This is the last part of Big Smelter project. I’ll finish this metal melting furnace by making refractory lining, drying, firing and finally testing. I can say that it’s my longest DIY project. It took me little more than 5 weeks to finish this work. I tested it by melting aluminum, brass and copper. The furnace passed all tests and got just minor damages.
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Step 1: The Refractory Mixture Formula
The final refractory mixture formula is 50% of grog, 43% of fire clay and 7% of graphite dust. We should mix all the components and add some water. A lot of people during making refractories recommend to use less water. I don’t agree with that. In my opinion, it’s important to use a lot of water (may be the same quantity as is used for making concrete). I tried to use a small amount of water during lining the lid and it worked very bad.
Step 2: Lining
Lining the furnace with the refractory mixture.
Step 3: Drying
The next stage is drying. I’ve decided to use a bulb as a source of heat. The temperature outside was from -5 °C to +8 °C (from 23 °F to 46 °F), and rain, snow from time to time. Therefore, it wasn’t easy and quickly to dry 50 kg (110lbs) of refractory material.
Step 4: Firing
When furnace lost most moisture it was a time to start firing. I made it very slowly. In the beginning I even didn’t blow the air inside. And after some time I could start blowing the air. During the final test the furnace was working during an hour. That’s usually enough time to melt copper.
Step 5: Conclusion
I’m satisfied with the result. Now my home foundry allows me to melt and cast metals when I need it and I don’t need to fix the furnace after every melting.
If this information was interesting for you, please watch the first and the second part here:
Part 2 - Big Smelter Project. Making the Lid