# Casting your own steam engine castings?



## HenryBanjo (Dec 7, 2021)

Hello,
I was wondering if anyone has tried to cast their own model steam engine castings? if so how did it go? any tips if I want to try it? 
Thanks


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## Jasonb (Dec 7, 2021)

Have  a read through this section of the forum






						Home Foundry & Casting Projects
					

Show your home foundry and casting projects.




					www.homemodelenginemachinist.com


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## HenryBanjo (Dec 7, 2021)

just had a read thought and I think that answers my questions, Thanks!


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## GreenTwin (Dec 7, 2021)

This one, made from 3 photos found online.
Making your own castings in iron is a blast to say the least.

This is my first engine, and my first attempt at making castings.

I would not say it is necessarily easy.
There is a learning curve, and some expense for equipment and molding sand.


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## GreenTwin (Dec 7, 2021)

Some photos.


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## GreenTwin (Dec 7, 2021)

Some crazy 3rd degree burns from tiny beads of iron that splashed back on my jacket and ran down into my gloves.
No pain though since the nerve endings are vaporized.
Use Curad "silver solution" if you get burns like this.


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## GreenTwin (Dec 7, 2021)

There is nothing quite like pouring molten iron.
There are a few here who pour their own iron engine parts.


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## GreenTwin (Dec 7, 2021)

My recommendations:

1. Start with a simple propane burner, simple crucible (perhaps made from steel), and a simple furnace from stacked hard fire brick.
2. Finding good casting sand can be tricky.  Be sure you don't pour molten meltal into anything that has ANY moisture in or on it (see my burns above).  Ingot molds have to be heated to perhaps 500 degrees to drive off the moisture.
3. Try a few simple castings in aluminum, without spending much money, and then if you really like it, you can ramp up to a more serious furnace and other equipment.
4. Wear lots of safety equipment such as leather jacket, gloves, and leather boots.  Full face mask attached to a hard hat.
5. Most of the things you need for a durable (long term) furnace and good molding sand cannot be found in a hardware store, in spite of what is often stated online.  You can make things that last a short period of time from hardware supplies, but if you want things to last, find a foundry supply house.
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## GreenTwin (Dec 7, 2021)

A simple furnace can be made by stacking hard fire bricks in a circle, with a few at the bottom.
Hack a hole in the bottom of one for a tuyrere (burner entry into the furnace).
Wire around them; they don't really need to be cemented initially for aluminum work.

I used a kiln shelf for a lid.
Very simple way to melt aluminum.

A simple propane burner design is a Reil.
A self-aspirating propane burner will melt aluminum, but needs a damper on it to adjust the combustion air.
Some propane burner designs do not show a damper, and they do not work well with a foundry furnace.


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## GreenTwin (Dec 7, 2021)

100model (aka luckygen1001, aka ironman) is a member here, and was one of my mentors with learning how to cast gray iron.
He taught me a lot.
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## GreenTwin (Dec 7, 2021)

This is one of my more recent iron pours, which was a belt buckle/plaque sort of a thing, so as to have something to cast during COVID, when all the iron pour events were closed down (and still are).

I showed this video to someone, and they said "Where is the fire extingisher?  There is none to be seen !!!".
My first thought was "Why would I need a fire extinguisher?", LOL, but of course that would be a good idea, assuming it is the right type of extinguisher.
You certainly don't want any type of water or even moisture near molten metal, else you can cause an explosion.

I use a Delavan siphon nozzle burner with 30 psi compressed air, and a Toro variable speed leaf blower for combustion air.
The start sequence is to put a lit paper towel into the furnace, turn on the diesel and compressed air at the same time (the burner can be operated this way without a combustion air blower if you are just melting aluminum), turn on the leaf blower (on the LOW setting) with the dump valve open, and slowly close the dump valve to put full combustion air into the furnace.  If you suddenly apply full combustion air, you can sometimes blow out the burner, in which case you close the compressed air and fuel ball valves and start over again.

The first air regulator delivers 30 psi to the Delavan siphon-nozzle burner, which operates at about 2.7 gal/hr diesel.
I put 10 psi on the fuel tank via the second air regulator, to give a consistent burn, and so I never have to adjust the burner.
The tank has a 30 psi safety valve on it.

The furnace and lid have a 1" think Mizzou 3,000 F castable refractory, then a layer of 2,600 F insulating fire bricks, then two layers of 1" thick ceramic blanket.  The exterior of the furnace remains cool to the touch during a melt.  The Mizzou is very durable at iron temperatures (perhaps in the 2,500-2,600 F range), and holds up well to iron splatters.  The interior is patched with a slight amount of plastic refractor as needed from time to time, rated 3,800 F.  The plastic refractory is like putty, and you just smear a bit onto the interior surface if a crack opens up.

For iron work, you need shaded lenses or facemask, such as is used with an oxy/acetelene torch, since the infrared energy coming off of the furnace interior and crucible will very quickly give you a bad case of eye sunburn, which is very uncomfortable (don't ask me how I know this).

I normally don't do open-faced pours, but in this case, it did not really matter, and so I did an open-faced pour.
I poured water on the back of the casting to cool it faster, and that caused all the scabbing on the back.
The ceramic mold coat works wonders, and the castings really come out of the mold that clean and shiny.

For an engine part, you would want to leave the casting in the sand overnight, and cool it as slowly as possible, to prevent hard spots in the casting.



			https://vimeo.com/manage/videos/479620524
		


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## HenryBanjo (Dec 8, 2021)

Thanks for all that info. What size crucible would you recommend? I think ill use my devil forge gas forge but if that's too small then I'll make something bigger. also what do you know about using coal? it seems a bit easier than gas


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## dazz (Dec 8, 2021)

Hi
I have absolutely no experience casting anything but I plan to learn to cast iron.  I have looked hard at what others have done, to avoid repeating their mistakes.
Based on what they have learned, I suggest the following:

Buy the book Complete Casting Handbook by John Campbell.  It is a long read but it contains a lot of practical info not found on Youtube tutorials.

I have looked at range of options for a burner.  I have settled on a diesel fueled pressure spray system.  It will have an electric fuel pump and blower, but no compressed air.    This avoids the cost, noise and complexity of including a compressor in the system.  The pressure spray system is commonly used by many commercial burners for many applications.   As such, parts are readily available.   I have the parts, I just haven't built and tested it yet.     I have not seen a pressure spray burner used by any DIY foundry, which is not to say they don't exist.

Some use discarded cooking oil with success.  I will use diesel because it is clean and with consistent properties.    I am working on the basis that successful casting depends on applying a consistent process.

Don't even try to use propane or gas to melt iron (ok for aluminium).  It can be done, but it is not a good thing too do.  The fuel consumption rate is very high.  The flame temp is too low.   I have not looked at using coal. 

I plan to use a thin walled refractory, backed with insulation to create a relatively low mass furnace (similar to Green Twins).    This will reduce the time and fuel required to melt iron.  Also, refractory is hideously expensive here. 

I plan to use casting sand and sodium silicate as a binder.
I plan to use a DIY recipe ceramic coating (I can't buy it ready made in my country)

I have a 3D printer to make the patterns.

If you look at Green Twins pour video, the work area is clear of clutter and everything is carefully laid out in advance.  There are no unnecessary movements made or required. Nothing exciting happens.   All of this is really important for safety.      Watch a few Youtube videos to see how not to do it.

Just my $0.02 worth.


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## GreenTwin (Dec 8, 2021)

dazz said:


> Buy the book Complete Casting Handbook by John Campbell.


The book is rather pricey, but the 10 rules for good castings can be found online, so I would recommend waiting on purchasing the book until you really are deep into castings things, and even then you may not need the book, but instead just use the 10 rules.

I am looking for the link to the 10 rules, and will post when I find that again.

Someone mentioned that gray iron can be melted with propane the other day, and while this is true, you either have to have a large tank, or somehow try to keep a small tank warm (without overheating it), since the vapor pressure will drop very quickly as the tank cools with the high pressure/flow required for iron melts.
Much easier to just use diesel, and then you don't have to worry about keeping the tank warm.
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## GreenTwin (Dec 8, 2021)

HenryBanjo said:


> Thanks for all that info. What size crucible would you recommend? I think ill use my devil forge gas forge but if that's too small then I'll make something bigger. also what do you know about using coal? it seems a bit easier than gas


Crucible size is relative.
I often use a #10, and some consider that size huge.
I have used a #30, and I have a friend who pours I think a #70.

The crucible size is roughly equal to the weight of molten aluminum it will hold, so a #10 will hold perhaps 10 lbs of aluminum (perhaps brim full), or about 3 times that for iron, or 30 lbs of iron.
Generally a brim full crucible is difficult to pour, and so you typically use a crucible that is perhaps 70-80% full.

I use Morgan Salamander Super clay graphite crucibles exclusively, and they can be purchased on ebay.
The Salamander Super can be used for any metal, but unlike most crucibles, it is ferrous-metal-rated, and also rated for iron temperatures.
I use a dedicated crucible for each metal type.

If the parts you intend to cast are small, then you could use a #5 or even smaller crucible.
It all depends on what size parts you intend to cast, with the understanding that you will need extra metal for the sprue, runners, gates, and any risers.

You can melt aluminum in a forge (a forge is sort of like a furnace laid on its side, with one end open).
No need to build a dedicated furnace if you just want to play around and melt a bit of aluminum.

The forges I have seen typically use a propane burner, but sometimes they are fitted with an oil burner.
For melting aluminum, a propane burner is sufficient.

Years ago, the trend was to put a crucible in a pit of charcoal, and burn the charcoal to melt the aluminum.
This method works, but is a bit tedious and time consuming compared to just using a propane burner.

I suppose you could burner coal around a crucible too, but I am not sure what that would do to the exterior of a crucible.
I have not seen anyone melt iron using charcoal or coal.

