Home Foundry

[GreenTwin]

It should be noted (perhaps I mentioned it before) that pouring iron cannot be a casual thing like pouring aluminum.

Aluminum melts at a low temperature, and can be melted in almost any container (steel containers/crucibles will degrade over time, but they can be learned if you are trying to learn to melt aluminum).
Almost any burner operating at almost any setting will melt aluminum.

Aluminum melts are very easy and is very forgiving of misadjustment of things.

Iron does not melt easily, and the burner output and combustion air setting has to be perfect, at 2.7 gal per hour, or approximately that. Any variance from the exact burner setting will prevent most iron from melting, or prevent the iron from reaching a good pour temperature, which is about 2,500 F.

The saying is "Iron takes no prisoners", and the sightest contact with molten iron on the skin causes immediate 3rd degree burns.

If you try melting iron, don't take a casual approach, since that most likely will not work, and you most likely will get burned.

Assume it is like taking a hike to the top of Mount Everest.
Its relatively easy to get to the top of Everest with the right equipment, training, preparation, etc.
Without the right setup, equipment and knowledge, climbing Everest will be a deadly affair.

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[GreenTwin]

Here is a video of a guy attempting backyard casting in aluminum.

Not a bad effort.
He has trouble with the petrobond, which is the same experience I had with petrobond, and why I now use resin-bound sand.

He notes that the basics of melting metal is pretty simple, but the mold making can be anything but simple or easy.

I went through a lot of his issues early on when I started pouring aluminum.

A few mistakes he makes:

1. Use 356 aluminum, not extruded aluminum. Don't use aluminum cans.

2. Don't lift a crucible with pliers or tongs on the upper top side of the crucible; that is a no-no.

3. Keep the sprue entirely full during the pour. He seems to be pouring at a good rate, but does not seem to be keeping the sprue full.

 

[GreenTwin]

This was a simple open-faced mold I used for an art-deco pour of a phoenix plaque.

This gives you an idea of the typical operation of an iron furnace.

Note, always start the burner with the lid open, and get the burner stabilized before closing the lid.

I also change into leather boots prior to pouring the iron.

 

[GreenTwin]

As far as using pour basins, I see a lot of videos of how critical it is to use an offset pour basin (the basin is offset to one side of the sprue).

But if you can make perfect castings by pouring directly down the spure, without a pour basin, then that sort of proves that the pour basin is not serving any useful function and can be omitted.

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[awerby]

For this pour, there is very little splillage, and the metal rose in the mold just to the point where the vent became full.
This is a good clean pour.

View attachment 140549

Greentwin - thanks so much for all this information! It makes iron casting at home seem a lot more feasible than I'd thought. A few questions:
Does the ferrosilicon lower the melting point of the iron to make crucible-melting more feasible? Does it change the working qualities of the metal in other ways, desirable or not?

Are silicon carbide crucibles just as good or better than the clay-graphite ones you mention?

Would natural gas - which doesn't have the icing-up problems of propane - have enough BTUs to melt iron, if paired with a pressure-blower, or is diesel fuel really necessary?

Do you need any special equipment to mix up the resin and the sand? Or is it a matter of shovel technique? Is it a two-part resin, like epoxy, or a single one like oil? How long do you have to get the material in place, once it's mixed? Do you know the brand name of that ceramic spray you recommend?

 

[GreenTwin]

Awerby-

Casting gray iron is very feasible, perhaps not nearly as cheap as casting aluminum, but technically/mechanically not much more complex than casting aluminum.

The biggest thing I think with iron is having everything rated for 3,000 F, which means using some commercial refractory like Mizzou, and using strategically located sheet metal heat shields on the pouring shank and skimming tongs.

I have not seen a silicon carbide crucible that was ferrous-metal-rated, and they had a much lower operating temperature rating than the Morgan "Salamander-Super" clay graphite crucible. I would not recommend using a silicon carbide crucible for ferrous-metal.

