Cupola furnace built on the cheap

...Possibly too cheap.

I don't have much confidence in this cupola, actually it's the fuel I don't have much confidence in. I find it hard to imagine that I'll be able to melt iron and keep a pool of it molten until each draining of the furnace. None-the-less I have plans to build a "cupolette" furnace for single batches of maybe 50 or 60 pounds of iron. Then hopefully the real fun will begin!... -June/20/2005

scrap iron

Here is a piece of scrap iron I found one day. It's actually an engine cylinder head from a vehicle that obviously hit the skids years ago. It weighs about 30 pounds and is somewhat hollow. Bits of the spark plugs are still in it.

I found this piece along the shore in an area that used to be a boat and scrap metal dumping ground. The area is now a recreational park but the shore is still littered with scrap iron, mainly from machines and old Victorian home style iron radiators (a piece of one is below the cyl. head). If this iron melts and casts well I'll be more than happy to help further clean the shore by collecting more of that scrap iron!


These are some oyster shells that I collected from the same Atlantic coast shore as the scrap iron above. I read that both oyster shells and powdered limestone are good fluxes for iron. And since I can gather all the oyster shells I want for free then that's what I'll do.

Unfortunetly no pearls were located. I'll continue to search for them since they also have usefulness, but not for the cupola, for my wallet!

Broken iron scraps

I don't want to buy the modern cupola fuel (coke) so I'm using homemade hardwood charcoal. Hardwood charcoal was often used for iron melting in the olden days. These are NOT barbecue charcoal briquettes which are ineffective for ironcasting. This charcoal is from oak, maple, ash and whatever other wood is burned in the fireplace. I just shovel some coals out, quench them with water and let them dry.

I have access to some regular coal so if the hardwood charcoal fails maybe I can use that, or heat the coal in a retort assembly to create "homemade coke". Coke is coal with the volatiles burned out. But I intend to "perfect" the use of homemade charcoal and make my own based on a method shown here or here. Here is the charcoal and iron measured out and put into bags. There is about 6 pounds in each bag of iron. I don't think my crucible would be able to safely collect a full 10 pound load from the furnace. This little cupola should melt about 10 pounds of iron at a time. It turns out that ten pounds is more scrap than I thought.

Starting the cupola

Now it's time to get this thing going. I start the cupola with a nice fire of paper and sticks. Believe it or not This photo was taken about 10 months after I actually built this cupola! I just never got around to firing it up and it just sat in the basement. Therefore I don't have any concerns with slowly drying the lining. This is my homemade refractory formula and It's plenty dry after 10 months!

The blower and manometer in position

Here you can see the blower and manometer in position.

Looking into the tuyeres

This is a look into one of the tuyeres (pronounced tweers). You can actually see right out the opposite tuyere.

Furnace charged with fuel and iron

You can't tell but the charcoal is blazing in the furnace. I've therefore dropped in a bag of iron and another bag of charcoal.

flame out the top of the cupola

I read that a cupola works best with a rather reducing flame (a bit low in oxygen). And this is indeed reducing. I think these flames result at least partially from the carbon monoxide burning further into carbon dioxide.

Page contents copyright © 2005 by L. Oliver II - www.BackyardMetalcasting.com
A look inside the furnace

Here's a look into the top of the furnace. Pretty hot. I can see iron glowing and the materials inside are lowering. But that just means that the fuel is burning, not necessarily that iron is melting. But hopefully I'll have molten iron soon!

Molten iron?

This little droplet is what I got from all that effort. When I first saw it I was very excited thinking that the iron was dripping down about to buildup in the base of the furnace to be drained out. But alas, I only got a few more drops like these.

Oh and get this... after a closer investigation I discovered that these droplets aren't even iron... they're slag! That mother fornicating.....

Well, I feel really defeated, so I guess that's the end of the cupola experimentation... SIKE! I'll try some thing different this time.

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Copyright © 2005 by Lionel Oliver II All Rights Reserved.
This site was created Sept. 28, 2000