Morgans wrote:
OK, so there has been a lot of talk around here, about casting aluminum for
VW heads. It was here that I first learned that you can not use iron
crucibles for melting aluminum.

So, what if you need to cast a little job for something that does not to be
a pure aluminum part, for a non-aircraft application, where strength is not
very important? Would it be good enough?

My part is a socket (retainer) to go on top of a tractor shift lever. Think
like a donut, with the inside of the hole shaped like would be formed around
the outside of a sphere, or half of it. It has a retainer that screws down
around the outside of the part, holding the shift lever and ball around it,
down onto the transmission.

I believe the metal part that needs to be replaced is/was made out of what
is usually called "pot metal." What the heck is that, anyway?

So, what do you all think? Contamination from a cast iron crucible OK for
this part?

Lots of people cast aluminum using steel pots. I don't -- but I spent
the money on a selection of graphite crucibles long ago and a big
carbide one as well. The steel "crucibles" will eventually fail with a
burn through (so will graphite for that matter , but there is a very
different event horizon).

Pot metal is generally some zinc alloy, like zamac. Decent strength,
easy pour, given to corrosion. Atlas used to make a lot of chrome
plated die-cast zamac parts for their tools, especially their lathe,
which they marketed directly and through Sears & Roebuck. When you
buy an old Atlas lathe, you have to make sure the gears, handles and
other Zamac doodads don't crumble. Sometimes it almost seems like the
chrome is filled with sand.

Seems to me I saw plans for a cupola furnace made out of flower pots
years ago and fired with BBQ briquettes -- no crucible required. Then
again, flower pots can be deadly too.

Charles