, and then added a layer of insulating fire bricks on top of the ceramic blanket.
Seemed like a good idea at the time, but if I had to do over again, I would just use four 1" layers of ceramic blanket, with a thin sheet metal cover over it.

I often do like others when building furnaces, and tend to over-design things, when there are much simpler and cheaper/easier methods.
Live and learn I guess.

One very successful professional foundry person told me a very wise adage about foundry equipment, which was in so many words "Less is More".
These have proven over and over again to be golden words in my experience.
I try to only build complex enough to get the consistent performance I want, and no more.

It is very easy to over-design and over-thing furnaces and burners.
I have seen numerous videos online of highly complex and many times poorly designed burners that don't last any time at all due to overheating, and people melt iron with them, and use them as proof that they are good (the best !) burner designs.
People compete for the title of "best burner", and often get into heated debates online, while never casting anything of any significance.

If you want to make good iron castings, focus on the end product (defect-free castings that are easy to machine), and use materials and a burner that 
work consistently ever single time.  Consistency of equipment operation is paramount to making good iron castings.
If you constantly have to stop in mid-melt and work on the burner, or constantly have to adjust the burner during a melt, then you will probably not be get good consistent castings.

The worst burner design in the world can often melt iron, but an overheated burner tube or burner component will fail relatively quickly.
The burner tube should be cool to the touch at every point except perhaps where it enters the tuyere.
You should never have to rebuild a burner, and there should not be any flame impingement on a burner tube (opinions differ on this, but my burner tubes last forever, and others of different designs often don't).

Occasionally you have to remove a little residue from the end of a siphon-nozzle tip, but using clean diesel and an inline-fuel filter, I have never clogged a siphon nozzle tip, and never had to rebuild a siphon nozzle burner.


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## GreenTwin (Jul 5, 2021)

Here is a good example of what happens when you don't preheat your ingot mold to perhaps 500F or so before you pour molten metal into it.
Even though the ingot molds may look dry, they have slight residual moisture on their surface, and that tiny amount of moisture will flash and pop the molten metal right into your face shield (you should wear eye protection and a full face shield).

I had this happen (before I found this video) and the iron splattered on my leather jacket and small beads ran into my gloves.
I had a few 3rd degree burns on the hands.

Also don't wear anything synthetic like clothing, shoes, etc., since it can catch fire an burn easily.
I use a leather apron, leather boots, leather welding jacket, leather gloves, head cover, etc.


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## GreenTwin (Jul 5, 2021)

And a good example of many mistakes when pour iron, which is why he posted this video, to save you from making the same mistakes.
And needless to say, you should not be anywhere near an iron pour without a full face shield, and shaded glassed for IR protection.

Water and molten metal to not mix at all, and most of the accidents I see involve water either in the scrap, in the sand mold, in the ingot mold, etc.

And I would say as a rule, never operate a foundry indoors.
One guy operated a furnace about a year ago, got dizzy, walked outside and passed out.
The rushed him to the hospital, and his blood oxygen was so low that they said they were not sure why he survived.
He was very lucky, and had just been operating his furnace for 15 minutes indoors, with the doors and windows open.


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## GreenTwin (Jul 5, 2021)

And check out this video at 0:15 and also at 7:06, the guy in the center has his face mask up when the molten cast iron errupts
from the damp moulding sand.
A near miss, and very close to being a blinded casting guy. 

These are art-iron folks, operating a cupula, using coke as fuel.  Coke is coal heated in the absence of oxygen.


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## GreenTwin (Jul 5, 2021)

Another blunder I made is using a pouring shank that did not retain the crucible well enough (the retainer was not a good fit at the top of the crucible).
I starting pouring iron, and as I rotated the pouring shank, the entire crucible fell out of the shank.
Needless to say, molten iron flew everywhere.

Making good functional reliable foundry equipment is essential for safety.

I have seen some spill molten metal on their rubber/plastic fuel lines.
Don't do this.

.


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## dazz (Jul 5, 2021)

GreenTwin said:


> I have seen some spill molten metal on their rubber/plastic fuel lines.


What could possibly go wrong??


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## dazz (Jul 5, 2021)

All great advice.  I wish I could follow it all.  Using a 55gal stainless steel drum for a shell is a great idea.  It would save a lot of work.  Where I live, none are available.    If it is available, anything specialised for foundry work is hideously expensive.  

I think the advice about safety gear is really important.    I know leather gear is very common but animal skin is probably not ideal. 
Nomex and Kevlar are modern alternatives.

I found a US supplier of heat resistant material PPE & Flame Resistant Clothing: Best Work Safety Gear .  I don't know if they do foundry type products or the prices but the material looks like it has good properties.

I see face shields being worn.  Many wear helmets.  I don't see flaps down the back of the helmet to stop metal droplets falling down the inside back of overalls.

I have seen terrible footwear.  I think industrial boots with spats should be worn.    

Dazz


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## GreenTwin (Jul 6, 2021)

I have attended several art-iron shows, and these folks have great talent, both from the aspect of operating cupolas and creating fabulous artwork in iron.
Looking at my photos, I see a few synthetic jackets/outfits, but generally they wear leather.

I guess I am old school.  I prefer a leather jacket, apron, gloves, etc.
I have never tried the synthetic material, and so I am not sure if I would like it or not.
I do have a good feel for how leather protects, and how long I can expose a leather glove to heat before it overheats my hand.

If you begin to overheat a leather glove, it will start to smoke, and that is a good warning signal that you better find a cooler place for your hand quickly.

Here are a few photos from one of the local art-iron shows.
These folks spill iron all over the place during an iron tap, and walk around in burning grass with impunity.
The have been a valuable resource when it comes to making resin-bound molds, safety, and all sorts of other things like mold coat.

The person tapping the cupola below is a person who works at the art-iron museum, and she is fearless.
She has been an excellent mentor and friend.
The iron pours have been shut down for the last two years, and I really miss those shows.
It is a tight knit group of really nice folks.

All the flying molten metal, flame etc. is like a walk in the park for these folks.
The do take safety extremely seriously, and have regular safety meetings, and well planned out events, were everyone has a task, and you watch each other's backs.
Everything is carefully choreographed beforehand.


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## dazz (Jul 6, 2021)

Hi
I have a set of naval anti-flash gear.  It is made of Kevlar which chars when burnt.  It is soft, breathable and light.  My daughter used to manufacture custom Nomex auto-race suits.  Neither the military or motorsports use the skin of dead cows for flame protection.   Leather is cheap and readily available and has been used for a long time.

I found reference to a set of European standards:

CE EN470-1 Welder use
CE EN366 Radiant heat
CE EN532 Flame resistant
CE EN373 Molten metal splash
CE EN367 Convective heat
It would be interesting to know if leather meets these, or similar standards of protection.

Dazz


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## Rocket Man (Jul 6, 2021)

Before I retired we use to buy firebrick from Boiler Supply.  They come in several ratings as you mentioned we use 2500° rated bricks.  Our furnaces were fired with natural gas.  Bricks are almost as light weight as Styrofoam and easy to cut like Styrofoam by hand with a hacksaw blade.  If we did a good job shaping the bricks we did not need to use furnace cement.  We always built an outer metal case with 1/4" steel welded together to hold the bricks in place.  Bricks hold up good as new for 20 years.  We bought factory made gas burners from boiler supply too they come in several BTU ratings.  BTU rating is nothing more than a different size fuel orifice.  If you have 200,000. BTU and you want 500K or 750K BTU all you do is change the fuel orifice.  Gas burners have a fan and a controller to throttle up the air with the gas for the perfect burn.  Burners are not expensive about $600 they have a small controller it is all 120 volts AC.  We used Fuji temperature controllers with a thermocouple.  We turned off all 11 furnaces every weekend, Monday morning flip the switch furnace is up to full temperature in 45 minutes and 2000 lbs of metal is melted quick.  Zinc & bronze are easy we never did cast iron.  It looks like you have it all figured out and working good.


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## GreenTwin (Jul 6, 2021)

dazz said:


> It would be interesting to know if leather meets these, or similar standards of protection.


I would say the one area that could be improved over leather is the refectivity.
If you can reflect the heat, I think you would stay cooler.
.


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## GreenTwin (Jul 6, 2021)

Rocket Man said:


> Before I retired we use to buy firebrick from Boiler Supply. They come in several ratings as you mentioned we use 2500° rated bricks. Our furnaces were fired with natural gas. Bricks are almost as light weight as Styrofoam and easy to cut like Styrofoam by hand with a hacksaw blade. If we did a good job shaping the bricks we did not need to use furnace cement. We always built an outer metal case with 1/4" steel welded together to hold the bricks in place. Bricks hold up good as new for 20 years. We bought factory made gas burners from boiler supply too they come in several BTU ratings. BTU rating is nothing more than a different size fuel orifice. If you have 200,000. BTU and you want 500K or 750K BTU all you do is change the fuel orifice. Gas burners have a fan and a controller to throttle up the air with the gas for the perfect burn. Burners are not expensive about $600 they have a small controller it is all 120 volts AC. We used Fuji temperature controllers with a thermocouple. We turned off all 11 furnaces every weekend, Monday morning flip the switch furnace it up to full temperature in 45 minutes and 2000 lbs of metal is melted quick. Zinc & bronze are easy we never did cast iron. It looks like you have it all figured out and working good.


I learned the hard way about 2,600 F fire bricks.
I build a great smaller furnace from them, and was so proud of that furnace (I will look for photos; I try to forget that furnace).
And like many things I tried, this small furnace was an abject failure, since it crumbled into dust the first time I tried to melt iron in it.
Live and learn I guess.
The main thing is safety though; you can always get more bricks.
I should have used a 3,000 F hot face over the insulating fire bricks on this little furnace.
It was a very sad sight indeed to open my new little furnace and see dust; LOL, I am still broke up about that.
RIP little furnace (sniff, sniff).












I have seen an aluminum making person use thermocouples and a feedback loop for burner control, but at iron temperatures, the thermocouples melt.
Perhaps if the thermocoulple were mounted not directly in the hot area.
I don't need burner control; I just run it a 2.6 gal/hr, which is pretty hot.

Here is a chart I found on BTU output of oil burners:

3412 BTU/hr = 1 KW

*Oil Burner Approximate Values:*

1 gal/hr = 138,500 Btu/hr (40.59 kW)
2 gal/hr = 277,000 Btu/hr (81.18 kW)
3 gal/hr = 415,500 Btu/hr (121.77 kW)
4 gal/hr = 554,000 Btu/hr (162.36 kW)

5 gal/hr = 692,500 Btu/hr (202.96 kW)
6 gal/hr = 831,000 Btu/hr (243.55 kW)
7 gal/hr = 969,500 Btu/hr (284.14 kW)
8 gal/hr = 1,108,000 Btu/hr (324.73 kW)

9 gal/hr = 1,246,500 Btu/hr (365.32 kW)
10 gal/hr = 1,385,000 Btu/hr (405.92 kW)
11 gal/hr = 1,523,500 Btu/hr (446.51 kW)
12 gal/hr = 1,662,000 Btu/hr (487.10 kW)


*Heat Value of Materials:*

#2 Diesel = 138,500 BTU/gal 

.


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## mnay (Jul 6, 2021)

GreenTwin said:


> This is how the pattern was assembled.
> 
> View attachment 126954
> 
> ...


Great idea!!!!


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## GreenTwin (Jul 6, 2021)

mnay said:


> Great idea!!!!


Thanks.
It seemed sort of like a crazy idea at the time, and I really wasn't expecting it to work very well, but it actually worked quite well, and it did not take me very long at all to make the pattern.
I was surprised at how well the casting turned out.
I had a bit of shrinkage on the rim, but that can easily be corrected with a few strategically placed risers.

The reason that I hand-carved the spoke is because I could not figure out how to model an accurate compound curve in Solidworks.
I have not tried to make a compound curved spoke in SW lately, but my approach these days would be to use a lofted shape along a curved path.

3D printing saves a lot of time if your printer works well, and if you can model the part in 3D.

Another approach I have seen from 100 years ago is to make one pie-shaped section of the hub, 1 spoke, and rim.
The pie shaped pattern/core box (which may be for a 12 foot diameter flywheel) was laid on the floor, and one section of the mold was rammed at a time.
If you look at old large flywheels, you can often see the joints around the rim where this method was used.
So a pie-shaped section of the rim/spoke/hub could be 3D printed, and then the entire pattern or part could be molded from this.

.


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## awake (Jul 6, 2021)

GreenTwin said:


> And a good example of many mistakes when pour iron, which is why he posted this video, to save you from making the same mistakes.
> And needless to say, you should not be anywhere near an iron pour without a full face shield, and shaded glassed for IR protection.
> 
> Water and molten metal to not mix at all, and most of the accidents I see involve water either in the scrap, in the sand mold, in the ingot mold, etc.
> ...




That was a terrifying video. The camera-man on the right in open sandals ... and the helper helpfully locked into position by being on his knees ... and doing all of this on a concrete floor ... oh, my.


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## GreenTwin (Jul 6, 2021)

awake said:


> That was a terrifying video. The camera-man on the right in open sandals ... and the helper helpfully locked into position by being on his knees ... and doing all of this on a concrete floor ... oh, my.


It was mentioned in the video description that this video was meant to be a learning experience, so others can avoid the errors shown.
Sometimes you can learn a lot more when things go wrong, especially from a safety standpoint, and I pay close attention to my failures and those of others, and try to anticipate safety issues in advance, so that they can be safely handled.

I cringe at some of my early videos too.  My first iron pour was in lace-up leather shoes with no spats, but we all live and learn.
If there were a foundry school that I could attend, I would have gladly signed up for that.

In India, there are many videos of very large iron foundries, where all of the workers generally wear short sleeve shirts, sometimes shorts, often open sandals, no face protection, no infrared eye protection (shaded glasses), no dust protection, etc, and yet they work under these conditions all day every day, and think nothing about it.
Generally speaking, splashing minor amounts of molten iron on your person is not that big of a deal, since the iron usually does not remain in contact long enough to do any damage.
UV damage to the eyes is another thing altogether, and that may be permanent damage.

Edit:
Some things I intend to do to make my setup a little safer include installing the fuel line in a flexible metal conduit to prevent any spilled metal from melting it.
I often see people using a 20 lb propane bottle or oil tank near the furnace, and I always remote my fuel tank at least 10 feet away from the furnace, or more.
Having a supply of sand with a shovel on hand is a good idea, since dumping sand on top of a molten iron problem will stop a fire.
The sand should be dry though, as wet sand could cause an explosion.
A good dry-type fire extinguisher is definitely wise.

I have heard the warning about not pouring on concrete, but I have always poured on concrete, and have spilled on concrete.
My concrete driveway is not very high quality, and so it has never exploded.
High grade concrete seems to be worse about exploding, but I don't think it is the danger that people make it out to be.
Generally you may get some spalding of the concrete, which is more about creating bad spots on the driveway than about safety.

I know a guy in Australia who has poured iron over concrete for 20 (+) years, and spilled on it many times.
Not that concrete won't pop if you spill iron on it, but its just not that big of a deal.

Some people make furnaces using concrete instead of refractory, or they don't dry their refractory slowly after casting it, and these situations will cause a massive explosion, and are extremely hazardous (video of a concrete furnace exploding is online).

My rule No.01 is to not use the furnace or have the fuel tank anywhere near the house (or near anything else flamable), and so if things go wrong, all I have to do is step back, and be sure the fuel tank is clear and turned off.

.


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## dazz (Jul 6, 2021)

Hi
The reason I am aiming to use a fuel pump with a constant output pressure, and a nozzle with a fixed flow rate is because the data indicates that nozzles have a relatively narrow fuel pressure range to produce a good atomized spray.   Combustion would only be adjusted with the air flow.  So if I find that I need to change the fuel flow rate, I would change out the nozzle for one with a different rate.

I did consider making a spinning disk and cup atomizer to allow for control of fuel flow rate but they are too complicated.

Dazz


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## GreenTwin (Jul 6, 2021)

dazz said:


> The reason I am aiming to use a fuel pump with a constant output pressure, and a nozzle with a fixed flow rate is because the data indicates that nozzles have a relatively narrow fuel pressure range to produce a good atomized spray. Combustion would only be adjusted with the air flow. So if I find that I need to change the fuel flow rate, I would change out the nozzle for one with a different rate.
> 
> I did consider making a spinning disk and cup atomizer to allow for control of fuel flow rate but they are too complicated.


I have seen one person using a fuel pump with a what I think is a siphon-nozzle burner, but I think they also use compressed air.
With enough fuel pressure, perhaps the fuel pump would work with a siphon nozzle without compressed air, but perhaps that would require a pressure nozzle?

The fuel flow rate for a siphon nozzle I think is determined by the compressed air pressure (check me on that).
The fuel flow rate for a pressure nozzle is controlled by the rate of fuel that you return to the fuel tank (for a given pump presure such as 100 psi constant).
Can the fuel flow be modified by changing the nozzle for one of a different rate?  I am not sure about that; you will have to research that.
The flow rates on siphon nozzles I think are all pegged at a given compressed air pressure, and the flow rate on the pressure nozzles I think depend on pressure delivered by the gear pump, assuming no return to the fuel tank.

There is a noticeable difference in the size of the hole in the end of a siphon nozzle tip, between a 1 gal/hr nominal rated, and the smaller flow nozzles.
I have used a 1 gal/hr siphon nozzle at 10 gal/hr, by increasing the fuel tank pressure slightly, and using a little more compressed air.
Note that a 10 gal/hr fuel flow rate is far more than most home foundries would use, but it can be done, and a siphon nozzle and pressure nozzle are easily rated for a 4:1 flow ratio, and can be pushed much heigher with perhaps some sacrifice in atomization.

The siphon nozzle has one fuel line from the fuel tank to the burner.
The pressure nozzle has two fuel lines from the fuel tank, a supply and a return.

The is a spinning disk burner build out there, and it has tons of views, but I have never seen it actually work; it was just a lot of experimentation, but never a functional burner.

Not that a spin type burner would not or could not work, but many of the comments the builder got was "it is too complex for a home foundry".
That being said, if it was proven that a spin disk burner worked better than anything else, I would consider using one.
Making a new burner type is very common on the net.
Demonstrating that a new burner type will reliably melt iron with no degradation over time, and no adjustments during a melt, is a rare thing.

.


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## dazz (Jul 6, 2021)

Hi
I looked at siphon-nozzle burners and rejected that option.  I would have to buy a compressor (=$$$), which is complex, noisy and takes up space I don't have.
As an energy source, compressed air is expensive (air is free but compressing it is not) and inefficient.  
I like the spinning disk burner concept and it would be great if there was a requirement to regulate fuel over a wide range of flows, but I though it would be too complex for a home foundry.   It is far easier to make something complex than elegantly simple.

So I have settled on an electric pump (cheap, quiet, simple) and matched spray nozzles.   I only need a power cable and a fuel line to connect up to the furnace.  

I have operated old 1960s built naval boilers.  They used multiple pressure nozzles with fixed flow and swirlers.   This is really old tech.   I am aware that the combustion process is noisy.

Of course all of my opinions are solidly based on nil foundry experience.  I try to learn from the mistakes of others so I don't make them.  Conversely, I look to replicate the success of others and claim it as my own.     

Dazz


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## GreenTwin (Jul 7, 2021)

dazz said:


> So I have settled on an electric pump (cheap, quiet, simple) and matched spray nozzles. I only need a power cable and a fuel line to connect up to the furnace.


I finally took a look at the pump you posted.
I sort of assumed that it was of the automotive fuel pump type that I often see in the US used with foundry fuel tanks, with a low pressure output.
But much to my surprise, it is actually a motor/pump combo that is designed to work with heating nozzles.
I had no idea such a thing was made/available, and have never seen it in the States.

It looks like pressure and flow are adjustable.
For a Suntec, pressure is adjustable via a screw that can be accessed inside the pump housing.
I am going to run my Suntec at a constant 100 psi, because that seems to be standard for a pressure nozzle.
So what that means is that my Suntec will produce about twice the flow I need at 100 psi.
I will shunt the excess fuel flow back to the fuel tank via a bleeder needle valve in the line to the nozzle.

So looking at the specs for the pump, selecting a point on the pressure/flow curve at 0.75 MPa, you would have 109 psi to the nozzle, which would be idea from what I have read.
If I am doing the math conversion correctly, the 0.75 MPa would give you between 11 and 13 liters/hr, or 2.9 to 2.4 gal/hr, which is very close to what I often seen in furnaces (I run about 2.6 gal/hr diesel).
The cut sheet says adjusting pressure is via the relief valve, and I am guessing that means it is like the Suntec, where you set the internal relief valve for the desired pressure, and you get whatever flow that produces.

So I think you will have the same situation I have, where you can just have a return line to the fuel tank, and bleed off any excess fuel flow.
I will look again to see what sort of nozzle adapter you are using.
The Delavan nozzle adapter has an inlet on the end, and an outlet on the side for return fuel flow (in a pressure nozzle configuration).

I have not run a pressure nozzle burner yet either, but I think I understand how they work.
It would seem your small fuel pump would work well, and it is highly efficient from an electrical standpoint too.
My gearpump motor is way oversized.

Typical packaged heating burners I have seen around here have a central motor that drives the integral fan, and also powers the gear pump, and so I probably looked at the motor sizes for the combo units, when really I will not be powering a combustion air fan.

So it makes me wonder if that pump is available in the US, or whether it would be a hard-to-find thing?

I think you have found a good pump, and more importantly a pump specifically designed for exactly what you are going to use it for (I missed that until a minute ago).

So you would use a standard pressure-type nozzle with it.
A siphon nozzle would not work with it (I don't think).

That is very cool.
I think you have found a good combination of equipment there for a pressure-style burner.
If this works for you, I am buying one, if I can find it.

.


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## GreenTwin (Jul 7, 2021)

dazz said:


> I look to replicate the success of others and claim it as my own.


LOL, its all good.
Claim away.

Everything I know was either posted online, or posted in an equipment cutsheet.
I can't really claim any original knowledge about oil burners.

I did find a great Audel's book about oil burners from perhaps the 1930-40's?
I guess when they started refining crude oil, many steam plants began to convert from coal to oil-fired.
Oil lamps as I recall have been around for a very long time (thousands of years?).

I have seen some of those Navy boiler burners, and some of them used steam instead of compressed air, so that they could burn very thick and heavy crude oil?

I have seen converted locomotives too.
It is much easier to handle, store, move and use oil than coal, in my opinion (no shoveling of oil).

I sort of absorb everyone else's information, and then generally come up with some sort of hybrid, just as you have done.
When do we get to find out if your new burner works as anticipated?
We can give you a couple of days to get it assembled if you really need that much time (LOL, just kidding of course, we will give you an entire week).

.


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## GreenTwin (Jul 7, 2021)

I don't see the Nippon pump for sale anywhere.

As I understand the Suntec pump operation, you can adjust it between 7 gal/hr at 100 psi, up to 150 psi at 3 gal/hr.
Operating at 100 psi will cause less wear and tear on the pump, and that is supposedly where the nozzle atomizes best.
I will shunt the excess fuel flow back to the tank.

Below is a Beckett schematic that I modified to show how I think my setup will look.
I have a remote combustion air blower (leaf blower), and I don't use electronic ignition.

The diagram assumes that a Delavan adapter with side return opening is being used.


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## GreenTwin (Jul 7, 2021)

Here are some old burner diagrams, I think from a vintage Audel's burner book.

These pages show a single tube to the nozzle, no adapter, and ignition electrodes.

I have never seen anyone use an air cone.
Typically if you choke down the combustion airstream, you increase its velocity to the point where the air/fuel flow strikes the back furnace wall and then climbs up the wall steeply and strikes the lid (this is observable at night with the lid open).

So my thoughts are to try to keep the combustion air velocity as low as possible, and thus probably the reason some commercial furnaces use dual burners at 180 degrees.
I have experimented with dual oil burners at 180 degrees, and the air velocity is 1/2 that of a single tube burner, with the result being a flame coming out of the burners that remains very low in the furnace, which is desirable and far more even a flame than a single burner.
At the time I was operating my dual burners, I didn't have a clue about fuel flow rates or anything else, and so I did not realize the befits of a dual burner arrangement, and went back to a single burner.

So your options may be to unscrew the fitting on the end of your tube, and replace it with a Delavan adapter that has the side return, and screw your nozzle into the adapter.
Or add a tee into the line to the nozzle somewhere, to bleed excess flow back to the fuel tank.


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## GreenTwin (Jul 7, 2021)

Comparing your photo below with the photos above, it would seen you have your electrodes assembled backwards.
The bare wire part of the electrodes would need to be near the end of the nozzle?

And the spin vane looks rather restrictive to air flow to me, as far as operating at 2.5 gal/hr.
I think you would be hard pressed to push enough air through the spin vane to reach iron temperatures.
I have not restrictions at all in my 2.5" burner tube, and there is quite a bit of back pressure on my leaf blower.

The arrangement below does not lend itself to using a Delavan adapter, so perhaps a tee in the pipe at the end of the burner tube away from the furnace? for return fuel flow.


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## GreenTwin (Jul 7, 2021)

I think the Suntec and some other oil pumps have an internal relief valve, to prevent over-pressuring the pump in the case of a clogged nozzle or line.
Here is a video of how that relief valve works, and I think this is how the Suntec allows pressure adjustment from 100 to 150 psi.


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## dazz (Jul 7, 2021)

GreenTwin said:


> I had no idea such a thing was made/available, and have never seen it in the States.


The one I purchased is the only one I have seen.  Liquid fuel domestic furnaces are not used here.
I purchased mine from aliexpress.com    search for VSKX125



GreenTwin said:


> So I think you will have the same situation I have, where you can just have a return line to the fuel tank, and bleed off any excess fuel flow.


No, the pump has a built-in return.    Single line to the fuel tank, single line to the nozzle.



GreenTwin said:


> I will look again to see what sort of nozzle adapter you are using.


This one.  Misting Oil Spray Nozzle



GreenTwin said:


> So it makes me wonder if that pump is available in the US, or whether it would be a hard-to-find thing?


It doesn't really matter if you buy it from China.  Note mine is 230V 50Hz.    



GreenTwin said:


> So you would use a standard pressure-type nozzle with it.


Yes


GreenTwin said:


> A siphon nozzle would not work with it (I don't think).


Yes,   No it wouldn't work.



GreenTwin said:


> That is very cool.


Oh no !!!   I was hoping it would be REALLY hot.  Over-inflated ego completely deflated.



GreenTwin said:


> I think you have found a good combination of equipment there for a pressure-style burner.
> If this works for you, I am buying one, if I can find it.


Phew.  Ego fully restored.


Dazz


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## dazz (Jul 7, 2021)

GreenTwin said:


> Comparing your photo below with the photos above, it would seen you have your electrodes assembled backwards.
> The bare wire part of the electrodes would need to be near the end of the nozzle?
> 
> And the spin vane looks rather restrictive to air flow to me, as far as operating at 2.5 gal/hr.
> ...


Hi
This is the supply side to the nozzle.  The nozzle is pointing down.    The igniter electrodes are correctly placed.
A single 6mm Cu tube connects this to the fuel pump outlet.
The only thing I can say about the swirler is that they all look similar for this style. 

Dazz


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## GreenTwin (Jul 7, 2021)

If this works, I am buying one, but I still say you may need a tee and a return line to the fuel tank.

.


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## GreenTwin (Jul 7, 2021)

And I read a post today about making thin parts in machinable gray iron.
I have read in several books that iron with high phosphorus should not be used to make engines.

So this guy who made a mini-V8 in gray iron said "I had to use old radiator scrap, which is high in phosphorus, due to its high fluidity".

LOL, so much for never using high-phosphorus iron for engine parts.

.


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## dazz (Jul 7, 2021)

GreenTwin said:


> If this works, I am buying one, but I still say you may need a tee and a return line to the fuel tank.


I am going to look really silly if I need one and don't fit it.

Dazz


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## dazz (Jul 7, 2021)

Phosphorous and its effects on Iron


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## awake (Jul 7, 2021)

GreenTwin said:


> Here are some old burner diagrams, I think from a vintage Audel's burner book.
> 
> These pages show a single tube to the nozzle, no adapter, and ignition electrodes.
> 
> ...


What is the title of the book? (Wondering if it is still in copyright, or available on GoogleBooks, or so on ...)


----------



## GreenTwin (Jul 7, 2021)

Here is the Audel's book.
Looks like I did find it somewhere online (not sure where), since I don't have the physical book (I don't think).
The copyright is 1946/1947/1955.