I think you could melt iron with natural gas, but you would need some significant pressure, ie: maybe as much pressure as with propane, or maybe not.
Ironsides (luckygen) could probably give a better answer on this. He has melted iron with propane.

When melting aluminum, you don't need a separate combustion air blower, and you can use a simple naturally aspirated propane burner.

With iron, you need some significant combustion air in order to get the iron to melt, regardless of the burner or fuel type.

The ferrosilicon prevents thin spots in the iron becoming "chilled".
The definition of "chilled" when referring to iron castings is a hard spot (or entire casting) that is the hardness of tool steel.
When you break gray iron with a sledge hammer, the break should be a clean uniform gray, with no white spots.
White spots are areas of the casting that cooled too fast, and the graphite did not have time to distribute evenly through the casting.

Iron castings should remain in the mold overnight after pouring, and should cool as slowly as possible, to avoid chills.

I have gotten away with not using ferrosilicon for castings that were perhaps 1" thick and thicker.
As the casting thickness goes below 1", you pretty much have to use ferrosilicon in order to have good machinability.
Generally between 0.04 - 0.06 oz of ferrosilicaon is used per lb of iron.
Using more than this slight amount causes excessive shrinkage, and often hot tears, and degrades the quality of the iron.

Below is what scrap gray iron looks like.
Some use old radiators, and while the books say avoid radiator iron for engine work, some I have seen have used it successfully for engine castings.
Cast iron is very strong in compression, but weak in tension, so try to break it up with a blow that puts it in tension.
You may want to wear shin guards when breaking up iron, since pieces can fly out at high speed.

And another myth is "Iron scrap must be clean and free of oil, rust, dirt, scale, paint, etc.".
This is totally false. I never clean my iron no matter what condition it is in.
All impurities come out of the melt in the form of slag.

 

[GreenTwin]

Do you need any special equipment to mix up the resin and the sand? Or is it a matter of shovel technique? Is it a two-part resin, like epoxy, or a single one like oil? How long do you have to get the material in place, once it's mixed? Do you know the brand name of that ceramic spray you recommend?

I have mixed resin-sand both ways, in a cement trough with a hoe, and later with a commercial kitchen mixer.
The commercial kitchen mixer does a better job of mixing.

The resin is toxic, so you have to wear nitrile gloves and a commercial chemical respirator.

The resin I use is a 3-part material that is frequently used in the art-iron community.
You mix part A in with the sand first. Part A is what I call the base resin material.
The sand has to be very low moisture, and I use commercial foundry sand called OK85, which I think is oven-baked.

Then you mix part B and C together.
I call part B the hardener (which may or may not be technically the correct term), and C is the catalyst.
Then you mix the B/C into the sand.

Resin bound sand has a "set" time, and a "strip" time.
You have X minutes before the sand sets (hardens), and then Y minutes to remove the pattern from the mold before the pattern becomes permanently adhered into the mold.

The set time is adjusted by the amount of catalyst.
The resin and hardener are fixed amounts based on the weight of the sand.

I generally use a 5 minute set time, if the mold is not too complex, and perhaps 10 minutes if the mold is complex.

The strip time I think is in the 20-30 minute range.
I try not to strip too early, and I keep the mold on a flat surface until strip time since it may otherwise warp slightly.

The spray-on ceramic is called "VelaCoat", and it is alcohol based.
You spray it on with a slurry sprayer, or a sandblaster, and then burn off the alcohol.
I generally use two layers, with the first layer burned off before applying the second.

I also lightly flame the interior of the mold before spraying on the mold coat, to drive off any uncured residual resin.

Here is a video of how resin-bound sand is commonly used.

I don't use a ceramic filter, but instead use a spin trap at the end of the runner, to catch the initial flow of the iron before it begins to enter the mold cavity via the gates.

Note that they do not use an offset pouring basin, but pour directly down the sprue, as I do.

You should wear a good dust mask when handling sand for the molds.

