Nichrome wire Gauge

I've been working with a charcoal fired Gingery style aluminium foundry for two years and am getting a little tired of the trouble of operating
it, the smell, reloading... so I've been thinking about building an electric foundry.
Unlike the charcoal or propane foundries there isn't much information available on the net. I'm mainly wondering what gauge of nichrome wire I should use if I want to be able to reach and hold a decent temperature.
Any tips concerning refractories would also be appreciated. I've used a Silica sand /Fireclay/Portland Cement/Perlite combination which has tended to flake with use. I've heard of a Perlite/Furnace Cement mixture which seems somewhat simpler to prepare.
Thanks Jon
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http://tinyurl.com/2kq78
JonJonJon wrote:

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Tap in to your local pottery supplies place. They will have the firebrick, refractory, and nichrome wires you need. Also available online.
JonJonJon wrote:

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

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JonJonJon wrote:

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.
--
Gary Brady
Austin, TX
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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.
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snipped-for-privacy@yahoo.com wrote:

http://www.cesiwid.com
makes heating elements, which I'm pretty sure were under the Carborundum/ Amoco brand name. The site mentions Global so it's possible it's the same company now.
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I looked at these for a glass melting furnace. These are silicon carbide heating elements. As I understand it the usual method of powering them these days is with a phase angle control and preferably a power sensing controller. The element resistance increases quite a bit as it ages and so the phase angle duration is increased to compensate for this. I spoke to Kanthal and was told that they would make them to my resistance spec within a given range at least. In the end I opted for Kanthal wire heating as the capital outlay for the SiC elements and control gear was much higher than for wire elements and I was intending to use the furnace occasionally not full time. The SiC element have benefit of higher temp capability, longer life and can be replaced in situ in a hot furnace if so designed.
Cydrome Leader wrote:

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You need another Ginger book. He wrote on on an electric furnace. see http://www.lindsaybks.com/dgjp/djgbk/found/index.html
look for Lil Bertha Electric Furnace
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 1/2 x 8 1/2 softcover 67 pages
No. 4163 ... $8.95 GmcD
On 4 Nov 2005 15:33:41 -0800, "JonJonJon"

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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

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On Tue, 08 Nov 2005 13:23:12 GMT, "Karl Vorwerk"

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.
--<< Bruce >>--
--
Bruce L. Bergman, Woodland Hills (Los Angeles) CA - Desktop
Electrician for Westend Electric - CA726700
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Good point. I worked for an electrician in high school and he came over and hooked the circuit into the panel with the right size breaker. Karl
wrote:

what
used
volts.
fiberfrax
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