What I often see in the art-iron world is coke used to melt iron in a cupola.
Coke is coal heated in the absence of oxygen.
I originally though that burning coke in a cupola was a good way to melt iron, but then I tried to buy some coke, and could not find any for sale anywhere, unless I bought an entire truckload of coke.

A cupola is a large, messy, labor intensive affair.
An oil fired furnace will do the same thing that a cupola will do, but the oil furnace can be operated by one person easily.
A cupola can produce a considerable amount of molten iron once it gets started, simply by continuing to feed coke and scrap iron in the top.

Running a cupola to melt iron is a bit of an art.
I have seen it done, but have not tried it myself because I can't find a source for coke.
I have seen some fail at getting the cupola going, and had the iron solidify inside the cupola, which creates a big problem.

Even if I could find small amounts of coke now, I would not build a cupola, because they are just too difficult and messy to operate compared to an oil burner furnace.

If the only source of fuel I had was coal, then I may try it melting aluminum.
If you had a source for coke, you could melt iron.

I burn about 2.7 gallons per hour of diesel, and I don't do that many iron melts, and so using diesel is clean (compared to burning waste oil) and not too expensive for me.

If diesel prices go too high, I will consider burning waste oil, but would wear a powered respirator to avoid the fumes.

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## Richard Carlstedt (Dec 8, 2021)

Those are all terrific suggestions that Green Twin mentioned
i made  and used a cupola several times years ago, but the coke was free (friend had it)
With modern supplies ( as mentioned above) , the crucible is the way to go. I do want to mention
iron sourcing. You want good cast iron. We had a good source----used flywheels from a farm implement/engine rebuilder . The iron was clean (no sand ) and good quality . Makes life easy that way
Rich


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## HenryBanjo (Dec 9, 2021)

GreenTwin said:


> Crucible size is relative.
> I often use a #10, and some consider that size huge.
> I have used a #30, and I have a friend who pours I think a #70.
> 
> ...





GreenTwin said:


> Crucible size is relative.
> I often use a #10, and some consider that size huge.
> I have used a #30, and I have a friend who pours I think a #70.
> 
> ...


Have you made any posts about your furnace? interested in making one similar


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## dazz (Dec 9, 2021)

Richard Carlstedt said:


> ...
> iron sourcing. You want good cast iron. We had a good source----used flywheels from a farm implement/engine rebuilder . The iron was clean (no sand ) and good quality . Makes life easy that way
> Rich



I plan to use cast iron engine blocks.    They should have exactly the properties I am looking for.


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## vederstein (Dec 9, 2021)

This link is to how I made my aluminum foundry from an old propane tank:









						Aluminum Foundry
					

Aluminum Foundry: This is my take on making an aluminium foundry furnace from an old propane tank.  It's not like this has never been done before (like here), but it never hurts to see another person's take on the same project. Before I started this project, I read m…




					www.instructables.com
				




This video is the entire creation of a flywheel for one of my steam engines:


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## dnalot (Dec 9, 2021)

It was a desire to try my hand at casting that got me started on making small engines. The Bottle Engine was my second engine build and is still my favorite. 

Mark T


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## GreenTwin (Dec 9, 2021)

HenryBanjo said:


> Have you made any posts about your furnace? interested in making one similar


There are a couple of approaches to furnaces that are common.
One is the coated (or sometimes non-coated) ceramic fiber blanket furnace, and the other is the cast refractory thin hotface furnace.

The consensus among the backyard casters I know is that an uncoated ceramic blanket furnace puts dangerous fibers into the air, and ultimately into your lungs.  Despite the junk science that has been posted about ceramic fibers in the lungs, the truth is that they don't break down, and they do ruin your lungs.
The only safe ceramic blanket furnace is one that has the blanket surface fully coated with some high temperature material such as satanite.
The coating must be maintained throughout the life of the furnace, and the ceramic blanket not allowed to degrade.

The good part about ceramic blanket furnaces is that they are relatively easy and inexpensive to initially build.
The downside to ceramic blanket furnaces (in my opinion, and opinions differ on this) is that the are not very rugged, and don't stand up to abuse very well, such as bumping into the surface with a crucible or lifting tongs.

I use a 1" thick cast refractory hot face that uses a material called Mizou, and it stands up well to iron temperatures and iron slag.
It should be noted that cast refractory that is operated at iron temperatures will crack, and cracked refractory should not be confused with refractory that is crumbling/disentigrating.
Patching cracks in Mizou is a minor thing, and the cracks don't really affect the long term performace of the hot face, or the durability.

I used a layer of insulating fire bricks around my hot face, basically to give a rigid surface to somewhat support the cast refractory.
Outside of my insulating bricks is two layers of 1" ceramic blanket, and then a stainless steel metal shell.

With both insulating fire bricks and ceramic blanket, the cost goes up exponentially with the temperature rating.
The only affordable insulating fire bricks and ceramic blanket is in the 2,600 F range as far as operating temperature.
They do make 3,000 F insulating fire bricks and ceramic blanket, and basically sell as if they were gold.

Mizou I think it rated around 3,000 F, and thus it makes a good hot face.
Mizou is a dense refractory, and thus it is important to minimize the use of it in the furnace, since the speed at which a furnace will melt metal is directly related to its mass.

My first furnace used a 3" thick wall of dense refractory, and that was a blunder, since the high mass of the furnace took over 30 minutes to come up to iron melting temperaures, and thus 30 mintues of time and fuel are wasted with every new melt.

My second and current furnace uses 1" of dense refractory, and it brings iron up to pour temperature much more quickly (generally in about an hour).

So a word of warning to the wise; protect the lungs at all cost when doing foundry work, because the cost can be total disability or death.
When using/cutting/handling foundry sand, fire bricks, ceramic blanket, cast refractory, parting dust, etc., wear a commercial grade respirator that will totally block all of this material from getting into the lungs.

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## GreenTwin (Dec 9, 2021)

Many use a beer keg as a shell for a furnace, and that is the material I used.
I ended up expanding several beer kegs, and my final exterior shell ended up being the diameter of a 55 gallon drum.
If I had to do over, I would have just purchases a stainless steel 55 gallon drum, since welding stainless steel with a nickle rod is a bit tricky.

My recommendation is to select a crucible first, and then let that dictate the overall size of your furnace.
Usually a 2"-3" clearance is required around the crubible for iron melts, and sometimes you can get away with a little less, especially for aluminum.

The burner tube enters the furnace on a tangent, off to one side of the crucible, so as to prevent any direct impingment of flame onto the crucible.
The burner tube entry into the furnace is called the tuyere (I think pronounced tweer), and the tuyere should be at the bottom of the crucible.
The crucible should sit up on a plinth made of dense high temperature refractor that is about the size of the bottom of the crucibl.
The plinth should elevate the crucible up above the bottom of the furnace at least several inches, and to allow the centerline of the burner tube to be located at the bottom of the crucible.

Here is the layout I used for my furnace, which can use anywhere from a #10 to a #20 (possible a #30) crucible.
If you are going to use a crucible smaller than a #10, then the entire furnace can be scaled down proportionally.

Most folks turn a flange out at the top of the hot face, but since I used a layer of rigid insulating fire bricks behing my hot face, I omitted the flange.
I flange at the top of the hot face is probably the best idea though, and if I had to do over, I would probably add that feature.

A less expensive furnace that would perform as well as the one below would use three layers of 1"ceramic blanket around the hot face, in lieu of the insulating fire bricks and two 1" layers of ceramic blanket that I used.
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## GreenTwin (Dec 9, 2021)

Many people read about furnaces online, and become fixated with features that a furnace MUST HAVE.
A furnace only needs enough features to work efficiently and to hold up to the temperatures and metal/slag that will be melted in it.
Many/most people use a drain in the bottom of their furnace, and then they complain about the drain leaking hot gases and causing all sorts of problems.

The thing to remember is that the furnace interior is pressurized by the combustion air blower, and so any crack or opening will generally leak hot gasses, which can cut through things like exterior shells like a hot knife.
The fewer openings you can have in a furnace, the fewer hot gas leaks you will have.

The junction of the furnace lid and the top of the hot face will leak hot gasses; there is no way to permanently stop that, but leakage at this joint does not create problems as long as it is not excessive.

The burner tube should be a tight fit to the tuyere, to prevent any significant hot gases from blowing out past the burner tube.
Any hot gases that blow past the burner tube will heat it up and perhaps overheat it.
The burner tube should operate cool to the touch, or perhaps warm, when operating the furnace.

You shoud use a quality crucible such as a Morgan Salamander Super clay graphite, and don't ram the scrap metal in it prior to a melt, because the metal will expand and crack the crucible.  If you take care of your crucibles, and use quality crucibles, you should never have one fail.
If the crucuble wall gets too thin, stop using it.

If your crucible full of molten metal for some reason does break inside the furnace, you should remove the burner to prevent it from running into the burner tube.  My plan if this ever happens is to turn my furnace on its side and run the burner, and let the metal melt and drain out.
I don't anticipate ever breaking a crucible inside the furnace though.

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## GreenTwin (Dec 9, 2021)

There are a large number of foundry burner videos on ytube, and the debate about who has the best mousetrap/burner can get very contentious to say the least.

The best burner for your furnace is the one that:
1. Works efficiently.
2. Has few or no moving parts.
3. Does not degrade over time.
4. Brings the metal you are melting to pour temperature in a reasonable amount of time.
5. Does not require adjustment during the operation of the furnace, even if the fuel tank level changes significantly.

For me, other critical concerns with a burner (used to melt iron) are that it starts easily using diesel only, and propane it not required at all, the burner must have fine and immediate control via a needle valve, and the burner can be brought up to full power in perhaps 15 seconds after starting without becoming unstable.
My siphon nozzle burner achieves all of the objectives listed above.
Very few other burner designs (perhaps none) will achieve all of the above.

The only change I am going to make is to convert my burner from a siphon-nozzle style to a pressure nozzle type, using a small gear pump.
This will allow me to operate the burner without using compressed air.  A gear pump uses a very small amount of 120 VAC power, and a small fractional horsepower motor.