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## GreenTwin (Jul 7, 2021)

dazz said:


> I am going to look really silly if I need one and don't fit it.


Yes, but the only way to learn is to try something, and if it does not work, figure out why.
I have been doing that for years with burners.

.


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## GreenTwin (Jul 7, 2021)

I think I will still avoid any scrap iron that has phosphorus in it.
Not worth the risk of getting defects in engine castings.

I think I can fill thin sections of engine castings by using an oversized runner, generous knife or other gating, and keeping the iron very hot when pouring.

My thin sections are nowhere as near complex as the cores in a V8 cylinder head or block, and so I don't really see needing ultra fluid iron in order to completely fill any mold that I would use.

I wonder if that V8 head could have been cast using only ferrosilicon.
The guy that made the V8 did not really do any scientific comparisons (that I am aware of) on a cylinder head casting with and without ferro/carbon additive, phosphorus, etc., so we don't really know what worked (he probably knows more about this).

The ferrosilicon does make the iron noticeably more fluid, but more than a slight amount can also cause excessive shrinkage and hot tears.
And too much ferro will ruin the metal altogether.

.


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## dazz (Jul 7, 2021)

Hi
Attached is a photo from a seller showing the components I have.  It shows how they are connected.  There is no return line and no where to put one.  It makes for a simple installation.    The electric spark igniter is a luxury, but I thought I would try it out.

You can also buy ready made burners in a range of sizes but they are expensive.


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## GreenTwin (Jul 7, 2021)

Looks like they have a wide variety of burners and burner parts.
I wish I had time to go test my pressure-nozzle burner, but I am too busy right now.

You will have to blaze the path through the wilderness for us.

If you look at my marked up Beckett diagram above, I would put a tee fitting at the nozzle tube, and a needle valve as shown, but that is just my guess about what may work.

.


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## dazz (Jul 7, 2021)

GreenTwin said:


> If you look at my marked up Beckett diagram above, I would put a tee fitting at the nozzle tube, and a needle valve as shown, but that is just my guess about what may work.


Course adjustment of fuel flow can be done with nozzle size selection
The pump has a screw adjustment for fine control of fuel pressure.    There is a spring under a big slotted plug.
I already have a pressure gauge to monitor fuel pressure.

If I fit a sleeve valve to the fan output tube, I will be able to control air flow.

I think that combination will give the control I need over fuel/air flows.
All I need to do is build it and try it.

Dazz


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## SmithDoor (Jul 10, 2021)

Any looking at Muller's
Try this small one it for food too.



			https://www.spectramelangers.com/melangers/spectra-11-chocolate-grinder-cocoa-stone-grinders/
		


Dave


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## GreenTwin (Jul 10, 2021)

The mulling process is very hard on a mixer/muller motor, so depending on exactly how much sand you want to make, I guess that would determine what you use to mull with.

I use bound sand exclusively, and so I don't mull my sand, but rather I mix the binding agent into it.
For small sand molds I use a small Hobart kitchen mixer, and for the larger molds, I use a commercial Hobart kitchen mixer, as shown below.
I made a custom heavy-duty beater bar for the mixer below, since the stock beaters were not strong enough for sand.

I bought the mixer below used, and the salesman asked me if I needed help carrying it out.
LOL, "No" I said, "I can handle it".
Turns out it weighs about 400 lbs, and it took 5 people to get it in the car, and an engine hoist to get it out of the car and into the shop.
I will mix well up to about 3/4 of the bowl full, but more than that and it starts to bog down.


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## GreenTwin (Jul 10, 2021)

I originally tried to use Petrobond (tm) sand, and I used the small Hobart mixer to mull it a bit, with some success, but you have to use a cap over the bowl since the sand will climb up and out the bowl as it mulls.

The art-iron folks use a cement mixer without the internal paddles, and add one or more weights (usually round) as the sand mixes to help with the mixing process.
This works well for the large batches that they mix up, but is a bit on the large size for the small mixes that I make.

I started to build a traditional muller when I was using Petrobond, and got that design about 1/2 complete before I converted to bound sand exclusively.

Most who make their own mullers in the traditional rotating wheel style make common errors in their design, which is to have a spinning head that is not sufficiently rigid to prevent flexing, and so the plows strike the drum, and chaos ensues.
Another common mistake when building a muller is to omit a shear pin the the drive train, and so the muller head flexes, the plow strikes the drum wall (or a small piece of metal in used sand jams the plow), and the muller proceeds to destroy itself (I have seen this numerous times).

And a geared muller is a powerful thing, so an e-stop in an accessible place is a good idea.
Some high-torque machines I have seen have an over-torque feature, which will stop the motor if the torque gets excessive, and will prevent overtorque damage.

For low volume mixing/mulling, a concrete mixing tub and a hoe will work, but requires some physical labor, and does not mull as well as a real muller, although it does mix well.
One person I have seen pours his sand in a tarp on the ground, and rolls the tarp/sand while stepping on it.
There is more than one way to mull sand, and you don't necessarily have to spend much money to do it, but for large quantities of sand, a muller will save a lot of grunt work.

.


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## GreenTwin (Jul 10, 2021)

This is a Simpson muller, which is used at a local art-iron foundry, and it is a workhorse of an industrial machine for sure.
Most mullers have dual wheels, but if the wheel is massive enough, you can use a single wheel, as shown below.


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## GreenTwin (Jul 10, 2021)

Most mullers have two plows.
In the photo below, the right plow scrapes the sand off of the exterior drum wall, and the left plow scrapes the sand up off the bottom of the drum and turns it over.

The wheel compacts the sand/clay mixture, and also works in a horizontal sheering action, which is what is suppose to give good green strength to the sand.
Green strength is the physical property of the green sand to remain in the shape in which it is compressed, and the ability to withstand erosion as the molten metal fills the mold.

Bound sand eliminates the entire green strength requirement, since bound sand becomes rigid once the binder sets.
Bound sand can also be drilled/carved, etc after it sets, which is an extremely useful feature, and there is no concerns about sand erosion with bound sand.
The downside to bound sand is that it cannot easily be reused like greensand.
The upside to bound sand is that it can produce professional results with a professional (excellent) surface finish when ceramic mold coat is used.
Bound sand can also be used to mold complex shapes that traditional green sand may not be able to mold.

And bound sand molds can be made multi-piece, with the pieces joined into an assembly, which is also a very useful feature, especially with complex molds.


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## Foketry (Jul 10, 2021)

GreenTwin said:


> The mulling process is very hard on a mixer/muller motor, so depending on exactly how much sand you want to make, I guess that would determine what you use to mull with.
> 
> I use bound sand exclusively, and so I don't mull my sand, but rather I mix the binding agent into it.
> For small sand molds I use a small Hobart kitchen mixer, and for the larger molds, I use a commercial Hobart kitchen mixer, as shown below.
> ...



what kind of bonded sand do you use?  there are many types of foundry sand binder (phenolic resin, urea resin, etc.) which one works well for your use?
This resin sand is a product for industrial use, can you buy it without difficulty for hobby use?


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## awake (Jul 10, 2021)

Would a ball mill work for mulling sand?


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## GreenTwin (Jul 10, 2021)

Foketry said:


> what kind of bonded sand do you use? there are many types of foundry sand binder (phenolic resin, urea resin, etc.) which one works well for your use?
> This resin sand is a product for industrial use, can you buy it without difficulty for hobby use?


I use LINO-CURE (tm), which is _an alkyd-oil three part binder system that works well for large cores and molds. It has a long available work time and strip time with excellent stripping characteristics. It works well with high pH sands such as olivine sand. _

Linocure also works well with iron castings.
You can vary the set speed anywhere from perhaps 5 minutes up to an hour or perhaps more.

The smallest amount I have found is a 5 gallon can of the resin, which will bind perhaps 3,000 lbs of sand.

I use OK85 sand, which is a very dry commercial foundry sand.
Sand that is not very dry will not work with resin binder.

An industrial chemical respirator must be used when mixing and ramming resin-bound sand.

Its not cheap, but if you need very high quality castings, resin-bound sand with ceramic mold coat will produce those, assuming your iron is correct.

Edit:
One alternative to resin-bound sand that I am looking at using is sodium-silicate as a sand binder.
It is easier to source, does not require a chemical respirator (still requires a respirator for sand dust).
You can buy it in a one gallon jug, and it works in a similar fashion as any other bound sand.









						BudgetFoundrySupply.com - Pyrosil Core Binder
					

Description: Pyrosil Core Binder is a sodium silicate based liquid material that can be mixed with sand to form a core. It is an easy binder to use because it is a "no bake" product that doesn't require a drying oven. This core binder is NOT PURE SODIUM SILICATE, but rather a mixture of sodium




					www.budgetfoundrysupply.com
				



(Sets with CO2).

Here is sodium silicate








						Clay Planet - Ceramic Supplies, Clay & Glaze Manufacturer - Powered by Network Solutions.
					

Clay Planet Ceramic & Pottery Supplies, clay supplies, glazes, ceramic clay, ceramic glazes, claymaker, pottery tools, kemper tools, ceramic tools, pottery wheels, pottery kilns, ceramic kilns, glass kilns, pottery clay, ceramic clay, skutt kilns, cress kilns, L&L kilns, paragon kilns, olympic...



					shop.clay-planet.com
				




or Chembond 4905, which I think is a sodium silicate binder hardened with a catalyst








						Clay Planet - Ceramic Supplies, Clay & Glaze Manufacturer - Powered by Network Solutions.
					

Ceramic Supplies, Pottery Supplies, Clay Supplies, Ceramic Glaze, , Western Glaze, online ceramic shopping, ceramic store, leslies ceramics, aftosa



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I have used sodium silicate with CO2 for cores and molds.
I have not used Chembond with a catalyst yet, but plan to try it.


The downside to sodium silicate sand is that it tends to stick to the pattern, and so you need generous wax or other release agent.
Sodium silicate is normally set with CO2, which requires a CO2 tank, regulator, etc.
Note that putting dry ice in a sealed container can cause the pressure to exceed several thousand pounds in a short period of time, and cause failure of the container.  I have read warnings about this online.

Sodium silicate can also be hardened with a catalyst, and the standard catalyst that can be found sets the sand in 45 minutes.
There are catalysts that set sodium silicate more quickly, but they can be difficult to source.

I am told that sodium silicate bound sand works with iron, but I have not tried it yet.
I don't know if sodium silicate bound sand works with an alcohol-base mold coat, and have not tried that either.
.


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## GreenTwin (Jul 10, 2021)

awake said:


> Would a ball mill work for mulling sand?


A ball mill seems to be a lot like a concrete mixer with weights in it.
I did mull some greensand that I tested (I did not like the surface finish results of the greensand I tried, and so reverted back to resin-bound sand).

The problem I see is the sand/clay packing against the outside.
With my very slow rotating concrete mixer, when I was mulling some greensand for a test (without the internal mixer blades installed), I uses a boat paddle to scrape the sand off the walls of the mixer.
A rather crude affair at best, and no substitute for a good muller.

.


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## dazz (Jul 11, 2021)

View attachment 127237


I have done some research on burners. 

The purpose of a high swirl swirler combined with a cone spray nozzle is to create a low pressure zone in front of the nozzle that draws in a reverse flow of combusting fuel/air.  This is rather like holding a blow torch in front of the burner nozzle, and pointing it back towards the nozzle, to create stable ignition.

The burner in the photo above is a low swirl burner.  It has a core of airflow around the nozzle.  Around that is a low swirl air flow.  This is supposed to locate the flame front away from the nozzle and to create a shorter and wider stable combustion zone.     Just what you need for a small domestic water heating furnace, or for a home foundry furnace. 

The literature is consistent in saying that flame impingement on the furnace walls is a bad thing.  Unavoidable for foundry furnace but it could be mitigated.

My intention is to try the low swirl burner as supplied.  If it works, I will use it.  If not, I will experiment. 

Dazz


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## GreenTwin (Jul 11, 2021)

dazz said:


> Just what you need for a small domestic water heating furnace, or for a home foundry furnace.


I think it can be a mistake to assume that a foundry furnace will act like a commercial heating unit.
The furnace is round, and the combustion area is narrow and limited, which can be different than a commercial heating unit combustion chamber.

I have read (but cannot prove) that a narrow flame distribution is better for a furnace to prevent flame impingement on the crucible.
Direct flame on the crucible will greatly shorten its life.



dazz said:


> My intention is to try the low swirl burner as supplied. If it works, I will use it. If not, I will experiment.


What we do know is that your burner arrangement will work well with a heating unit.
The only difference I see with what I and many others use and yours is the spin vanes.
Some folks use spin vanes and some do not.
Some started out using spin vanes, only to discard them later.
I don't use spin vanes.

I am not sure what angle your nozzle is designed for (the angles vary).

So as you suggest, try your burner unmodified, and if it works well, then your work is done.
If it has problems, it would be easy enough to either cut out most of the vanes on the spin vane piece, or use pliers to straighten them to be almost parallel to the air flow.
I don't think it will requiring much effort/modification (if any) to make your burner work correctly.
That configuration is almost identical to what most siphon-nozzle foundry folks use.

The pressure return line with needle valve is where I think you will need to modify things a bit.
But if it works well without a return fuel line and needle valve (unmodified), then stop right there and use it as-is.

The expression is "don't fix things that are not broken".

Edit:
Here is a test I did on my siphon-nozzle burner, to study the compressed air pressure effect on the way the burner operated.
What I discovered in the test is that under about 30 psi compressed air, I don't get full atomization of the fuel (especially when the burner is attached to the furnace).
If you turn the compressed air down enough, you just get a stream of liquid fuel out the tip.
This test was run on diesel.

Note: Don't turn the burner towards your face during a test on a windy day, or you may singe/burn off your eyebrows as I did at 3:36.
Of course you should have sense enough to have a full facemask on during the test.  I think I only had safety glasses on.

Also note that this test does not use combustion air (the blower is off), and so is not an exact test, but an approximate one that allows you to see the atomization that occurs with various compressed air pressures.  You can use more than 30 psi compressed air pressure, but more pressure does not make the burner operate hotter, and may actually make it run cooler.
The science of fuel oil combustion is not that simple, and a finer droplet size is not necessarily one that burns hotter.
It is more a matter of getting as much surface area of the very hottest flame around the droplets.

Diesel is rather tame fuel as far as flammability.
Kerosene is noticeably more flammable than diesel.
Kerosene would work just as well as diesel, but for some reason kerosene is about four times more expensive than automotive diesel in this part of the country.



			https://vimeo.com/user82094693
		


.


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## dazz (Jul 11, 2021)

Hi
My reading is that high pressure nozzles have a narrow range of working pressure, centred around 100psi or so.   I expect to buy a selection of nozzles to try so I can find the right one.

Preventing flame impingement in a small furnace filled with a crucible is unachievable.  I think some things could be done to reduce impingement.  eg.  Shape the furnace interior so the fuel nozzle is set back to give some volume for "normal" combustion to happen before the flame hits the wall.  A short wide flame should maximise energy intensity in the confined space of a furnace.

Combustion is clearly a really complex process subject to a lot of variables that are unlikely to be controlled or measured in a backyard setting.


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## dazz (Jul 11, 2021)

Hi 
What to people use for fuel containers???
I am thinking of using metal jerry cans with a modified all-metal pouring spout to create a fire and hot metal resistant fuel supply.


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## Ed T (Jul 11, 2021)

Possibly dragging this further off subject, but here goes. I have been planning to do some casting for some time and I have gathered all the bits needed to do it. AFA burners go, there seems to be a lot effort put into making various kinds, all of which seem to work adequately if not efficiently. Why wouldn't an ordinary fuel oil gun burner work? It seems that it is already designed to do exactly what is needed and comes in a nice compact package and uses readily available fuel which is reasonably priced. There must be a reason that I have never seen it done. Comments?


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## GreenTwin (Jul 11, 2021)

dazz said:


> What do people use for fuel containers???


I was using 5 gallon plastic containers for fuel, and I was not that pleased with those.
The new fuel containers have so many safety features on them that the are almost impossible to use.

For bulk transport from the gas station to home, I use these containers.
They can be a bit heavy when full, but I don't need very many of them, and only have to lift them down out of the van to the ground, where I can wheel them around after that with a two-wheeler.

I intend to pump the fuel from these containers (I have two) over to my operating fuel tank for the pressure nozzle, which I will show below, so I don't actually ever lift and pour these containers.


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## GreenTwin (Jul 11, 2021)

For my siphon nozzle burner, I used a new 40 lb propane tank (never cut into a used propane tank); the new tanks are empty and clean.
The siphon nozzle fuel tank runs with diesel and operates with 10psi on it, and has a 30 psi safety valve in case of air regulator failure (I know of one person who had a regulator failure and it overpressurized his fuel line and blew the fuel line off the fitting.  He had a big inferno in just a few seconds.

I am going to retire my siphon nozzle burner, so that I don't have to operate an air compressor anymore, and will transition to a pressure nozzle burner, which is almost exactly like dazz's above.

This is the fuel tank I will use with the pressure nozzle burner, and it will not be pressurized.
It will have a supply line from the tank to the burner, and a return line from the burner to the tank.


----------



## GreenTwin (Jul 11, 2021)

Ed T said:


> Possibly dragging this further off subject, but here goes. I have been planning to do some casting for some time and I have gathered all the bits needed to do it. AFA burners go, there seems to be a lot effort put into making various kinds, all of which seem to work adequately if not efficiently. Why wouldn't an ordinary fuel oil gun burner work? It seems that it is already designed to do exactly what is needed and comes in a nice compact package and uses readily available fuel which is reasonably priced. There must be a reason that I have never seen it done. Comments?


When you say "fuel oil gun burner", I assume you are talking about a packaged burner unit like the Beckett unit below?





I have seen one person use a packaged burner system with their furnace for a while, and then they changed to a more traditional burner tube / nozzle arrangement with remote mounted gear pump.

*Packaged Burner Assemblies:*

There are several problems I see with using packaged burner with a foundry furnace, as follows (I have not used a packaged burner):

1. A packaged burner is a rather bulky assembly, and that would make getting the burner tube in exactly the right place at exactly the right elevation would be far more difficult than just a burner tube.

2. The output tube appears to be about 4" diameter, which is really too large for many/most furnaces used for hobby work.
I guess the output tube could be changed to a 2.5" diameter tube?

3. All furnaces sooner or later will leak hot gasses past the burner tube at the tuyere (the tuyere being the entrance low in the furnace).
When the tuyere leaks, and generally before you notice that it is leaking, anything that can be ruined/melted in the vicinity of the tuyere is melted/ruined, such as a packaged burner unit.

4. When a furnace is open, and the crucible is pulled out and set on the ground, the radiant heat is very intense (this is especially true for an iron furnace).
The radiant heat will melt plastic 10 feet away, so I tend to think that over time it would ruin a packaged burner unit.

5. My general rule is that anything in the furnace area (say a 20 foot radius around the furnace) should not be plastic; this includes wheels, and anything else.
There are a lot of furnace photos out there with melted plastic wheels, and melted plastic burner parts/gauges, etc.
The only thing that is plastic/rubber in the furnace vicinity is the fuel line, and that is somewhat at risk.
I intend to slide a piece of flexible metal conduit over my fuel line, to give it mechanical protection, and also to give it heat protection from spilled metal/slag.

*Comments on hot-tube burner designs:*

The burner tube should remain cool to the touch along most of its length, except perhaps right at the furnace end, which may get a little warmer, but not really hot.  There is a school of thought that the burner tube should be operated red hot, and a type of burner that uses a flame impingement out of the side of the furnace and onto the burner tube, I guess with a drip-style burner, to assist with atomization of dripped fuel.
I think that for a typical backyard foundry application, there is no need to run a hot-burner-tube design, and many many reasons why you should not run a hot-burner-tube design.

The main reasons that a hot-burner-tube design is not desirable is that it tends to cook whatever is inside the burner tube, and build up varnish on the hot surfaces, and the burner tube steel will degrade over time, even if it is stainless steel.
But the #1 reason why I don't use a hot-tube-burner design is that it does not work any better than a cold burner design, and I have seen some folks have a lot of problems with their hot-tube burners.
Why introduce new "features" to a burner that are known to cause problems?  (Short answer:  Because you can get millions of views and likes on ytube featuring all sorts of Rube Goldberg burner deigns).

There are folks out there who make burners and such seemingly only for the purpose of proving that they can make a better (new and improved better mouse trap) burner, and so there are droves of burner styles that actually will melt metal well, and they are almost universally of a bad design from the standpoint of providing a maintenance-free burner that operates consistently every melt without the need for adjustment during the melt.

There are folks out there who embark on multi-year Don Quixote type quests to design and build the ultimate foundry burner.
The problem is their quest never seems to lead to a functional new burner type, or if the burner does function, it functions in a highly unreliable way that often will not melt iron.
There are numerous burner folks out there in videoland, and many/most never cast anything, or anything of any value other than a lump of metal.
For the professional burner builders, its not about foundry work and casting usable parts; it is about endless burner experiments, and maximizing ytube views.

I have done my share of burner experiments, and have done enough to have a good feel for what works for an oil burner.
When it comes to oil burners, I can say that a cool burner tube and proper atomization of the fuel are what is important to good burner operation.
Beyond that is just a matter of how you want to assemble the parts.

I have never gotten a drip-style oil burner to operate or control correctly, or burn cleanly at all output levels, and so I don't use that style.
A siphon nozzle burner will burn cleanly and control precisely at any fuel flow level within its designed operating range, which is a very wide range of outputs.
A siphon nozzle burner will operate without combustion air (it will naturally aspirate if the combustion air tube is left open), for smaller melts, and most folks are not aware of this function.

*Summary:*

My siphon and pressure nozzle burners weigh perhaps 5 lbs, and their critical components are located far away from the furnace, out of heat range and spilled metal danger.
It is easy to support my burner tube at the tuyere, and easy to adjust the height of my burner tube to work with multiple furnaces (I have more than one furnace, and the tuyere heights are not the same).

Everyone has their favorite burner and melting methods.
I can't say what works best for others, but I can say what has proven to work well for me.
To each their own, but in my mind the real proof is in the quality of the castings created.
"Show me the castings" as they say, and then we talk about burners.

Edit:
I do know of folks who make very good castings, and use very problematic burners.
They use the fact that they can make very good castings to justify using their problematic burner style.
I make quality castings, and my burner is maintenance-free, and does not require adjustment every.
I see no justification for using equipment that is problematic.  Would you drive a car that breaks down constantly?  Some do; I am not sure why.

.


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## GreenTwin (Jul 11, 2021)

*Furnace heat stratification* is an interesting topic with home foundry burners.

The general consensus is that once the furnace interior is up to its maximum operating temperature, then fuel/flame stratification is not important.
I am not sure I agree with this consensus, but I can't prove it to be incorrect either.

I have been told by many that once the furnace interior is up to temperature, you cannot puddle fuel in the bottom of the furnace, since it would vaporize immediately.
I know for a fact that you can indeed puddle a lot of fuel in the bottom of a furnace when it is red hot, and this is a dangerous thing, since the fuel could flash and cause a lot of problems.
Fuel puddling inside the furnace means that your burner is not atomizing the fuel correctly, or your nozzle tip is too far up in the burner tube, and so the spray is impinging on the side of the burner tube and dripping into the furnace, instead of being injected into the furnace via an atomized spray.

Many backyard casting folks (myself included) elevate the crucible in the furnace as high as possible on a plinth, because the top of the furnace is hotter than the lower portion.

If you think about it (you can also directly observe this inside the furnace) the fuel/air mixture is entering the furnace at ambient outdoor air temperature, and so the region in front of the burner tube is at ambient air temperature (approximately).
You can see the effect in the photo below.
The green arrow indicates the coolest part of the flame, and it is what I call the pre-combustion region.


----------



## GreenTwin (Jul 11, 2021)

The hottest part of the flame I think is the brilliant yellow region, but that region is basically limited to 1/2 the furnace.

A dual 180 degree burner arrangement solves the uneven flame distribution problem, and I have tried a dual 180 degree burner previously, as shown below.
Where the dual 180 degree burner arrangement works better for the average backyard melting person is a topic of discussion.
Most backyard folks successfully use a single-tube burner like the one in the previous post, and they work well in this arrangement.

This is a view of the interior of a furnace operating on two siphon nozzle burners at 180 degrees.
The flame is even around the crucible, and the combustion air velocity is divided by 1/2 for each burner tube.
The lower combustion air velocity helps keep the flame low in the furnace, and reduces the tendency of the flame from striking the back wall of the furnace opposite the burner tube and then climbing upwards towards the lid.

At some point I will probably transition back to a dual 180 degree burner arrangement.
At the time I was experimenting with the dual burner setup, I did not know how to melt iron, and so I was unable to gauge how the dual burner worked compared to a single burner.


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## GreenTwin (Jul 11, 2021)

Here is a good example of the wall climbing affect that happens with a single burner tube.
The wall climbing does not seem to adversely affect the furnace operation, but it makes me wonder if I could save a bit of time with a dual burner 180 degree arrangement that did not wall climb.


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## dazz (Jul 11, 2021)

Hi
Having never seen a package burner, never done any burner experiments and never cast iron, I looked at the packaged burner option and rejected it.   They are too expensive to buy and to ship.    They are all designed to operate on the cold side of an insulated furnace wall so they have meltable plastic fittings.  They are not designed to be modified, so any sort of experimentation could require a lot of work.

High pressure low swirl nozzle burners work differently to commonly used backyard casting furnaces, in almost every respect.   I anticipate experimentation will be required to end up with a usable design.    That is where my complete lack of experience will help because I will be unencumbered by the irrelevant knowledge gained from other burner types.    At least that is the theory.   Reality tends to wreck theory.


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## GreenTwin (Jul 11, 2021)

The logical response of some to prevent the cool spot in front of the burner tube inside the furnace is to use what I call a pre-combustion style burner.
One example of a pre-combustion burner is the Ursutz type.
I built and tried an Ursutz, and did not care for the bulkiness of it, the radiant heat from it, the rapid degradation of the burner metal due to oxidation, the poor control, etc.

Problems with the Ursutz design:

1. If made from metal, the metal will degrade over time and fail, often in a dangerous way.
2. The Ursutz burner at full output works too well, and it causes rapid crucible and plinth failure, which defeats any gains from using this style of burner.
3. The Ursutz is heavy, bulky, difficult to handle and store.
4. An Ursutz burner made from a high-grade, high-temperature refractory will last for a while, but then will need to be rebuilt.
A good siphon or pressure nozzle burner never needs to be rebuilt.

Here is a photo of my Ursutz-style burner in operation:


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## GreenTwin (Jul 11, 2021)

dazz said:


> That is where my complete lack of experience will help because I will be unencumbered by the irrelevant knowledge gained from other burner types.


This is absolutely true, and I have seen more than once where someone comes up with a better design simply because they were unaware of what what others told them would not work.
I have done this myself.
Better to start without being encumbered by what other's think works and does not work.

That being said, the folks that routinely cast a lot of iron successfully that I am aware of use either a siphon nozzle or drip-style oil burner, with an occasional propane burner guy jumping in to prove that cast iron can be melted with propane/natural gas.

I think more if not most would use a pressure style burner like you are designing if they had that design in front of them, especially if you could demonstrate that it functions well.
I have seen at least one video of someone demonstrating a pressure-style burner.
I will look for that.

.


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## GreenTwin (Jul 11, 2021)

Here is an example of a pressure nozzle setup, with a commercial heating unit.

My setup for my pressure nozzle will be very similar, but my gear pump will run at 1725 rpm, and will send 100 psi to the nozzle.

Good filtration is a must with a pressure nozzle.
I am going to put my spin-on fuel filter on the low pressure (intake) side of the gear pump.
I am not sure a spin-on fuel filter is designed to operate under pressure, and I will not operate mine on the 100 psi side of the gear pump.

I will have to study this video a bit more to get a full understanding of how he is using all of his components, but this is how you can remotely install the gear pump from the pressure nozzle/burner.

I think this person is using the gear pump more as a means to send a constant pressure to his packaged pressure nozzle burner, but with this arrangement, you could omit the packaged burner completely, and just use a pressure nozzle in a burner tube, as jazz is proposing (he would still need the combustion air blower).
He is basically running two gear pumps in series.
The gear pump at the packaged burner increases the fuel pressure to 100 psi, and the gear pump at the fuel tank provides a consistent low fuel pressure to the input side of the packaged gear pump.
More complex than it needs to be, but it does look like it accomplishes what he is trying to do, which it not have burner fluctuations due to temperature changes, and so a successful project build.

