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1st pour with electric foundry furnace

Posted: Sat Jan 16, 2010 3:47 pm
by Chet
Put together a modified Big Bertha type furnace using a 220 volt commercial heating coil.
Crucible was schedule 40 pipe with welded bottom, then painted with pottery slip.
Raw aluminum was pieces of former propane grill.
I hobbled together a digital thermometer using a Craftsman multi-meter and a commercial probe tip.
It took just over 2 hours to bring the furnace to 1220 degrees.
As the raw material heated up there would be small bursts of flame as remnants of grease burned off.
So far everything was as anticipated.
What was not anticipated was the amount of crud on top of the liquid aluminum.
I'd thought it hadn't completed melting, but a poke with a rod revealed liquid beneath.
The crud was aluminum colored and seemed pure, but quickly collected on the rod leaving the liquid behind.
Poured the remaining molten aluminum into a steel muffin tin.
Conclusions:
Have to make sure aluminum pieces are small enough so plenty can be packed into crucible.
Convert to propane at first possible opportunity!
Yes, electricity is clean and readily available, but life is short...
Chet

Posted: Sun Jan 17, 2010 9:07 pm
by tomc
Chet, nice going. You need flux to seperate impurties in your pot. Get some Morton's Lite salt and add about a teaspoon or so and stir. Should help. Next, make a skimer to remove the overburden before you pour. Did you kiln wash the muffin tin? Not a bad idea if you didn't.

Tom C.

Posted: Mon Jan 18, 2010 10:39 am
by Chet
Hi Tom!
Thanks for the info on adding salt to the melt.
I'll give it a try.
Chet