Some folks seem to just like to endlessly experiment with burner types, and I have done my fair share of that.
After trying perhaps 10 different burner types/configurations, I finally settled in on the Delavan siphon nozzle arrangement, but will convert to the Delavan pressure nozzle type as soon as I get the time.  I have purchased the gear pump and a fractional 120VAC motor to power it.

There is one burner that uses hot gasses out of the furnace to impinge back on the burner tube, thus heating it red hot.
This is a terrible design, but the people who use it swear that it is the best.
Again, I go back to the items listed below, and ask of any burner design will it achieve them.
If not, you are perhaps using a sub-optimal burner design, that used gimmicks when they are not required.

Burner designers tend to be like snake oil salesmen; their burner will always cure any ill, and also save the whales.
It all goes back to the items listed above though, and whether you want a burner that operates consistently without degredation over time.

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## dnalot (Dec 9, 2021)

dazz said:


> Buy the book Complete Casting Handbook by John Campbell.



This is the furnace I built after reading Mr Campbell's book. I cast the floor first and then the walls using a cardboard tube as a form. I cast the walls in two steps. The first casting I used a large tube that made a 1" liner with a low temp refractory and then I used a second smaller tube to to cast a second 1" layer of high temp refractory. It has held up well for many years (no cracks or crumbling) mostly casting brass and bronze. Heat is provided using a naturally asperated propane torch. I have also melted cast iron by adding a blower. A propane torch requires a bell shaped end. I cast the bell shape into my refractory walls and that has worked great.

Mark T


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## GreenTwin (Dec 9, 2021)

Most people seem to have the a lot of trouble with their furnace lid, and that part of the furnace is probably the hottest, with a lot of combustion air turbulence.
The bottom of the furnace is the coolest, and thus one of the reasons you want your crucible elevated on a plinth.

My solution to a furnace lid is to use Mizou (dense castable refractory) to make a domed lid with a short chimney.
If a domed lid cracks, it will not colapse into the furnace, since the shape acts like a Roman arch, and is self supporting.

Making a domed lid from cast refractory is not the easiest thing to do, but for long term durability, especially with iron melts, it is somewhat necessary.
The other option is to use a coated ceramic blanket on the lid, and expect to replace it frequently.

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## GreenTwin (Dec 9, 2021)

dnalot said:


> This is the furnace I built after reading Mr Campbell's book. I cast the floor first and then the walls using a cardboard tube as a form. I cast the walls in two steps. The first casting I used a large tube that made a 1" liner with a low temp refractory and then I used a second smaller tube to to cast a second 1" layer of high temp refractory. It has held up well for many years (no cracks or crumbling) mostly casting brass and bronze. Heat is provided using a naturally asperated propane torch. I have also melted cast iron by adding a blower. A propane torch requires a bell shaped end. I cast the bell shape into my refractory walls and that has worked great.
> 
> Mark T
> 
> ...


I like that design a lot.
There are many good features to it.

If I were building it (everyone has their favorite features, and every furnace is a bit different depending on what individual features you want/like), I would:
1. Sit it on the ground and not elevate it.
2. Omit the drain hole in the bottom.
3. Omit the small second lid, and just have a single opening in the main lid, perhaps 4" in diameter.
4. Use a clay graphite crucible, although a steel crucible will work pretty well with aluminum.
5. Make the top of the plinth the same diameter as the bottom of the crucible.
6. I would use a hinged/swivel lid design, so that the lid remains horizontal when opened, and you don't get the heat from the lid reflecting directly onto your body (not really critical for this size furnace, but gets critical for a larger iron furnace).
7. The centerline of the burner tube is generally kept exactly at the bottom of the crucible, at least that is what I have seen on commercial furnace designs.
8. Put a slight amount of clearance/slop into the lid hinge, so that the lid can close evenly with no gaps.  My experience with a rigid/fixed hinge is that it creates a gap on one side at the lid/furnace junction that leaks hot gasses excessively.

This is probably the best 20 lb cylinder furnace design I have seen.
Very nice, and no doubt highly functional.

A belled end on a propane burner is important if the burner is used outside of a furnace, or with a forge, but actually you don't need a belled end with a furnace.  The commercial furnaces do used a belled tuyere though, and no doubt the bell assists with propane flame propagation, and helps keep a propane burner lit, especially during startup.

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## GreenTwin (Dec 9, 2021)

If I were going to build a furnace today, I would make the hot face from 3,800 F plastic refractory.
I would roll the plastic refractory out like cookie dough, perhaps 3/4" thick, and then wrap it around a waterproofed sonotube, with a flange/lip at the top.

Diddo for the bottom of the furnace.

For the lid, I would put 3/4" thick plactic refractory over a piece of metal that had a dome shape.

I discovered plastic refractory a few years ago, and while it has to be purchased at a foundry supply store and may be a bit tricky so source, it really changes everything as far as simplifying making furnaces, and also patching furnaces.

I ran across plastic refractory used by the art-iron folks to patch the interior of their cupolas, and they basically just hand-pack new refractory in place to repair the interior of their cupolas, as needed.  You can keep a furnace or cupola in operation indefinitely using plastic refractory to patch it, and it totally eliminates the need to ever rebuild a furnace.

I will probably never use cast refractory again, as long as I can get 3,800 F plastic refractory.
I think it does have a shelf life though, so don't purchase more than you can immediately use.

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## dnalot (Dec 9, 2021)

GreenTwin said:


> If I were building it (everyone has their favorite features, and every furnace is a bit different depending on what individual features you want/like), I would:



You have made some very good points. My drawing was from a time when I had no experience in building a furnace. I never needed the hole in the bottom. I never used a steel crucible but did buy several graphite crucibles. I did as you suggest making a plinth the diameter of my crucible. The crucible I use for bronze is gazed and I did put a layer of cardboard between it and the plinth to keep it from sticking but ultimately it did stick.  I did have problems with the top not sealing do to the hinge but fixed that by replacing the hinge pin with a smaller diameter. I have had mixed feelings about the second lid. I normally use it to feed the crucible and then close it as that reduces the noise quiet a bit. Sounds like a jet engine otherwise. To help with melting cast iron I added a 2" thick ceramic blanket and covered it with a sheet metal shell. And I added some wheels for moving the furnace around. 

I admire you guys that have successfully mastered casting cast iron. For my little furnace it is just a little out of reach. I had never seen plastic refractory and will keep that in mind. I shaped some foam insulation  material to cast the top. So far the top is holding up well and will probably last the rest of my years. 

Mark T


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## dazz (Dec 9, 2021)

GreenTwin said:


> The book is rather pricey, but the 10 rules for good castings can be found online, so I would recommend waiting on purchasing the book until you really are deep into castings things, and even then you may not need the book, but instead just use the 10 rules.



The book is pricey but good value for the $$$.   I figure a book like that will help get me far enough up the learning curve to have a reasonable chance of success with metal casting.  

At present, I am trying to clear a backlog of unfinished projects before starting metal casting.


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## GreenTwin (Dec 9, 2021)

Here is the link I was looking for the other day, and this link contains John Campbell's 10 rules for good castings.
Hit the "next" button at the bottom left to go to the next rule.



			10 rules for good casting
		


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## GreenTwin (Dec 9, 2021)

dnalot said:


> You have made some very good points. My drawing was from a time when I had no experience in building a furnace. I never needed the hole in the bottom. I never used a steel crucible but did buy several graphite crucibles. I did as you suggest making a plinth the diameter of my crucible. The crucible I use for bronze is gazed and I did put a layer of cardboard between it and the plinth to keep it from sticking but ultimately it did stick.  I did have problems with the top not sealing do to the hinge but fixed that by replacing the hinge pin with a smaller diameter. I have had mixed feelings about the second lid. I normally use it to feed the crucible and then close it as that reduces the noise quiet a bit. Sounds like a jet engine otherwise. To help with melting cast iron I added a 2" thick ceramic blanket and covered it with a sheet metal shell. And I added some wheels for moving the furnace around.
> 
> I admire you guys that have successfully mastered casting cast iron. For my little furnace it is just a little out of reach. I had never seen plastic refractory and will keep that in mind. I shaped some foam insulation  material to cast the top. So far the top is holding up well and will probably last the rest of my years.
> 
> Mark T


I tried a dual-lid design, and it leaked so much that I abandoned it.
I do like the dual lid design a lot though, and so I have not give up on it completely, and if I can figure out a good seal, I will start using it again.
There are many advantages to opening a smaller lid like yours, and not opening the big furnace lid.
I can skim and add scrap through a 4" diameter lid opening, but an 8" 2nd lid is infinitely better/easier, and shields you from most of the furnace heat.

I use two layers of cardboard beneath the crucible, and have never had a crucible stick using this method.
If you spill a significant amount of slag over the side of a crucible and it runs down to the plinth, chances are your crucible will stick to the plinth.
Caution should be used with skimming slag.  The slag also is highly corrosive to the exterior of the crucible.

I think you could easily melt cast iron in your furnace (and I think you already do).
The cast refractory linings you have would make melting cast iron easy with low maintenance.
I have a buddy who has melted large amounts of cast iron (perhaps 1,000 pounds) in a furnace about the size of yours, with a very similar design.