It looks like in the video they use a simple paint sprayer to apply the mold coat.
It is a pretty thin slurry.

 

[GreenTwin]

One thing that I notice as I watch the various iron pour videos is that a smaller crucible is much safer and easier to handle than a large one.

Here is an iron pour with a small crucible.




Note, I would never operate a furnace indoors.
One guy on a casting forum was running his furnace in his shop, with all the doors open, and almost died from carbon monoxide.
The doctor said he had never seen anyone survive a blood oxygen level that low.

The rating of the crucible in iron is roughly three times the crucible number, so I #10 will hold a bit less than 30 lbs of iron.
I generally don't pour a crucible if it is completely full, so I use more like 20-25 lbs iron in a #10.

A #30 crucible is a bear to handle, and I have hand-lifted those, and hand poured one that was about 1/2 full.

Here is a #30 that I poured.
Note that this was one of my very early iron pours, and I had no idea what I was doing, so don't copy any of these methods.
And don't operate a furnace next to your house or garage either.

 

[GreenTwin]

Here are various crucible sizes.

Smaller crucibles are definitely less expensive.

I purchase my Morgans on ebay.

Note that Morgan uses the term "Salamander" for more than one crucible type.
Be sure to use a Morgan "Salamander Super" clay graphite crucible.
One seller on ebay mistakenly listed the salamander super as "for aluminum only".
Ebay folks don't know what they are talking about.

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[GreenTwin]

It should be noted that resin-bound sand is just resin and sand, and does not contain clay like greensand or petrobond does.

If you start ramming resin-bound sand, instead of compressing the clay (there is no clay to compress), you begin to shift the sand away from the pattern.

Resin bound sand is pressed tightly around the pattern using the fingers (wear nitrile gloves), and then the rest of the mold is filled in, with the heel of the hands pressing it down, but not pressing so hard that it begins to cause it to shift.

And a resin-bound mold can be very thin, since it sets into a very hard state.
Resin bound molds can be perhaps 20-25% the size and mass of a greensand mold.

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[100model]

Does the ferrosilicon lower the melting point of the iron to make crucible-melting more feasible? Does it change the working qualities of the metal in other ways, desirable or not?
Would natural gas - which doesn't have the icing-up problems of propane - have enough BTUs to melt iron, if paired with a pressure-blower, or is diesel fuel really necessary?

Ferrosilicon does not lower the melting point of cast iron so what it does is it makes sure that all the graphite comes out and makes the iron soft enough to machine. If no ferrosilicon is used there is a strong possibility that white cast iron will form on the edges of castings and cutting tools will bounce of that part of the casting.

Propane will easily melt cast iron but there are two problems with it 1. you have to pay for propane 2. In small amounts it tends to get very cold so the furnace is starved for gas. To solve that problem most people use small propane bottles so the trick is to put the propane bottle in a larger container and fill it with hot water so the propane can change from a liquid to a gas. I use a 45kg propane bottle and it does not have this problem until there is 5-8 kg left and then the icing problem comes back again. The same method is used but you have to find a larger container for the larger propane bottle. I don't use propane any more to melt cast iron because waste motor oil is for free.

 

[ajoeiam]

Cast iron was commonly used for machines, engine blocks, and all sorts of other things.
You can find it at most scrap yards.
If you strike steel with a sledge hammer, it bends.
If you strike gray iron with a sledge hammer, it will break, leaving a rough edge.

Wear a face shield when breaking up iron.
Some will cut it on one side with an angle grinder, to weaken it.

And some use disk brake rotors, but I think they are on the hard side, and I don't use them.

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Hmmmmmmmmmm - - - - that means that supply if I were to get into this would be problematic!
Local scrap yards only allow material IN - - - anything out is to the smelter only.
Absolutely NO sales of anything.

