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Making my own iron melting furnace


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#1 Kanus_oq_Seruna

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Posted 18 May 2011 - 12:24 PM

Hello everyone. I've been blacksmithing as a hobby for a couple of years now and even resurrected my grandfather's old forge.

I've recently been thinking about doing things with cast iron, or perhaps just melting down the iron so that I can pour it into more manageable shapes. But the first thing I'd need is to set up the furnace. I am wondering where I can get a crucible, and what all I might need for a simple coal fired furnace for melting iron.

#2 NN4N

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Posted 18 May 2011 - 12:58 PM

Hey,

I've too had some interest in metal casting and think I can give you a few tips. You want to start with cast iron, this is both hard to cast and getting some materials is more difficult (crucible and furnace than can handle those temperatures). Maybe it's better to start with some other materials:

Metals than can be cast very easily are tin and lead, but these metals are poisonous so I advice you not to use those.

A material I found easy to cast is aluminium. You can make your own steel crucible easily (just weld a steel plate on a piece of pipe).

Other materials that are relatively easy to cast are brass and bronze, but I have less experience with these.

Furthermore I advice you to read some of the info on this site: backyard metal casting. This guy is somewhat of a hobby metal caster, but he gives a lot of interesting info (including on cast iron), as well as links to sites by guys similar to him.

Hope this helps!

NN4N

#3 ThomasPowers

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Posted 18 May 2011 - 01:42 PM

For casting cast iron what you want is a cupola not a crucible; they run on coke not coal and can be done in a moderate sized back yard with understanding neighbors on a small scale. (invite the fire department over for a BBQ the first time you run it to get everybody used to it.)

Take a look at this link: http://www.lindsaybk...hcup/index.html

Lindsay books is a go to place for this type of weirdness!

I strongly suggest you attend an iron casting or even work on a crew for one---VERY IMPORTANT to learn the proper safety precautions as casting iron is far more dangerous than forging steel!
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#4 Kanus_oq_Seruna

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Posted 18 May 2011 - 02:35 PM

Thank you for the responses. I was wondering where I might be able to find a cupola now that I know what I'm looking for.

Further what makes for the best material for holding in heat for a small melting furnace? Would mudbrick and dirt work properly enough for a sort of mound furnace?

#5 ThomasPowers

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Posted 18 May 2011 - 02:49 PM

These are generally home built as they can be made relatively cheaply and purchased versions are quite expensive! Lindsay books has several books on building your own.

Mud and dirt will NOT work; way to hot to hold molten iron you will need a high temperature firebrick rated for the purpose. (I remember how amused I was the first time I tried to use a terra cotta flower pot for an enamelling kiln in my coal forge and it *boiled*!)

Of course the *best* material would be something like the space shuttle re-entry shield tiles; probably do it for a couple of hundred thousand dollars but you did say *best*!

Can you share where you are at---just in general. Knowing if you are in the USA or Europe can be a help in directing you to resources.

(We have an annual cast iron cupola run and pour at Mesalands Community College here in New Mexico USA)
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#6 Kanus_oq_Seruna

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Posted 18 May 2011 - 03:12 PM

I live in western South Dakota on a family ranch. Right now my forge setup is all outside.

I suppose in terms of cost verses efficiency, what sort of material might be affordable but effective. I've looked at http://www.backyardm...ncasting01.html and wondered what material he might be using for the drum.

#7 ThomasPowers

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Posted 18 May 2011 - 03:55 PM

Did you read page 2?

"This was the aftermath of my first "controlled" iron melt. The inner chamber's refractory is seriously melted, vitrified and glazed.... The only drawback is that the higher temperatures require furnaces to be built with high temperature refractory rather than the homemade stuff that you can get away with for aluminum."

The cupola pours I have seen do a much better job of melting, the iron is much more fluid and you are not as restricted to size of the crucible.
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#8 OddDuck

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Posted 18 May 2011 - 05:32 PM

Yup, Lio's homebrew refractory just ain't up to iron. Like the others, I do suggest starting with aluminum and work up to iron. The temperature difference is (relatively speaking) night and day. Molten iron throws off a LOT of radiant heat. You will need to learn to make molds with greensand anyways, might as well walk before you run. As far as fuel, you can do cast iron in a crucible furnace (that is what I do), mine is fueled with waste oil, but you can do iron even with a charcoal furnace. You will be using a lot of fuel however. Check out the forum over to BYMC, lots of info and the crowd there is just as friendly and free with info as the folks here.
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#9 Bentiron1946

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Posted 18 May 2011 - 07:30 PM

Melting and casting iron is not something to inter into on a whim. I suggest that you attend at least one organized iron pour so you get an idea of what is going on and what is required as far as safety and equipment. Yeah, you can read a book or two but that will never prepare you for the amount of heat, fumes, pace and danger involved in pouring iron. I have been to the Iron Pour at Mesalands Community College in Tucumcari, NM for a number of years now and a couple of pours done a foundry at this naught heads house. I'll take the organized one, it's a whole lot safer! That naught head was so disorganized that he tapped the furnace and didn't have any bots made up ahead of time so all his iron spilled out on the ground, dang that was hot! The next time he had his little pour he had bots but carrying crucible burned through the bottom on about the fourth tap and molten iron leaked out all over the place. Just a dangerous situation. You have got to plan your pour out to the last detail and not mess around, molten iron is a dangerous animal, BE SAFE and learn all you can before you start. :blink:

#10 Kanus_oq_Seruna

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Posted 18 May 2011 - 10:34 PM

Well I finally figured out what all I need to do for a Cupola, but I will start out light with aluminum. I can probably make use of some cans for material and will just need to get me a working crucible. I suppose I could use a Cupola for aluminum too.

#11 OddDuck

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Posted 18 May 2011 - 11:40 PM

Nope, a cupola , as far as I know, won't work for aluminum. Bronze, yes, Al, no. A small popcorn tin furnace is duh-simple to construct, and will let you try out metalcasting for a minimum investment. I know we all want the ultimate do-all one hit wonder super forge/furnace, but a small dedicated melter will be your best bet starting out. Keep it simple, and learn the process so success will build on success.
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#12 Steve Sells

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Posted 19 May 2011 - 08:43 AM

Metals than can be cast very easily are tin and lead, but these metals are poisonous so I advice you not to use those.

since when is TIN poisonous ???
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#13 ThomasPowers

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Posted 19 May 2011 - 09:51 AM

Tin is fairly non-toxic but various forms can be trouble: like Stannous chloride? (first MSDS I found: http://www.jtbaker.c...hhtml/s6434.htm)


Note that Al cans are a terrible alloy for melting and pouring. Very little metal and tons of dross when melted and does not pour well. What you want is items that were originally cast as they generally are made from a good casting alloy. Old pistons are often suggested.
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#14 Kanus_oq_Seruna

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Posted 19 May 2011 - 11:41 AM

Mostly what I would do with Al would be to learn how to form molds and make ingots for easier taking to a recycling place. I'll do some more research on making a furnace for melting Aluminum and Tin, and I'll probably get me a decent crucible, but will need to treat it first I imageine.

#15 ThomasPowers

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Posted 19 May 2011 - 12:46 PM

You will generally get paid *less* for ingot than for clean cans---so if you want to spend money on fuel, spend time on converting it into ingot and then turn it in for less money---knock yourself out!
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