Edit:
I see what looks like a compressed air pressure regulator at the packaged burner, which seems to indicate that he is using a siphon-nozzle burner with his packaged unit?  I will have to study this, but anyway, it does demonstrate a gear-pump in action.


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## dazz (Jul 11, 2021)

GreenTwin said:


> ...
> This is a view of the interior of a furnace operating on two siphon nozzle burners at 180 degrees.
> The flame is even around the crucible, and the combustion air velocity is divided by 1/2 for each burner tube.
> The lower combustion air velocity helps keep the flame low in the furnace, and reduces the tendency of the flame from striking the back wall of the furnace opposite the burner tube and then climbing upwards towards the lid.
> ...



I suspect that a low swirl pressure nozzle  burner, that does not require a high velocity compressed air flow, will achieve the same benefits of a two burner siphon nozzle burner.  A short wide  (high intensity) flame should help reduce wall climbing.



GreenTwin said:


> ...
> The wall climbing does not seem to adversely affect the furnace operation, but it makes me wonder if I could save a bit of time with a dual burner 180 degree arrangement that did not wall climb.
> ...



With a closed container like a furnace, it is relatively easy to calculate the thermodynamic heating effects of surface radiation.  It turns out the thermal radiation from the furnace walls is really important.  The time required for a burner to heat the furnace walls is dependent on the thermal mass of the hot face and beyond.   If you want to save time heating metal, try building a furnace with a thin light hot face, backed by really good insulating material ( = low thermal mass).    At least, that is the theory.


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## GreenTwin (Jul 11, 2021)

One guy online uses a high-pressure relief valve on the pressure side of the gear pump, so if the nozzle clogs, then the relief valve opens and returns fuel to the fuel tank.

I think I will add one of these to my pressure nozzle setup.

.


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## GreenTwin (Jul 11, 2021)

dazz said:


> If you want to save time heating metal, try building a furnace with a thin light hot face, backed by really good insulating material ( = low thermal mass). At least, that is the theory.


Yes that is exactly what I did with my second furnace, and it heats up much faster than my first high-mass furnace.

.


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## GreenTwin (Jul 11, 2021)

The pressure nozzles come in solid and hollow cone styles, with varying angles.

I am going to try a solid cone (blue), 2.5 gal/hr, 45 degree angle first, and see if that works.
















.


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## dazz (Jul 12, 2021)

*Gear Pumps*
I have noticed that shaft driven gear pumps are normally fitted to package burners.   I think that is probably so that if the fan stops, so does the fuel flow.  A really good safety feature for unattended boiler operation. 

My electric pump will continue to run if the fan stops.  I think that will be OK for attended casting operation.  It also means if I have got the wrong sized fan (highly likely), I can make a change without needing to modify other items.   Other than that, as long as a pump of any type can reliably deliver fuel at pressure, it doesn't matter.

*Propane Fuel*
This is something I do know about.  Any form of gas fuel would be a poor choice for a DIY furnace because the gas takes up more space than a heavier liquid fuel.  As a result, there is less volume available for air, leading to low energy density in the furnace.   Diesel has greater peak energy density than natural gas-by a factor of more than of three (generally 129btu versus 37btu).    It will take longer to heat a melt with gas.

The solution is to pressurize the furnace to raise the energy density.  Not practical for a home furnace.  It is done at a larger scale.  The GE LMS100 gas turbine generator has a strengthened CF6 engine at its core.  On liquid aviation fuel, the CF6 engine puts out around 50MW when installed on a 747.  The LMS100 includes a compressor and inter-cooler (like a turbo-charged car engine) and puts out over 100MW burning natural gas.    So yes I can see that burning propane to melt iron is possible, but so is poking a stick into your eye. 

*Burner nozzle set back*

I think it will be desirable to locate the nozzle about 5cm to 10cm from the interior of the furnace hot face (set back), so the flame has time to heat the air before hitting the base of the crucible.   This may require some bell mouth shaping of the turere to accommodate the combustion zone, a little like a rocket engine.     What is the best setup?  The answer is that I don't think anyone knows the answer, so this will be something that requires a lot of experimentation.

The same for nozzle spray pattern.  I have gone for a hollow cone type nozzle because this will maximise the fuel in contact with the air.  The volume where the fuel and air will burn (pure air doesn't burn.  pure fuel doesn't burn) is a thin sheet.   Is that the right choice?? Who could know without trying it.

*Fuel Tank / Line*
I agree with your choice of steel fuel tank and protected fuel line.  I plan something similar.  Safety first.


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## GreenTwin (Jul 12, 2021)

dazz said:


> *Burner nozzle set back*
> 
> I think it will be desirable to locate the nozzle about 5cm to 10cm from the interior of the furnace hot face (set back), so the flame has time to heat the air before hitting the base of the crucible. This may require some bell mouth shaping of the turere to accommodate the combustion zone, a little like a rocket engine. What is the best setup? The answer is that I don't think anyone knows the answer, so this will be something that requires a lot of experimentation.
> 
> The same for nozzle spray pattern. I have gone for a hollow cone type nozzle because this will maximise the fuel in contact with the air. The volume where the fuel and air will burn (pure air doesn't burn. pure fuel doesn't burn) is a thin sheet. Is that the right choice?? Who could know without trying it.


I have noticed that nozzles are very prone to drip into the furnace if they are not about 1/2" from the furnace end of the burner tube.
You may get a combustion zone working, but I could never get that to work without dripping into the furnace, and I seen others getting the dripping when they deviate from the 1/2" dimension.

I suspect it will not make any measurable difference between a solid and hollow cone, but I have not tested that.

It may make more of a difference with the spray angles, especially if it is so wide that it causes dripping.
I have not tried a wide angle nozzle, so I am not sure if it would work with a furnace.
My guess is that the flow of combustion air coming out of a 2.5" diameter burner tube will tend to create a narrow slip stream that would probably drag along the nozzle discharge at a wide angle.

.


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## dazz (Jul 12, 2021)

Hi
A dripping nozzle would be a safety issue and something to watch for.    

Unless the nozzle spray shape causes some significant problem or deficiency, I don't think it will be practical to see any meaningful difference.

I am thinking of achieving burner set back by adjusting the shape of the furnace in the immediate vicinity of the burner as conceptually shown in the attached sketch.  The attached sketch is a view of the bottom section of a proposed furnace. The furnace is truncated in the drawing for clarity.
Above this section, the furnace would be the conventional cylindrical shape.

The aim would be to provide a reasonably clear volume for the flame to form and burn before impinging on the furnace wall or crucible.    That should improve the performance of the furnace.  

Dazz


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## GreenTwin (Jul 12, 2021)

There was one guy who used a pool noodle (round foam) to make a spiral in the cast refractory low in the furnace.
I considered that, but did not use it since it made the furnace design much more complex, and more difficult to repair.

I think his idea was to give the air and fuel one good spin to reach full combustion, while holding that first spin low in the furnace.
I never heard back from him how it operated.

I think you are using a similar technique.
If I were making such a shape, I would extend the tuyere out, but not change the round shape of the furnace.
I sort of did this with my 2nd furnace, but it was from the standpoint of having a longer tuyere so that the burner tube would have enough area to seal correctly.

My tuyere extension was removable, which can be a good and bad feature.
If you used a removable tuyere extension, then you could try different sizes and shapes.

That is my 2 cents on giving more combustion area.

If you did use your design below, you should extend out the end of the spiral slightly, so as to start to turn the air before it strikes the flat wall on the left, otherwise you could disrupt the combustion air flow.

I will post some photos of my 2nd (120 lbs of cast refractory) furnace, which was a fraction of the weight of my first furnace.

.


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## GreenTwin (Jul 12, 2021)

The only things I would change on this furnace are:

1. Bring out a lip on the top of the hot face, to make a 2" wide sealing joint, where the top of the hot face contacts the lid refractory.

2. Make the tuyere extension from soft 2,600 F fire bricks, and use a hole saw to drill the burner tube opening in them.
I am going to retrofit this change to my furnace #2.
The bricks will be flat on the bottom, and so will rest on the base, and not rely on the hot face or a strap for support.


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## GreenTwin (Jul 12, 2021)

Furnace #2 build:


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## GreenTwin (Jul 12, 2021)

Furnace #2 build:


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## GreenTwin (Jul 12, 2021)

Furnace #2:


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## GreenTwin (Jul 12, 2021)

Furnace #2:


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## GreenTwin (Jul 12, 2021)

Furnace #2:


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## GreenTwin (Jul 12, 2021)

Furnace #2:


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## GreenTwin (Jul 12, 2021)

Furnace #2:


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## GreenTwin (Jul 12, 2021)

Furnace #2:


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## GreenTwin (Jul 12, 2021)

Furnace #2:


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## GreenTwin (Jul 12, 2021)

Furnace #2:


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## GreenTwin (Jul 12, 2021)

Furnace #2:


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## GreenTwin (Jul 12, 2021)

Furnace #2:
I would never build another furnace without using some plastic refractory, especially for the domed lid.

Two layers of 1" ceramic blanket go over the insulating fire bricks, and then the stainless shell on the exterior.


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## dazz (Jul 12, 2021)

Hi
Furnace 2 looks like the product of a lot of learning and experience.  Nice.



GreenTwin said:


> If you did use your design below, you should extend out the end of the spiral slightly, so as to start to turn the air before it strikes the flat wall on the left, otherwise you could disrupt the combustion air flow.



Hi
I had considered this because I think the spinning air flow could collide with, and distort the combustion zone.  
So I thought that rather than mold a flat base, I could mold in a spiral ramp that raises the hot gas to just above the turere.    It is likely that the hot gas will spiral upwards anyway. so maybe not an issue.    

I could start with a flat base, then try just placing molded wedge shaped bricks on the base to form a spiral ramp.  Easy to try.

One of the advantages of using close fitting morterless bricks made with 3D printed molds that I posted much earlier, is that I can produce bricks in any shape quite easily.    If I do things right, it should be easy to dismantle/assemble the hot liner bricks for maintenance or replacement.    More importantly, I could make changes to the furnace shape by just changing the affected bricks.  Ideal for experimentation.  

Dazz


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## GreenTwin (Jul 12, 2021)

dazz said:


> It is likely that the hot gas will spiral upwards anyway. so maybe not an issue.


I think you are right about that.



dazz said:


> I could start with a flat base, then try just placing molded wedge shaped bricks on the base to form a spiral ramp. Easy to try.


Another good idea I think.



dazz said:


> One of the advantages of using close fitting morterless bricks made with 3D printed molds that I posted much earlier, is that I can produce bricks in any shape quite easily. If I do things right, it should be easy to dismantle/assemble the hot liner bricks for maintenance or replacement. More importantly, I could make changes to the furnace shape by just changing the affected bricks. Ideal for experimentation.


A LEGO furnace !
Yes not a bad idea at all, and there are commercial furnaces that are made in a similar modular way, which does allow for easy brick replacement.
If you have access to plastic refractory, you may not need to replace bricks, but you never know.

I think I linked this previously, and added the parts that I don't agree with that are stated in the MIFCO manual.
See page 34 for a B-301 furnace.
A B-301 is about the same as my furnace build #2.
Note that the B-301 is a dual-burner furnace, with two tuyeres at 180 degree spacing.



			https://mifco.com/wp-content/uploads/2019/12/B-C-furnace-manual-revised-12-19.pdf
		


.


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## Foketry (Jul 13, 2021)

GreenTwin said:


> Furnace #2:
> 
> View attachment 127525
> View attachment 127526
> ...



exceptional work !!!
what material did you use for (120 lbs of cast refractory) ?
how thick is it ?


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## GreenTwin (Jul 13, 2021)

The hot face is 1" thick Mizzou.
The 120 lbs includes the refractory for the lid, which is also Mizzou.


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## Ed T (Jul 14, 2021)

GreenTwin said:


> When you say "fuel oil gun burner", I assume you are talking about a packaged burner unit like the Beckett unit below?
> View attachment 127437
> 
> 
> ...


Thanks for taking the time to reply and for the experience based insight.


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## dazz (Jul 14, 2021)

GreenTwin said:


> A LEGO furnace !


Yes that's it.

Nice job on your hot liner.

The thing that is delaying my attempt at furnace building is a queue of unfinished projects.  If I started building a furnace, that would only add to the list of unfinished projects.       In the mean time I am looking and learning.

You have made repeated references to the amount of radiant heat from the crucible after removal from the furnace.  
I see a piece of sheet metal if often fitted to the lifting handle to shield the hands.
Has anyone considered using a light polished stainless steel shield around the crucible to reflect the heat back to the crucible??
Obviously the shield would need cutouts to avoid interfering with the pour, but even if the shield could wrap half way around, the radiated heat loss would be a lot less.

The melt should stay hotter for longer.


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## GreenTwin (Jul 14, 2021)

dazz said:


> The think that is delaying my attempt at furnace building is a queue of unfinished projects. If I started building a furnace, that would only add to the list of unfinished projects. In the mean time I am looking and learning.


I know the feeling well.



dazz said:


> Has anyone considered using a light polished stainless steel shield around the crucible to reflect the heat back to the crucible??
> Obviously the shield would need cutouts to avoid interfering with the pour, but even if the shield could wrap half way around, the radiated heat loss would be a lot less.


A shield around the crucible would most likely get in the way of pouring.
The trick with keeping the metal in the crucible at pour temperature is to do most of the skimming in the furnace.
I do the initial skim with the furnace/burner running, and use a long handled skimmer (I will be adding a heat shield to this skimmer), reaching through the opening in the lid.

I do another skim with the lid open, sometimes with the burner running, and sometimes not.
Often this skim is the last one I do, and unless I spot something floating, I don't skim the melt outside the furnace.

And I add ferrosilicon and stir it in while the crucible is in the furnace.

I like to do the lift out and pour within 60 seconds maximum, with iron, to keep the pour temperature as high as possible.
I have not measured the time-to-pour after I pull the crucible, but I will do that.
30 seconds would be even better.

Iron cools down very quickly after you pull the crucible out of the furnace, and you have to work fast, else you will get a partial mold fill.
With an induction furnace, or a cupola, it seems you can get some superheat with iron, and get an elevated pour temperature above what an oil furnace would produce, so you have a bit more time after pulling the crucible.

The art-iron folks use a synthetic ladle, which is quite light; I am not sure what the material is, and it is insulating, so the have a lot of time after tapping the cupola.

The art-iron folks often use old radiators, which have phosphorus in the iron, and so between that, the ferrosilicon, and the insulating ladle, and the cupola superheat, they seem to mill around for ages with the iron in the ladle before they pour.
You can't do that with a crucible with iron.  It basically has to be poured almost immediately after pulling the crucible.


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## dazz (Jul 15, 2021)

GreenTwin said:


> View attachment 127060



Hi 
Are you willing to post a CAD file of this drawing?
I want to change the dimensions to metric and blatantly plagiarize it.

Dazz


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## dazz (Jul 15, 2021)

Larry G. said:


> VelvaCoat from ASK Chemicals LP
> 495 Metro Place South
> Suite 250 Dublin, OH 43017
> Phone: +1 800 848 7485
> ...


Has anyone purchased from this company and used their product for iron casting?
Do they sell their products pre-mixed or as a dry powder?

Dazz


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## GreenTwin (Jul 15, 2021)

dazz said:


> Has anyone purchased from this company and used their product for iron casting?
> Do they sell their products pre-mixed or as a dry powder?


You generally have to go through a distributor in your area.

.


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## GreenTwin (Jul 15, 2021)

dazz said:


> Are you willing to post a CAD file of this drawing?
> I want to change the dimensions to metric and blatantly plagiarize it.


PM sent.
.


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## dazz (Jul 15, 2021)

GreenTwin said:


> You generally have to go through a distributor in your area.


That guarantees it is unobtanium for me.  I doubt there is a distributor within a few thousand miles.


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## dazz (Jul 15, 2021)

What is the recommended face shield??

The "proper" protection is gold coated but these are expensive. More so for me because I have to pay $$$$$ for shipping.

This video  Casting explosion and the importance of face shields  shows people wearing a variety. Clear and tinted plastic.   The metal mesh type, normally used by forestry workers.

I am thinking that the tinted plastic will likely melt as it absorbs/blocks the infra-red.  The mesh type look like a good option, combined with welding/safety goggles underneath.


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## dazz (Jul 15, 2021)

GreenTwin said:


> And I read a post today about making thin parts in machinable gray iron.
> I have read in several books that iron with high phosphorus should not be used to make engines.
> 
> So this guy who made a mini-V8 in gray iron said "I had to use old radiator scrap, which is high in phosphorus, due to its high fluidity".
> ...


I can't see how radiator scrap could make good iron for engine parts.
My plan is to use cast iron engine blocks because the metal properties and quality of the iron would be optimised for long engine life.


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## dazz (Jul 15, 2021)

It has been about 20 years since John Campbell published his first book on casting, yet I rarely see examples of his guidance being applied.
Here is an example of casting the John Campbell way. Only worth watching the first half.


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## GreenTwin (Jul 15, 2021)

dazz said:


> The "proper" protection is gold coated but these are expensive. More so for me because I have to pay $$$$$ for shipping.


I use a faceshield that fits onto a hardhat.
I have clear and tinted face shields.
I wear tinted glasses under the faceshield to protect from the IR radiation.

It is a good idea to wear some thin leather or something under the hardhat, and extending over the shirt/leather jacket collar, to protect the neck.

The plastic faceshields will melt easily if you lean over a bit to look into the lid opening.
I use a refrigerator shelf in front of the face shield when I have to look into the furnace.
I also have a metal mesh face shield, and it works well, but does not fit onto a hardhat.

.


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## GreenTwin (Jul 15, 2021)

dazz said:


> I can't see how radiator scrap could make good iron for engine parts.
> My plan is to use cast iron engine blocks because the metal properties and quality of the iron would be optimised for long engine life.


I use electrical motor end bells, but I believe that engine block gray iron would also work (one of those things I disagree with MIFCO on).

.


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## GreenTwin (Jul 15, 2021)

dazz said:


> It has been about 20 years since John Campbell published his first book on casting, yet I rarely see examples of his guidance being applied.
> Here is an example of casting the John Campbell way. Only worth watching the firs half.


I have John Campbell's book, which contains the 10 rules for good castings.
There are John Campbell believers/followers, and John Campbell's detractors.
However you feel about Campbell, I feel his 10 rules are important to making consistently high quality castings.

One summary of the 10 rules is here:


			http://pmt.usp.br/ACADEMIC/martoran/NotasFundicao/JOM-CampbellRules.pdf
		


and another link here:  (click on the NEXT link on the lower left side to go to the next rule)


			10 rules for good casting
		


As with all things foundry, I use a hybrid of rules.

1. Many use a pour basin; I do not; I pour right down the sprue, while keeping the sprue as short as possible.
Sometimes I use a ring of steel sitting on top of the mold, but it is not what I consider a pour basin, but rather a spill container.
I don't try to keep the ring of steel full, but rather focus on keeping the sprue full.
I keep the lip of the crucible as close to the sprue opening as possible, sometimes resting the lip of the crucible on the top of the mold (you can do this with bound sand).

Pours are not linear, and you have to be able to quickly adjust the pour rate during the pour.
Typically the flow is fast as you are filling the runners, and then slows as the gates begin to regulate the metal flow.
I often see folks spill metal all over the side of the flask when the runner(s) get full, but that can be anticipated and minimized; you don't have to spill any metal while pouring a mold.

2. I keep the sprue and runner about the same size (sometimes I oversize the runners), and try to make a smooth transition from vertical sprue to horizontal runner(s).

3. I use a spin basin at the end of each runner, with the runner entering the spin basin on the tangent.
My spin basins open to the top of the mold.  The spin basin(s) stop the bounce wave that occurs with dead end runners.  The bounce can eject metal through the gates in a sudden spray, which is undesirable.

4. I use gates at the top of the runner(s), with both the gates and runner(s) typically located in the drag or bottom half of the mold.

5. I initially pour quickly to fill the sprue, and then be sure to keep the sprue full at all times during the pour.
If you pause slightly during a pour and interrupt the pour, you will probably have a cold joint in the casting where the fill was interrupted and then restarted.

6. I don't use tapered runners.

7. The mold does not begin to fill until the entire runner system is full, and any impurities in the mold such as loose sand are swept into the spin cavity, along with theoretically any floating slag, and air-entrained metal caused by the turbulence of filling the sprue.

8. The gates control the flow into the mold cavity, and the gates tend to scrap any slag from the metal flowing down the runner (another reason to put the gates at the top of the runners).
The gates should be sized to allow a complete mold fill at pour temperature with the sprue/runner/gate size you select.
The gates should be sized to reduce the metal velocity to obtain a fill that is free of turbulence.
I often fill the mold cavity upwards, and use the gates at the bottom of the mold cavity (one of John's rules I think, don't waterfall into the mold cavity).
Molds will fill upward.  With bound sand, you need small vent holes at the high points in the cope, else you will trap air.
And cores should have vents in them/through them, with the ends of the core vented out the top of the mold.

9. I use smooth curves and transitions in the runners.  No sharp corners.
I often oversize the runners a bit to get a really hot flow of metal running down the mold before metal begins to fill the mold cavity.
Some folks do not use runners at all, but rather feed directly into the mold cavity from the sprue.   I think this is asking for problems.

10. High velocity and turbulence are two things to avoid when metal casting.

11. I use risers in strategic locations when I feel like there may be shrinkage in the part.
Keeping the ferrosilicon to a bare minimum keeps shrinkage to a bare minimum.

12. I keep the iron castings in the mold overnight, until they cool naturally.
Pulling iron castings out of the mold when they are hot can make the metal very difficult to machine.

13. Another of John's rules concerns keeping the thickness of the part even if possible (old castings generally have a consistent thickness).
If the casting has thick and thin sections, then the thin sections will solidify first, and then draw from the thick sections, which can cause hot tears.

14. Sharp corners should be avoided in castings/patterns.
Sharp corners often set up high stress points, which can turn into cracks/points of failure.

The methods above work well for me, and after I adopted them (after reading John's book) have provided very consistent and high quality iron castings that are easily machinable.

Everyone has their own sprue/runner/gate/riser layout favorite methods, and there is no one exact method that works universally.
If you come up with your own system, and it consistently produces high quality castings, then it really does not matter too much what that system is.
Generally speaking though, I think if you are producing high quality castings, chances are you are following many if not all of the 10 rules, and perhaps a few of your own.

.


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## GreenTwin (Jul 15, 2021)

dazz said:


> That guarantees it is unobtanium for me. I doubt there is a distributor within a few thousand miles.


If I did not have access to high grade refractory, I would look for hard fire bricks, and stack them in a circle.
Hard fire bricks actually work with iron temperatures, and they are used around the world to line wood stoves, pizza ovens, etc., so perhaps more obtainable.

.


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## dazz (Jul 16, 2021)

GreenTwin said:


> If I did not have access to high grade refractory, I would look for hard fire bricks, and stack them in a circle.
> Hard fire bricks actually work with iron temperatures, and they are used around the world to line wood stoves, pizza ovens, etc., so perhaps more obtainable.


I can get castable refractory for the hot face and lower temp soft insulating bricks or fibre for backing.
I have not seen plastic refractory but only a slim chance of finding it.
I can't get ceramic mold coating.

Catalogues only make me envious.


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## dazz (Jul 16, 2021)

GreenTwin said:


> I wear tinted glasses under the faceshield to protect from the IR radiation.
> It is a good idea to wear some thin leather or something under the hardhat, and extending over the shirt/leather jacket collar, to protect the neck.
> I also have a metal mesh face shield, and it works well, but does not fit onto a hardhat.


Steel mesh visors and helmets like the one shown are widely used in the forestry industry.  The neck protecting cloth in the picture will definitely not be heat resistant, but easy to change to something that is.
The ear protection might not be needed for a home furnace, but they are removable.  If left on, they would provide some level of protection to the side of the head.
The black plastic might melt but application of some heat reflecting adhesive tape would add protection from infra-red heat.

I think  a helmet/steel mesh combination looks like the best option for a home foundry.


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## dazz (Jul 16, 2021)

GreenTwin said:


> I have John Campbell's book, which contains the 10 rules for good castings.
> There are John Campbell believers/followers, and John Campbell's detractors.
> However you feel about Campbell, I feel his 10 rules are important to making consistently high quality castings.
> 
> ...


A good read.



GreenTwin said:


> As with all things foundry, I use a hybrid of rules.
> 
> 1. Many use a pour basin; I do not; I pour right down the sprue, while keeping the sprue as short as possible.
> . . .
> ...



Am I reading the GreenTwin 14 Golden Rules??


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## GreenTwin (Jul 16, 2021)

dazz said:


> Am I reading the GreenTwin 14 Golden Rules?


Some/most of these are John Campbell's rules.
The ferrosilicon is by trial and error, and watching what happens with other's shrinkage vs ferrosilicon level, as is the premature removal of the casting from the mold.

There is a guy named Bob Puhakka who is John Campbell's protege, and he runs a foundry in Canada.
Bob has made a few videos discussing how to make good aluminum castings.  Bob's videos tend to come and go, but he does show evidence of making very high grade aluminum castings using John Campbell's methods.
I have learned a lot about John's methods by observing how Bob Puhakka applies them in a commercial foundry setting.

.


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## dazz (Jul 21, 2021)

Hi

Here is a photo showing commercially made keyed refractory bricks.  The difference to mine is that I would mold specific shapes to form a furnace.
These are also a lot thicker than I was planning, but these will be for mens sized furnaces.  Not a little DIY backyard casting furnace.
At least I know the concept is proven.


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## dazz (Jul 21, 2021)

Hi
Attached is an image of a Ceramic Foam Filter, for use in casting iron, aluminium and other metals.  
These are made in China but I have seen them advertised elsewhere for 3x the price.


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## GreenTwin (Jul 21, 2021)

dazz said:


> These are also a lot thicker than I was planning, but these will be for mens sized furnaces. Not a little DIY backyard casting furnace.
> At least I know the concept is proven.


The industrial refractory business is very big.
I can't name all the industries that use it, but I suspect refineries, steel mills, etc.
I have seen photos of enormous rooms/chambers that are completely lined with refractory.

There are all sorts of precast refractory shapes available, as shown in the photo below.
I got the bright idea I would make a furnace lining from some of the curved shapes below, and got a quote on them, and WOW, the price!
It would be much cheaper to just line the furnace with gold than those precast refractory units.

I was able to purchase some 2,600 F insulating fire bricks for a reasonable price.

And the MIFCO furnaces use sections of refractory blocks in a modular fashion.


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## GreenTwin (Jul 21, 2021)

I used ceramic filters for several aluminum pours, and tried it with cast iron also.

The aluminum pours were successful with the filters.

The cast iron pours were not successful, but this was when I was still trying to learn how to melt gray iron, and I don't think my pour temperatures were high enough for use with a filter.
Now I use spin traps with iron, and no filter.

If you skim correctly, and use spin traps, slag inclusions are not a problem, and so a filter is not necessary.


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## dazz (Jul 22, 2021)

How much fuel is burned to do a melt??
If I used a 20litre Jerry can with diesel, would that be enough for a melt??
Would I need 2x Jerry cans?


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## GreenTwin (Jul 22, 2021)

Looks like 20 litre is about 5.3 gallons (we are in gallon land here).
I burn about 2.6 gal/hr (9.8 liters/hr) for my furnace dimensions, and an iron melt using a #10 crucible generally takes 1 hour (+ -), assuming you know how to tune your burner, which is simple, just adjust the combustion air for a few inches of flame out the lid opening.

I have seen people melt iron using a 5 gallon container, no problem, and I am sure it can be done if your burner is running at 2.6 gal/hr.
I think my smaller fuel tank is about 10 gallons, but for me it is more a matter of not wanting to have to refill it every time.

When I first started melting iron, I was not sure what the correct fuel flow should be, and so I would panic and open the fuel valve too much.
Too much fuel will drain your tank quickly, and will actually operate the furnace cooler than 2.6 gal/hr.

A given furnace will only pass so much air through it, and so the idea is to find the fuel flow rate that burns 100% of the fuel INSIDE of the furnace, or most of it inside the furnace at any rate.
Big flames out the lid are a total waste of fuel, but are impressive at night, if you are into the impressive sort of thing (some are).

.


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## awake (Jul 22, 2021)

GreenTwin said:


> If you skim correctly, and use spin traps, slag inclusions are not a problem, and so a filter is not necessary.



You mentioned spin traps before, and I am curious about what that is. Is this a particular shape you give to the sprue or basin or ??