 

[Richard Hed]

Hmmmmmmmmmm - - - - that means that supply if I were to get into this would be problematic!
Local scrap yards only allow material IN - - - anything out is to the smelter only.
Absolutely NO sales of anything.

where the hek do you live? Must be terrible. I was just at a scrap yard yesterday--bought a "chiller" (restaurant equip?) it lookt like to me, for the stainless sheet that was on it. Cost 15c a lb, weight 280lbs--43$, only had 42$--SOLD! They are glad to get cash (there was no reciept, wink wink). There was CI all over the place had I wanted to buy some. Your local scrap yard must be very peculiar. Do you live close to another city, town, megopolis? I notice you live in "blank". Is that a nice place? Maybe you should consider moving to the Soviet.

I need a piece of steel 16X5X1.25". I lookt for such a piece but this day there was nothing resembling that. Didn't have the $$ for it anyway. But tomorrow I WILL have some extra dough. I needs to be careful, as I bought some scrap there last year that was various shapes X 1.5" thick, some large enough to be difficult for me to pick up--they don't need to be very large for that! At that time, I was able to see a strapped package of steel that was at least 4 feet thick, 6 or 8 feet wide and lookt like 10 or 12 feet long. I couldn't tell from the way it was situated if it was "shells", that is, left overs from lazer cutting which is what the parts I was buying were from. The guys in the yard were cutting the shells up with acetylene. I've used a lot of it but want some more. Will have to keep an eye on the scrap yard till I can get some more. the little pieces that are left over are great for making a lot of small steel parts like we guys are making all the time.

 

[ajoeiam]

where the hek do you live? Must be terrible. I was just at a scrap yard yesterday--bought a "chiller" it lookt like to me, for the stainless sheet that was on it. Cost 15c a lb, weight 280lbs--43$, only had 42--SOLD! They are glad to get cash (there was no reciept, wink wink). There was CI all over the place had I wanted to buy some. Your local scrap yard must be very peculiar. Do you live close to another city, town, megopolis? I notice you live in "blank". Is that a nice place? Maybe you should consider moving to the Soviet.

One city of 750k about a good hours drive away.
After that - - - - the nearest city of over 300k is likely 6 hours drive or so.
For some things - - - - were I live IS terrible.
For some other things - - - not too bad.

Moving to the Soviet - - - - no thanks - - - - I'm not into grey skies and no sun all winter.
(Been there - - - well close - - - didn't like the no sun part!!!!)

 

[Richard Hed]

One city of 750k about a good hours drive away.
After that - - - - the nearest city of over 300k is likely 6 hours drive or so.
For some things - - - - were I live IS terrible.
For some other things - - - not too bad.

Moving to the Soviet - - - - no thanks - - - - I'm not into grey skies and no sun all winter.
(Been there - - - well close - - - didn't like the no sun part!!!!)

Ha ha haww. That is really funni! We have you completely fooled. I live in the Eastern part (actually central) part of the Soviet where it gets cold in the winter, but there is rarely a lot of cloud couver in the sky. I know because I do nite-time telescoping. Look on a map and you can find the Cascade Mts. which stretch from BC to N. California (actually further). Those mountains block the rain. Seattle has a bad rep for rain--and a certain time a year it is pretty bad, however, my nephew lives in Eugene, Ore, which I thimpfks if MUCH worse. Funny thing is Oregon does not get that rainy bad rep,but I thimpfks Ore. is actually worse. Ore. on IT'S Eastern side is also like the Soviet, far less rain, even a desert.

In the Soviet itself, as you approach Spokane, it starts to become wetter but not the type of area that has much fir, it is mostly pine which thrives in an almost desert like area. As you get into Idaho, you start climbing the 4th of July pass (or is that in Montana?) and you get lots of snow, don't know about rain. The people that live in the area (Idaho and MOntana) seem to like it.

Moses Lake, at one time, had the longest runway for fighter jets in the nation--it was SAC headquarters till '72, but the runway has been cut down now. The area is being considered for the HTOL space vehicle but it won't happen (me thimpfks) for two reasons: too much population and the weather HAS indeed become less sunny.

