Small foundry question?

[dmerc]

Hi Guys!

I've used a stainless steel tube (motorcycle muffler) to melt aluminum (using charcoal) and I'm wondering why I couldn't just put a SS tube, inside a bigger SS tube, and fill the space in between with sand? Or clay?

The SS muffler casing, actually works fairly decent with NO insulation......

I've since made up another using a propane tank, with refractory cement/perlite mix. I haven't tried it yet, and would like to have a backup plan if it doesn't hold up. (which I'm afraid, is likely)

So please,let me know if I'm wasting time even thinking about it?

Thanks, Don

[Joe S.]

Hi Don,
are you using that SS tube as a crucible ?
As I understand it metal used as a crucible contaminates the Alum. I found all sizes of crucibles on eBay. I made my foundry out of a huge cookpot from smart and final and about 400 pounds of refractory cement, homemade burner, 0 -100 psi regulator.

[beone]

If you are not making 'critical' castings, a metal crucible is fine. A double wall crucible would not be good because it would insulate the charge and thus take more fuel to melt and the inside shell will still hole thru. Crucibles are an expendable item. If you mean for the furnace itself you dont want a metal inner lining as it will have a short life and the life of the refractory if good and well placed is good enough.

[dmerc]

No, I meant the SS tube as the furnace. My crucible is just one of the little propane cylinders with the top cut off. So the stainless won't hold up long to the heat?

[jhowelb]

I used a propane weed burner from Harbor Freight, some angle iron and fire brick to build mine. One brick near the bottom has a hole cut in it with a hole saw and a drill press. I use a cast iron lead pot for a crucible....no "critical" castings.

[beone]

Firebrick or a good hitemp castable for the lining will have a very long life. My main furnace was built in 1986 out of pacocast28 as an electric 'LiL Bertha'. I later made a fire ring for a propane burner as the elec is too slow. The nice thing about the bertha design is it is in multiple parts-top-mid-bot. I haave replaced the firering out of mizzou and other castables several times but the top and bottom and origional body are going strong.