Thanks so much for your posts - very informative!!


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## GreenTwin (Jul 22, 2021)

Gating and risering is an art, and not an art that many people agree upon.
My approach has been to find a method that works, and stick with it, while generally adhering to John Campbell's 10 rules for good castings.

Traditionally the layout used for the passageways into the mold cavity consisted of a pour basin (where you pour the metal initially into; located on the top of the mold), a tapered sprue, which conveys the metal from the pour basin vertically down to a horizontal runner or runners, which are often located at the junction between the upper mold (the cope) and the lower mold (the drag).

The runner(s) are usually V-shaped, probably so you can remove the runner form from the sand; I have used non-V-shaped runners and they work also.
Metal runs horizontally down the runner(s) to one or more gates.
The gate is the horizontal passage from the runner into the mold cavity.

The gates are generally rectangular, and generally narrow and thin.
Gates serve several purposes; they slow down the metal velocity, skim the slag off the top of the metal flowing down the gate (if you put your gates at the top of the runner), and allow the casting to be easily cut off from the sprue/runner/gate assembly after casting.

Much of the discussion I have seen by the folks who are making high grade castings in commercial foundries with virtually zero defects and zero rejection rates centers around metal velocity as it flows into the mold cavity.
High metal velocity is bad, since it churns air, sand, slag, etc. into the molten metal, and thus often causes defects in the casting.

Below are a couple of software simulations used for both fill and solidification.
One of John Campbell's rules is to not let a thinner section of the casting cool first and then draw metal from across the mold cavity from a thicker section, else you will get hot tears.


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## GreenTwin (Jul 22, 2021)

Another of John Campbell's rules is to avoid waterfalling, which churns air and debris into the casting.

To avoid waterfalling, I don't use a pour basin.
A pour basin seems to be what you want to avoid as far as splashing and entraining air and sand into the mold cavity.
I pour directly down the sprue, keeping the crucible lip as close to the top of the sprue as possible, and often the lip of the crucible touches the top of the mold.

At the bottom of the sprue, there needs to be a curved transition into the runner(s).
Traditionally a basin was used at the bottom of the sprue, but it has been found that this entrains air and debris into the metal.

The metal (for my layouts) travels down the horizontal runners (in the bottom part of the V-channel) to the spin trap located at the end of each runner.
The spin trap is nothing but a vertical hole in the cope sand, perhaps 1" or 1.5" diameter, that extends to the top of the mold cavity.
Without a spin trap, the metal will hit the end of the runner and bounce back, causing a jet stream of metal into the mold cavity, with ensuing air/slag/sand entrainment and casting defects.

The runner enters the bottom of the spin trap at a tangent, ie: the runner enters one side of the vertical hole, so that the metal spins as it begins to rise in the trap, and thus there is no bounce back and no sudden change in pressure when filling the mold.

The air, slag and debris caused by the initial filling of the sprue flows down the runner and into the spin trap.
By the time the runner is fully filled, and the level in the runner reaches the gates, the debris and entrained air have been swept past the gates and into the spin trap(s).

The gates then begin to fill the mold, and I often put the mold cavity in the cope, or as much as possible in the cope, to avoid waterfalling from the gate down into the mold cavity.  The mold cavity basically fills from the bottom upwards, which gives a smooth even fill with a velocity that is controlled by the gate size.

The sprue has to be kept full during the pour, else you will send a large amount of air down the runner system, which will generally give a defective casting.  An interrupted pour can also cause a cold joint in the casting, where the metal stopped flowing, began to solidify, and then started to flow again.

The fill has to be fast enough to completely fill the mold before any part of the casting begins to solidify, but slow enough to prevent a churning action.
You don't want the metal to have so much velocity that it acts like waves breaking on a shoreline.
If the metal is rolling like waves, and splashing/bouncing around, you will have defects in the casting.

I don't try to restrict the metal velocity with the sprue or runners, but rather use the gates to control the velocity.

The runner/spin trap method uses more metal than a system that does not use these, and so the crucible may have to be larger for a given pour.
There are many examples of people just filling a mold by feeding the sprue directly into the mold cavity, but there are also numerous examples of defective castings too.
People use shortcut and quick methods to make castings, and for simple work, and especially non-structural parts such as artwork, you can often get away with that.
There is always that person who violates all of the 10 rules for good castings, and gets seemingly perfect castings, but I think what really happens is that there are defects within castings made that way, and the defects may show up when you begin to machine the parts (inclusions, slag, hot tears, voids).
I have read many times that people purchase castings, begin to machine them, and then discover problems that makes the parts unusable, or the part fractures under stress.
I have no desire to try and find out what I can get away with, but rather I use a method that so far has produced 100% perfect castings inside and out.
Often people don't have time to lay out an effective sprue/runner/riser/trap/gate system, but they always have time to recast the part (often numerous times) when the casting turns out defective.

My motto: Do it once; do it right the first time.

For engine parts in gray iron like I make, and with resin-bound sand, it is tedious to mix and make up the mold, and so I want the castings to be defect-free on the first attempt.
So far, using resin-bound sand, and using my new furnace, I have never had to re-pour a cast iron part, and have not had any defects in the iron castings.

So the spin trap is just a vertical straight hole that goes from the end of each horizontal runner up through the cope and out the top of the mold.
The trap is offset from the centerline of the runner, so that the metal enters the trap on a tangent, and spins as it rises upwards.

For those who have machined their spin traps, they report that the top 1" or so of the trap metal is not usable due to slag, sand inclusions, voids, etc. which sort of reinforces the idea behind using the spin trap, ie: to sweep entrained air, sand, slag, etc. past the mold cavity, and not feed trash into the mold cavity.

I have not actually tried to machine a spin trap casting, but I believe they work, and I believe they prevent the splash-back into the mold cavity effect.

As I said before, show me a perfect casting, and section the casting (cut it down the center) to make sure it is void/inclusion free, and then I will consider a different sprue/runner/gate/trap layout; otherwise I use the method that works for me every time.
.


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## dazz (Jul 22, 2021)

GreenTwin said:


> I used ceramic filters for several aluminum pours, and tried it with cast iron also.
> 
> The aluminum pours were successful with the filters.
> 
> ...


My plan is to not try filters until after the inevitable casting failures.   I need to get good enough to the point where I might see an improvement in casting quality using filters.  That is likely to take a long time after a lot of failures.


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## GreenTwin (Jul 23, 2021)

For me it took a few steps.
I had to figure out pattern making (pretty easy), draft angle (relatively easy), and shrinkage (I use about 0.015 for iron).

Then I had to figure out how to set the correct fuel and air flow on the burner.

Next was learning how to handle the slag on top of iron.

Discovering ferrosilicon for machinability, and figuring out the exact amount to add.

Sprue, runners, gates, risers, etc. are pretty forgiving; I see all sorts of types that work pretty well (generally).

Sand conditioning (mulling/mixing).
Creating the molds (build some flasks first).

It is a multi-step learning process.
Master one step at a time, and you will probably be pouring good castings rather quickly.
I have seen one individual get it worked out in a month, with assistance/advice from a professional foundry.

It took me about six years to figure it all out to the point where I could match commercial iron foundry quality.

If you avoid all the trial and error, and blunders that I made, you can be making quality castings very quickly.

I know of one individual who was at a brass/bronze level, and the transition to iron for him was pretty easy.
He had a few defects in his first iron pour attempt, and had it all figured out on his second iron pour.

If you can get feedback from individuals who have poured a lot of iron (I received quite a bit of feedback from various folks), it makes things much easier.

.


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## dazz (Jul 23, 2021)

I requested John Campbell's book for my birthday in Sept.  It arrived yesterday from Amazon, but I can't read it until I receive my "surprise" birthday present.

I don't know anyone that pours hot metal, and the nearest professional foundry is 2 hours drive.  I want to do some horribly complicated engine castings so I expect to be doing a lot of trial and a lot more error.


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## GreenTwin (Jul 23, 2021)

I have followed an individual for several years who was the first to my knowledge to cast a V-8 engine all in gray iron.

If you can make the cores for a V-8 manifold, and successfully cast one of those in iron, chances are you are pretty good with the iron stuff.
Everything has to be exactly right to fill intricate molds, but as he has shown, it can be done.
It took he a while to figure it out.

.


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## dazz (Jul 24, 2021)

Here is what I am aiming to cast.  None of that simple easy stuff.  This is a compound engine top casing for a Yorkshire Patent Steam Wagon.  The prototype is only one of 3 remaining.  It is located in Invercargill, New Zealand.  It is an ugly duckling but quite unique.

The plan is to build a 1/3 scale miniature. This CAD drawing is produced from the factory drawings held in an archive in Leeds UK.    The green flange is the beginning of the centre casing.   The original full size casting was only 5/16" thick.  Too thin to cast to scale.

I am not going to start learning casting on this piece.  There are plenty of other less complex parts to make first.


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## GreenTwin (Jul 24, 2021)

There is nothing like a good challenge as I say, and that crankcase will take some thought.

Very nice 3D work there for sure, and a great unique (unique to me at least) engine.

There are several approaches to intricate castings such as the one you illustrate.
One is the "lost foam" approach used by industry to cast engine blocks and other objects such as pump housings etc. that don't lend themselves to a traditional pattern/sand mold method.
I have studied the lost foam method, but without the exact foam material, it would seem that the results are substandard.
And another problem with lost foam is the need to make a permanent/semi-permanent die in which to cast the foam.

Another approach is the "lost PLA" method, and this method actually works if you use a 3D printer filament that burns out cleanly.
The lost PLA lends itself to smaller parts though, mainly due to 3D printer size limitations.

Lost wax is similar to the other "lost xxx" methods, but again, it required making a rather intricate die in which to inject the wax.
I have not seen lost wax used on a large scale.

There were some intricate objects cast back in the old days such as lathe beds, or even steam engine crankcases, and these used greensand molds.
One engine in particular that I have studied extensively is the Soule Speedy Twin.
I live a few hours away from the factory that manufactured the Speedy Twin, and that factory is still intact, and most of the patterns and core boxes are still at the foundry that is located in a building adjacent to the factory.

The secret of the Speedy Twin engine casting was the ability to make some very intricate cores using I believe linseed oil and sand, which was then baked to create durable hard cores for the multitude of passages that are located in the top of a Speedy Twin engine.
Baked linseed oil cores were the early equivalent of the modern bound sand cores, and the results were very impressive for the early 1900 period.

Luckily the original Speedy Twin crankcase corebox is still at the factory, and I have studied it in great detail.

For complex castings such as steam engine crankcases, "retracts" are your friend.

The second secret to successful Speedy Twin crankcase castings is the extensive use of "chaplets".
Chaplets are small pieces of steel that are used to hold the cores in an exact position during the mold fill.
The chaplets become part of the castings, and are generally totally enclosed by the molten metal, or nearly totally invisible after casting a part.

Cores have a tendency to float or shift position while the mold is being filled, and the lifting force on a core is very significant, especially with iron.
Cores also tend to shift due to the stream of iron striking them during the mold fill, since iron is very dense.


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## GreenTwin (Jul 24, 2021)

The good part about copying an existing engine design that was actually manufactured is that you know that someone long ago was able to cast the part using greensand and perhaps baked cores.

For new designs, one has to figure out if the part can be cast without resorting to the lost foam or some similar method.

Here is the incomplete 3D model for the Speedy Twin.
The Speedy Twin is an extremely compact and powerful engine that was designed to operate sawmill carriages.
For many years, its performance (in measured output of sawn timber) was unmatchable by any other engine or even by electric motors.

The Speedy Twin is a unique engine in that it is fully reversible, and yet it only has two eccentrics (one for each cylinder), and it does not have a valvegear reversing mechanism such as a Stephenson's link.

The Speedy Twin has a D-valve for each cylinder, and the pressure is reversed on the D-valves when the engine is reversed, and yet the D-valves do not lift off their seats (I defy anyone to explain how this is possible; it took me a year to figure out how it can be done).


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## GreenTwin (Jul 24, 2021)

The good part about the Speedy Twin is that it seems to be a unique and highly functional "designed for a specific task" type engine, similar to the Dake engine.

The bad part about a Speedy Twin, if you intend to build one, is that the engine was way ahead of its time, and is an extremely advanced design, both in function and in the foundry work involved.  I have never seen a steam engine design like the Speedy Twin, and I think it is a one-of-a-kind design.

Luckily I ran across a disassembled Speedy Twin for sale a few years ago, and so I have all the parts for the engine; otherwise I don't think I would have ever figured out how it functions.

The Soule factory (now a museum) displayed one of the patent drawings for the Speedy Twin, with highlights in red showing how the steam flowed in the maze of passages.  I looked at that diagram for a year, and then told the folks at the museum that their diagram was incorrect.
They did not believe me at first, but I proved to them how the Speedy twin steam actually flowed in the passages on a working engine.

Here is a good video of a Speedy Twin being reversed.
The efficiency of the Speedy Twin design was that it could reverse the sawmill carriage very quickly, and since a steam engine produces 100% torque at zero rpm, the speed at which a Speedy Twin could return the carriage to the opposite position was unmatchable by any other mechanism available at the time.

Steam enters the steam chest on the top of a Speedy Twin, where it is controlled by the reversing valve, which is a single D-valve arrangement.
The exhaust is the hole on the right of the steam chest, and in the video, there is no exhaust pipe attached to the engine.


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## GreenTwin (Jul 24, 2021)

Here is a 3D print I made for the Soule museum folks.
It is not a complete design, but rather how far I had progressed on the engine at the time.
More of a table ornament type print, but it could be used to build an engine if the lost wax/PLA method was used.
It is an exact (not quite finished though) scale model of a Soule Speedy Twin.

There is speculation about how large or small of a scale the Speedy Twin could be built.
The museum would like a 1/4 scale model.
I am sure some out there could build a Speedy Twin at that scale, but then some models use microscopes to built model engine parts.

I am more of a big-scale builder, since I have trouble machining on a watchmaker's scale (or any small scale), and have further trouble seeing small parts.


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## GreenTwin (Jul 24, 2021)

dazz said:


> Here is what I am aiming to cast. None of that simple easy stuff. This is a compound engine top casing for a Yorkshire Patent Steam Wagon. The prototype is only one of 3 remaining. It is located in Invercargill, New Zealand. It is an ugly duckling but quite unique.
> 
> The plan is to build a 1/3 scale miniature. This CAD drawing is produced from the factory drawings held in an archive in Leeds UK. The green flange is the beginning of the centre casing. The original full size casting was only 5/16" thick. Too thin to cast to scale.
> 
> I am not going to start learning casting on this piece. There are plenty of other less complex parts to make first.


So back to the crankcase on this engine.

One thing I learned by trial and error is the art of transforming a 3D model into a pattern.

If a sand mold will be used, generally speaking (there are no absolutes in foundry work) there needs to be draft angle on all the surfaces (sometimes I do not use draft angle on parts, and there is an art to doing that successfully).
The draft angle allows the part to be withdrawn from the sand mold without damaging the mold.

The second consideration for creating a pattern from a 3D model is machining allowances.
The surfaces to be machined must have an extra layer of material added to them in the 3D model, so that when those surfaces are machined, they will have the correct dimensions.

And the correct shrinkage factor needs to be considered for any patterns that are 3D printed, ie: the pattern must be larger than the final cast part, since metal shrinks as it cools.  For gray iron, I think I generally use a shrinkage of 0.015 uniformly, which generally gets me in the ballpark and creates usable castings of the correct dimensions.

I suspect you will need several retracts, which are parts of the pattern that can be separated, and the retracts are generally doweled into the correct position, with the dowels allowing the pieces to be separated using a sliding motion.

I would definitely use bound sand for this piece (I use bound sand for everything including molds and cores).

.


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## GreenTwin (Jul 24, 2021)

For my 3D models that are converted into patterns, I sometimes use a coreprint, which is what was used on the Speedy Twin.
The coreprints are protrusions in strategic locations that allow for support of the cores, such as the bore cores.

Scaled down engine parts do tend to get too thin, and I often add material on the inside of the pattern, so that the outside of the casting remains to scale.

You can also glue multiple cores together, and that is yet another trick to successfully casting an intricate engine.
The core glue is a ceramic-type material generally what will withstand heat long enough to let the iron solidify.

I first thoughts on casting that crankcase would be to face the open window upwards, with the crosshead guides horizontal.
I would fill it from the bottom using two long knife gates.

Sometimes you have to cast a part that contains a window as a solid, and then machine out the window area, in order to get a complete mold fill.
I suspect you may have to do that to get that very thin part to fill.

Bore cores must be proportionally smaller than the final machined bore size, which is a way of adding machining allowance.

I don't try to cast bolt holes, although I have seen bolt holes accurately cast using the lost PLA/wax method.
It is easy enough to drill and tap a bolt hole, and I see no need to try and cast bolt holes.

.


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## GreenTwin (Jul 24, 2021)

For your pattern, I would probably section the crankcase through the crosshead guides, and anything protruding 90 degrees to that plan would have to be a retract of some type.

You could have one large coreprint coming out the bottom of the crankcase, and then use a modified 3D printed pattern as a corebox to make a core that captures all the interior details.

.


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## dazz (Jul 24, 2021)

Hi
The current 3D CAD drawings are straight copies of the original 2D drawings.    Once they are completed, I then need to scale the drawings and modify them to produce 3D drawings suitable for making patterns.  This includes machining allowances, pattern draft, filling in bolt holes, shrinkage, cores etc.

The factory drawings do not include any draft.  Changing the design/pattern to include draft would have a lot of downstream side effects.  It will be easier to make a complex, multipart pattern, than change the design to include draft.  Fortunately I already have a 3D printer.

I plan to use Sodium Silicate bound sand because it is obtainable.  

It will be a long time before I am ready to attempt to cast this.  The bottom case, and maybe the centre case, may be easier to fabricate rather than cast.


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## GreenTwin (Jul 24, 2021)

dazz said:


> The factory drawings do not include any draft.


I think much/most of the required draft angle is inherent in the design; ie: most of the surfaces are either sloped, curved, or circular in shape, and so I don't see the need for much if any draft angle that needs to be added to the model.



dazz said:


> The bottom case, and maybe the centre case, may be easier to fabricate rather than cast.


But much more interesting to cast because then you will know how to cast a lot of engines and other things.

I think I would split the crankcase into four pieces.
I would tape the interior of the patterns with blue painter's tape, ram the cope with two taped pattern pieces, ram the drag with two taped pieces, break the patterns slightly from the molds but leave the patterns in the molds, join the mold halves, and then ram the interior to make the core.

To remove the core, separate the two mold halves, and then remove 1/4 of the pattern at a time.

Piece of cake.

Sodium silicate bound sand will work I think as well as resin-bound sand.
Use plenty of wax or mold release on the patterns.
Sodium silicate seems to try to stick more to the patterns than resin-bound sand.

Here is an example of someone casting a large intricate engine part.
I would not have done it the way he did it (I recommended he make the entire mold all at once instead of in multiple parts).
Still an impressive casting, and so close to being a good casting.









						Bugatti T57/59 Engine Project
					






					oldschool.co.nz


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## dazz (Jul 25, 2021)

Hi 
All good advice. 

I foresee the problem with Sodium Silicate is that it melts at 1088 deg C, that's below iron mp.    So I would expect the sand in contact with the iron to become separated from the mold and embedded in the iron.  

I am wondering about doing a home-brew ceramic mold coating with something like Zirconium ceramic powder with a binder.  I can buy raw powder from China.   The problem being that I have no idea what chemistry is used in the commercial products.  There is absolutely no danger of me being able to by a proper foundry mold coating.  I may be over-thinking this problem.


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## GreenTwin (Jul 25, 2021)

I don't think I have ever tried using sodium silicate with iron.
Perhaps with a core or something; I can't really recall.

One of the reasons I switched from sodium silicate (when I was doing aluminum castings) to resin binder was that I only knew about the CO2 method of setting the SS bound sand.  Sodium silicate bound sand is very sensitive to SS percentage (3% max worked best for me), and very easy to over-gas, as well as undergas with a thick mold.
Any more than 5 seconds of CO2 gas on a SS core/mold, and you have ruined it.

A few years ago, I found out that SS can be set using a catalyst, and so I actually purchased some catalyst, but have not tried it yet.
The catalyst will cause all the sodium silicate to harden at the same time, throughout the mold or core, just as the resin binder does.
Sometimes with CO2, it can be difficult to inject into deep molds without missing a part of the mold.

I visited a local art-iron foundry in town, and noticed that they had both resin-bound sand and sodium silicate bound sand materials.
I asked them if SS could be used with iron, and they said yes, that the surface finish with SS sand was almost as good as with resin bound sand.

The thing to remember is that the bound sand only has to last long enough for the exterior of the metal to solidify.
Resin burns too, and it creates a charred interior of the mold, which I think actually helps with surface finish.
Since the binder is a small percentage of the sand, then the main point of contact between the molten iron and the mold is the face of the grains of sand, not the binder.

If a mold is made of some material that is too hard, supposedly it can cause a casting failure; not sure of the exact mechanics of that.

A buddy of mine makes his own sodium silicate, but I am not sure how.

.


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## Richard Carlstedt (Jul 25, 2021)

Dazz- Yours is a big order and I admire you for the undertaking of it.
Be sure to record your work.  Years ago I built a cupola and poured iron for my model steam engines.
There is much to learn about iron and fluidity has it's tricks . I was guided by a real iron metallurgist at the time who showed me some ropes
Are you going to pour it yourself or have a Commercial or Art Foundry do it for you ?
( pardon me for not reading all the threads to date)
My first comment is you should probably look at Silicon iron and definitely use a Vanadium additive. This will improve fluidity and machining immensely ( Vanadium) . Years ago this additive which is put in just before the pour was called "Hot Shot" as it creates a exothermic reaction ( sparks) and raises the temp of the pour which adds to being able to pour thin walls.

Remember 'draft" is only needed for withdrawing a pattern . I like the multipart sand molds shown in the Bugatti  video  and think you should consider using core molding sand (baked ) to assemble your mold.
The more complicated the part , the less "quick and dirty or easy"  effort is required .
Dynamic changes in part thickness are a bugaboo  ( Like  going from a 1/2" thick to 1/8" wall )
Flow becomes an issue , as the iron cools going through the mold and if it hits thin part , will be too cold, so how the iron flows is important.
You probably know these factors already , but your thread made me  remember issues i encountered
Good luck
Rich

If you use a foundry - be sure to spend time  "early" with them to get the parameters you need !


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## GreenTwin (Jul 26, 2021)

The guy who built the V8 in iron resorted to using scrap that had phosphorus in it, which is traditionally the material added to iron that is used for radiators and other intricate shapes that need extreme fluidity to fill completely.

The "books" say that for engine work phosphorus iron should not be used, due to problems with strength (if I recall correctly).
Obviously the V8 engine build proves that phosphorus iron will work on a model engine scale, and so the phosphorus scrap iron may be one option, as opposed to an exotic additive that may be difficult or impossible to source.

I am not going to resort to using phosphorus iron unless I get really desperate, but I think I can fill any molds I need to make without it, by using the correct pour temperature and ferrosilicon.

The base of my Frisco Standard engine is almost identical to the base of your engine, and I think I can get the base of the Frisco Standard to fill with multiple large runners in strategic places.  (screencapture below).
The key to thin fills is long knife gates.  You can see this in the work that people do casting thin plaques.

Ferrosilicon does help quite a bit with fluidity and with machineability of thin parts, and it is readily available from most foundry supply houses.
Ferrosilicon is not absolutely necessary for parts 3/4" thick and thicker, and I have cast parts without ferrosilicon, and they machine well as long as the part is perhaps 3/4" thick or thicker.

Having your burner tuned correctly is also critical to getting a very hot iron melt.
Getting iron melted and getting iron to pour temperature can be two entirely different things.
If the iron is slightly on the cold side, mostly likely it will not fill the mold completely.

I would also omit any filters when attempting to cast thin parts in iron.

It is easy to add superheat to aluminum, which is temperature above the pour temperature, and actually very easy to overheat aluminum.
Adding superheat to iron is not as easy with an oil burner, but I can be done with a properly tuned burner.
I have an optical iron-rated pyrometer, and I need to get it out and try using it again with my new furnace.
I would guess I am pouring in the 2500-2600 F range below.

You can tell when the iron is really hot because it begins to shoot out sparklers, which are tiny blobs of molten metal that look sort of like mini-fireworks.
I circled in green one of the sparklers from an iron pour where the metal was quite hot.
Also the reason you need to wear good leathers or similar protection during a pour; the sparklers fly in every direction.


----------



## Richard Carlstedt (Jul 26, 2021)

GreenTwin,  Very informative post !
I forgot about the knife gates .
Didn't know about the Phosphorus application .
 Used "Silver"  Coke  ( The best) in the Coke Cupola and had to  run my forced air supply through a 3 inch SS Tube first, that was buried in coals in a Weber grill to preheat the air for hotter pours. The Hot Shot kicked it up 300 degrees- added to the crucible at the moment of pouring .
Yes, Hot is good and Hotter  is even better for good pours .

Tip from the metallurgist -- to read the machine-ability of the Cast Iron part  even before touching it with a machine tool , do this 
Make a  Flat Wooden Wedge (pattern ) like the wedge in a old hammer handle 
Make it 3 inches long and 2 inches wide and taper the long dimension from 3/8" thick , down to 1/16"
Put a "V" groove on each of the long sides. make sure the V's match in location.
When ready to pour your Iron, stick the wedge into some sand  and remove it.
(you have made a miniature mold ) 
Now pour your regular mold and then pour the wedge mold 
When it is cold, place it in a bench vise  horizontally ( 3" wide x 3/8" deep) with the groove at top of jaw and hit it with a hammer, breaking it into two wedges 3 x 1"  .. now  "Read" the crustal structure at the break.---"White"  iron is bad ( Hard) . This is a gauge of what to expect if you were to machine the part . My early pours had white halfway up the break  ( 1 1/2") and later when I got to less than 1/2" white, I knew I had it . My first pours were too cold and the iron frooze to fast creating hard spots
The exact size of the wedge  ( ~3") means nothing - the V allows the wedge to break at a predetermined spot ( weakest) 

Rich


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## GreenTwin (Jul 26, 2021)

The problem with the wedge test in a backyard setting is that unlike an industrial foundry, there is not a large furnace/ladle full of iron to sample from that will easily remain at pouring temperature.
I guess you could leave the crucible in the furnace during a wedge test.

But the wedge test seems counterproductive because in order to check the wedge in real-time, the wedge would have to be cooled quickly after it was poured, and cooling iron quickly is the best way to get chilled spots in it.

Any iron parts poured should remain in the mold overnight, and allowed to cool as slowly as possible, otherwise any thin parts will not be machinable.

I guess you could pour some wedge tests, and let them cool overnight, and then test them, but that wastes a lot of fuel, and wear and tear on the crucible.

Another test I have seen is the spiral test, and it measures how far along a spiral the iron will flow.
The spiral test could be used as sort of a chill and flow test.

With the correct amount of ferrosilicon, the chills can be eliminated (I am not having chill problems).
Too much ferrosilicon, and there will be excessive shrinkage and hot tears.
It just takes a tiny amount of ferrosilicon, but that tiny amount works wonders for eliminating chilled spots, and helps a lot with fluidity too.

Comparing a cupola iron pour and a crucible iron pour is not really comparing apples to apples, although they are similar.

There is about a 30 second window after pulling the crucible out of the furnace to pour iron while maintaining a good pour temperature.
The iron goes cold very quickly once the crucible is out of the furnace.
For thin parts, pouring as quickly as possible is essential.

Pat J
.


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## GreenTwin (Jul 26, 2021)

Rich-

You got a sneak preview of the green twin at NAMES 2019.
It was not quite finished at the show, and I must say it did not seem to impress the crowd because only about three people looked at it.
Most of the work at NAMES is museum-grade, and so the humble little green twin did not stand a chance at getting any attention.

Before completion, at NAMES 2019:







After completion, published in Live Steam 2021:








And the man himself.
It is always humbling to be in the presence of one of the great masters of steam engine modeling.
If you have seen Rich's work, you will understand what I mean.


----------



## GreenTwin (Jul 26, 2021)

2019 was my first visit to NAMES, and boy and I glad I made that trip because who knows if and when things will ever return to normal enough to have these shows again.

I was surprised to run into my casting buddy who does an aluminum pouring demonstration at the Soule Live Steam festival.
I said "What are you doing here?".
He said "What are you doing here?.
I said "Doing the modeling thing".

