This will reply to me2's questions. My furnace is 18x18x18 inch #16 gage
sheet steel case with 2-inches high temp block and 2-inches low temp
insulation on all surfaces. Thus, the chamber is 10x10x10 inches. The
spiral 1500 watt element in on one vertical side wall. Actually, my first
trial was with two identical elements on opposite sides, but it was
overkill, and now I find that a single 1500 watt element is ok. I use it
for wax melt-out for lost wax castings in brass. First phase about 250 deg
for initial melt, then ramp up to 750 for two hours, then up to 1100 degF
for final burn out. Never tried to melt brass or aluminum - for that I use
propane fired naturally aspirated burner - about 1-1/2 inch x 10 inch pipe
with #57 drilled orifice for the gas, modeled after Ron Reed's design.
Bottled propane fuel at about 15 psi pressure. An earlier model used a old
vacuum cleaner blower and natural gas, but this one is better. I am
currently wiring up an Omega temperature controller so I can use the
furnace unattended - right now it is on 100% manual control. If you build
one, I would like to hear from you. Regards, Dave



"me2" wrote in message
news
On Sat, 04 Feb 2006 03:59:40 +0000, David Anderson wrote:

My home made furnace uses one 220 volt 1500 watt domestic stove-top
spiral
wound element from the junk pile. Cost zero$. Dave

Where do you place said element in the furnace ? On the floor of the
chamber and then suspend a false floor above it ?

I'd like to hear more about this setup.