I have some experience in making metal melting furnaces. That’s my second project where I construct the smelter which will be much bigger than my first one. That’s why I called this project “Big Smelter”. :) According my plan this smelting furnace should meet such requirements:

1. It shouldn’t be very expensive but in the same time it can’t cost 0 $ as my previous furnace. I’ll try to make it as cheap as possible but without losing in quality.

2. It should sustain high temperature. I’ve decided that 1600 C° (2912 F) should be enough. That will be fine for melting lead, aluminum, brass, bronze, copper and many other metals may be even some grades of pig iron but critical for steel.

3. My future smelter should be enough big, so I could use bigger crucibles. In the same time there should be enough space for fuel. When we use charcoal and coal, we demand more space than when we use propane.

4. I want to make it efficient. I’d like to use as little fuel as possible. In the same time it should allow me to achieve at least 1200 C° (2192 F).

5. I’d like to make it Hybrid. Now I use charcoal and when I need to increase the temperature, I add coal. In the future, I want to be able to use propane without any reconstruction.

6. Finally, last but not least is safety. Higher temperature - greater risk. Therefore, my small foundry should be as safe as possible.

It was a long introduction and now the practice. I’ll say about the first part of “Big Smelter Project. Making outer skin”.

Step 1: Thick Steel

I have a stove which was a part of heating system in a greenhouse. It’s enough big and has thick walls (1 cm or 0.39 in). I’ve decided that it’ll be a good outer skin.

Step 2: A Smoke Duct

First of all, I cut off a piece of a smoke duct.

Step 3: Cut Off the Top Part

The next thing was to cut off the top part. It should be the lid of the smelter. This process took me a long time because it was hard to cut such a thick steel with a small nonprofessional angle grinder.

Step 4: Using Bolts and Nuts for Additional Fixation

Using a steel sheet welding the place where was a piece of the smoke duct. I’ve decided to use bolts and nuts for additional fixation because it was hard to weld that sheet.

In addition, I had to weld 2 doors. They were demanded from the stove but no need in the metal melting furnace. I didn’t weld everything just fixed them.

Step 5: The Outer Pipe

I’ve also made a reentrant pipe. It has a diameter 60 mm (2.36 inches). I don’t need such a big diameter for now but it will be needed if I use propane. That’s important to make it Hybrid. This pipe will be outer pipe of the air supply system.

After that, I cut an ellipse for the pipe into the furnace body and welded outer pipe.

Step 6: Air Supply

I have to upgrade my air supply system again. I made blowpipe wider and longer. In addition, I made some changes because of the outer pipe and new fixation.

In the second part you can see how I've made a lid. The lining with refractories in the last 3d part. To be continued…