Here is the finished tin can furnace (a.k.a. coffee can furnace). I built a welded steel framework to hold the furnace and the burner for table top use.
The refractory was rammed into place just like any regular furnace. The can is 6" diameter and actually came with pineapple slices in it. So it's not technically a coffee can furnace. But it's the same size as the large coffee cans and "coffee can furnace" is easier to say than "pineapple slices can furnace." Actually the lid is cut from a second can so this is really 1-1/3 cans. The lid is 2" thick but for a furnace this small it seems out of proportion so maybe 1-1/2 or 1" would have been better.
This is the gasoline filled blowtorch I'm using to heat the furnace. I bought it on Ebay for $20 or something. It seems to be a modern version of the antique torches. They are still manufactured in China and other countries where propane is not commonly available. The pump pressurizes the gasoline and also works as a safety pressure release valve. I use this torch for a variety of jobs (soldering copper pipe, heating and bending steel, etc.). It's much cheaper to use than the disposable propane cylinders and puts out MUCH more heat. I even use it to heat rusty bolts when restoring my antique metal lathes (but that's a future webpage).
The only drawback of these torches is that you have to heat them up to initially vaporize the gasoline in the burner head passages. I do this by pouring rubbing alcohol into the fuel tray and igniting it. Alcohol burns cleanly with no smoke nor soot. 91% works best but 70% rubbing alcholol works also but is harder to ignite and leaves a little water in the tray. As the amount of alcohol in the tray decreases it begins to boil and the flame really grows as shown in the photo.
Here is another blowtorch that I have. This one is designed to burn kerosine. I had this burner brought in from Australia. This torch is possibly antique, and it was made in Sweaden. I don't use it though because it doesn't have a pressure relief valve. But the fuel vaporizing assembly in the torch head is interesting (a tubular ring that the flame passes through). I didn't have kerosine so this flame is actually from a mixture of home heating oil thinned with gasoline. The leather pump piston was shot when I received it so I had to replace it with a scrap of leather. It was probably fake leather "naugahide" or whatever it's called, and however you spell it. It's still bad and I can barely pressurize the fuel tank with it.
The blowtorch flame does heat this unit but melting is still slow.
The lid raises up and back remaining horizontal for safety. Wanna see more mini furnace pictures? Check out Gene’s page in the guest pages!