Melting and pouring cast iron is surprisingly easy if................
1. You tune your burner correctly.  This was probably my biggest problem; learning how to correctly tune an oil burner for iron.
2. Your furnace refractory is rated for iron temperatures.
3. You use a Morgan Salamander Super clay graphite or equivalent crucible that is iron (ferrous-metal) rated.
4. You use heat shields on your skimmer handle, and pouring shank handle.
5. If you start with a small melt, create a molten pool, and then add relatively small pieces of (very dry) scrap to that pool, pushing the scrap completely under the slag that is on top of the melt.  This was the step that I really did not understand, and one of the reasons it took me so long to figure out how to cast gray iron.  Without doing this, the slag can turn into a solid hard mass on top of the melt, and actually insulate the melt and cool it.  This method also greatly reduces the amount of slag that is created, and leaves a minimal amount to be skimmed at pour time.
6. Use a slight amount of 75% ferrosilicon in the melt, and pour as soon as the ferro is stirred into the melt.
The ferro keeps the iron from developing hard spots, and makes the iron very machinable.
7. Pour iron as fast as possible after removing the crucible from the furnace, and within about 30 seconds, else you may get cold metal.
Molten iron drops below pour temperature very quickly after the crucible has been removed from the furnace.
I add the ferrosilicon while the crucible is still in the furnace, and with the burner running, with the furnace lid open (yes, this is a very hot thing to do, but it works).
8. Leave the iron castings in the sand mold overnight, and allow them to cool very slowly.

Like you, I have learned so much over time.
There is really only one way to learn how to cast metal, and that is to get in there and build a furnace, and see what works (using all of the appropriate safety precautions of course).
.


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## 100model (Dec 9, 2021)

dazz said:


> The fuel consumption rate is very high.  The flame temp is too low.


To melt 14 kgs of cast iron the furnace burns 8 kgs of waste motor oil and 8.8 kgs of propane. Both fuels take about the same time to melt 50 - 60 minutes.


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## GreenTwin (Dec 9, 2021)

I have seen discussions about different fuel types, and so I dug up this information online, which seems to be accurate.

I think if you do the math on _100model's data_ in the post above, you will see that it does not matter if you are inputting oil BTU's or propane BTU's (or any fuel type).
What is important is that you input approximately the same BTU's into the furnace regardless of the fuel type, along with sufficient combustion air to fully burn that fuel inside the furnace.

*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)

*Common Flame Temperatures*

Acetylene with Air                   4532 F
Acetelene with pure Oxygen      6296 F
Natural Gas with Air                3562 F
Propane with Air                     3596 - 3623 F
Propane with pure Oxygen       4579 - 5110 F
Wood                                   3596 F
Kerosene                              3810 F
Light Fuel Oil                         3820 F
Medium Fuel Oil                     3815 F
Heavy Fuel Oil                       3817 F
Coal                                     3950 F approx.

Standard propane torch           2,012 F

Air = 21% oxygen

*Furnace Efficiencies*

Crucible (gas)       7-19%
Cupola                 40-50%
Dirct Arc              35-45%
Induction             50-70%

*Heat Value of Materials*

#2 Diesel             138,500 BTU/gal
Kerosene             135,000 BTU/gal
Natural Gas          100,000 BTU/therm
Propane                92,500 BTU/gal
Sawdust (green)    10,000,000 BTU/ton
Sawdust (dry)        18,000,000 BTU/ton
Electric                  1.0 kWh = 3,412.14  Btu

*Miscellaneous*

1KWH = 1 kilowatt operated for a 1 hour period

1 BTU = 0.000292071 kWh

.


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## GreenTwin (Dec 9, 2021)

Checking the math, #2 diesel (assuming it is roughly approximate to waste oil) produces 138,500 BTU's/gal.

For waste oil or diesel:

8.0 kg of waste oil is 17.63 lbs.
Waste oil or diesel is about 7.0 lbs per gallon.
17.63 / 7 = 2.52 gallons of fuel to melt 14 kg (32 lbs) of iron, using 100model's data from above.

138,500 BTU/gal x 2.52 gallons =  349,020 BTU's to melt 14 kg (32 lbs) of iron using waste oil.

This is almost identical to the fuel flow rate I use for diesel, and my furnace is similar in size to 100model's furnace.
I have talked with others who also have approximately the same furnace size, and the same number keeps coming up, which is about 2.5 or 2.6 gal/hr to melt iron.
Everyone I have talked to has reached this fuel flow number independently (all using approximately the same furnace size).

For propane:

8.8 kg of propane is 19.4 lbs.

One gallon of propane weighs about 4.11 lbs.
(a full 20 lb propane cylinder contains about 4.7 gallons of propane, per the internet; check me on this)

19.4 lbs / 4.11 gal/lb = 4.72 gal of propane to melt 14 kg (32 lbs) of iron using propane.

92,500 BTU/gal x 4.72 gal  = 436,600 BTU's to melt 14 kb (32 lbs) of iron using propane.

Ratio:

The ratio of waste oil to propane gallons used should equal the ratio of BTU values between waste oil and propane.

4.72 gal propane / 2.52 gal waste oil  = 1.873 ratio

#2 Diesel             138,500 BTU/gal
Propane               92,500 BTU/gal

138,500 / 92,500 = 1.49 ratio

I can't quite prove the correlation between BTU/gal of propane and BTU/gal of waste oil, but you get the idea, ie: a fuel with a higher BTU/gal value will require less total fuel to melt a given amount of iron than a fuel with a lesser BTU/gal value.

.


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## GreenTwin (Dec 9, 2021)

From what I have read in various white papers, the trick to achieving the hottest temperature inside of a furnace is to find the optimum fuel droplet size that produces the largest surface area of the hottest part of the burning droplet.

Perhaps you have seen the candle experiments where the interior of the candle flame is actually cool, and the hottest part of the candle flame is on the outside of the flame envelope.

Its the same way with fuel droplets.
For maximum heat, maximize the area of the hottest part of the flame envelope around each fuel droplet.
What this means is that a finer fuel droplet size does not necessarily burner hotter than a more coarse droplet.

Pulsing the fuel pressure is reported to save a significant amount of fuel oil when used to fire a furnace, but I have not tried this yet, and not sure how I would produce the pulses.
The pulsing is helping to maximize the hottest part of the droplet flame envelope.

.


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## GreenTwin (Dec 9, 2021)

Some have questioned the data above that shows that a fuel fired crucible furnace generally as a 7-19% efficiency, which is incredibly wasteful, but this is a realistic value I think.

I call an oil-fired furnace "a poor man's induction furnace".
But an oil fired furnace can produce about 400 kW (with dual burners), and it would be very difficult to draw this much energy out of a typical residential electrical service.

Electrical services often have a demand charge, and so if you fire up your 400 kW induction furnace once a year, you pay for 400 kW per month whether you use the furnace every month or not.  The utility company charges you for the capacity they have to guarantee you, regardless of whether you actually use that much capacity.

400 kW at 240 volts, single phase is 1,667 amperes.
400 kw at 208 volt, 3-phase is 1,111 amperes.

Buying an induction furnace is one thing (I have seen this recently), and finding enough power to operate it is an entirely different thing.
Do the math before you buy an induction furnace.

And if the induction furnace inverter does not come with input line reactors, then you can put so many harmonics onto the power company system that you can actually damage their equipment, and they are never happy when you burn up their equipment.

.


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## Richard Hed (Dec 10, 2021)

GreenTwin said:


> Many use a beer keg as a shell for a furnace, and that is the material I used.
> I ended up expanding several beer kegs, and my final exterior shell ended up being the diameter of a 55 gallon drum.
> If I had to do over, I would have just purchases a stainless steel 55 gallon drum, since welding stainless steel with a nickle rod is a bit tricky.
> 
> ...


Ha!  Just as you say.  I am trying to find out the physical sizes of some crucibles, as I intend to build a furnace around the crucible, rather than first build the furnace then select a crucible.  But the vendors, when asked what the physical dimensions, said, "they are in the description".  Well, no they aren't.  What is there is the number of lbs/kgs which is NOT the dimensions of the crucible.


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## Jasonb (Dec 10, 2021)

Not looking at the right suppliers 

One of our suppliers to the hobby use lists the size, don't forget to allow for the size of teh open tongs





						Crucible A1/0 Salamander Super (Clay Graphite)
					

SALAMANDER SUPER  (Choose crucible size and capacity from table below) I can supply all sizes in the table plus larger ones if required contact me for prices of other shapes. This is a hi...



					www.artisanfoundry.co.uk


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## dazz (Dec 10, 2021)

GreenTwin said:


> ...
> The thing to remember is that the furnace interior is pressurized by the combustion air blower, and so any crack or opening will generally leak hot gasses, which can cut through things like exterior shells like a hot knife.
> The fewer openings you can have in a furnace, the fewer hot gas leaks you will have.
> ...


This is the first comment I have seen on cracking and air bleed in a home foundry.    I have been speculating that hot liner cracking would lead to problematic hot air bleeds.   It is a problem on full sized furnaces.

I have been considering controlling (throttling) burner air flow by diverting surplus air into the cavity between the hot liner and the exterior sheet metal shell.   Ideally this would raise the air pressure slightly above the furnace pressure.  Air would then leak into the furnace.  I expect this would not be enough to cool the hot liner, but it would reduce the damaging effects hot air bleed leakage.    I suspect the added injection of fresh heated oxygen rich air through cracks would slightly increase furnace combustion temperature.  

The way I was thinking of implementing this feature is to drill a series of holes in the burner tube along a helix. I would then have a value tube that was a sliding fit over(or inside) the burner tube.    If the holes are located between the hot liner and the shell, any uncovered holes will dump pressurised air into the cavity.  Sliding the value tube in/out would throttle the burner air flow and the cavity air flow.


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## dazz (Dec 10, 2021)

Richard Hed said:


> Ha!  Just as you say.  I am trying to find out the physical sizes of some crucibles, as I intend to build a furnace around the crucible, rather than first build the furnace then select a crucible.



The total thermal output of a furnace depends on the volume available for air/fuel to burn.    If you shrink wrap the furnace around the crucible, two things will reduce furnace output.
1.  If the combustion volume is too small, the furnace will take longer to heat the melt.
2.  The furnace wall area will be reduced.  Radiant heat from the furnace wall is the main energy source for heating the crucible.   Reducing the furnace size reduces the surface area. and the radiant heat. I did the calcs a while ago and from memory, about 75% (or something like that) of heat is from the wall.  