 

[GreenTwin]

I forgot to mention that I got the motor end bells from an electrical motor rebuild shop.

Any repair shop that rebuilds anything that is made from gray iron will have some discards.

If you can't find anything else, use automobile or truck disc brake rotors.

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[delalio]

Hello Everyone,

So I'm not a caster. I've played about in the garden with some greensand and a propane torch, but nothing very serious.

I did however go visit Cringle Engineering and recorded some video of the castings Luke does up there. I was very impressed.
Anyway, I made a little video of the work he does, with some cool slow-mo and in 4k.

The video goes live at 18:45 this eve if you are interested in watching it.

I'd love to hear your comments.
Please note, again, I am not a caster, just narrating my observations. But some of you may find it interesting or find the video nice to look at.



Kindest Regards,

Del

 

[GreenTwin]

The cringle guy has a great shop setup, and is producing some nice pieces.

A few comments (coming from an amatuer backyard guy with limited foundry experience):

1. I would run a carbon monoxide detector if I operated a gas or oil-fired furnace indoors, even if I had an exhaust fan.

2. I have heard some say that a steel crucible used with aluminum can contaminate the metal.
Some coat their steel ladles with something to stop any interaction, and I forget the name of this coating.
I used a steel crucible with aluminum for several years, and have never noticed any problem with the castings, even over a 10 year period.
Steel crucibles can have a huge capacity, due to the thin wall, for a given size.
The steel does degrade over time, so don't let them get too thin.

3. The matchplate layouts are nice, as is the jolt table, automatic sand feeder, and pneumatic (?) mold separator/pattern extractor.

4. I did not see him use a pyrometer, but some can accurately judge the metal pour temerature with aluminum visually.
However cringle is judging metal temperature, his casting surface finish indicates he is at a very good pour temperature, which is typically in the 1,350 F range.

5. I would use a rolling conveyor going from the molding area to the pour area, and would not lift the molds from the tabletop to the ground, and then back up to tabletop height again. I have seen Clarke Easterling use non-powered rolling conveyors like this.

6. His pour technique is very good. He keeps the lip of the crucible right at the top of the sprue, to avoid the waterfall effect.
He keeps the sprue full at all times.
Note that he pours directly down the spure, and does not use an offset pour basin, which how I recommend pouring molds.

7. A water quench gives aluminum castings a bit more hardness. A two step process can approximate a T6 temper, and gives a more cleanly machining casting with low tool loading.

8. Throughput is limited by flask quantity, sand quantity, and crucible/furnace capacity.
I have seen commercial shops with a large electric furnace and tub full of aluminum, and they use a ladle to dip out the aluminum for pours.

9. Many have said online (somewhere) that you must discard the burned petrobond sand that is next to the mold.
The folks I know who use a lot of petrobond (art-iron folks with aluminum) never discard any petrobond, but instead use fresh petrobond for a thin facing sand, backed up by used petrobond.
I think petrobond can be reused indefinitely without discarding any of it, if you add a little alcohol every now and then and mull each time you make molds.

10. The muller is a nice simple design.
If he stays in the business, he should consider building a muller with rotating wheels.
I started to build my own muller, and then changed to resin-bound sand.

11. His flasks are a manageable size, and not too heavy to lift and handle.
A larger flask means more sand required per flask, and some heavy lifting/flipping.

His 3D modeling is very good too, as is his pattern work detail.

All in all, he has what I consider a very functional setup, and a great product.

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[GreenTwin]

Here is the muller I started to build.
It is made from trailer fenders, which are a bit thin for long term use, but would probably last a few years.

 

[GreenTwin]

More muller build photos.

Note: It is important to have either a sheer pin, or something that can slip, since a small piece of slag can jam a muller, and without some release mechanism, the muller drive train will destroy itself.

Some use a microwitch activated by an over-torque mechanism to stop the motor in case of a jam.