He is from Louisiana, and so had an even longer drive than myself (on left in photo).


----------



## GreenTwin (Jul 26, 2021)

Here is John at the Soule Live Steam festival, with some of his jumbo coin castings.
He gets a superb finish on his coin castings, and typically like the one on the left in the second photo.


----------



## GreenTwin (Jul 26, 2021)

Some of the patterns on display at the Soule Museum, Merridian Mississippi:


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## GreenTwin (Jul 26, 2021)

More patterns from the Soule museum:


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## GreenTwin (Jul 26, 2021)

Here is the big cupola at the Soule foundry.
The coke and scrap iron were fed into it via a doorway located at the mezzanine level.
Must have been an impressive tap when it was full.


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## Richard Carlstedt (Jul 26, 2021)

Pat, I knew I had seen that Green Engine somewhere ..at NAMES of course ! and You as well !
Thank you for the very kind words
Yes, you leave the wedge and the rest of the pour overnight. The wedge break came before any machining the next day , and I have to say my first castings were very cold, until the metallurgist got involved 
I would not try to do castings again  without the vanadium shot 
Wonderful Pics 

Rich


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## GreenTwin (Jul 26, 2021)

Rich-

I a still chuckling about you dropping that screw under the table, and getting your wife out of bed at 1:00 A.M. to help find it.
I would have been tempted to bean you on the side of the head if you woke me at 1:00 to look under a workbench, but that is just me  of course.

If I tiny screw falls under my workbench, I immediately call it "gone for good", but your shop is a lot cleaner than mine!
If I need 10 screws or nuts, I always turn 12, because there is some law of physics that two will vanish into some mysterious black hole under the bench, never to be seen again.

The consensus at least in the backyard circles that I read these days (and have found to be true with what I do) is that you can drill and/or break one or more of the gates after the casting has cooled.
If you can easily drill a gate, which is very thin, that is really all the test you need.
And if you can break a gate and get a clean gray surface, you are good to go.

Once you get the ferrosilicon level figured out, there really does not seem to be a chill problem, but some people add things for "insurance".
I prefer to not fix things that are not broken.
Similarly, I don't degas melts that are not producing gas defects.  Some folks just degas everything, regardless of the need.

I think I am in the range of 0.04-0.06 oz of ferro per pound of iron.
I use a graphite rod to stir it into the melt, while the crucible is still in the furnace, and often with the burner still running (with a very long handle on the stirring rod, and a hand sheild).
I use 75% FeSi, obtained from a foundry supply house; works very well.

Pat J

Edit: I am told that you can heat a chilled casting to a cherry red, and then let it cool overnight, and you can salvage it from hard spots (chills).
I have not tried this method because I have not had chills when using ferro with the new furnace.

I did create some partial mold filled thin parts in the early days of my casting adventure, with the first furnace, and those were as hard as tool steel ("uncutium" is what I call the alloy), and that was before I discovered ferrosilicon.
.


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## Richard Carlstedt (Jul 27, 2021)

Yes on that reheating . Had a Foundry cast railroad wheels ( like 100) for a club project and they were as hard as a IRS agent  and we sent them back and that is what they did , reheat to cherry and then bury them under a sand pile for a day or two and they came back redish rusty, , but nice and soft. 

True story fellows  and yeah ! , my wife is a "Keeper" 

Not worked with Ferro at all-  I used broken Flywheels from a farm tractor repair shop at the suggestion 
of the metallurgist ...It is really good iron as they can;t take chances with slipshod material in a high RPM application..according to him.  
"broken" means application of a sledge hammer by your truly to get my size down..by the way , he also told me not to use limestone because i was not using pig iron ( but good flywheels) -  boy did that make a difference in the melt ( cleaner)

Rich


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## GreenTwin (Jul 27, 2021)

I have been following Kory Anderson's work the last year or so.
Kory is one of those unique individuals who are just unstoppable when they make up their mind to build something.

If you have not heard of Kory, he decided to build the world's only 150 hp Case tractor, and so he made the patterns, cast his own parts, and created his own tractor !!!!
Phenomenal is all I can say.



But the reason I mention Kory is that he has some photos on his website (somewhere?):


			https://koryanderson.com/projects
		


that show a flywheel with a cracked spoke (I can't find the link to the photo, but if I do, I will post it).
He cast some new flywheels in ductile iron.
That is the first cracked flywheel spoke I recall seeing on a steam engine.
I suspect that many of his 150 hp Case parts were cast in ductile iron.

My next foundry mission is to master the art of making ductile iron.
I know how to do it.
I am trying to find the correct additives that I need, and as usual, sourcing those has been extremely difficult.
Nobody wants to sell a little bit of anything.


Edit:
Found a few photos here.  Not the photos I was looking for, but interesting just the same.




__





						150 HP Case Project by Kory Anderson – James Valley Threshers Association
					





					www.jamesvalleythreshers.com
				




Edit2:
Quite a few build photos here, but still not the flywheel I was looking for.








						the engine -
					

Learn more about the 150 case history and how Kory Anderson recreated the engine from scractch. Eventually debuting in 2018, he gained 1M+ followers on YouTube interested in the story.




					150case.com


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## dazz (Jul 27, 2021)

Richard Carlstedt said:


> Dazz- Yours is a big order and I admire you for the undertaking of it.


I just need to make a hole in the sand and fill it with iron.  How hard could that be??
I am reasonably confident that the path to success will be paved with failures.


Richard Carlstedt said:


> Are you going to pour it yourself or have a Commercial or Art Foundry do it for you ?


This is DIY.  Getting a commercial foundry to do the job here would cost $$$$$$$$$$$$$$$



Richard Carlstedt said:


> My first comment is you should probably look at Silicon iron and definitely use a Vanadium additive. This will improve fluidity and machining immensely ( Vanadium) . Years ago this additive which is put in just before the pour was called "Hot Shot" as it creates a exothermic reaction ( sparks) and raises the temp of the pour which adds to being able to pour thin walls.


The plan is to use cast iron engine blocks.  These will already have the right metallurgy for my application.



Richard Carlstedt said:


> Good luck
> Rich


I will need more than luck !!


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## dazz (Jul 27, 2021)

GreenTwin said:


> A few years ago, I found out that SS can be set using a catalyst, and so I actually purchased some catalyst, but have not tried it yet.


After a bit of research, I found that SS can be set with an acid.   Any acid would work but you would not want to use something like HCl that would release Chlorine into the metal.




Richard Carlstedt said:


> The thing to remember is that the bound sand only has to last long enough for the exterior of the metal to solidify.
> Resin burns too, and it creates a charred interior of the mold, which I think actually helps with surface finish.
> Since the binder is a small percentage of the sand, then the main point of contact between the molten iron and the mold is the face of the grains of sand, not the binder.


I have found references to using ships bottom coal as an additive to improve surface finish.  This is very fine coal that get ground down as a result of the ship's motion.  On contact with hot metal it will burn all the oxygen then just form a carbon layer.    Fe2O3 (rust) has also been used but modern ceramic powders seem to be the modern approach.  



Richard Carlstedt said:


> If a mold is made of some material that is too hard, supposedly it can cause a casting failure; not sure of the exact mechanics of that.


Google hot tears and rat tails.


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## GreenTwin (Jul 28, 2021)

Until I saw John's jumbo coin castings at the Soule museum, I had no idea that they were manufactured and available.

I was able to find a selection of jumbo coins online for sale, and so I purchased some of them.
I am not sure who makes these, but the are exactly accurate.

John sometimes mixes and matches his coins, with two different styles back-to-back.

I tried casting on jumbo coin using petrobond, but did not have much success with it.
At the time I did not know much about casting work, so I need to revisit the jumbo coin casting thing.

These castings make a great demonstration and give-away at shows, and it does not take much of a furnace or burner to cast them.
John uses a propane torch to melt the aluminum, and I think a steel crucible.

Steel crucibles are prone to degradation and failure, and so I would recommend using a small clay-graphite crucible, or even a small jewelry ceramic crucible.
The Morgan Salamander-Super clay graphite crucibles work very well with iron (they are ferrous-metal rated, unlike most other crucibles, and rated for 2,900 F), and they come in very small sizes such as a #0.5, which is quite small.

The 0.5 Salamander Super is 3" tall.


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## GreenTwin (Jul 28, 2021)

This is my optical pyrometer.
I have not tried to use it with my new furnace, but I need to get it back out and try it again.
I was not able to get a good reading with it when I tried it with my 1st furnace, but I want to try again.

I converted it to use standard alkaline batteries.

The emersion pyrometers for iron are extraordinarily expensive, and the expensive iron-rated tips do not last long either.
Iron temperatures will immediately destroy an immersion pyrometer thermocouple/tip that is used for aluminum.

Hopefully I can get this unit working.
I can pour iron without it, but it would be nice to be able to verify what sort of iron pour temperature and superheat that can be achieved.


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## Richard Hed (Jan 8, 2022)

GreenTwin said:


> I have been following Kory Anderson's work the last year or so.
> Kory is one of those unique individuals who are just unstoppable when they make up their mind to build something.
> 
> If you have not heard of Kory, he decided to build the world's only 150 hp Case tractor, and so he made the patterns, cast his own parts, and created his own tractor !!!!
> ...



That is really something.  Wish I had it in my yard.


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## Richard Hed (Jan 8, 2022)

GreenTwin said:


> Until I saw John's jumbo coin castings at the Soule museum, I had no idea that they were manufactured and available.
> 
> I was able to find a selection of jumbo coins online for sale, and so I purchased some of them.
> I am not sure who makes these, but the are exactly accurate.
> ...


Damn!  That guy REALLY has small hands!


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## GreenTwin (Feb 23, 2022)

Continuing the discussion of sodium silicate bound sand............

_I have used sodium silicate bound sand with aluminum, but not with iron._
_I have had discussions with the local art-iron group, and they have used SS sand with iron, and report good results.

One thing I do with resin-bound molds is to flame them lightly with a wide propane flame, to drive off any residual resin or moisture.
A second thing I do with resin-bound molds is to spray them with a ceramic mold coat, which helps greatly with creating a smooth surface finish.

I have not tried spraying ceramic mold coat (alcohol-based) onto a SS mold, and don't know if it would dissolve the SS or not.

The resin molds have to be flamed first, the ceramic mold coat sprayed on, and the molds flamed again.

If I had a bit more time, I would go out to the shop and experiment with some SS molds, and mold coat.

I think one can get results similar to resin-bound sand, using sodium silicate bound molds; that is what I have heard.

And sodium silicate is readily available at pottery supply houses too, unlike resin for molds.

Sodium silicate molds can be cured with CO2, or a catalyst can be added that automatically cures SS molds.

It is important to keep the patterns well waxed with bound sand, since they tend to cling to the sand._
_And if you leave your pattern in bound sand after the strip time, then your pattern is basically permanently glued into the mold (don't ask me how I discovered this). _

I found some sodium silicate catalyst at Clay Planet.
The catalyst is at the bottom of the page.
Unfortunately it is slow acting, and I can't find the faster acting catalyst.
The slow catalyst may work if you are patient.









						Clay Planet - Ceramic Supplies, Clay & Glaze Manufacturer - Powered by Network Solutions.
					

Ceramic Supplies, Pottery Supplies, Clay Supplies, Ceramic Glaze, , Western Glaze, online ceramic shopping, ceramic store, leslies ceramics, aftosa



					shop.clay-planet.com
				




The 3-part resin-binder system I use has a resin, a hardener, and a catalyst, and so I can dial in the set time to as short as 5 minutes.
You have to allow enough time to mix for about 2 minutes, and also time to ram the mold, so you don't want the sand to set too quickly.
The binder sets more quickly on a hot day, and I have had the sand set in the mixer (no fun cleaning that out).

.


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## GreenTwin (Feb 23, 2022)

Common mistakes I see with people using sodium silicate binder:

1. They use too much sodium silicate, and like me, assume more is better (false).

2. They over-gas their sodium silicate sand.  Any more than a 5 second gas with CO2 ruins sodium silicate mold strength (less is more).

3. Using the recommended percentage (I think it is 5%, but check me on that) allows a sodium silicate core to be broken down and removed from a casting. 
High concentrations of sodium silicate make a rock-hard core which can be very difficult to remove.

.


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## moose4621 (Mar 20, 2022)

GreenTwin said:


> Common mistakes I see with people using sodium silicate binder:
> 
> 1. They use too much sodium silicate, and like me, assume more is better (false).
> 
> ...


When using your resin bonded sand, do you use a release agent on the pattern to prevent it sticking?
I have a fair amount of epoxy resin left over from another project and so thought I might try it for bonding sand.


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## GreenTwin (Mar 20, 2022)

I wax the pattern well.

I have heard of people using epoxy resin for making sand molds, but I don't recall exactly the outcome.

Sodium silicate-bound sand is commonly used, hardened with CO2.

It does not take much resin to bond sand.
Lino-Cure (tm) resin binder is a 3-part oil-modified alkyd resin, with resin, co-reactant, and catalyst.

Resin is used at 1.5% of the sand weight.
Co-reactant is 20% of the weight of the resin.
A slight amount of catalyst is used to control the set speed.

Bound sand has a set time (when it gets hard enough to become rigid), and a strip time (you need to remove the pattern from the mold during the strip time, else the pattern will be permanently adhered to the sand.

Most epoxy seems to be a 50/50% mix, ie: resin and hardener.
So a guess would be to add 0.75% of the sand weight in resin, mix that with the sand for at least two minutes, then add 0.75% of the hardener and mix for 2 minutes.

If the epoxy is a slow setting variety, then you could have a long wait before the sand mold sets (gets rigid).
Be sure to keep the mold on a flat surface after the set time has been reached, since the sand can warp a bit right after the set time if you put it on an uneven surface.  A fully hardened sand mold will not warp.
Select some time after set time, and then pull the pattern.
I use an automotive slide hammer to give a quick (light) impact force on the pattern, to break it lose from the mold.

And the sand that is used with resin binder has to be very dry, such as less than 0.25%.

The beauty of sodium silicate molds is that they set right after you gas them with CO2.
Never gas a sodium silicate mold for more than 5 seconds, else you will ruin it.

I have never used epoxy as a binder, so the above is my best guess at how to use it.

.


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## moose4621 (Mar 20, 2022)

Great info, thanks.
The resin I have is a 4:1 resin / hardener ratio and is a laminating resin so is quite thin. You get about a 20min pot life and about an hour to harden. It takes 24hrs to reach max strength.
I have used it before to make a few cores which went ok apart from the stench of the burning resin.
I thought it might work ok for the main sand moulds.


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## GreenTwin (Mar 20, 2022)

So at that ratio, you may be closer to 1.5% of the weight of the sand for resin, such as used with Lino-Cure.

But again, mix the resin with the sand first, then add the hardener.

It should work; you may have to play a bit with the ratios.

I would not inhale the fumes after the pour.

Use plenty of wax on the pattern.

Perhaps pull the pattern a little after an hour.
And don't use an expensive pattern on your first try, in case the pattern sticks to the sand.

.


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## Rains (May 11, 2022)

Great and creative work


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## GreenTwin (Aug 2, 2022)

I have seen a couple of videos of people pouring into molds that were not quite dry, and I have done it myself and had molten iron splattered back on my leather jacket, and then run down inside my gloves.

Everything has to be extremely dry when you pour molten metal into it, or when you add scrap metal to a furnace.
I hold the scraps in the exhaust stream for about 15 seconds, to drive off residual moisture.

Green sand molds have water in them, so I am not sure how they don't explode.
I guess the green sand absorbs the steam that is created?

Ingot molds have to be brought up to perhaps 600 F to drive off surface moisture.
I had actually flamed my steel ingot molds with a propane torch prior to pouring iron into them, but that was not enough, and the metal just ejected itself out of the mold.

Sometimes folks use the wrong sand and refractory material for molds, and it seems that trapped moisture can expand violently.

I will post a few videos that I have found, so others can wear sufficient protective gear, and be ready should there be a moisture problem.


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## GreenTwin (Aug 2, 2022)

Another ingot mold that was not heated, and thus retained a slight amount of surface moisture.

One should always avoid wearing synthetic clothes while casting metal.
I wear cotton only clothes.
Synthetic clothes will burn and be difficult to extinguish.


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## GreenTwin (Aug 2, 2022)

This person posted this video, to make light of a serious topic, which is foundry safety, and so while he could have hidden his blunders, he shares them in all their glory, so that perhaps others can avoid his mistakes.


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## GreenTwin (Aug 2, 2022)

And check out this video at 0:15 and also at 7:06, the guy in the center has his face mask up when the molten cast iron errupts
from the damp moulding sand.
A near miss, and very close to being a blinded casting guy.

Be safe, and be prepared.


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## ajoeiam (Aug 3, 2022)

GreenTwin said:


> Another ingot mold that was not heated, and thus retained a slight amount of surface moisture.
> 
> One should always avoid wearing synthetic clothes while casting metal.
> I wear cotton only clothes.
> Synthetic clothes will burn and be difficult to extinguish.


Wool clothes will also work well.


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## GreenTwin (Aug 3, 2022)

And I see a lot of youtube casters in tennis shoes, which are synthetic, and will melt onto your foot.

I see some wear leather boots, but with laces.
Laces on the boots are a no-no in the casting world.
I was using a cutting torch years ago, and a molten blog of metal went down inside my lace-up boot.
You can't get boots unlaced fast enough in that situation, and I had a 3rd degree burn on my foot.

It needs to be smooth leather boots, with the pants leg over the boot.

I wear a leather apron, and a leather jacket over that.

Most have a neck sheild hanging down off the back of the hardhat, to ward off showers of sparks and molten metal.
I need to get a neck shield.

I have been told to adhere to the waterfall approach, which is if it is raining molten iron, will the iron run off of your leathers and hardhat, or will it find its way into an open spot?  There should be no open spots.

.


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## ajoeiam (Aug 3, 2022)

GreenTwin said:


> And I see a lot of youtube casters in tennis shoes, which are synthetic, and will melt onto your foot.
> 
> I see some wear leather boots, but with laces.
> Laces on the boots are a no-no in the casting world.
> ...


I think I would be wearing leather work boots and would try to find some spats. 
Any good source for a leather apron?
Leather jackets - - - -similar to the ones for welders? 
Have you ever found something that could function like a neck shield?
I'm a wondering if a boot spat might work - - - or two stitched together.


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## GreenTwin (Aug 3, 2022)

I bought my jacket from a welding suppy store.
That is probably where I got the apron too.

Some wear the silver-coated stuff, or the chemically-treated clothes, but I prefer leather everything.

Many wear boot spats, but if your boots are not lace-up, you don't need spats.

I have seen some attach a leather flap to the back of the hardhat, and others just put a neckerchief over their head under the hardhat, and let the neckerchief hang out over the jacket collar.

The welding supply places have face shields that fit onto most hardhats, and that is what I use.
For iron work, the IR emitted is very intense, and so I use a shaded face shield and shaded glasses, to prevent sunburn in the eyes.

And I use leather welding gloves.
With iron work, you need sheet metal shields on the various tools, to prevent the gloved hand nearest the furnace or crucible from overheating.

Lifting the crucible out of the furnace is done as quickly as possible.

The furnace is open, and you are getting the full radiant heat from the furnace walls and from the crucible, so one does not want to dilly-dally around.

I use a glass shelf from an old refrigerator to lean over slightly to peer into the opening in the furnace lid (to check on the progress of the melt).
Without the glass shelf my faceshield begins to melt in seconds.

.


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## GreenTwin (Aug 3, 2022)

For the larger crucibles such as a #30, I use a crane and pouring cart.
This is a video from my very early days of casting, and this was a very sloppy pour, and an interrupted pour (never interrupt the pour).





Your browser is not able to display this video.


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## GreenTwin (Aug 3, 2022)

This was a good clean lift and pour.





Your browser is not able to display this video.


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## 57mm_M18 (Aug 4, 2022)

I have watched a lot of videos of casting brass, aluminum and iron on this blog & it makes my skin crawl in some cases.  I have not commented in the past but, when I see individuals wearing sport shoes, sandals & lacking even the simplest of protective eye wear it makes my skin crawl.  First, and foremost is the number of times I see someone filling molds with these hot metals while the mold is sitting on a concrete floor.  This is strictly forbidden in all the foundries I have worked.  Sand floors in and around the furnaces & pouring floor is a must.  Concrete will explode due to the retained moisture in it, I don't care how old it is.  This will turn the molten metal into molten projectiles.  Second the use of protective clothing and face wear.  Third, and uncluttered pouring floor with a shovel and piles of sand if a mold happens to breach.  You cover the molten escaping metal with dry sand to contain the problem.  Each one of the metals that we use to make our projects has its hazards.  Learn what they are and treat them all with the respect they require.

Most molds breach because of improper sand formulation or improper venting & design.  Those who attempt to pour high temperature metals should first understand how a mold is made.  I have not seen the use of weights being used on the green sand molds in most of the videos.  Most molds breach due to improper venting.  The trapped steam causes the mold to break apart.  The mold is more than just a container with a net shape of some part.  All these little things add up to success or failure.  Be safe and do a deep dive into this skilled trade so you don't injure yourself or others.

CW


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## GreenTwin (Aug 4, 2022)

I have watched a number of backyard pouring videos on youtube, and I agree, many if not most make me cringe too.
The backyard folks often pour metal in tennis shoes, with little or no protection, synthetic clothing, etc.
And they often pick up their crucibles at the top by a pair of channel locks, or something similar, which is a very bad idea.

_"Concrete will explode due to the retained moisture in it, I don't care how old it is."_

I have heard this statement over and over again, and I know from experience that it is false.
I have spilled aluminum, brass, bronze, and iron on my concrete driveway perhaps 20 or more times, and no explosions.
I know a fellow who has poured literally tons of iron in Australia on a concrete floor, with many spills, and again, no explosions.
So while it may be a good idea not to pour over concrete, since it can explode in some cases, to say that "All concrete will explode" is a myth, and I know that from experience.

I don't use sand around the foundry area since it gets tracked everywhere, and the sand will get wet when it rains, and retain moisture, which can explode if you spill molten metal on it.
It is not a big deal if you break a mold during a pour.  There is nothing that is going to happen; one does not need to panic and start throwing sand around.  Just stop pouring and move to the next mold.
Again I speak from experience.
Throwing wet sand on molten metal will cause an explosion, and most of the sand I see laying around outdoors is wet.
I never let any sand get near my foundry area (other than the sand molds).

_Most molds breach because of improper sand formulation or improper venting & design._

Almost all of the mold breaches I have seen have been caused by a lack of weight on top of the mold/flask.
The bouyant force of the metal on the cope (the cope contains the top half of the mold) lifts the cope and separates it from the drag (the drag contains the lower half of the mold), causing the molten metal to drain out of the cope mold.
I witnessed one vertical mold that breached with iron because the steel straps failed due to the heat.
If the top of the mold is weighted correctly, the mold won't breach unless you have done something really wrong, which is possible/probable on youtube.
It is pretty safe to say that you should never do 98% of the backyard casting stuff that you see on youtube.

_Most molds breach due to improper venting._

Some molds fail due to the sand being too wet, in which case you get an explosion/eruption.
I have never seen a mold fail due to improper venting, and if you watch luckygen1001 on youtube (who has poured tons of iron), he shows that he never vents his molds, and says mold venting is totally unnecessary.
I do vent the high spots on my molds because I use resin-bound sand that does trap air.

_The trapped steam causes the mold to break apart._

The trapped steam causes the mold to explode because too much water was mixed into the sand, or in the case of a resin-bound sand mold, the mold was not flamed with propane, or left outside overnight and absorbed moisture.

_Be safe and do a deep dive into this skilled trade so you don't injure yourself or others._

I absolutely agree with this 100%.
There are many hazards associated with casting metal of any type, and one must completely understand the hazards, and be fully prepared for a worst-case scenario.

Some extremely dangerous things I have seen on youtube, more than once:

1. Folks operating a furnace using a propane burner, inside of a garage.
I saw one video of a guy lifting a #16 crucible and the tongs slipped, spilling the entire contents of molten metal onto the garage floor.

2. Folks operating a furnace with one or more propane bottles very close to the furnace.
This is a very good way to leave the earth quickly, and leave a huge crater in the ground.

3. Folks spilling hot metal onto their rubber propane or oil lines.
One guy ended up with an ocean of fire in his backyard.
I think he was using kerosene or some relatively flamable fuel.
I have not seen diesel spread like this if spilled, which is one reason I use diesel.
I also am working on a metal sheath to cover my fuel and air lines, and I need to finish this task.

4. Folks not using a full face shield.

5. Folks using Rube Goldberg combination lifting tongs and pouring shank.
You may be able to get away with using combo tongs/shank with light aluminum pours, but for heavier pours, the combo unit is downright dangerous to use.

6. Lifting the crucible by the upper lip using channel locks, and pouring the metal also using the channel locks.
This is a disaster waiting to happen.

7. Folks operating a furnace right next to their house (I did this in the early days, due to sheer ignorance; don't repeat my mistakes).
The furnace, molds, and fuel tank(s) should all be well away from the house, cars, and anything flamable.
If everything goes wrong, and it all goes up in flames, that should not be a problem at all, since you should not be near anything flamable.

8. Folks using plastic or rubber components on a furnace, or very near a furnace.
Anything rubber or plastic within about 10 feet of a furnace (especially an iron furnace) sooner or later will catch fire.
I use steel caster wheels, and run my pouring cart wheels on bare steel rims (no rubber tires).

9. Folks trying to operate a furnace burner without any knowledge of how to safely operate a burner.
One guy reported that his burner did not work well at all, and said "That burner design is crap", after he launched his furnace lid over the top of his house.  The burner he used is the same burner that many of us use, and there is nothing wrong with the burner design, and everything wrong with his lack of safety and knowledge of how to operate burners.
It is shocking how many backyard casting folks never learn how to correctly adjust their burner.

10.  I would have to say that burner safety is probably the most critical item with a backyard foundry.
I have seen so many folks mount their cutoff valves right next to the furnace, which is the last place you want to have to reach when things are going wrong.
The heat from the furnace can also melt the parts in valves.
I use remote valves for fuel and oil, and I can turn the fuel off in a fraction of a second.
I always am ready to turn off the fuel, and I make sure it is within easy reach.

11.  Keep your fuel tank well away from the furnace.
You should never have a situation where an out of control fire in a furnace can reach a nearby fuel tank.
Have a shut-off valve at the fuel tank.

12. Never use concrete as a refractory material to make a furnace.
There is one video out there (I need to find that), where someone's entire furnace explodes violently as it heats up.

13. Never use uncoated ceramic blanket as a furnace interior.
The airborn fibers can do permanent lung damage.

I lay out all of my equipment before I start the furnace, and I actually do a dry-run before I light the furnace, and choreograph every step, opening the furnace lid, lifting out the crucible, setting the crucible in the pouring shank, lifting the crucible and doing a fax pour over the mold, and shanking the pouring shank with the crucible upside down to make sure the crucible is securely locked into the shank.

I often hear "You should NEVER operate a foundry at night".
The temperatures in the mid-south along with the humidity pretty much mean that you will have a heat stroke during a summer pour.
I don't fear night pours; basically all of my pours are at night; I fear heat strokes, and you can overheat very quickly with full leathers on.
What I fear is folks operating a foundry who don't know what they are doing, during the day or night.

The dry run also is to make sure your equipment is layed out so you don't trip over anything, and everything you need such as lifting tongs, skimmers, pouring shank, etc. is in the right place and easily accessible, without being a trip hazard.

I basically use something similar to the work triangle in a kitchen, which is a defined area where I will work and handle metal.
I generally don't stray out of this area during a melt.
I don't leave the furnace while it is running.

Often I see people panic if something goes wrong (illustrated well in one of the above videos).
Panic is what will get you hurt.
You must remain calm at all times, and always keep in mind the fuel cuttoff valve location.
Have a backup fuel cutoff valve at your fuel tank.
Have a clear escape path away from the furnace, and behind where you sit/work.

Make sure your crucible retainer works well.
My first retainer design did not work well, and a full crucible of iron spilled right out of the shank (onto the concrete driveway) just as I began to pour (the concrete did not explode).  I am not advocating that others pour over concrete, but I am just saying it is not necessarily the disaster that I keep hearing about over and over again.


Just a few thoughts.
Be safe.
Wear lots of safety gear, and expect the unexpected.
When in doubt, err on the side of caution.

Have several backup plans.
The first backup plan is to quickly back away from the danger, and then immediately turn off the fuel.
Don't do anything foolish that will make the problem worse, such as throwing something damp or wet into the inferno.