Conversely, there are a number of good reasons not to oversize the furnace.   There is almost certainly an optimal size furnace for a given crucible size, but I don't know how to calculate that.  A non-optimal furnace will increase time and/or fuel required to do a melt.    Not a show stopper.


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## Richard Hed (Dec 10, 2021)

dazz said:


> The total thermal output of a furnace depends on the volume available for air/fuel to burn.    If you shrink wrap the furnace around the crucible, two things will reduce furnace output.
> 1.  If the combustion volume is too small, the furnace will take longer to heat the melt.
> 2.  The furnace wall area will be reduced.  Radiant heat from the furnace wall is the main energy source for heating the crucible.   Reducing the furnace size reduces the surface area. and the radiant heat. I did the calcs a while ago and from memory, about 75% (or something like that) of heat is from the wall.
> 
> Conversely, there are a number of good reasons not to oversize the furnace.   There is almost certainly an optimal size furnace for a given crucible size, but I don't know how to calculate that.  A non-optimal furnace will increase time and/or fuel required to do a melt.    Not a show stopper.


Yes, of course.  Even so, my problem is the size of the crucible--all else depends on that, ultimately.  However, I thimpfks that the first furnace I build will be a "propane tank" furnace for aluminum.  I wants to get a bit of understanding before I goes to brass and/or iron.  Iron is my goal, long term.  I will, I know, do the opposite of what I said at antoher time, that is, instead of building the furnace to the size of the crucible, I will build a furnace and then get a crucible that will fit inside that.


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## GreenTwin (Dec 10, 2021)

Here are Morgan Salamander-Super A-shape crucibles in inch dimensions (for the non-metric types like myself).
Note that the bilge shaped crucibles will hold more metal for a given size, but bilge crucibles are not as readily available as A-shaped.

*Super-Salamander A-shape*

Size     Top OD    Bottom OD    Height    Brass Capacity   CI Capacity     AL Capacity        
           inches       inches             inches        pounds             pounds            pounds                         

A0.5     2.625      1.875          3.125           2.2                  1.98               0.7
A3        4.125      2.75            5.0              8.2                  7.38               2.7 
A5        4.875       3.375         6.0              15                  13.5                4.9
A6        5.11        3.74            6.49            20                  18                  6.4                   
A10      6.29        4.33            7.87            40                     36                11               
A16      7.24        5.11            9.13            51                     46                16                      
A20      7.75        5.70           10.23           66                     60                21    
B20      7.75        5.70           10.5             74                     67                24   
A25      8.26        6.10           11.02           79                     71                26                        
A30      9.13        6.29           11.41           95                     86                31
A40      9.12        6.25           12.5           120                   108                40


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## GreenTwin (Dec 10, 2021)

The software is distoring the data a bit (removing the spaces).
Here is another view of it.


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## GreenTwin (Dec 10, 2021)

I think JasonB is right in that the space required around a crucible is as much about getting the lifting tongs into place as it is about combustion.
I have seen some pretty tight furnaces work with melting iron, and they had more like 1" around the crucible, instead of the more typically recommended 2-3" clearance.

.


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## Richard Hed (Dec 10, 2021)

GreenTwin said:


> The software is distoring the data a bit (removing the spaces).
> Here is another view of it.
> 
> View attachment 131753


Ah, thanx.  To start with, I thimpfk (without having the furnace built yet) something like the A5 is about right size.

And absolutely about the tongs--that is part of my calculations.  I don't want an extremely tight fit, as I thimpfks that banging the sides of the hot oven could damage the bricks or mortar or whatever it is called on the inside of the furnace.


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## GreenTwin (Dec 10, 2021)

dazz said:


> This is the first comment I have seen on cracking and air bleed in a home foundry.    I have been speculating that hot liner cracking would lead to problematic hot air bleeds.   It is a problem on full sized furnaces.
> 
> I have been considering controlling (throttling) burner air flow by diverting surplus air into the cavity between the hot liner and the exterior sheet metal shell.   Ideally this would raise the air pressure slightly above the furnace pressure.  Air would then leak into the furnace.  I expect this would not be enough to cool the hot liner, but it would reduce the damaging effects hot air bleed leakage.    I suspect the added injection of fresh heated oxygen rich air through cracks would slightly increase furnace combustion temperature.
> 
> The way I was thinking of implementing this feature is to drill a series of holes in the burner tube along a helix. I would then have a value tube that was a sliding fit over(or inside) the burner tube.    If the holes are located between the hot liner and the shell, any uncovered holes will dump pressurised air into the cavity.  Sliding the value tube in/out would throttle the burner air flow and the cavity air flow.


The easiest way to handle cracking is to just patch the cracks with a slight amount of refractory, or better yet 3,800 F plastic refractory.
A little plastic refractory will really work wonders on cracked refractory.
Here is an example.

I used a metal band around my 1" thick cast refractory hot face, and I think that exacerbated the cracking.
I lifted my hot face to put it in the van (for taking the furnace to a local show), and the hot face fell into about four pieces.
All of the pieces were solid, and not crumbling, and when I got to the show, they were patching the cuplolas with plastic refractory.
I borrowed some of their plastic refractory (the stuff is like stiff puddy), and patched my hot face back togther.

I continue to use this hot face, and the cracks have not opened up again.
3,800 F plastic refractory is some really tough stuff, as is the Mizou cast refractory that this hot face is made from.

Someone asked if you have to go through a long dry-out schedule after using plastic refractory, and the answer is no, just fire the furnace on a lower burner setting for about 10 minutes, and then go to full burner output.


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## GreenTwin (Dec 10, 2021)

More photos of the rebuild while at a local iron show.
My furnace is modular, ie: the insulating fire bricks are not physically adhered to the hot face, and this allows repair and/or replacement of the hot face without damaging the expensive insulating fire bricks.


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## GreenTwin (Dec 10, 2021)

This is the furnace after I got it home from the show, and the interior looked pristine.
There is really no reason to discard a hot face, even if it is cracked.
Just patch it.
If you use a low grade/low temperature rated refractory, it will crumble at iron temperatures, and there is no patching that (don't ask me how I know this, LOL; proverbial trial-by-fire thing I guess).

I seal any cracks, no matter how slight, every time I fire the furnace.  It just takes a tiny amount of plastic refractory to do this.
Cracks don't seem to propagate nearly as bad if you seal the small ones every time you use the furnace.
If you let a crack open up, it causes a lot of problems with injecting hot gasses behind the hot face into areas that are only rated for 2,600 F.

.


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## Richard Hed (Dec 10, 2021)

GreenTwin said:


> More photos of the rebuild while at a local iron show.
> My furnace is modular, ie: the insulating fire bricks are not physically adhered to the hot face, and this allows repair and/or replacement of the hot face without damaging the expensive insulating fire bricks.


Oh, very nice, very jealous.  do you have marshmallows and hotdogs?  Mustard?


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## GreenTwin (Dec 10, 2021)

Those art-iron folks are really fun to be around.
Extremely creative bunch, and very good about sharing information/tricks about casting iron too.

They use coke by the truckload at the local event near me, sometimes operating three cupolas at once.

.


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## GreenTwin (Dec 10, 2021)

Richard Hed said:


> Oh, very nice, very jealous.  do you have marshmallows and hotdogs?  Mustard?


LOL, there is a guy online who cooks on his furnace after a melt, I think just for jollies.
See 6:30 in the video.
Note:  "myfordboy" refers to a "Myford" lathe, not "my Ford truck".


.


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## GreenTwin (Dec 10, 2021)

The local art-iron folks have been a great resource for me, especially regarding using resin-bound sand, which they seem to use exclusively in the art world.
Great folks to be around too, and very supportive.

.


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## Richard Hed (Dec 10, 2021)

GreenTwin said:


> LOL, there is a guy online who cooks on his furnace after a melt, I think just for jollies.
> See 6:30 in the video.
> Note:  "myfordboy" refers to a "Myford" lathe, not "my Ford truck".
> 
> ...



Actually, that is very clever, using that excess heat in this fashion!


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## GreenTwin (Dec 10, 2021)

If you ever get a chance to attent an art-iron event, I highly recommend it.
Its an awesome experience.
The first photo is the woman in charge of tapping the cupola.


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## GreenTwin (Dec 10, 2021)

A few more photos.
The pouring ladle is a high temperature fiber unit, and very lighweight and insulating.
I really did not believe you could pour iron into a lighweight synthetic ladle, but indeed you can.

.


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## mnay (Dec 10, 2021)

this thread has been very informative.  Thanks for taking the time to share the information.
What is the brand name of the high temp refractory you are using to patch your furnace and where did you get it?
My propane furnace has developed a couple of cracks that i would like to fill.


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## GreenTwin (Dec 10, 2021)

The brand of high temperature plastic refractory I use is called "Plastic A", but it would seem that it must be made locally, since I have only found one source for it, and it does not seem like that is a national brand name, and not a manufacturer's name associated with it either.
It comes in a brown box with a stamped label reading "Plastic A".

The foundry supply houses are generally wholesale, and they sell bulk products, often by the ton.
It is rare to find a foundry supply house that will sell small amounts of anything, and if they do sell a small amount, it is generally 100 lbs minimum.
I have had some suppliers sell me some small quantities, and it was so much trouble for them that they no longer return my calls or emails.
I have walked into foundry supply warehouses and literally begged them to sell me small quantities of materials; most will not sell to an amateur/hobby person.

Finding quality foundry supplies is quite challenging.

A few notes on foundry safety (for those who decide to try foundry work):

For any foundry product that is purchased, you should get the MSDS (material safety data sheet) for it, and keep those sheets in a binder.
Many foundry products can be hazardous if not used and handled correctly (with the correct safety gear).
Inhaling silica sand dust, ceramic blanket fibers, cast refractory dust, parting compound dust, etc can cause you to need a lung transplant, and it is essential that commercial respirators that completely filter this material be used when you are handling and using it.

Uncoated ceramic blanket type furnaces should not be used.

