Nichrome wire Gauge

Go to a ceramics/pottery hobby store, and ask about kiln elements.

Steve R.

No comment on the nichrome gauge, other than the fact that I used a dryer element, which I don't recommend, unless nothing else is available. But as far as refractory, I strongly recommend you go to the trouble of finding a bag or two of commercial refractory. It will work much better than the homemade stuff, and you'll be much happier with it. I used A.P. Green Cast-O-Lite 30. A.P. Green is now owned by Harbison Walker, IIRC.

I have nothing on refractory materials, but on heating elements I would stongly suggest that you research the device called a "Globar".

These are resistive stick roughly 1/4 to 3/8" inch in diameter that become heated to an incandescent temperature when current is passed though them. These are what were used to heat all of our refractory furnaces used for semiconductor melts at RCA Laboratories during the late 1950s.

Sorry, but I don't recall who made "Globars", but I suspect that they must be still marketed. We controlled their heat simply by simply connecting them to a variable-voltage transformer like a Superior Electric 'Powerstat' or a Genrad "Variac" rated at 15 or 20 amps.

As I recall, the nice thing about Globar heating elements was that it was so very easy to assemble a small, high-temperature, refractory oven that could melt gold, copper, iron and steel using only a small pile of firebricks on top of a lab bench.

Harry C.

brand name. The site mentions Global so

You need another Ginger book. He wrote on on an electric furnace. see

Dave will show you how to use common, low-cost materials to build a 220 volt electric furnace for melting aluminum. You get detailed how-to on making the three-part body, installing the element, and adapting other components to make a fast, convenient and safe melting furnace. Capable of 2300 degrees for hours. 5

No. 4163 ... $8.95 GmcD

I built an electric furnace for brass about 25 years ago. Kanthal A1 is what I used. get wire from a ceramic supply house and spin your own coils. I used a kiln design book and my old college physics book to figure out how much and what gauge. Basically use the amount of wire for 20 amps at 110 volts. Support the wire continuously or it will sag and burn out. I used fiberfrax for insulation. Very efficient but will burn out faster than refractory. Karl

Nit to pick: If you don't want to chance the breaker tripping out on the thermal overload in mid run, size the load to around 80% of the breaker rating continuous, or install a larger circuit. A 20A circuit shouldn't be loaded higher than 16A continuous.

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