I'm currently working on a large steel melting crucible furnace. As a precursor,
I built this small melting furnace. This was intended on being a non-ferrous
melting furnace. I found out the hard way that it will in fact melt
a stainless crucible! The pics below show it's inaugural lighting!
The first pic is the whole furnace. It's made from some 12" dia, 12 gauge stainless pipe found at the scrap yard ($0.40/lb). I had some scrap stainless laying around the shop that I welded up the bottom and lid from. I used a steel door hinge on the lid. The legs are made from and old bed frame I had laying around. These are great for a free source of angle-iron. You can always find one in someone's trash if you just keep an eye open. For heat, I use a 3/4" venturi burner (Ron Reil's burner site) and a 0.032 jet (MIG welding tip). Refractory lining is 2" of Kaowool with ITC-100 coated on thick. Total cost for this was about $20...not including the high pressure propane regulator. The Kaowool, ITC and gas valve are the most expensive items. Since I have many forges/furnaces, I buy these in large amounts and usually have them on hand for projects. Next is the initial lighting...easiest done by lighting a piece of newspaper and tossing in the chamber, then turning on the gas. Next is the chamber with the gas turned up to 5psi as it starts to warm up. Then, the crucible being loaded with brass and copper scrap (with a little enameling and assorted trash!). Next up, partial melt as the brass liquefies. the last pic is the last of the copper melting down. I poured the first melt into an ingot form and placed the stainless crucible back in the furnace without turning the gas down (10 psi). I melted a few holes in the base of the stainless (12 ga thick!)! Lack of heat is definitely not a problem! Another thing worth noting is with regards to hinges. I discovered that large door hinges have a nylon insert inside them. I was a bit suprised to see black burning "goo" bubbling out of my hinge! It burned off in a couple minutes, though! I'll eventually get some more pics up of casting and such. |