Combustion type furnaces should not be used indoors, due to the fire hazards, and the hazards of low oxygen situations, and especially carbon monoxide situations.  One hobby guy reported last year that he was operating his furnace in his shed, but with the door open.
Due to either low oxygen or carbon monoxide buildup (in spite of the open door) he got dizzy and stumbled outside, and passed out.
He eventually was discovered and rushed to the hospital where they were able to save him, but the doctor said that his blood oxygen level was so low when he arrived at the hospital that normally this condition is irreversible and fatal.  He was very lucky.

Some folks go to the scrap yard and buy metals that are toxic.  There is a type of brass/bronze that should never be melted and machined, and I forget the name of it unfortunately.  Some folks try to burn the plastic off of electrical wiring, and those fumes are extremely toxic, and can do permanent damage in seconds even when inhaling just a slight wiff of them.

Zinc fumes can cause some ill effects, and should be avoided.
Alloys of brass and bronze can have zinc in them, and the zinc will burn off before you reach melt temperature.

I stick with known metals such as 356 aluminum, and gray iron scrap that breaks cleanly with a sledge hammer.

I wear nitrile gloves when handling foundry materials to avoid skin exposure.

Waste motor oil is known to contain heavy metals, and is one reason I use diesel.
The other reason I use diesel is that it is clean and uniform, with low viscosity.
Diesel will self-light using a siphon or pressure nozzle burner down to at least 35F, whereas waste oil often has to be mixed with 20-30% diesel.
Waste oil is often contaminated with toxic compounds such as antifreeze, water, or other materials, and often required straining to remove solids that will clog many burner nozzles.
I have heard that hydraulic fluid/oil is very toxic when burned.


Alternate materials/suppliers:

One way I have worked around the foundry supply difficulties is to find alternate hobbies that may use some of the same materials.
Kiln and pottery suppliers sell small quantities of high temperature materials that can be used to patch refractory in kilns or furnaces.

One material that I used a few years ago was called ITC-100, but it has gotten very expensive.
I have also used ITC-200, and I think it is less expensive and costs less.
Both of these products will dry out over time (and sometimes arrive from the suppplier dried out), in which case they can be ground back into a powder and a little water added to rejuvenate them.  Never discard ITC product; it is expensive.

One company I have purchased from online (a pottery supplier) is called Clay Planet








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

Raw Materials, Stains, Dry Clay & Glaze Ingredients



					shop.clay-planet.com
				




Here is a list of materials from the Clay Planet website:








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

Glaze Making Materials



					shop.clay-planet.com
				




One product that I have not tried is bentonite, but I have seen it used as a spray-on coating for ceramic blanket for furnace interiors.
A good and inexpensive sprayer for slurry materials such as a bentonite powder/water mix is cheapest sandblaster gun that Harbor Freight makes (about $20.00 US).
I have sprayed on a slurry mix of ITC-100 on furnace interiors until the price became too excessive.

Some raw materials here including bentonite:








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

Raw Materials, Stains, Dry Clay & Glaze Ingredients



					shop.clay-planet.com
				




Here is some ITC-200 for sale, and I have used it for crack repair, and it works well.
I have not purchased from this particular supplier.








						ITC-200EZ Ceramic Fill
					

ITC-200EZ is an excellent durable solution for repairing broken, chipped, or cracked bricks, castables, and fiber material. The trowelable compound bonds rapidly and eliminates the need for costly re-bricking and re-lining while minimizing downtime. This coating makes the repair of old equipment...




					www.ceramaterials.com
				




ITC-100 is on this page, and is much more expensive than ITC-200.   I don't think ITC-100 is needed for furnace repair.  It is used more as a spray on reflective coating for furnace interiors.  For an iron furnace, your furnace interior will soon be coated with slag, and so don't waste your money on ITC-100 for an interior furnace coating.








						ITC Coatings
					

ITC-100HT Ceramic Coating ITC-296A Ceramic Top Coating ITC-148 Heavy Duty Ceramic Repair ITC-200EZ Ceramic Fill ITC-213 Graphite & Metal Coating




					www.ceramaterials.com
				




Insulating fire bricks (IFB) generally can be found in the 2,600 F rating range, and get very expensive at ratings above that.
2,600 F IFB's will not stand up to iron temperatures, and will crumble after just one firing with an oil burner, unless you use perhaps 3,000 F IFB's.
Insulating fire bricks can be hand-cut or drilled using a wood or hacksaw (avoid the dust), and so are very easy to work with.

Tractor supply and many other places sell hard fire bricks, and they stand up to iron temperatures.
Hard fire bricks cannot be easily cut, and are generally wet-cut using diamond-type tools.

.


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## GreenTwin (Dec 10, 2021)

Some people make the mistake identifying magnesium as aluminum (there is some sort of a test, I think with something acidic to check for magnesium; you will have to research this).

They toss a chunck of magnesium into a molten crucible of alumium, and start a very intense fire and/or explosion that cannot be extinguished.
The crucible is destroyed, and whatever is nearby sometimes gets burned to the ground.
The magnesium will continue to burn until it burns itself out, and there is no stopping it.

Avoid magnesium.

.


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## GreenTwin (Dec 10, 2021)

If I did not have plastic refractory, I would use either ITC-200, or purchase some bentonite, and mix a small amount of it into a putty and try that to patch the furnace interior.
I have not used bentonite, and am not sure how well it would work at iron temperatures, so take your chances with that.
.


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## dazz (Dec 11, 2021)

GreenTwin said:


> Pulsing the fuel pressure is reported to save a significant amount of fuel oil when used to fire a furnace, but I have not tried this yet, and not sure how I would produce the pulses.
> The pulsing is helping to maximize the hottest part of the droplet flame envelope.
> 
> .



We may have read the same reports.  I have considered pulsing fuel supply using the conceptual device below.
The Green is a pin with a tapered end.  It is sealed with an O-ring in the purple housing.    As the pin rotates, it covers and uncovers a fuel supply hole in the side of the housing.  The on/off ratio can be varied by adjusting the depth of the pin into the housing.  
The green pin would be rotated with a geared low voltage DC motor.


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## dazz (Dec 11, 2021)

GreenTwin said:


> Some have questioned the data above that shows that a fuel fired crucible furnace generally as a 7-19% efficiency, which is incredibly wasteful, but this is a realistic value I think.
> 
> I call an oil-fired furnace "a poor man's induction furnace".
> But an oil fired furnace can produce about 400 kW (with dual burners), and it would be very difficult to draw this much energy out of a typical residential electrical service.
> ...


Hi

I can't see induction being a viable option for a home foundry. 

I looked really hard at an electric element furnace.  The thing with electric element furnaces is that all of the heat can be contained in the furnace.  If the insulation was perfect (it never is), you could use a 100W light bulb to melt iron.  It might take a week or two.  
The thing that killed it was the difficulty and expense of suitable elements that could survive cast iron temps.


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## Richard Hed (Dec 11, 2021)

dazz said:


> Hi
> 
> I can't see induction being a viable option for a home foundry.
> 
> ...


Induction?  or heating elements?  I thimpfks induction might be possible for home foundry if one had a heavy enough energy source.  Not sure how it would work in a home situation.  wojuld it work better at higher frequencies?  There are induction heaters for stove tops, why would it not work for a home foundry?


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## GreenTwin (Dec 11, 2021)

I have seen 240 volt induction melters about the size of a tower personal computer, and they work well for small melts, but are difficult to scale up for many reasons.  One guy who used one fed so much harmonic load back into the power company meter that he burned it up.

The induction melters also require a chiller to cool the coil, and so you need two rather complex pieces of equipment.
The one I saw actually had water cooled electrical components in it (the induction unit), so you hope you don't get a leak in the plumbing inside the cabinet.

A residental electrical panel (in the US) may be rated for 200 amperes at 120/240 volts, 1-phase, but is not rated for continuous duty.
You would be lucky to be able to run a 100 ampere continuous load at 100 amps, 240 volts, 1-phase, and that would be 24 KVA.
You would probably have to use an expensive line reactor to prevent harmonic damage to the utility company equipment.

My oil burner produces about 120 KW, and I have used it with a #30 crucible, but I think it would work with perhaps up to a #70 (I have seen others do this).
By using two oil burners, you could operate a furnace with I believe up to a #200 crucible, for a burner output of 240 KW.

At 208 volts, 3-phase, 120 KW would draw perhaps 320 amperes, which is a significant load, and would required probably in excess of a 400 ampere 3-phase electric service, or more if you have other loads that must operate at the same time.

If you had access to a 480 volt, 3-phase electrical service, 120 KW would be a circuit of about 150 ampere.

In all cases, there is no guarantee that your power system is set up to carry that much continuous load; most are not set up for that.

And the higher KW induction melters get quite expensive.
Don't forget the chiller required also gets much more expensive as the KW goes up, and it needs its own electrical circuit on top of the furnace requirements.

For someone making jewelry, a tabletop induction melter makes sense.
For someone melting iron in a #10-#30 crucible, the cost of an induction melter is a very large expense, with a very large and expensive electrical service.  Don't forget that an induction unit has a given life before the electronic components fail, and will need replacing, so over time, it is not a maintenance-free arrangement either.

I have heard of someone operating a larger induction melter from a diesel generator, and that is perhaps the only practical way to run an induction melter where you don't have a large 480 volt electrical service.

As I have said before, an oil burner is a "poor man's induction furnace".
With oil burners, you could make a 240 KW furnace for very little money, and operate it for the price of the fuel.

There are examples dual burner commercial furnaces that indicate that this is a readily available and viable configuration in the #200 crucible size range.
Oil fired furnaces work quite well, they are just not nearly as efficient as an induction furnace.

.