.


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## GreenTwin (Aug 4, 2022)

Here is a video about what can happen with concrete when heated.


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## GreenTwin (Aug 4, 2022)

The guy in this video says its a complete mystery as to what happened in his fire pit.

He built a fire on top of damp concrete, and it exploded.


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## GreenTwin (Aug 4, 2022)

Don't pour molten metal down a wet anthill, and don't have your propane tank right next to your burner.


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## GreenTwin (Aug 4, 2022)

Here is the video I was looking for.
Guy used concrete as a furnace refractory (never do this).

Furnace refractory (I use Mizzou) must be dried out slowly to drive out the moisture, and not overheated while is still has moisture in it.


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## GreenTwin (Aug 4, 2022)

This guy has some good backyard foundry safety tips.
I can't begin to cover all backyard foundry safety, and I am not going to try.

Some good ideas in this video.


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## ajoeiam (Aug 5, 2022)

GreenTwin said:


> This guy has some good backyard foundry safety tips.
> I can't begin to cover all backyard foundry safety, and I am not going to try.
> 
> Some good ideas in this video.



Thank you for sharing your experiences and information that you have gathered. 

Greatly appreciated here!!!


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## GreenTwin (Aug 5, 2022)

I a glad to share, and hope others can get into the hobby, or improve their methods perhaps if they are already in the hobby (we have several very talented backyard casting folks right here on this forum).

I got into backyard casting out of a desire to find a better method to build model engines.
The bar stock method I tried was very hard on my inexpensive lathe and mill, and the results were not even close to what I was looking for as far as appearance, accuracy, athenticity, etc.

I started reading about backyard casting in 2011, and decided to take the plunge after I ran across a website called backyardMetalcasting.


			Melting metal in a home foundry, backyard metalcasting, metal casting
		


The fellow who ran the above backyard website also sponsored a forum called Alloy Avenue, and so I began to read about how various folks created their foundries.
I basically read every single post on that forum for years (thousands of posts).

I paid very close attention to what worked, and what did not work, and in particular I studied all of the iron furnaces and methods.

Unfortunately the Alloy Avenue forum stopped working a year or so ago, and a lot of information was lost.

So I have been casting metal, including gray iron, for over 10 years now, and I enjoy the backyard foundry work as much as any hobby I have been involved in.

I have talked with folks who worked in steel foundries, to see how the big mills make iron and steel.
I have also attended a number of art-iron events, where they use cupolas to melt iron, and had extensive discussions about how to best melt and cast gray iron.

I also chat frequently with a buddy of mine who started his own iron foundry a few years ago.

The king of gray iron backyard castings (in my opinion) is a guy from Australia, who goes by "luckygen1001" on youtube.
This fellow has shared a lot of his casting knowledge with me and others, and his gray iron castings are pretty much unparalleled from what I have seen in the backyard world.


			https://www.youtube.com/user/luckygen1001/videos
		


The best aluminum casting guy I have seen is called "olfoundryman" on youtube, also from Australia (these guys know each other).
This individual use to work in a foundry as the metalurgist, and he really knows his stuff about the professional foundry business.


			https://www.youtube.com/channel/UC90RoN_IjSRF18jAG0HIA6g/videos
		


I agree with most of what these two guys say, and have learned a great deal from both of them.

Another fellow I watched early on is called "myfordboy" on youtube, from the UK (the "myford" name comes from the UK lathe manufacturer, not the auto company).
Myfordboy has is own style of casting methods and equipment, and while I don't prescribe to much of how he does his foundry work, nobody can deny that this fellow is an extremely talented backyard casting person, and a prolific backyard casting video producer.
Myfordboy's engines speak for themselves, such as his custom-cast Ball Hopper Monitor, and other engines.


			https://www.youtube.com/c/myfordboy/videos
		


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## GreenTwin (Aug 5, 2022)

There are a large number of what I call "weekend warrior" foundry burner and casting guys on youtube, and it is pretty safe to say that you should ignore virtually every one of them and their equipment.

Everyone wants to make that "better mousetrap" burner, and so you see the most bizarre burner designs, many or most of the being terrible designs for use with a foundry furnace.

Many of the casual backyard folks build furnaces with hardware-grade materials, and homemade refractory, and these furnaces often only last for a few melts with aluminum.

One big trend these days is to melt aluminum cans, and pour ingots.
Aluminum cans make a very poor grade of aluminum for engine work.
For engines, AL356 should be used.

I must say I was as proud as any human of my first aluminum ingot.
It was like stepping onto the surface of the moon for me.
I still have one of those ingots.
But if you want to cast engine parts, don't get stuck in "ingot land".

Some folks make their own crucibles.
I did use a welded steel crucible in the beginning and I must say it worked pretty well, but eventually the steel will fail, and you will have a molten metal spill.
These days I exclusively use Morgan Salamander Super clay graphite crucibles for all metals (a separate crucible for each metal type).

.


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## awake (Aug 5, 2022)

GreenTwin said:


> The backyard folks often pour metal in tennis shoes ...


I guess this is one way to make a metal model of your shoes!


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## minh-thanh (Aug 5, 2022)

GreenTwin !
Thanks for sharing !!
 Maybe I will build a small smelter to test


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## ajoeiam (Aug 6, 2022)

GreenTwin said:


> I am glad to share, and hope others can get into the hobby, or improve their methods perhaps if they are already in the hobby (we have several very talented backyard casting folks right here on this forum).


snip


GreenTwin said:


> Unfortunately the Alloy Avenue forum stopped working a year or so ago, and a lot of information was lost.


snip

I checked using the wayback machine (your search term) and it seems like there were a lot of 'snaps' (snapshots) of the forum.
You would be able to tell if everything is still there but to me it looked like everything was.
My problem would be that I would have to page through each tread to find what is useful and that's time consuming!!!!

Any suggestions on highlights or things to look for?


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## SmithDoor (Aug 6, 2022)

minh-thanh said:


> GreenTwin !
> Thanks for sharing !!
> Maybe I will build a small smelter to test


At time a foundries was simple.
They locate the foundry witch had good molding sand. 
The furnace was just stack of bricks and used coal or charcoal AKA Blacksmith forge. The curable was just a household clay pot. 

Today most use think oil bonded sand but large foundries still use water not oil. 

I started a thread using Sodium Silicate with great for just few parts needed for model engine.
It is very strong and buy all materials from local stores.  

Any can melt aluminum in simple backyard BBQ. 

Patterns are still same as clay sand but less is need. 

Hope this helps 

Dave


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## minh-thanh (Aug 6, 2022)

Hi Dave !

Thanks  for  informations .
  I have read a lot about casting here , watched many youtube videos about casting , but the Big Problem is not practice
  I want to cast some parts for the engines I will make - just a few parts - like the picture attached
    Build a small smelter  - cast a few small samples - to practice before I can cast something more complex


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## abby (Aug 6, 2022)

If you are hoping to eventually cast something as complex as the above manifold then forget sand moulding , investment casting is the way to go.
Although some extra equipment is required and the process costs more , the learning curve is far less steep and results are easily achieved which far outway anything that the home sand foundry could produce.
This is a very simple steam manifold for a 5" gauge railway engine cast in red brass (gunmetal)









​To cast this in sand would require core boxes to produce cores for the internal spaces as well as patterns .
As an investment casting the cement flows inside the hollow wax pattern to create the cores , this makes the production of such parts quite easy.


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## minh-thanh (Aug 6, 2022)

abby !​Thanks for your opinion !
There is a problem: I only cast a few parts so I don't want to invest too much money


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## GreenTwin (Aug 6, 2022)

I haven't done investment castings, and so I can't add any information on that process.

.


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## GreenTwin (Aug 6, 2022)

ajoeiam said:


> snip
> 
> snip
> 
> ...



I was on Alloy Avenue (backyard casting forum) from 2011 to about 2017, and I read everything that was posted, daily, for about 8 years.
In the beginning, people were trying a lot of different methods/materials/techniques, and there was not so much a consensus about what worked and what did not work.

One guy who was learning how to cast gray iron was called "scavenger", and his posts were very interesting, since he poured a lot of iron for about 2 years, and he tried quite a few furnace and furnace lid designs, as well as burner designs.

The racing motorcycle cylinder castings by Jeff Henise "jhenise" were very impressive.

There were a lot of failures by myself and others over the years, and it became important to understand why a certain process or technique failed, and everyone weighed in on how best to do things.

Alloy Avenue was somewhat of a collective thing, group learning over time.
If you have a particular interest, such as "lost wax", or "investment casting", you could perhaps do searches for that, if searches work on the wayback machine.

I tried many types of burners and burner configurations, including siphon nozzle, drip-style, and Ursutz oil burners, propane burners, large burners, small burners, two siphon nozzles in a single burner tube, two siphon nozzle burners mounted at 180 degrees on a furnace, combination oil and propane burners, etc.

In the end, I decided to use a siphon-nozzle burner with diesel as a fuel, and I really like the controllability (wide operating range), and the fact that it will operate down to at least 34F without any problems with the diesel fuel being too cold, etc.
A siphon nozzle burner will light instantly using diesel, and no propane preheat is required, and can output full power without any warmup.

I still use a propane burner for small aluminum melts.

Several backyard casting folks use drip-type oil burners, but I could never get any significant fine control out of those, and they don't operate as smoothly and consistently as a siphon-nozzle burner.

Every type of homemade refractory was tried, and the consensus was finally reached that commercial refractory was well worth the expense, and it will typically hold up well over time.
I use a Mizzou 1" thick refractory hot face in my furnace.

And another big advantage to that forum is you could post your casting defects, and folks could generally zero in on what type of casting defect it was, and tell you how to avoid those defects.

The moderator for the Alloy Avenue forum was a mechanical engineering student named Ben Baker, and wrote a backyard casting guide, which is a pretty good resource in my opinion.
Ben's book is not the final word in backyard casting ideas, but is definitely a good start, and is free.



			http://prometheus-foundry.com/The%20Hobbyist's%20Guide%20to%20Casting%20Metal--2nd%20Edition%20(web).pdf
		


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## GreenTwin (Aug 7, 2022)

Here is a pretty good summary of common casting defects.









						21 Casting Defects and How to Prevent Them in Your Products
					

Are your products suffering from casting defects? What happened? How can you prevent them? Read on for causes and prevention of the top casting defects.




					www.intouch-quality.com
				




Casting defects that I have experienced include sand inclusions, when I used Petrobond with an iron casting, and the sand eroded due to the iron temperature and metal velocity, gas bubbles in aluminum castings, caused by overheating the aluminum and holding the aluminum for too long at elevated temperatures, and hard spots in thin gray iron parts due to a lack of the correct amount of ferrosilicon, and cooling that was too rapid.

I have seen hot tears in other's castings, and that can be caused by uneven solidification in the mold, where one part of the casting solidifies before the other, and thus metal is drawn across the mold from the hot part to the cold part during shrinkage/solidification.

I have seen people use too much ferrosilicon in iron, and this causes excessive shrinkage and hot tears.
You only need a slight amount of ferrosilicon in gray iron.

Pouring at too high of a temperature is probably the #1 cause of poor surface quality on castings.
The pour temperature should be as low as possible while still allowing full mold fill.

I often seen interrupted pours on youtube, where someone begins to pour metal down the sprue, then pauses for a fraction of a second (for whatever reason), and then begins to pour again.  This should always be avoided.

And people often fail to keep the sprue full, and thus they entrain air into the metal stream.

You should always try to avoid any waterfalls, ie: keep the lip of the crucible as close to the top of the sprue as possible.
I often rest the crucible on the top of the mold when pouring, to eliminate almost all of the vertical column of molten metal.

Youtube backyard casting folks can often be seen vigorously stirring their aluminum melts, which is about the worst thing you can do with aluminum, and this mixes all sorts of oxide bifilms, slag, etc. into the metal, which will show up in the casting as defects.  One should NEVER stir aluminum melts.  Heat aluminum as fast as possible to pour temperature (about 1,350 F), then a quick skim to remove slag, and pour immediately.

Degassing is seldom required for aluminum if you don't overheat the melt, and if you pour immediately after reaching pour temperature, before the metal has time to absorb gas.

I failed to vent the top of one mold, and it trapped large air bubbles, and ruined the castings by leaving two voids that were perhaps 2" across, and about 1/2" deep.
The high points of the cope mold (cope is the top half of the mold) should be vented with small holes, perhaps 1/16" diameter holes or even a little less.
Some say that greensand does not need to be vented, but why take chances with something that can be added so easily and quickly?

.


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## minh-thanh (Aug 7, 2022)

GreenTwin !​Thank you very much !!
After reading, watching, listening to advice......I think it's time to practice  .


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## GreenTwin (Oct 9, 2022)

At the risk of being repetitive, I will add a few more comments on backyard casting, and how I learned the process (to date).
Chances are I may have already mentioned some of these items, given my current state of memory (or lack thereof), but some may get some use out of this.

When I got interested in building model steam engines in about 2007, I tried hogging/machining some engine parts out of large chunks of cast iron.
My machines are not very high quality, and not very rigid, and I found the hogging (heavy cutting) process to be inaccurate, time consuming, boring, and very tedious.

I decided that there must be a better way to make model engine parts, and so I started looking at foundry technology.

I looked at what others were doing on model engine forums, and backyard casting forums, and the only folks I recall who were doing extensive 3D modeling work for model engines were Brian Rupnow and a fellow from the UK named Rob Wilson.
It seems like Brian has been doing 3D modeling forever, and I could tell from his work that this was the future of modeling.

Rob Wilson built his own foundry, and began casting his own model engine parts, some of which were in gray iron.
Rob vanished from the internet after a short while (at least as far as what I can find), but his combination of 3D modeling and foundry work basically were what caused me to start learning foundry work.

I found a backyard casting forum called Alloy Avenue, and was on that for years.
A number of backyard casting folks are the art-casting type, and their work is often sort of avant-garde, as is often their attitude towards life, if that is a correct use of the description.
Alloy Avenue was useful for learning the fundamentals of melting metal, but the artwork castings are typically a bronze alloy, and the methods used to melt metal are often as simple as possible, and only complex enough to get bronze to pouring temperatures.
Art castings don't have to be perfect, and so any imperfections (large and small) are often just brazed up after the castings are made.

I had trouble finding anyone who was doing what Rob Wilson was doing, ie: designing his own steam engines, making the patterns, and then castings his own engine parts. 

I ran across myfordboy on youtube, and those videos were pretty helpful in getting started with some rudimentary pattern making (in wood), and basic aluminum casting.



			https://www.youtube.com/c/myfordboy/videos
		



I noticed that the guy who started Alloy Avenue was melting and casting gray iron, and so I decided that I had to learn how to do that.

I ran across "ironman" (he has many names; goes by "100model" on this forum).
He goes my "luckygen1001" on youtube.


			https://www.youtube.com/user/luckygen1001/videos
		


Ironman is the best description for luckygen1001 because he has mastered the art of iron castings in a spectacular way.
I have learned a great deal from ironman's videos, and from direct conversations with him.
He has a long history of backyard iron casting, and makes excellent iron castings of all types.
He is by far the most knowledgeable iron caster I have ever met.

I ran across "olfoundryman", whose name is Martin, and he has some serious aluminum casting experience, and was a metalurgist at a foundry (as I understand it).
Martin is the best aluminum casting person I have ever run across.



			https://www.youtube.com/channel/UC90RoN_IjSRF18jAG0HIA6g/videos
		


.


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## GreenTwin (Oct 9, 2022)

There was a fellow in Texas who went by the screen name "scavenger", and he built an iron foundry, and was in the iron casting business for a while, selling replacement hit-and-miss mufflers (full sized) on ebay.

I watched scavenger's threads carefully, and since he did a lot of iron melts, he basically had to discover what would hold up long-term at iron temperatures, as far as refractory, construction methods, etc.

Scavenger has vanished like many others, into the internet ether, never to be heard from again.

.


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## GreenTwin (Oct 9, 2022)

Another person I ran across was Bob Puhakka, and he use to have a number of foundry videos online.

Bob uses John Campbell's methods, and he operates his own foundry in Canada.

Bob's story is that he started a consulting firm to teach foundries how to apply and use John Campbell's and I guess some of his own methods to improve productivity and casting quality.

Bob ended up purchasing an aluminum foundry, and applied John Campbell's techniques.
Bob makes world-class aluminum castings, certified by xray and other means.

Bob is a colorful and outspoken individual, and backyard casting people either seem to love Bob and his castings/methods, or profusely hate him and his castings/methods.

I don't really care what sort of personality Bob has.
I appreciate his frankness, believe in his and John Campbell's methods, and aspire to making world-class castings as he does.

Bob Puhakka and John Campbell are very close friends.

.


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## GreenTwin (Oct 9, 2022)

In one of Bob Puhakka's videos (they have all vanished into the internet ether unfortunately), he discusses "bifilms", and talks about why they are important to control.

If you think about molten aluminum as it is poured and flows into the mold, the outer surface solidifies into a very thin skin as the metal is flowing.

The skin does not cause problems as long as the metal flow into the mold is smooth and uniform.

If the molten aluminum is disrupted during the pour, the outer skin on the metal is churned into the flowing metal, and the end result is weak spots in the casting.
If you are making structural-grade aluminum castings, or pressure-tight castings, you should pay very close attention to controlling bifilms.


Lucky for me, gray iron does not seem to have bifilm problems, at least as far as I can tell.

.


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## GreenTwin (Oct 9, 2022)

So as I have learned about casting methods and materials from various sources and people, I have taken notes.

I compare what each successful casting person is doing with the patterns, molds and sand types, sprues, runners, gates, risers, burner types, refractory types, etc.

Along the way, I have discovered a few myths that are very pervasive, because they were seen on popular youtube channels, and so got viewed and repeated over and over.

One myth is using washing soda as a degassing agent for aluminum.
If you dump washing soda into molten aluminum, you will see a gassing effect, and so one would think that the washing soda is removing dissolved hydrogen from the melt.

But if you do like I and others have, and bake your washing soda in the oven to get it completely dry, then you discover that when you add it to molten aluminum, there is no gassing at all, and it has no effect at all on the aluminum, but instead just floats as a powder on top the melt.

There is a degassing agent that does work with aluminum, and I forget the name of the product.
"Masteryoda" (a member here) told me what he uses.
If you do use any material for aluminum degassing, be aware that it may produce very toxic fumes that must be avoided.

.


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## GreenTwin (Oct 9, 2022)

Another item that I consider a myth is the need for a pouring basin.
Many folks, even very experienced casting folks, will insist that a pouring basin must be used in order to get good castings.

But if you look at what happens when you pour any liquid, including liquid metal, into a basin, you should realize that this process churns air, bifilms, slag, sand, and other unwanted material into the melt, and does far more damage than any perceived good that it is suppose to deliver.

Here is a video of a liquid pouring simulation:




Some will point out that they use a pouring basin, and they get great castings.
For hobby work, and non-structural work in aluminum, few things are critical.
If you do more critical aluminum work, you should consider eliminating the pour basin.

.


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## GreenTwin (Oct 9, 2022)

I often hear that you should never pour straight down the sprue, but this is indeed the method I use.

Most folks on youtube pour their metal with the crucible elevated some height above the top of the sprue (the sprue is the hole in the sand into which you pour the metal), and this should never be done.

The lip of the crucible should be as close to the top of the sprue as possible, to avoid a waterfall effect, which can entrain air and slag into the melt.

There should be a trap at the end of the horizontal runner, such that the initial flow of metal that contains air and slag has somewhere to go before metal begins to enter the mold cavity.

The sprue should be sized so that it fills very quickly, and remains full during the entire pouring process.
If the pour is interrupted for any reason, you will aspirate air down the spure, interrupt the mold filling process, and generally ruin the casting.

The sprue should transition smoothly from vertical to horizontal, to prevent turbulence in the metal.

Turbulence anywhere in your sprue/runner/gate/mold system will churn air, slag, bifilms, and often mold sand into the casting, causing defects.

I generally use a 3" diameter short length of steel pipe (perhaps 1" long) at the sprue, just to catch any initial spill from when the pour starts.

You can practice pouring water from a container into a small opening or basin, and try to keep the sprue full, minimize splashing and turbulence, and avoid the waterfalling.  Pouring metal from a crucible into a sprue is a bit of an art, and you get better at it as you go.

Ironman (luckygen1001) has excellent pour control with minimal spill, most of the time.
Watch his videos to get an idea of good pour technique.

.


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## GreenTwin (Oct 9, 2022)

Another myth that I see over and over is the need for a very tall sprue in order to get a complete mold fill.

Ironman pointed out this myth to me.

I never use an elevated sprue, and I don't have mold fill problems.

If your mold is gated correctly, you should not need an elevated sprue.

An elevated sprue just exacerbates problems with excessive metal velocity.

.


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## awerby (Oct 9, 2022)

GreenTwin said:


> Another myth that I see over and over is the need for a very tall sprue in order to get a complete mold fill.
> 
> Ironman pointed out this myth.
> 
> ...





GreenTwin said:


> At the risk of being repetitive, I will add a few more comments on backyard casting, and how I learned the process (to date).
> Chances are I may have already mentioned some of these items, given my current state of memory (or lack thereof), but some may get some use out of this.
> 
> When I got interested in building model steam engines in about 2007, I tried hogging/machining some engine parts out of large chunks of cast iron.
> ...


I'm enjoying this thread, and appreciate all the links to informative videos. But without actually watching all of them, it's hard to tell what exactly you all are doing in order to cast good iron engine parts in your back yards. Can you summarize the process for us? I gather this involves melting iron in a crucible furnace and pouring it into a mold. But what sort of furnace are we talking about? Is it one of those naturally-aspirated propane-fired things that are so popular these days? Or do you have to do something special to get up to iron-melting temperatures? 

Are you making sand molds or doing some kind of lost-material casting? If it's sand, does regular Petrobond work, or is something more refractory required? For the lost-wax (or whatever) molds, are people really mixing up ceramic shell and keeping it perpetually mixing, or is there a simpler method? I've done a lot of non-ferrous metal casting, (being one of those Bohemian arty types) but never tried iron. Is it maybe not as problematic as I've always thought?


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## GreenTwin (Oct 10, 2022)

Once you get set up for iron, the process is not much more difficult than casting aluminum.

Getting set up for iron requires some meticulous preparation though, and it is not a casual thing.
Skipping a few steps to save time or money generally leads to failure with iron.

*Furnace:*
Many backyard casting folks use a thin hot face (1" thick or so) made from poured high-temperature commercial refractory, such as what I used (Mizzou).
Mizzou is 3,000 F rated, very high slag resistance.  Iron furnaces splatter a lot of slag on the walls of the furnace when they run.
Behind the hot face can be either insulating fire bricks, and ceramic blanket, or just multiple layers of ceramic blanket.
The lid interior needs to be a cast dome, using Mizzou or equal material.
If you try to use materials rated less than 3,000 F, they will not last long at iron temperatures.

Ironman uses a coated ceramic blanket, I think with a material called Zircon, which I have not been able to find.
Some use a product called satanite to coat their ceramic blanket, and operate at iron temperatures.
I prefer a Mizzou hot face for long term reliability and easy repair.

*Crucible:*
The crucible needs to be a Morgan "Salamander Super", clay-graphite, 2,900 F rated.
This is a ferrous-metal-rated crucible, and works well with iron.
Never put borax on a crucible for any reason; else you will severely damage the crucible.
Ignore any recommendation of using borax for iron work.

*Plinth:*
The crucible sits on a pedastal inside the furnace, which is called a plinth.
Make the plinth from Mizzou.
Use two layers of cardboard on top of the plinth, so the crucible does not stick to the plinth.
Don't spill slag down the side of the crucible, else you will cause the crucible to stick to the plinth.

.


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## GreenTwin (Oct 10, 2022)

*Burner:*
Ironman uses a drip-style oil burner, running on a mix of diesel and waste oil, perhaps 20% diesel (perhaps only the diesel mix in cold weather).
I have never been able to get a drip style burner to have any decent controllability, and so I use a Delavan siphon-nozzle burner running on 100% diesel.
You need an inline automotive filter right before the fuel line enters the burner, else you may clog the nozzle.
You need a ball valve for fast shut-off of the diesel, and a second needle valve for fine flow control, in series with the ball valve.

Most videos on building Delavan siphon-nozzle burners show a propane connection too.
With diesel, you can omit the propane; it is not required since diesel lights easily even in cold weather with a siphon-nozzle.

My burner operates at about 2.7 gallons per hour, which produces about 112 KW.

*Lifting Tongs and Pouring Shank:*
Some folks on youtube detail "better mousetrap" devices such as combination lifting tongs and pouring shank, for use with aluminum pours.
Don't screw around with gizmos with iron and iron temperatures.
Use standard foundry lifting tongs with an adjustable stop in the closed position, and a separate pouring shank with a good functional crucible retainer.  Both of these devices can be fabricated at home if you can weld.

.


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## GreenTwin (Oct 10, 2022)

Propane can be used to melt iron, but due to tank cooling, I find it very problematic, and with cooler outside temperatures, the tank cooling becomes worse.

I highly recommend using an oil burner to melt iron, and not propane.
I prefer using diesel, since waste oil can contain heavy metals, or other contaminates that can cause an uneven and unpredictable burn.

Melt times for a #10 crucible of aluminum is 12 minutes with an oil burner.
Melt time for a #10 crucible of gray iron is about 1 hour for my setup.

.


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## GreenTwin (Oct 10, 2022)

*Sand:*
Many use what is called greensand when casting iron.
Greensand is sand mixed with a special clay, water, and generally some fine materilal like coal.
Greensand is reusable, but you have to mix it in a mixer that is called a "muller" to fluff it up.
You have to control the water content of greensand somewhat exactly, else you can have a steam explosion.

I tried greensand and got very poor results.
Ironman said it took him a long time to perfect his greensand.

Petrobond can be used with iron, but is prone to errosion problems, which can cause sand inclusions (voids in the casting).
Be aware that if you open a petrobond mold while the casting is still hot, the smoke can explode in a large ball of fire (don't ask me how I know this, just take my word for it).

I sidestepped the entire greensand issue by using resin-bound commercial foundry sand called OK85, which is what the art-iron folks use for their iron pours.
Resin-bound sand is used commercially for iron and steel castings, and is a proven molding material for iron and steel.
I additionally spray two coats of an alcohol-based ceramic mold coat on the interior of each mold, burning off each coat after I spray it.
The ceramic mold coat prevents any burn-on of the sand onto the iron, and gives a perfectly clean shiny finish to iron castings right out of the mold.

Resin-bound sand is not easy to find, and not reusable, but it produces excellent castings with very repeatable quality control.

.


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## GreenTwin (Oct 10, 2022)

*Melt Process:*

The burner should be adjusted for a reducing burner, which is a slightly rich burn, and with about 4" of yellow flame coming out the furnace lid.
This prevents much of the oxidation that can otherwise occur if you run an oxidizing tune on the burner, which is slightly lean.
If you don't run a reducing burn, you will have excessive metal loss due to a large amount of slag generated.

I fill the crucible with broken scrap iron pieces, being sure they are not jammed, since they expand when heated and can crack the crucible.
If you use garbage iron, you will have garbage castings.
Don't every use sash weights; they are made from discarded trash metal.
I use electric motor end bells only for iron scrap.

I let the initial iron charge melt and create a puddle in the bottom of the crucible.
I hold each piece of additional scrap added over the exhaust stream for about 30 seconds to completely drive off any residual moisture, and then drop the scrap through the lid opening into the crucible.  Driving off residual moisture is critical if you don't want a crucible/iron explosion in the furnace.

As each additional piece of scrap is added, a piece of rebar is used to push the scrap through the surface slag, and completely under the surface of the molten pool.  This process of pushing the scrap through the slag on top the melt really helps minimize slag, and keeps a hard slag cap from forming on top of the melt during the melting process.

Keep adding scrap pieces one or two at a time, until you have the desired amount of iron in the crucible.

.


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## GreenTwin (Oct 10, 2022)

*Radiant Heat:*
The radiant heat coming off of the walls of the furnace (when the lid is open), and/or the crucible is extreme.

Any skimmer handles, or pouring shank need a sheet metal hand/glove guard, else you will overheat your glove in seconds if you are within 30" or less of the furnace or crucible.
Use a skimmer with a long handle.

Full leathers and leather boots, or spats must be worn.
I wear a hard hat with face shield, and safety glasses under the face shield.
My safety glasses are cutting-torch tinted.
Without tinted glasses, the infrared rays will quickly burn your eyes (like sunburn in the eyes).

