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This is the furnace, started life as a 2.5 gal propane tank. I cut the bottom off and
used that as the top.
Used 3000 degree refractory and fireplace rope to seal the lid,
which wasn't the best idea. The seal works fine when melting aluminum, but I
melted the
rope when I tried to melt copper. It's ready for storage in the picture,
you don't want a propane tank that close when melting. |
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My first brass casting, a combination of old brass fittings. I used the Reil type burner
to melt the brass, it took
about 45 minutes to pour. The flame looks good, just wanted
to see if I
could get more, so I built a new venturi.
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This is a heat using the Reil burner. If you look close, I'm melting the lost foam
castings, they were nasty anyway. I have no idea what the
temperature is. But it
melts aluminum. Guess I need a pyrometer. Soon, just one thing at a time.
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When designing this furnace, I studied everything I could about furnace design. Yea right. Actually I already had an old propane tank that I figured I could fit a
#6 crucible into and leave 1 1/2" refractory all around. I used a stove pipe for a form and 2400 degree refractory. I got that from a hardware store.
It was a paste, and worked for about 5 heats. I thought I had dried it good enough, but when applying heat it bubbled and cracked, not the way to go.
After chipping it all out, I made wood plugs and got some real castable refractory, 3000 degree, cool. This all worked better, anyway. With the draft on the plugs,
I may have improved the furnace. Theory: The bottom of the furnace tapers to closely match the taper of the crucible, with 7/8" to 1" air space around the
crucible, the top has about 10 degrees of draft. Which when
fired up the crucible heats at about the same rate bottom to top. When watching aluminum melt, it melts at the top just about as fast as at the bottom. This is one area
I'm going to have to experiment with. I am going to build a larger furnace, #10 crucible max. I'll use the same figures for this furnace. Just to see if
my burner will work with a larger furnace.
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Pattern of the venturi. It needs some changes, so a wood pattern is a good
medium to work with, modifications are easy. |
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Looking down the rough casting, the center vane is air foil shape, this is
one area that needs change. |
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In the construction of this furnace, I had no goal but to melt some aluminum. After reading, a lot, and then
building this furnace. I have some theories I need to try out. With the next one.
I started with a 2.5 gallon propane tank, cut the top off. Then added 3000 deg castable
refractory. There is a 3/4" drain hole and a 2 3/4" exhaust hole. I can use a #6
crucible, which is a little on the small side for what I want to do. The next furnace
will be built around a #8 or #10 crucible. That will allow for some nice size castings.
The next part of the project was to
build something to remove the lid, without having to touch it. I decided to make a roll around
cart that can be used for storage as well. The nice part, I had all the scrap already. So does that mean it was free?