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## Richard Hed (Dec 11, 2021)

GreenTwin said:


> I have seen 240 volt induction melters about the size of a tower personal computer, and they work well for small melts, but are difficult to scale up for many reasons.  One guy who used one fed so much harmonic load back into the power company meter that he burned it up.
> 
> The induction melters also require a chiller to cool the coil, and so you need two rather complex pieces of equipment.
> The one I saw actually had water cooled electrical components in it, so you hope you don't get a leak in the plumbing inside the cabinet.
> ...


Thanx for that.


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## moose4621 (Dec 12, 2021)

I have just built my second furnace after several years of casting aluminium successfully. I now want to progress onto casting iron and built my second furnace with that in mind.
I have read this thread with great interest and picked up a few pointers along the way.
The one ingredient I see as universal amongst most home iron foundries is  ferrosilicon. I have not been able to find a source for this in Australia and hope someone here has some insight as to where to procure some of this ferrosilicon-unobtainium.
Regards Chris

PS. I live in a remote rural location so it has to be a supplier who posts.


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## Richard Hed (Dec 12, 2021)

moose4621 said:


> I have just built my second furnace after several years of casting aluminium successfully. I now want to progress onto casting iron and built my second furnace with that in mind.
> I have read this thread with great interest and picked up a few pointers along the way.
> The one ingredient I see as universal amongst most home iron foundries is  ferrosilicon. I have not been able to find a source for this in Australia and hope someone here has some insight as to where to procure some of this ferrosilicon-unobtainium.
> Regards Chris
> ...


Is it possible it might go by another name like -- diffitanium, or maybe some other tradename?

How far out from "civilization" doe you live?  You are lucky in that, but it does come with that cost of finding diffitanium and other materials.  How about metal?  Is it difficult to get?  What type of fuel are you going to use for the iron?  Have you lookt into possibly making the stuff ?  Is there a university with a chemistry department within internet distance?  What kinds of things do you cast?  Got any photos?


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## GreenTwin (Dec 12, 2021)

moose4621 said:


> I have just built my second furnace after several years of casting aluminium successfully. I now want to progress onto casting iron and built my second furnace with that in mind.
> I have read this thread with great interest and picked up a few pointers along the way.
> The one ingredient I see as universal amongst most home iron foundries is  ferrosilicon. I have not been able to find a source for this in Australia and hope someone here has some insight as to where to procure some of this ferrosilicon-unobtainium.
> Regards Chris
> ...


Here is a page on how to manufacture ferrosilicon (not something I would try).





						Ferro Silicon Manufacturing Process Method
					

Ferrosilicon is a silicon-iron alloy composed of silicon and iron in a certain proportion and is mainly used for steelmaking, casting and other ferroalloy production. Ferrosilicon will react deoxygenation with steel, formula as: 2FeO+Si=2Fe



					www.sialloy.com
				




Rich C mentioned using something other than ferrosilicon for machinability, but I have never heard of the material he mentioned.
Every art-iron and backyard iron casting person I have met over the last 8 years uses 75% ferrosilicon to improve the fluidity of the melt, improve machinability, and to prevent hard spots (called chills) in the iron.

I cast a flywheel in gray iron before I knew about ferrosilicon, and it had a rim that was perhaps 3/4" thick.
I used standard carbide bits, and did not have any problems machining it (photo below).
It is an often repeated myth that all iron castings must have ferrosilicon added in order to be machinable, and in order to prevent chills/hard spots; this is not true for thicker parts that are cooled very slowly.

Where I ran into problems was with thinner iron castings.
I made a few thin castings, perhaps 1/4" thick, and could not cut them with any saw, including a Portaband with a new (and immediately ruined) blade.

It only takes a tiny amount of ferro per melt, along the order of 0.04 to 0.06 oz/lb of iron.
The ferro I use is granulated, in chips that are perhaps 1/4" in size.
I get the melt to pour temperature, which generally takes about an hour, and then mix in the ferro while the crucible is in the furnace (sometimes turning off the burner, and sometimes leaving it running).
I stir in the ferro with a dried graphite rod (from ebay), skim, pull the crucible from the furnace, and immediately pour.

You cannot wait very long after adding the ferro, since the effects of the ferro will not last long.

And another trick to prevent chills is to keep the castings in the sand mold overnight, until they are completely cool.
Pulling an iron casting quickly out of the sand does not give the graphite in the metal time to form the nodules that make iron so machinable.

So if you are casting thick pieces, and are using carbide to machine them, you probably don't need ferro.
For thin pieces, you need ferro, or something that works just like it.

What does it cost to ship say a 1 lb package to down yonder.
I buy 75 lbs of ferro at a time.

.


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## moose4621 (Dec 12, 2021)

Richard Hed said:


> Is it possible it might go by another name like -- diffitanium, or maybe some other tradename?
> 
> How far out from "civilization" doe you live?  You are lucky in that, but it does come with that cost of finding diffitanium and other materials.  How about metal?  Is it difficult to get?  What type of fuel are you going to use for the iron?  Have you lookt into possibly making the stuff ?  Is there a university with a chemistry department within internet distance?  What kinds of things do you cast?  Got any photos?


I am not in "Outback" Australia. Although it depends on your interpretation of "outback". I am 2 hours inland from Bundaberg, Queensland. Which is not very remote by Australian standards but it is a 2 day trip to the states capital and back.
Living in a rural area comes with the advantage that any scrap metal is usually BIG and HEAVY!  I don't have any problem getting scrap alloy wheels for casting aluminium, and hardenable steel alloys for machining and blacksmithing usually consists of big coil or leaf springs, and large dia drive shafts, axles, and tortion springs. And discarded hydraulic rams are a good source of material too. As for iron, I hope it will fall as easily as the other materials have.
I cast many practical or replacement parts for all sorts of things. From side covers for a quad bike, blower housing for the forge blower, tool post grinder, gearbox housing for a pto drive, adjustable tablet mounts for tractors, and a Bonelle tool and cutter grinder where I substituted many cast iron parts for cast aluminium.




I am unaware of any other name the  ferrosilicon may go by. It has been called that by a couple of utube posters from OZ who I may try to contact. My fear is that they just pop down to their local foundy and by at bit as required. Not going to work for me.


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## moose4621 (Dec 12, 2021)

GreenTwin said:


> What does it cost to ship say a 1 lb package to down yonder.
> I buy 75 lbs of ferro at a time.
> 
> .



Lots of good info there thank you very much.

75lbs!!!! I would imagine that to be a lifetimes supply.
According to this link it is anywhere from $16 USD to $74USD for 2Kg or 4.4lb.
There is no hurry, so the cheaper rates would be adequate I am sure.


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## Richard Hed (Dec 12, 2021)

GreenTwin said:


> Here is a page on how to manufacture ferrosilicon (not something I would try).
> 
> 
> 
> ...


that looks an awful lot like steel.


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## GreenTwin (Dec 12, 2021)

moose4621 said:


> I am not in "Outback" Australia. Although it depends on your interpretation of "outback".


My interpretation of "outback" is Australia......LOL, no offense intended, its is just that it is way down there.

I could mail you some ferro, but I thinkif I were you, I would send 100model a pesonal message first.
He is a member here, and has been pouring iron for over 100 years (just kidding, he has been pouring iron for a very long time).
He goes by luckygen1001 on ytube.


			https://www.youtube.com/user/luckygen1001/videos
		

He may actually live close to you; I seem to have a fuzzy recolletion of him living sort of south and east in Australia, if that means anything (geography was never my strongpoint).
He would have a lot of ferro.

If he does not respond to your PM, let me know, and we will make some sort of arrangement.

I typically purchase the smallest amount of material that a foundry supply house will sell me.
If you walk in and want to buy tiny quantities, they will throw you out the door, and kick you on the way out.
Ferro is relatively cheap, or it was prior to the massive inflation we are experiencing now.

.


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## moose4621 (Dec 12, 2021)

Hmmm, turns out I have been searching with a hyphen between ferro and silicon. 
Makes all the difference if you leave out the hyphen.
There are sources on ebay available.
Thanks to those who offered assistance.
Chris


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## Richard Hed (Dec 12, 2021)

I just lookt up ferrosilicon  on alibaba and moslty what it displayed was ferrosilicon magnets.  Is this the same material, I wonder?  iF so, you could probably get some of it from used electronics junk.  I see it all the time and just toss it.  It is relatively easy to break into pieces.


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## moose4621 (Dec 12, 2021)

GreenTwin said:


> My interpretation of "outback" is Australia......LOL, no offense intended, its is just that it is way down there.


None taken. 
I secretly enjoy being distanced from all the commotion up there.


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## GreenTwin (Dec 12, 2021)

The ferro on ebay does not look like foundry grade material.
Generally I see 75% ferro in a fine granulation.

Here is a place that sells it (may not sell less than bulk though).





						Ferro Alloys – Mathews Industrial Products
					






					mathews.com.au
				




I would still contact luckygen1001 (100model here).
He may live 4 blocks away from you.

This is the composition I typically see for foundry work.
I use the size of about 1/2"x1/4", or more like 1/4"x1/4".








						75% Ferro-Silicon
					

Miller and Company LLC is one of the most integrated and diversified suppliers of raw materials to the ferrous foundry and steel industries.




					www.millerandco.com
				



.


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## GreenTwin (Dec 12, 2021)

Good news and bad news to those pursuing ductile iron.
I found a nickle-mag supplier in the States.
Bad news; it is available in 551 lb steel drums, 4 drums per pallet.

Cost would probably be $1,000,000.00 (just kidding, it would probably only be $50,000.00).

Back to the drawing board.

.


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## Richard Hed (Dec 12, 2021)

GreenTwin said:


> The ferro on ebay does not look like foundry grade material.
> Generally I see 75% ferro in a fine granulation.
> 
> Here is a place that sells it (may not sell less than bulk though).
> ...


Those look like the ferrosilicon toroids out of electronics when they are broken apart.  Grainy and greasy looking.


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## GreenTwin (Dec 12, 2021)

This is the 75% ferro composition that Miller sells.