Anything plastic, rubber, or other combustible material must be more than 10 feet from the furnace (like 20 feet away).
The rubber fuel lines should be protected with something that won't easily burn, like a welding blanket.

Don't use any water or moisture anywhere near the furnace.
Don't use water to put out a furnace fire.
If you use sand around your pour area (I don't), try to make sure it is dry sand.

.


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## GreenTwin (Oct 10, 2022)

*Pour Temperature:*
When the iron reaches pour temperature, I open the furnace with the burner running, skim off the slag, add a slight amount of 75% dry ferrosilicon, stir slightly with a piece of rebar, lift the crucible and set it on an external plinth and onto the end of the pouring shank, secure the crucible retainer, lift, and pour the iron into the sprue.
The iron should basically pour with the consistency of ice tea if you are at pour temperature.
A good iron pour temperature is about 2,500 F.
Iron pyrometers are extremely expensive, and so most don't measure their iron temperature, but just judge by the color and fluidity of the melt.

If you are not wearing sufficient leathers, you will not be able to open the furnace with the burner running and skim the slag.

.


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## GreenTwin (Oct 10, 2022)

I don't use lost foam due to the toxic fumes, and I have seen horrible quality if used with iron.
I have seen some very bad quality when the lost-foam process is used with aluminum too.
The backyard lost-foam method is not the same as a commerical foundry lost foam method, so don't confuse the two.
Commercial lost foam castings are excellent in any metal, and they use polystyrene beads expanded in a permanent metal mold.

Backyard foam castings often use foam that is too dense, or coatings that are not permeable, and so the results can be very bad, or sometimes surprisingly good.  I have not seen backyard lost foam castings that approached the real commercial lost-foam method though.

I don't use lost wax or lost PLA, but I have seen it used with iron, and the results were superb.

The slurry material I think most use is called Suspendaslurry.
It has a finite shelf life, and you cannot let it freeze.
The process as I undersand it is to make a pattern in either wax, or 3D printed, dip the pattern into the slurry, shake on dry sand, and then repeat the dip and sand application multiple times.
The coated pattern is then inverted and the wax or filament is burned out in a high-temperature kiln, which also dries the slurry coatings.

The burned out shell is then poured with metal.
I typically see folks pour the shell while it is still very hot, and the shell is typically imbedded in dry sand prior to the pour.

.


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## GreenTwin (Oct 10, 2022)

Melting gray iron is highly problematic if you don't follow the above items religiously.

If you have a good iron setup/equipment, pouring iron is not much worse than melting alumium, but with a lot more radiant heat.

Don't lean over the opening in an iron furnace lid while it is running, else you will melt your faceshield in a few second.
I use an old glass refrigerator shelf in front of my faceshield, to be able to get a look at what is happening inside the furnace during a melt.

I must admit I was terrified when I started trying to melt and pour iron, and to took quite a few pours to get comfortable with the method and equipment.
Iron pours now for me seem as routine as aluminum pours, but with much more leather protection.

.


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## GreenTwin (Oct 10, 2022)

Look at post #5 of this thread, and you can see my furnace running, and the results of some iron pours.

I use a Toro variable speed leaf blower for combustion air, and I put the full blower output into the furnace while the blower is on its slowest speed.

I start the burner with the leaf blower off, to prevent blowing out the burner.

.


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## ajoeiam (Oct 10, 2022)

GreenTwin said:


> snip
> 
> I fill the crucible with broken scrap iron pieces, being sure they are not jammed, since they expand when heated and can crack the crucible.
> If you use garbage iron, you will have garbage castings.
> ...



Hmmmmmmm - - - - wondering - - - how does one acquire said electric motor end bells? 

Are there other sources of material?


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## Richard Hed (Oct 10, 2022)

GreenTwin said:


> Another item that I consider a myth is the need for a pouring basin.
> Many folks, even very experienced casting folks, will insist that a pouring basin must be used in order to get good castings.
> 
> But if you look at what happens when you pour any liquid, including liquid metal, into a basin, you should realize that this process churns air, bifilms, slag, sand, and other unwanted material into the melt, and does far more damage than any perceived good that it is suppose to deliver.
> ...



Hold on here.  This vid has some probs for pours:  viz: there is no liquide draining at the bottom like a casting would have, and also, if one could, wouldn't one pour directly into the hole in the bottom of tshe bowl, if one could?  Lastly, this demonstration is dropping the liquid directly downward which never happens with a real pour--a real pour comes from the side and has some sideways momentum.  What then?

Thanx for that "thin skin" discussion on aluminum.  I've seen than on alum but not on iron.  What about brass?  does brass have it?  I don't remember seeing it on brass.


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## Richard Hed (Oct 10, 2022)

GreenTwin said:


> I generally use a 3" diameter short length of steel pipe (perhaps 1" long) at the sprue, just to catch any initial spill from when the pour starts.


This is intriguing to me, but It is not completely clear (thimpfks I understand), can you show a photo?  Ah, just viewed luckygen1001's vid.  It shows a "bowl like" round as you describe.  I thimpfks, however, that a cone shape would be better.  What do yuou thimpfK?

While watching luckygen1001 I waS amazed at his setup.  I was thimpfking how is he going to pour that without help?  Then he trukt the whole thing out to his shed door.


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## Richard Hed (Oct 10, 2022)

Home foundry guy shows his sprues and explains the "basin/bowl"


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## GreenTwin (Oct 10, 2022)

ajoeiam said:


> Hmmmmmmm - - - - wondering - - - how does one acquire said electric motor end bells?
> 
> Are there other sources of material?


Cast iron was commonly used for machines, engine blocks, and all sorts of other things.
You can find it at most scrap yards.
If you strike steel with a sledge hammer, it bends.
If you strike gray iron with a sledge hammer, it will break, leaving a rough edge.

Wear a face shield when breaking up iron.
Some will cut it on one side with an angle grinder, to weaken it.

And some use disk brake rotors, but I think they are on the hard side, and I don't use them.

.


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## GreenTwin (Oct 10, 2022)

Richard Hed said:


> Hold on here.  This vid has some probs for pours:  viz: there is no liquide draining at the bottom like a casting would have, and also, if one could, wouldn't one pour directly into the hole in the bottom of tshe bowl, if one could?  Lastly, this demonstration is dropping the liquid directly downward which never happens with a real pour--a real pour comes from the side and has some sideways momentum.  What then?
> 
> Thanx for that "thin skin" discussion on aluminum.  I've seen than on alum but not on iron.  What about brass?  does brass have it?  I don't remember seeing it on brass.


I had a link to an actual pour basin simulation but lost it.
But the metal acted much like this video, with lots of splashing and other undesirable effects.

.


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## GreenTwin (Oct 10, 2022)

This is the small basin I use over the spure.

The molds have to be weighted on top, else the hydraulic lifting force will lift the top of the mold (the cope) off of the bottom of the mold (the drag), causing a "runout", where the top half of the mold drains out onto the ground.


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## GreenTwin (Oct 10, 2022)

Richard Hed said:


> Home foundry guy shows his sprues and explains the "basin/bowl"



Effectively he is doing the same thing I am doing, ie: he has a small basin over or near the top of the sprue.
His basin is very small, and if you use a basin, make it as small as possible.

I still think pouring straight down the sprue is better, but as I mentioned, I use a ring to sort of catch any misguided initial metal.

I think olfoundryman also sometimes uses a basin just like mine.
I will look for that video of his.

Probably the most critical think from his video though is that the lip of the ladle is very close to the sprue opening, and he fills the sprue very fast, and keeps the sprue full during the mold filling.

Here is a video where he uses a pouring cup, which is basically what I am doing with my metal cup.
The cup basically catches and directs the initial flow of metal at the start of the pour, so you don't slosh metal all over when you start pouring.
See 10:58.

The pouring cup also gives you a slight amount of elevation, so that molten metal can run out of the vent holes and ensure a complete mold fill.


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## GreenTwin (Oct 10, 2022)

For this pour, I stopped pouring a little late, and so had some overrun.


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## GreenTwin (Oct 10, 2022)

For this pour, there is very little splillage, and the metal rose in the mold just to the point where the vent became full.
This is a good clean pour.


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## GreenTwin (Oct 10, 2022)

It should be noted (perhaps I mentioned it before) that pouring iron cannot be a casual thing like pouring aluminum.

Aluminum melts at a low temperature, and can be melted in almost any container (steel containers/crucibles will degrade over time, but they can be learned if you are trying to learn to melt aluminum).
Almost any burner operating at almost any setting will melt aluminum.

Aluminum melts are very easy and is very forgiving of misadjustment of things.

Iron does not melt easily, and the burner output and combustion air setting has to be perfect, at 2.7 gal per hour, or approximately that.  Any variance from the exact burner setting will prevent most iron from melting, or prevent the iron from reaching a good pour temperature, which is about 2,500 F.

The saying is "Iron takes no prisoners", and the sightest contact with molten iron on the skin causes immediate 3rd degree burns.

If you try melting iron, don't take a casual approach, since that most likely will not work, and you most likely will get burned.

Assume it is like taking a hike to the top of Mount Everest.
Its relatively easy to get to the top of Everest with the right equipment, training, preparation, etc.
Without the right setup, equipment and knowledge, climbing Everest will be a deadly affair.

.


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## GreenTwin (Oct 10, 2022)

Here is a video of a guy attempting backyard casting in aluminum.

Not a bad effort.
He has trouble with the petrobond, which is the same experience I had with petrobond, and why I now use resin-bound sand.

He notes that the basics of melting metal is pretty simple, but the mold making can be anything but simple or easy.

I went through a lot of his issues early on when I started pouring aluminum.

A few mistakes he makes:

1. Use 356 aluminum, not extruded aluminum.  Don't use aluminum cans.

2. Don't lift a crucible with pliers or tongs on the upper top side of the crucible; that is a no-no.

3. Keep the sprue entirely full during the pour.  He seems to be pouring at a good rate, but does not seem to be keeping the sprue full.


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## GreenTwin (Oct 10, 2022)

This was a simple open-faced mold I used for an art-deco pour of a phoenix plaque.

This gives you an idea of the typical operation of an iron furnace.

Note, always start the burner with the lid open, and get the burner stabilized before closing the lid.

I also change into leather boots prior to pouring the iron.


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## GreenTwin (Oct 10, 2022)

As far as using pour basins, I see a lot of videos of how critical it is to use an offset pour basin (the basin is offset to one side of the sprue).

But if you can make perfect castings by pouring directly down the spure, without a pour basin, then that sort of proves that the pour basin is not serving any useful function and can be omitted.

.


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## awerby (Oct 10, 2022)

GreenTwin said:


> For this pour, there is very little splillage, and the metal rose in the mold just to the point where the vent became full.
> This is a good clean pour.
> 
> View attachment 140549


Greentwin - thanks so much for all this information! It makes iron casting at home seem a lot more feasible than I'd thought. A few questions:
Does the ferrosilicon lower the melting point of the iron to make crucible-melting more feasible? Does it change the working qualities of the metal in other ways, desirable or not?

Are silicon carbide crucibles just as good or better than the clay-graphite ones you mention? 

Would natural gas - which doesn't have the icing-up problems of propane - have enough BTUs to melt iron, if paired with a pressure-blower, or is diesel fuel really necessary? 

Do you need any special equipment to mix up the resin and the sand? Or is it a matter of shovel technique? Is it a two-part resin, like epoxy, or a single one like oil? How long do you have to get the material in place, once it's mixed? Do you know the brand name of that ceramic spray you recommend?


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## GreenTwin (Oct 10, 2022)

Awerby-

Casting gray iron is very feasible, perhaps not nearly as cheap as casting aluminum, but technically/mechanically not much more complex than casting aluminum.

The biggest thing I think with iron is having everything rated for 3,000 F, which means using some commercial refractory like Mizzou, and using strategically located sheet metal heat shields on the pouring shank and skimming tongs.

I have not seen a silicon carbide crucible that was ferrous-metal-rated, and they had a much lower operating temperature rating than the Morgan "Salamander-Super" clay graphite crucible.  I would not recommend using a silicon carbide crucible for ferrous-metal.

I think you could melt iron with natural gas, but you would need some significant pressure, ie: maybe as much pressure as with propane, or maybe not.
Ironsides (luckygen) could probably give a better answer on this.  He has melted iron with propane.

When melting aluminum, you don't need a separate combustion air blower, and you can use a simple naturally aspirated propane burner.

With iron, you need some significant combustion air in order to get the iron to melt, regardless of the burner or fuel type.

The ferrosilicon prevents thin spots in the iron becoming "chilled".
The definition of "chilled" when referring to iron castings is a hard spot (or entire casting) that is the hardness of tool steel.
When you break gray iron with a sledge hammer, the break should be a clean uniform gray, with no white spots.
White spots are areas of the casting that cooled too fast, and the graphite did not have time to distribute evenly through the casting.

Iron castings should remain in the mold overnight after pouring, and should cool as slowly as possible, to avoid chills.

I have gotten away with not using ferrosilicon for castings that were perhaps 1" thick and thicker.
As the casting thickness goes below 1", you pretty much have to use ferrosilicon in order to have good machinability.
Generally between 0.04 - 0.06 oz of ferrosilicaon is used per lb of iron.
Using more than this slight amount causes excessive shrinkage, and often hot tears, and degrades the quality of the iron.

Below is what scrap gray iron looks like.
Some use old radiators, and while the books say avoid radiator iron for engine work, some I have seen have used it successfully for engine castings.
Cast iron is very strong in compression, but weak in tension, so try to break it up with a blow that puts it in tension.
You may want to wear shin guards when breaking up iron, since pieces can fly out at high speed.

And another myth is "Iron scrap must be clean and free of oil, rust, dirt, scale, paint, etc.".
This is totally false.  I never clean my iron no matter what condition it is in.
All impurities come out of the melt in the form of slag.


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## GreenTwin (Oct 10, 2022)

awerby said:


> Do you need any special equipment to mix up the resin and the sand? Or is it a matter of shovel technique? Is it a two-part resin, like epoxy, or a single one like oil? How long do you have to get the material in place, once it's mixed? Do you know the brand name of that ceramic spray you recommend?


I have mixed resin-sand both ways, in a cement trough with a hoe, and later with a commercial kitchen mixer.
The commercial kitchen mixer does a better job of mixing.

The resin is toxic, so you have to wear nitrile gloves and a commercial chemical respirator.

The resin I use is a 3-part material that is frequently used in the art-iron community.
You mix part A in with the sand first.  Part A is what I call the base resin material.
The sand has to be very low moisture, and I use commercial foundry sand called OK85, which I think is oven-baked.

Then you mix part B and C together.
I call part B the hardener (which may or may not be technically the correct term), and C is the catalyst.
Then you mix the B/C into the sand.

Resin bound sand has a "set" time, and a "strip" time.
You have X minutes before the sand sets (hardens), and then Y minutes to remove the pattern from the mold before the pattern becomes permanently adhered into the mold.

The set time is adjusted by the amount of catalyst.
The resin and hardener are fixed amounts based on the weight of the sand.

I generally use a 5 minute set time, if the mold is not too complex, and perhaps 10 minutes if the mold is complex.

The strip time I think is in the 20-30 minute range.
I try not to strip too early, and I keep the mold on a flat surface until strip time since it may otherwise warp slightly.

The spray-on ceramic is called "VelaCoat", and it is alcohol based.
You spray it on with a slurry sprayer, or a sandblaster, and then burn off the alcohol.
I generally use two layers, with the first layer burned off before applying the second.

I also lightly flame the interior of the mold before spraying on the mold coat, to drive off any uncured residual resin.

Here is a video of how resin-bound sand is commonly used.

I don't use a ceramic filter, but instead use a spin trap at the end of the runner, to catch the initial flow of the iron before it begins to enter the mold cavity via the gates.

Note that they do not use an offset pouring basin, but pour directly down the sprue, as I do.

You should wear a good dust mask when handling sand for the molds.

It looks like in the video they use a simple paint sprayer to apply the mold coat.
It is a pretty thin slurry.


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## GreenTwin (Oct 10, 2022)

One thing that I notice as I watch the various iron pour videos is that a smaller crucible is much safer and easier to handle than a large one.

Here is an iron pour with a small crucible.




Note, I would never operate a furnace indoors.
One guy on a casting forum was running his furnace in his shop, with all the doors open, and almost died from carbon monoxide.
The doctor said he had never seen anyone survive a blood oxygen level that low.

The rating of the crucible in iron is roughly three times the crucible number, so I #10 will hold a bit less than 30 lbs of iron.
I generally don't pour a crucible if it is completely full, so I use more like 20-25 lbs iron in a #10.

A #30 crucible is a bear to handle, and I have hand-lifted those, and hand poured one that was about 1/2 full.

Here is a #30 that I poured.
Note that this was one of my very early iron pours, and I had no idea what I was doing, so don't copy any of these methods.
And don't operate a furnace next to your house or garage either.





Your browser is not able to display this video.


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## GreenTwin (Oct 10, 2022)

Here are various crucible sizes.

Smaller crucibles are definitely less expensive.

I purchase my Morgans on ebay.

Note that Morgan uses the term "Salamander" for more than one crucible type.
Be sure to use a Morgan "Salamander Super" clay graphite crucible.
One seller on ebay mistakenly listed the salamander super as "for aluminum only".
Ebay folks don't know what they are talking about.

.


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## GreenTwin (Oct 10, 2022)

It should be noted that resin-bound sand is just resin and sand, and does not contain clay like greensand or petrobond does.

If you start ramming resin-bound sand, instead of compressing the clay (there is no clay to compress), you begin to shift the sand away from the pattern.

Resin bound sand is pressed tightly around the pattern using the fingers (wear nitrile gloves), and then the rest of the mold is filled in, with the heel of the hands pressing it down, but not pressing so hard that it begins to cause it to shift.

And a resin-bound mold can be very thin, since it sets into a very hard state.
Resin bound molds can be perhaps 20-25% the size and mass of a greensand mold.

.


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## 100model (Oct 10, 2022)

awerby said:


> Does the ferrosilicon lower the melting point of the iron to make crucible-melting more feasible? Does it change the working qualities of the metal in other ways, desirable or not?
> Would natural gas - which doesn't have the icing-up problems of propane - have enough BTUs to melt iron, if paired with a pressure-blower, or is diesel fuel really necessary?


Ferrosilicon does not lower the melting point of cast iron so what it does is it makes sure that all the graphite comes out and makes the iron soft enough to machine. If no ferrosilicon is used there is a strong possibility that white cast iron will form on the edges of castings and cutting tools will bounce of that part of the casting.

Propane will easily melt cast iron but there are two problems with it 1. you have to pay for propane 2. In small amounts it tends to get very cold so the furnace is starved for gas. To solve that problem most people use small propane bottles so the trick is to put the propane bottle in a larger container and fill it with hot water so the propane can change from a liquid to a gas. I use a 45kg propane bottle and it does not have this problem until there is 5-8 kg left and then the icing problem comes back again. The same method is used but you have to find a larger container for the larger propane bottle. I don't use propane any more to melt cast iron because waste motor oil is for free.


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## ajoeiam (Oct 11, 2022)

GreenTwin said:


> Cast iron was commonly used for machines, engine blocks, and all sorts of other things.
> You can find it at most scrap yards.
> If you strike steel with a sledge hammer, it bends.
> If you strike gray iron with a sledge hammer, it will break, leaving a rough edge.
> ...


Hmmmmmmmmmm - - - - that means that supply if I were to get into this would be problematic! 
Local scrap yards only allow material IN - - - anything out is to the smelter only. 
Absolutely NO sales of anything.


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## Richard Hed (Oct 11, 2022)

ajoeiam said:


> Hmmmmmmmmmm - - - - that means that supply if I were to get into this would be problematic!
> Local scrap yards only allow material IN - - - anything out is to the smelter only.
> Absolutely NO sales of anything.


where the hek do you live?  Must be terrible.  I was just at a scrap yard yesterday--bought a "chiller" (restaurant equip?) it lookt like to me, for the stainless sheet that was on it.  Cost 15c a lb, weight 280lbs--43$, only had 42$--SOLD!  They are glad to get cash (there was no reciept, wink wink).  There was CI all over the place had I wanted to buy some.  Your local scrap yard must be very peculiar.  Do you live close to another city, town, megopolis?  I notice you live in "blank".  Is that a nice place?  Maybe you should consider moving to the Soviet.

I need a piece of steel 16X5X1.25".  I lookt for such a piece but this day there was nothing resembling that.  Didn't have the $$ for it anyway.  But tomorrow I WILL have some extra dough.  I needs to be careful, as I bought some scrap there last year that was various shapes X 1.5" thick, some large enough to be difficult for me to pick up--they don't need to be very large for that!  At that time, I was able to see a strapped package of steel that was at least 4 feet thick, 6 or 8 feet wide and lookt like 10 or 12 feet long.  I couldn't tell from the way it was situated if it was "shells", that is, left overs from lazer cutting which is what the parts I was buying were from.  The guys in the yard were cutting the shells up with acetylene.  I've used a lot of it but want some more.  Will have to keep an eye on the scrap yard till I can get some more.  the little pieces that are left over are great for making a lot of small steel parts like we guys are making all the time.


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## ajoeiam (Oct 11, 2022)

Richard Hed said:


> where the hek do you live?  Must be terrible.  I was just at a scrap yard yesterday--bought a "chiller" it lookt like to me, for the stainless sheet that was on it.  Cost 15c a lb, weight 280lbs--43$, only had 42--SOLD!  They are glad to get cash (there was no reciept, wink wink).  There was CI all over the place had I wanted to buy some.  Your local scrap yard must be very peculiar.  Do you live close to another city, town, megopolis?  I notice you live in "blank".  Is that a nice place?  Maybe you should consider moving to the Soviet.


One city of 750k about a good hours drive away. 
After that - - - - the nearest city of over 300k is likely 6 hours drive or so. 
For some things - - - - were I live IS terrible. 
For some other things - - - not too bad. 

Moving to the Soviet - - - - no thanks - - - - I'm not into grey skies and no sun all winter.
(Been there - - - well close - - - didn't like the no sun part!!!!)


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## Richard Hed (Oct 11, 2022)

ajoeiam said:


> One city of 750k about a good hours drive away.
> After that - - - - the nearest city of over 300k is likely 6 hours drive or so.
> For some things - - - - were I live IS terrible.
> For some other things - - - not too bad.
> ...


Ha ha haww.  That is really funni!  We have you completely fooled.  I live in the Eastern part (actually central) part of the Soviet where it gets cold in the winter, but there is rarely a lot of cloud couver in the sky.  I know because I do nite-time telescoping.  Look on a map and you can find the Cascade Mts. which stretch from BC to N. California (actually further).  Those mountains block the rain.  Seattle has a bad rep for rain--and a certain time a year it is pretty bad, however, my nephew lives in Eugene, Ore, which I thimpfks if MUCH worse.  Funny thing is Oregon does not get that rainy bad rep,but I thimpfks Ore. is actually worse.  Ore. on IT'S Eastern side is also like the Soviet, far less rain, even a desert.

In the Soviet itself, as you approach Spokane, it starts to become wetter but not the type of area that has much fir, it is mostly pine which thrives in an almost desert like area.  As you get into Idaho, you start climbing the 4th of July pass (or is that in Montana?)  and you get lots of snow, don't know about rain.  The people that live in the area (Idaho and MOntana) seem to like it.

Moses Lake, at one time, had the longest runway for fighter jets in the nation--it was SAC headquarters till '72, but the runway has been cut down now.  The area is being considered for the HTOL space vehicle but it won't happen (me thimpfks) for two reasons:  too much population and the weather HAS indeed become less sunny.


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## GreenTwin (Oct 11, 2022)

I forgot to mention that I got the motor end bells from an electrical motor rebuild shop.

Any repair shop that rebuilds anything that is made from gray iron will have some discards.

If you can't find anything else, use automobile or truck disc brake rotors.

.


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## delalio (Oct 11, 2022)

Hello Everyone, 

So I'm not a caster. I've played about in the garden with some greensand and a propane torch, but nothing very serious. 

I did however go visit Cringle Engineering and recorded some video of the castings Luke does up there. I was very impressed.
Anyway, I made a little video of the work he does, with some cool slow-mo and in 4k. 

The video goes live at 18:45 this eve if you are interested in watching it.

I'd love to hear your comments.
Please note, again, I am not a caster, just narrating my observations. But some of you may find it interesting or find the video nice to look at.



Kindest Regards,

Del


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## GreenTwin (Oct 11, 2022)

The cringle guy has a great shop setup, and is producing some nice pieces.

A few comments (coming from an amatuer backyard guy with limited foundry experience):

1. I would run a carbon monoxide detector if I operated a gas or oil-fired furnace indoors, even if I had an exhaust fan.

2. I have heard some say that a steel crucible used with aluminum can contaminate the metal.
Some coat their steel ladles with something to stop any interaction, and I forget the name of this coating.
I used a steel crucible with aluminum for several years, and have never noticed any problem with the castings, even over a 10 year period.
Steel crucibles can have a huge capacity, due to the thin wall, for a given size.
The steel does degrade over time, so don't let them get too thin.

3. The matchplate layouts are nice, as is the jolt table, automatic sand feeder, and pneumatic (?) mold separator/pattern extractor.

4. I did not see him use a pyrometer, but some can accurately judge the metal pour temerature with aluminum visually.
However cringle is judging metal temperature, his casting surface finish indicates he is at a very good pour temperature, which is typically in the 1,350 F range.

5. I would use a rolling conveyor going from the molding area to the pour area, and would not lift the molds from the tabletop to the ground, and then back up to tabletop height again.  I have seen Clarke Easterling use non-powered rolling conveyors like this.

6. His pour technique is very good.  He keeps the lip of the crucible right at the top of the sprue, to avoid the waterfall effect.
He keeps the sprue full at all times.
Note that he pours directly down the spure, and does not use an offset pour basin, which how I recommend pouring molds.

7. A water quench gives aluminum castings a bit more hardness.  A two step process can approximate a T6 temper, and gives a more cleanly machining casting with low tool loading.

8. Throughput is limited by flask quantity, sand quantity, and crucible/furnace capacity.
I have seen commercial shops with a large electric furnace and tub full of aluminum, and they use a ladle to dip out the aluminum for pours.

9. Many have said online (somewhere) that you must discard the burned petrobond sand that is next to the mold.
The folks I know who use a lot of petrobond (art-iron folks with aluminum) never discard any petrobond, but instead use fresh petrobond for a thin facing sand, backed up by used petrobond.
I think petrobond can be reused indefinitely without discarding any of it, if you add a little alcohol every now and then and mull each time you make molds.

10.  The muller is a nice simple design.
If he stays in the business, he should consider building a muller with rotating wheels.
I started to build my own muller, and then changed to resin-bound sand.

11. His flasks are a manageable size, and not too heavy to lift and handle.
A larger flask means more sand required per flask, and some heavy lifting/flipping.

His 3D modeling is very good too, as is his pattern work detail.

All in all, he has what I consider a very functional setup, and a great product.

.


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## GreenTwin (Oct 11, 2022)

Here is the muller I started to build.
It is made from trailer fenders, which are a bit thin for long term use, but would probably last a few years.


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## GreenTwin (Oct 11, 2022)

More muller build photos.

Note:  It is important to have either a sheer pin, or something that can slip, since a small piece of slag can jam a muller, and without some release mechanism, the muller drive train will destroy itself.

Some use a microwitch activated by an over-torque mechanism to stop the motor in case of a jam.


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## 100model (Oct 11, 2022)

awerby said:


> or is diesel fuel really necessary?


Diesel fuel is not really necessary, you can use waste motor oil. In this video a simple waste oil burner is made and he melted lava so if he can melt lava he can melt cast iron.


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## GreenTwin (Oct 11, 2022)

A few words of caution on using waste motor oil.
As mentioned in the video, waste motor oil contains heavy metals.
Is there enough heavy metals in waste oil to cause problems?
The video guy is just speculating, he has no idea what levels of heavy metals are in waste oil, or what level may be harmful, and I don't know either.

And sometimes folks use waste oil that has been contaminated by radiator fluid, etc., and this won't give a good or safe burn.

It should be noted that diesel combustion fumes are considered hazardous too, in spite of the fact that all diesel trucks on the highway burn it, and you drive behind them and breath the fumes.
You should avoid any fumes coming out of a furnace, regardless of the fuel type used.