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## moose4621 (Dec 12, 2021)

GreenTwin said:


> I would still contact luckygen1001 (100model here).
> He may live 4 blocks away from you.


A couple of thousand kilometers away as it turns out, but left him a message. Thanks. I have seen most of his videos.

This seller seems to be offering casting ferrosilicon.

Thanks again.


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## Richard Hed (Dec 12, 2021)

moose4621 said:


> A couple of thousand kilometers away as it turns out, but left him a message. Thanks. I have seen most of his videos.
> 
> This seller seems to be offering casting ferrosilicon.
> 
> Thanks again.


Not such a bad price but cleverly has no estimate of postage.


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## GreenTwin (Dec 12, 2021)

moose4621 said:


> A couple of thousand kilometers away as it turns out, but left him a message. Thanks. I have seen most of his videos.
> 
> This seller seems to be offering casting ferrosilicon.
> 
> Thanks again.


Bingo, that looks like the right stuff.

I often see folks online from Tennessee, and I say "great we live in the same state", but then they turn out to be 440 miles away in Tennessee.
TN is a very long state.

.


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## GreenTwin (Dec 12, 2021)

Richard Hed said:


> Not such a bad price but cleverly has no estimate of postage.


The seller is in Cogburg North Australia, so the shipping should be reasonable, or far more reasonable than shipping it from the States I would guess.

.


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## moose4621 (Dec 12, 2021)

GreenTwin said:


> I often see folks online from Tennessee, and I say "great we live in the same state", but then they turn out to be 440 miles away in Tennessee.
> TN is a very long state.


Lol. The state of Queensland is more than 2200km long with around 7000km of coastline.
Distance is a subjective thing. Depends what you are used to.


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## moose4621 (Dec 12, 2021)

GreenTwin said:


> The seller is in Cogburg North Australia, so the shipping should be reasonable, or far more reasonable than shipping it from the States I would guess.
> 
> .


Coburg is in Victoria, Southern Australia. but postage is quoted as $12.50.


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## Richard Hed (Dec 12, 2021)

moose4621 said:


> Coburg is in Victoria, Southern Australia. but postage is quoted as $12.50.


Lucky lucky lucky


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## GreenTwin (Dec 12, 2021)

Keep the ferro in an airtight container so that it does not absorb moisture.
Adding anything to molten iron with even a very tiny amount of moisture can cause an explosion.

Many people (myself included) started out with too much ferro (more is better as they say), but with ferro, less is actually better.
As I mentioned, it only takes a tiny amount of ferro per melt, along the order of 0.04 to 0.06 oz/lb of iron.

Using too much ferro causes large shrinkage and often hot tears in the metal as it shrinks excessively.
Using excess ferro also is a waste of ferro.

.


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## dazz (Dec 15, 2021)

Hi
White cast iron can be heat treated to turn it into gray iron.  
Even here, the cost to commercially heat treat are reasonable.  

This is a random article I found.








						Heat Treatment of Cast Irons
					

Thinking back to our high-school days often brings a smile to our faces. As a freshman, the daunting task of picking a foreign language to study fell to The Doctor’s mother, who immediately chose Latin for him.




					www.industrialheating.com


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## Richard Hed (Dec 16, 2021)

dazz said:


> Hi
> White cast iron can be heat treated to turn it into gray iron.
> Even here, the cost to commercially heat treat are reasonable.
> 
> ...


Thanx for that info.  I don't need it right at the moment, but it's good info.


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## 100model (Dec 16, 2021)

GreenTwin said:


> I often see folks online from Tennessee, and I say "great we live in the same state", but then they turn out to be 440 miles away in Tennessee.
> TN is a very long state.


So is Victoria, the state where I live. It is 1000 kms from east to west in a straight line and if you travel by road it is about 1300 kms.


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## dazz (Jan 6, 2022)

dazz said:


> Hi
> White cast iron can be heat treated to turn it into gray iron.
> Even here, the cost to commercially heat treat are reasonable.
> 
> ...


Hi
Just reading John Campbell's book.
His experience is that heat treating CI seriously damages the micro structure, degrading the properties, including strength.
So, before trying heat treatment on something important, it would be prudent to heat treat a sample to see what happens.

Ideally any heat treatment should follow a defined time-temp profile so that it is repeatable.


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## Old Gold (May 26, 2022)

GreenTwin said:


> The induction melters also require a chiller to cool the coil, and so you need two rather complex pieces of equipment.
> The one I saw actually had water cooled electrical components in it (the induction unit), so you hope you don't get a leak in the plumbing inside the cabinet.


True, that.   I own a 50 Kw Ajax Magnethermic induction furnace.  It's a second generation machine (motor/generator) and is fully water cooled, right down to the high frequency transformer contained within.  It requires a circulation of ten gallons/minute of water not beyond 90°F for proper cooling, and will automatically shut down if the temperature of the discharged water exceeds 130°.



> A residential electrical panel (in the US) may be rated for 200 amperes at 120/240 volts, 1-phase, but is not rated for continuous duty.
> You would be lucky to be able to run a 100 ampere continuous load at 100 amps, 240 volts, 1-phase, and that would be 24 KVA.


To power my furnace, I have three phase Delta 240 volt 400 amp service.   The motor generator demands a huge amount of amperage (1,509 amps for six seconds) while spooling up, so I have been known to blow the primary fuses on the service.  Fortunately, the service is mine exclusively, so the provider has upgraded the primary fuses to limit the problem. It has operated well since the fuse upgrade.  The amperage mentioned, above, was the result of recorded information from instrumentation installed by the provider to determine why we were blowing fuses.


> You would probably have to use an expensive line reactor to prevent harmonic damage to the utility company equipment.


That isn't a problem with a motor generator system, but operation of this type of system is operator dependent on pretty much everything.  One must control voltage, amperage and switch capacitors on an almost continuous basis, as conditions are ever-changing as the metal heats and melts.  Unlike later generation melters (solid state), which are pretty much fully automatic.

Old Gold


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## Old Gold (May 26, 2022)

GreenTwin said:


> I stir in the ferro with a dried graphite rod (from ebay), skim, pull the crucible from the furnace, and immediately pour.
> 
> You cannot wait very long after adding the ferro, since the effects of the ferro will not last long.


I am not aware of that problem, although it may be unique to melting in a crucible with flame.   What you had to say is true of ductile iron, however, where the window of opportunity to pour the inoculated metal is relatively short.   



> Pulling an iron casting quickly out of the sand does not give the graphite in the metal time to form the nodules that make iron so machinable.


That's not true.   Nodules are not formed in gray iron, nor in white iron. Nodules are formed when gray iron, low in sulfur, is inoculated with a magnesium (or other) inoculant.   Glomag is one that is readily available.   Gray iron precipitates free graphite in the form of flakes, which is the chief difference between ductile (nodules) and gray iron.  Aside from the need for lower sulfur, ductile and gray are pretty much otherwise identical chemically.  

Gray iron is often treated with calcium carbide to lower sulfur content so it can be converted to ductile.  American States Cast Iron Pipe, in Utah, does exactly that, melting with a 96" water cooled cupola.   I had a tour of their facility in the early 90's to witness their operation.   Fascinating to see large pipe poured in 20' lengths in water cooled permanent molds.   The pipe was removed and sent to annealing ovens in huge racks, as the water cooled molds instantly chilled the pipe. 

Old Gold


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## GreenTwin (May 27, 2022)

Old Gold said:


> I am not aware of that problem, although it may be unique to melting in a crucible with flame.   What you had to say is true of ductile iron, however, where the window of opportunity to pour the inoculated metal is relatively short.
> 
> 
> That's not true.   Nodules are not formed in gray iron, nor in white iron. Nodules are formed when gray iron, low in sulfur, is inoculated with a magnesium (or other) inoculant.   Glomag is one that is readily available.   Gray iron precipitates free graphite in the form of flakes, which is the chief difference between ductile (nodules) and gray iron.  Aside from the need for lower sulfur, ductile and gray are pretty much otherwise identical chemically.
> ...


I think I am mixing my metaphors in my statement about "forming nodules".
The correct statement would be "forming graphite flakes".
I am just getting into researching ductile iron, and so still learning the correct terminology.

I would love to have an induction melter, but alas I am stuck with a "poor-man's induction furnace", which is an oil-fired furnace.
Induction motors generally pull six times their rated amperage when starting, and if they are started under load, perhaps more than that, or perhaps the same amount for a longer period.

One definitely does not need a quick instantaneous setting on a circuit with heavy motor starting.

I have been on a quest (like a Holy Grail type thing) to make ductile iron crankshafts, and I cannot get anyone to sell me a reasonable amount of nickle-mag additive.  I have begged more than a few people for some of it, to no avail.
I even have the calcium carbide that I need, but no nickle-mag.

The center of the iron pipe industry was just a few states over from here (Birmingham Alabama to be exact), and there is still a lot of foundry activity in Alabama, as well as a large coke industry.

I initially thought I would melt iron with coke, but I could not find a source for that either.
In the end, I am glad I went with an oil-fired furnace, since it is an easy one-person operation, even if hundreds of pounds of iron are poured (using a pouring cart).

You have any photos of your furnace/pouring operation?
That sounds interesting to say the least.
.


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## GreenTwin (May 27, 2022)

My first few pours did not include any ferro, but they were relatively thick castings, perhaps 1" thick, and so there was no problem with hardness.

Then I poured some thin parts in iron, without ferro, and I discovered that the alloy "uncutium", which means that the metal is basically tool steel, and it will take all the teeth off of a new portaband blade in a few seconds (don't ask me how I know this, LOL).

Too much ferrosilicon causes excessive shrinkage, and often hot tears.
It takes just a slight amount of ferro added to the melt to get machinable thin parts.
The ferro helps a lot with fluidity too.

I have never waited to see if the ferro effect wears off, since if iron is not poured within about a minute, the crucible starts to go cold, and you can drop below pour temperature, which often means an incomplete mold fill.

.


----------