The reason I don't like or use drip burners is that they have poor fine control, and tend to surge.
As ironman shows, a drip burner does work well for melting iron, so there is no question that a drip oil burner works well.
The beauty of a drip burner is its simplicity.
I still dislike drip-style burners, and will never use one (it is a personal preference thing, to each their own).

I use diesel with a spray nozzle because you don't need propane preheat with sprayed diesel; you just light it, and almost immediately you have full burner output.
2nd reason I like diesel is that it is relatively clean to handle, unlike waste oil which is very black and dirty to handle.
Both fuels are oily, but waste oil leaves black marks on everything ot touches.

3rd reason I like diesel is I can dispense it from any gas station that sells diesel into a gas can, and then pour that into my foundry fuel tank.
Or I can take my foundry fuel tank to the gas station and fill it there.

A reason I don't like waste oil is sometimes it contains globs of foreign material, and a siphon nozzle has zero tolerance for anything other than perfectly clean fuel.
You can filter waste oil.
If I used waste oil, I think I would use an inline spin-on auto oil filter.

I use a small automotive inline fuel filter just before my burner, and that is all I need with diesel.

The only downside I see with diesel is cost, and if you do a lot of metal casting, diesel could get expensive.
Some foundry folks use offroad diesel, and it is a cheaper fuel than automotive diesel.

Most mix 20% or so of diesel with their waste oil to thin it a bit, expecially in cold weather.

Diesel is impervious to cold weather, and I have started my siphon nozzle at 30F with no problem at all during either starting or operation.
And diesel is a consistent fuel, so you will always get the same burner output every time.
I literally never have to adjust my siphon nozzle burner.  I don't adjust it before a melt, or during a melt, or between melts.
Diesel with a siphon nozzle and a fuel tank pressurized to 10 psi gives a rock-solid almost instant and non-varying burner output.


Propane has a lot of issues with cold weather operation, and the colder it is, the more problems you will have with propane.

And beware of the statement that "almost any oil can be burned in a furnace".
I have heard that burning hydraulic oil is extremely toxic (I have not verified this), so do your homework and don't burn something with known toxicity when it burns.  This goes for any metal you melt too.  Never burn the insulation off of electrical wires; those fumes are deadly toxic.

A buddy of mine uses waste food oil, from a fry grille, and with the right filtering, he says this works well for melting iron, if you can find a source.
I looked at using waste food oil, but these days they seem to have it all locked down like Fort Knox, and nobody wants to give anyone anything.
Waste food oil supposedly has a sort of french fry odor to it when it burns, which would be pretty cool in my opinion.


As fuel prices soar ever higher, we will probably all end up burning waste oil, just as a matter of staying solvent financially.
There seems to be no end to inflation these days, and it would be rather difficult to operate an iron furnace from the new"green" batteries that seem to be so politically correct now.

I think I would just add a spin-on filter if I convert to waste motor oil.
I always avoid breathing when I am near the furnace lid opening, so it does not matter if I am using waste oil.

I also have a powered respirator that I have used when trying to melt brass, to avoid the zinc fumes, but that is a pretty extreme solution.

.


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## 100model (Oct 11, 2022)

GreenTwin said:


> Waste food oil supposedly has a sort of french fry odor to it when it burns, which would be pretty cool in my opinion.


That is a myth that if you burn waste veg oil it smells like french fries. I have used waste veg oil in my furnace to melt cast iron and never noticed any smell. The same goes for waste motor oil it smells really bad when using a very rich smokey flame in my furnace.


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## GreenTwin (Oct 11, 2022)

If I do start using waste oil, and it seems like that is becoming more likely with each day, I think I would preheat with diesel instead of propane.

It is easy enough to go get a 20 lb bottle of propane, but that takes perhaps 45 minutes to drive to the store and get an exchange, and I don't really have 45 minutes to spare.

I can buy 20 gallons or more at a time of diesel, and do that quickly.

I guess I would use a 3-way valve, and start on straight diesel, and once the furnace was hot, switch to waste oil.

If veggy oil did burn with a smell, I would insist upon Crispe Creme oil, from the legendary "hot donuts" place.
I think you could market Crispe Creme oil just for the odor, if you could get that same smell as cooking donuts.

.


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## D and D (Oct 12, 2022)

ajoeiam said:


> Hmmmmmmmmmm - - - - that means that supply if I were to get into this would be problematic!
> Local scrap yards only allow material IN - - - anything out is to the smelter only.
> Absolutely NO sales of anything.


Brake disks are the go to for me.


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## master53yoda (Oct 12, 2022)

I use waste oil for my scrap processing furnace,  The 2 burners have a small (60,000 BTUH) adjustable propane burner built into the combustion air for the waste oil, the propane flame surrounds the nozzle for stable cold furnace ignition and shuts off when the furnace temp gets to the 750F manual to programed Control point of the oil firing rate.

The furnace holds about 200 lbs of scrap automotive engine parts, Depending on how much oil etc. is on the parts, I  start and close the furnace but, if it needs more air for a clean burn I will fire with the lid open until the furnace and all the metal gets up above 400F or the oil has burned off the scrap. then I can close the lid.   The actual melt time once the furnace hits the melt point is about 20 minutes.  I am looking at increasing the 6" exhaust to 8" and adding more combustion air,  The 8" will have a propane after burner to burn off any smoke that I get on the initial startup.  The after burner will shut off at the 750F change over point. The initial 20 to 30 minute manual control deals with fuel/air variables caused by the oil on the scrap parts.

I use a 20 gallon tank that I pressurize to about 5 psi, the oil leaves the tank through an automotive spin on filter, I do use the high efficiency 5 micron ? filters, they cost about triple the price of a normal Fram filter but it does eliminate any particulate problem and they will last through 500+ gallons of waste oil , I have only changed it once in 4 years and that was due to a drum of oil that had water in it. To eliminate the water problem, when I start into another 55 gallon drum I pump out the bottom of the drum into another drum  until I get only fuel.  most drums have a few gallons of water in the bottom.

The oil runs through a pre-heater set for 150F, depending on what weight oil is in the drum, the heater provides stable consistent viscosity on the oil even below freezing temps outside.  

The oil then flows through a 120 vac primary solenoid control valve then to servo controlled needle valves for firing rate control, I have override pots on the needle valves for control until the furnace gets above 750F it then is controlled based on the melt pool temp. it goes from full fire (6 - 7 GPH up to 1400f and modulates down to low fire (1 burner off and 2nd burner about .75 GPH) at 1475f.   The control system uses an Arduino MEGA2560.

My burner atomizing air pressure is about 10 psi. using siphon type burners.   

I will add some pictures from todays melt this afternoon.


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## ajoeiam (Oct 12, 2022)

Richard Hed said:


> Ha ha haww.  That is really funni!  We have you completely fooled.  I live in the Eastern part (actually central) part of the Soviet where it gets cold in the winter, but there is rarely a lot of cloud couver in the sky.  I know because I do nite-time telescoping.  Look on a map and you can find the Cascade Mts. which stretch from BC to N. California (actually further).  Those mountains block the rain.  Seattle has a bad rep for rain--and a certain time a year it is pretty bad, however, my nephew lives in Eugene, Ore, which I thimpfks if MUCH worse.  Funny thing is Oregon does not get that rainy bad rep,but I thimpfks Ore. is actually worse.  Ore. on IT'S Eastern side is also like the Soviet, far less rain, even a desert.
> 
> In the Soviet itself, as you approach Spokane, it starts to become wetter but not the type of area that has much fir, it is mostly pine which thrives in an almost desert like area.  As you get into Idaho, you start climbing the 4th of July pass (or is that in Montana?)  and you get lots of snow, don't know about rain.  The people that live in the area (Idaho and MOntana) seem to like it.
> 
> Moses Lake, at one time, had the longest runway for fighter jets in the nation--it was SAC headquarters till '72, but the runway has been cut down now.  The area is being considered for the HTOL space vehicle but it won't happen (me thimpfks) for two reasons:  too much population and the weather HAS indeed become less sunny.



Well - - - so you're 'that' far east - - - grin! 

Oh well - - - I like my garden - - - so I'll still pass on that offer - - - grin! 

Sure wouldn't mind your scrap guys though!!!


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## Richard Hed (Oct 12, 2022)

master53yoda said:


> I use waste oil for my scrap processing furnace,  The 2 burners have a small (60,000 BTUH) adjustable propane burner built into the combustion air for the waste oil, the propane flame surrounds the nozzle for stable cold furnace ignition and shuts off when the furnace temp gets to the 750F manual to programed Control point of the oil firing rate.
> 
> The furnace holds about 200 lbs of scrap automotive engine parts, Depending on how much oil etc. is on the parts, I  start and close the furnace but, if it needs more air for a clean burn I will fire with the lid open until the furnace and all the metal gets up above 400F or the oil has burned off the scrap. then I can close the lid.   The actual melt time once the furnace hits the melt point is about 20 minutes.  I am looking at increasing the 6" exhaust to 8" and adding more combustion air,  The 8" will have a propane after burner to burn off any smoke that I get on the initial startup.  The after burner will shut off at the 750F change over point. The initial 20 to 30 minute manual control deals with fuel/air variables caused by the oil on the scrap parts.
> 
> ...


Whoa?!  200lbs?  you must have a really nice setup to hold that much.  I can barely lift 20 lbs without help.  (I only weigh 98 lbs myself).  You didn't tell me you live in the Soviet!  Me thimpfks there are more HMEMembers in the Soviet than any other place.  You should invite me to see hyour setup.  I sometimes come out to Spokane to go to Costco as there is none in Moses Lake.  I also invariably go to Alcobra on Freya ST.


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## Richard Hed (Oct 12, 2022)

ajoeiam said:


> Well - - - so you're 'that' far east - - - grin!
> 
> Oh well - - - I like my garden - - - so I'll still pass on that offer - - - grin!
> 
> Sure wouldn't mind your scrap guys though!!!


Yes, I went there again today (actually yesterday by now) but with no $$, will get a check today and got some cast iron billets and some special iron, the type of steel that I got there before that I have needed and wanted since I bought it a couple years ago.  They had some, it costs 35c / lb!  More than the stainless!  It is some kind of special stuff, it's the stuff that Genie makes their Genie bodies with.  Whatever, I stashed it in a corner and will pick it up after work today.  I thimpfk I will pick up more than I planned.  The piece I need is 1-1/2 " thick, and that is what I found at tshe scrap yard.  (Yay)


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## GreenTwin (Oct 12, 2022)

master53yoda said:


> I use waste oil for my scrap processing furnace,  The 2 burners have a small (60,000 BTUH) adjustable propane burner built into the combustion air for the waste oil, the propane flame surrounds the nozzle for stable cold furnace ignition and shuts off when the furnace temp gets to the 750F manual to programed Control point of the oil firing rate.
> 
> The furnace holds about 200 lbs of scrap automotive engine parts, Depending on how much oil etc. is on the parts, I  start and close the furnace but, if it needs more air for a clean burn I will fire with the lid open until the furnace and all the metal gets up above 400F or the oil has burned off the scrap. then I can close the lid.   The actual melt time once the furnace hits the melt point is about 20 minutes.  I am looking at increasing the 6" exhaust to 8" and adding more combustion air,  The 8" will have a propane after burner to burn off any smoke that I get on the initial startup.  The after burner will shut off at the 750F change over point. The initial 20 to 30 minute manual control deals with fuel/air variables caused by the oil on the scrap parts.
> 
> ...



Art B (masteryoda) has a heck of a nice aluminum scrapping furnace setup.

And he sells some really nice aluminum ingots too (I have quite a few of them).

.


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## GreenTwin (Oct 12, 2022)

As far as melting iron using natural gas, I recall some converstations years ago about this, but it is all hazy now.

As I recall (check me on this stuff) you need a 2" gas line to your furnace.
Your natural gas regulator may or may not be able to provide enough flow to your furnace for an iron melt.
You may starve your other natural gas appliances if you put too much demand on your gas regulator.
You many need a higher flow and perhaps higher pressure? natural gas regulator.

I also recall reading about installing a natural gas generator at a home, and the things you have to do to make sure you have sufficient natural gas to feed it.  Generally they put natural gas powered gensets very close to the gas regulator.

Hope this helps.
This is all I can recall.

I am sure natural gas can melt iron, but as with propane, you need a high-flow and somewhat high pressure regulator to get the flow that you need to melt iron.  And you need a blower for compressed air.

.


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## Richard Hed (Oct 12, 2022)

ajoeiam said:


> Well - - - so you're 'that' far east - - - grin!
> 
> Oh well - - - I like my garden - - - so I'll still pass on that offer - - - grin!
> 
> Sure wouldn't mind your scrap guys though!!!


Damn!  Was at the scrap yard to pick up my winnings and was going to take photos so you could drool but I forgot.  Was too excited to get the metal home.  Want to take a small piece and see if I can harden it.  If  so, it will be even better for the project I have in mind for it.  did I tell what that project is?  It's a cross slide for the lathe.  

Remember the older lathes (and the tiny hobby lathes today) used to have slots for mounting tools on the cross slide?  They don't do that nowadays so I am going to build my own.  Also, I am going to add a couple inches in length to it.  Was hoping to be able to harden the project so I could grind the ways on it.


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## GreenTwin (Oct 12, 2022)

One guy online broke up an old lathe for iron scrap.
He never lived that down.

One thing you don't do (apparently) is break up old lathes.
Something sacrosanct about old lathes.

Old machinery was typically made from gray iron.

Some have suggested weights, like you see at the local health place, but I have found the new ones to be of compressed metal, and not good for any foundry use.  I am not sure about old dumbell weights.  I have never tried to break one.

.


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## master53yoda (Oct 13, 2022)

The residential Natural gas system is limited at about 600,000 BTUH ( 4.25 GPH diesel) that the meter will actually pass.  In order to get that flow you need to have a very short piping run.   Most NG utilities wont put a higher pressure system in residential. 
On my furnace as I run the Propane through 1/4 lines Because of the line loss I need the 10 PSI that comes of the main tanks.  I can get about 175,000 on my gas burners with an open line and using the line loss as an orifice.  My burners have needle valves on the propane which allows me to vary the firing rate down to about 5000 BTUH when the burner is acting as a pilot for the oil.

On the scrap issue I end up with a lot of camshafts and I think they are mostly cast but I'm not sure

Art b


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## master53yoda (Oct 13, 2022)

Here is a few pics of the furnace firing 1 with the furnace after the metal is melted, the other 2 are cold fire running about 60%, if i closed it this would have smoked due to not enough air.

Art  B


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## 100model (Oct 13, 2022)

Green twin have you watched this video about a burner for cast iron melting? Hmmmmmm there was no cast iron melting and he sounded like a politician in election mode.


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## GreenTwin (Oct 13, 2022)

100model said:


> Green twin have you watched this video about a burner for cast iron melting? Hmmmmmm there was no cast iron melting and he sounded like a politician in election mode.




I think I have touched on the "youtube burner guys" before, but it is worth noting again.

There are profession youtube "burner guys", and "ingot casters" (olfoundryman has some other terms for the ingot guys, which I will not repeat, but it has to do with polishing things).
It is not my place to tell people how to have fun, and so its all good as far as I am concerned, but not necessarily all good if you are trying to find a reliable foundry burner.

Generally speaking, the quantity of videos and view count for the burner and ingot guys is directly proportional to the usefulness of their content, ie: the more videos they have, and the higher the view count, the less useful it seems the information they offer is to a typical backyard casting person.

There also seems to be a correlation between the size of the flame from their burner and how useful the burner is, ie: the bigger the flame they are shooting out the end of the burner, the less useful it is for foundry work.  A good foundry burner may not operate well at all if it is not inserted in the furnace opening (the opening in the furnace for the burner tube is called the tuyere, pronounced "tweer" I think).

There are a number of what I consider "junk" burners on youtube, and by "junk" I mean not useful for foundry work, or not reliable for long term foundry work.  These burners may have other useful purposes.

*How to tell if a burner is not useful for foundry work:*

1. The burner tube gets red hot during operation.  Red hot burner tubes do not last very long, even if made with stainless steel.
There is no reason to operate a red hot burner tube or burner for foundry work.

2. Used car salesman shrill pitches about burners that seemingly will do just about anything, including powering a Saturn V rocket are useless burners for foundry work in my opinion.

3. "Better mouse trap" burners are generally some unique twist to a standard foundry burner, to make a better mouse trap, but these burners in my opinion add useless gimicks to a burner that serve no purpose, and often give a burner that degrades over time.  Some burner types appear to be outright dangerous, such as those using high fuel pressure.

4. High velocity burner outputs are not useful for foundry use.  The high velocity flames just climb up the back of the furnace to the lid, instead of swirling around the crucible and transferring heat to the crucible.

5. BIG burners are not better for foundry use.  I have tried some big burners, and they actually run cooler than the smaller ones.
The secret to operating a very hot burner and furnace is to introduce exactly the amount of combustion air and fuel into the furnace that a given size of furnace can completely combust, and making sure that complete combustion occurs INSIDE the furnace around the crucible.
Excess fuel and/or combustion air cools a furnace.
Bigger is definitely not better in the foundry burner world.

6. Burners that preheat the fuel like a Coleman gas stove burner does are not useful for foundry work.  Running a fuel line through a hot part of the burner or furnace just cokes up the tube, and clogs it.  There is no need to preheat fuel for a foundry burner unless you are running thick waste oil in the winter.

7. The Ursutz burner is what I call a "precombustion chamber" burner (not sure if that is an official term or not).
The Ursutz burner uses a chamber outside of the furnace, and the fuel is combusted in the chamber, and then piped into the furnace.
I have tried an Ursutz burner, and they get red hot when operating, and degrade quickly over time.
The Ursutz burner is reported (by someone who has used one a lot) to be easily capable of destroying crucibles due to producing too high a temperature inside the furnace, when the burner is operated at its maximum.
The Ursutz burner is also said to be capable of degrade the plinth quickly.
Given all of the problems that Ursutz burners cause, I can't think of any reason for using one for foundry applications.

8. It should be noted that some videos show burners that are not installed on a tangent to the side of the furnace, and thus the burner flames impinge upon the side of the crucible.
The crucible should never have direct flame impinging upon it, else it will fail very quickly.

BIG burner/BIG flame videos are great entertainment, but are not useful for foundry applications, in my opinion.

*The burner types that have been demonstrated to work well for foundry work, that I have seen are:*

1. The drip-style oil burner, which I hate, but others love.

2. The siphon-nozzle burner, or its cousin the pressure-nozzle burner.
I use a siphon-nozzle burner, and will soon be converting to a pressure-nozzle burner so that I don't need compressed air for atomizing the fuel.

3. The propane burner works well for aluminum melts, some brass/bronze melts, and even cast iron melts, if you have a high pressure/high flow regulator, and if your tank does not get so cold that it will not longer vaporize.
I use propane burners for aluminum only to avoid the cold tank/low pressure problem.

4. The Ursutz burner can I guess be argued about.
I know of one individual who has used an Urstuz for years to melt iron, and he likes it.
I would not go so far as to consider the Urstuz a good foundry burner, but I can't deny that this individual has melted perhaps a thousand pounds of iron (or more) using his Urstuz.
He has also had a lot of problems with his Ursutz, and problems caused by his Urstuz, which he just tolerates for whatever reason.
He sees lots of burner and furnace rebuilds which I think can be attributed to the Ursutz, which to me is totally unnecessary, and wasted time and money.

At the risk of sounding like one of those angry old gray haired guys who shouts at the schoolchildren "GET OFF MY LAWN !!!! ", I offer the following thoughts:

Rube-Goldberg style burners are not useful for foundry work, in my opinion, although they may be impressive to observe.
Many (perhaps most) burners on youtube are what I consider Rube-Goldberg style burners.
Millions of views, thousands of subscribers and likes, hundreds of videos, totally useless burners for foundry work.
Many burners on youtube are better classified as flame throwers I think, so perhaps they could serve some useful purpose.

.


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## creast (Oct 14, 2022)

GreenTwin said:


> I often hear that you should never pour straight down the sprue, but this is indeed the method I use.
> 
> Most folks on youtube pour their metal with the crucible elevated some height above the top of the sprue (the sprue is the hole in the sand into which you pour the metal), and this should never be done.
> 
> ...


We all find out methods.
Luckygen and olfoundryman are my heroes too but Martin would disagree about pouring basins and has stressed the importance of them when pouring aluminium.
Cast iron is a different fish I guess.
I know he has also criticised extended sprues but I note he has also used them.
As you know, I have broken accepted methods to achieve a result and I think aluminium has to be treated differently due to its oxidation during pouring.


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## GreenTwin (Oct 14, 2022)

I have studied myfordboy's methods, and he has great success with aluminum, but often does not use runners and gates in the same fashion I do.
Myford gets great results, and so it is tough to argue with success.

Aluminum melts easily, pours easily, flows very well, and is easy to get a good surface finish with, especially with petrobond.

With the backyard version of "lost foam", which is not the same as the industrial version of "lost foam", I have seen mixed results; sometimes pretty impressive results, and sometimes very rough results, with aluminum.
The backyard "lost foam" with iron is a disaster, from what I have seen, and the industrial method needs to be followed for that to work.

I have not dabbled in investment casting, so I can't really say what does or does not work well.
I have seen some pretty impressive results with aluminum (see creast's thread).

I like to watch anyone's casting work really, with the hope that I can always learn new tricks and techniques.

And I like to play with fire, so there is that.
The "danger-factor" makes it pretty exciting.
The pours where I don't kill myself are especially pleasing.

I like the model engine hobby, but I REALLY like the model engine/foundry hobby !
One of the more fun and interesting things I have ever done.

.


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## Richard Hed (Oct 14, 2022)

GreenTwin said:


> I have studied myfordboy's methods, and he has great success with aluminum, but often does not use runners and gates in the same fashion I do.
> Myford gets great results, and so it is tough to argue with success.
> 
> Aluminum melts easily, pours easily, flows very well, and is easy to get a good surface finish with, especially with petrobond.
> ...


I want to know about the pours where you DID kill yourself.  How did they work out?


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## GreenTwin (Oct 15, 2022)

Richard Hed said:


> I want to know about the pours where you DID kill yourself.  How did they work out?



LOL, I got better.

What I meant was to avoid killing myself.

Summer pours here are very hot, since we often have 80-90% humidity, and 90-110 F temperatures in the summer.

So I generally keep a box fan right next to my chair, and sometimes don't put on full leathers until pour time.

Heat stroke is pretty much my biggest worry.

I have learned to preheat everything very hot, including ingot molds, scrap metal, skimming tools, and lifting tongs.

The way I got the burns below was I preheated an ingot mold using a propane burner, and that did not get the mold hot enough, so there was residual surface moisture on the mold.

When I poured into the mold, the iron popped back out, in a mini-explosion of sorts.
No big deal with a full face shield, helmet, leathers, etc., except a few molten beads of iron went down the gloves.

I think I posted these photos previously.
3rd degree burns in a few spots on the back of the hands.
Nothing to write home about.

I kept the Curaid Silver on it till it dried over in a few days, and eventually the scar tissue filled it all back in.

Someone watched one of my videos, and asked "Where are the fire extinguishers?".
I watched the same video and I could not spot one either.
I do keep a few extinguishers in the shop.

There is nothing really in the vicinity of the furnace area that will burner, other than perhaps the fuel lines.
Diesel is pretty tame stuff.  You can drop lit matches into a jar of room-temperature diesel, and it will not light.

My burner is extremely stable, and so I never have a flame-out.

One guy did melt his fuel line, and had a large puddle of flame on the ground.
Diesel just does not catch fire in a puddle very easily.

Kerosene is much more volatile, and you have to be a bit more careful with that fuel.
Kerosene is like gold around this area for some reason, and so I use diesel.

Molten iron is about 2,400-2,500 F, and so it does a lot of damage quickly.

Skin burns are annoying.
The good thing is all the nerve endings are vaporized, and so there is no pain.

I wear a full face sheild mounted on a hardhat, and safety glasses under the face shield.
Eye burns would not be fun.


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## GreenTwin (Oct 15, 2022)

I attended Algonquin the other day, and it was a blast.

Nice smallish show in rural Ohio.
Nice folks, great food, perfect weather.
I will post some photos in the shows section.

There was a cast iron skillet collector there, and he had a skillet out on the table with a bunch of other stuff.
I fogot to get a photo.
So I asked him "Why the skillet?"
He said "Pick it up".
I picked it up, and it was about 1/2 the weight of a typical cast iron skillet.

I did not get a chance to ask him more about it.
It was also about 1/2 the thickness of a typical cast iron skillet.

I asked a buddy of mine who was at the show if he thought the guy would sell it, and he said "Not in a million years, and if he did, you could not afford it".

So that makes me wonder what sort of hoops one would have to jump through to cast a super thin cast iron pan.
Lots of phosphorus I guess.

I could see the faint outline of knife gate across the bottom of the pan, perhaps an 8" long gate.

.


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## Richard Hed (Oct 15, 2022)

GreenTwin said:


> LOL, I got better.
> 
> What I meant was to avoid killing myself.
> 
> ...


I'd say you are really lucky on that finger burn.  You could have severed a tendon.  do yuou tape yuour gloves now?


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## GreenTwin (Oct 15, 2022)

Richard Hed said:


> I'd say you are really lucky on that finger burn.  You could have severed a tendon.  do yuou tape yuour gloves now?



No I don't tape the gloves.
It is not practical, since you have to take them on and off during the process of melting metal.

I do preheat the ingot molds very well, as well as anything else that comes in contact with the molten iron.

They do make some gloves with longer sleeves on them, but that would be rather cumbersome.

Edit:
There are tendons in there ?
.


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## Richard Hed (Oct 15, 2022)

GreenTwin said:


> No I don't tape the gloves.
> It is not practical, since you have to take them on and off during the process of melting metal.
> 
> I do preheat the ingot molds very well, as well as anything else that comes in contact with the molten iron.
> ...


get some velcro and sew a long handle to it so you can grasp it with your gloves on, then you can take lthem on and off quickly  .  I know how that goes.


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## GreenTwin (Oct 15, 2022)

The problem with an iron foundry is the radiant heat.

Anything that is not leather basically melts from the radiant heat.
My hardhat and face shield are plastic, and if I lean over the furnace, they will melt quickly.

I read where the radiant energy is related to the cube of temperature, so while melting aluminum at 1,350 F can be a bit warm as far as radiant heat, melting iron at 2,500 F is really very very hot as far as radiant heat.  My burner produces almost 200 KW.

Shaded glasses have to be worn when working with iron to prevent burns to the eyes from the infrared.

One can wear leather or cotton clothes around an iron furnace, but pretty much anything else as far as syntheticl clothing is going to melt.

I wear a leather apron and a leather jacket, so two layers of leather.

I generally use heat shields on the pouring shank, and am going to add a heat shield to the skimmer.

A gloved hand can be within about 24" of the crucible for about 15 seconds, and after that your glove is on fire, or is smoking and is about to catch on fire.

Its really pretty simple to avoid explosions though, just preheat everything, and don't have any water or even anything damp anywhere near the furnace area.

.


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## GreenTwin (Oct 17, 2022)

Richard Hed said:


> I'd say you are really lucky on that finger burn.  You could have severed a tendon.  do yuou tape yuour gloves now?


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## Bentwings (Nov 5, 2022)

GreenTwin said:


> interesting when I was in about 7th grade in industrial arts we had a welding and forging class  ultimately doing a little casting  and pattern making this wasn’t very beginning in metal trades we lived in Virginia minnesota the heart of the minn iron range including rail roads . The school had a very big machine shop that we eventually had classes in . I could write a whole story if industrial arts that were taught back then   There was even an automotive machine shop that was very popular in high school  looking back I YHINK they were smoking periods as many kids smoked I was athletic  on the swimming team  playin industrial hockey the baseball and football with broom ball in the winter  so smoking did not appeal to me at all  the coal and coke bins were almost like being at a forge with all the guys smoking there considering the dust it’s surprising there weren’t more fires than there were .
> At the risk of being repetitive, I will add a few more comments on backyard casting, and how I learned the process (to date).
> Chances are I may have already mentioned some of these items, given my current state of memory (or lack thereof), but some may get some use out of this.
> 
> ...


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## Bentwings (Nov 5, 2022)

GreenTwin said:


> we all had heavy leather aprons and gloves   There were special glasses or goggles too . I don’t remember just how many forges there were but more than enough for rash student , it was incredibly noisy with all the hammering on anvils  probably party why I don’t hear well  today
> The problem with an iron foundry is the radiant heat.
> 
> Anything that is not leather basically melts from the radiant heat.
> ...


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