"Terry Coombs" wrote in message
...

It's been a while since I molded and cast anything , so I decided
to get a little practice today . First melt was an old cast aluminum
decorative skeleton key . Wall hanging doodad , about 2 feet long
and 4 or 5 lbs of aluminum . Next was to mold up a disc that'll be
an end cap on a ball mill cylinder . That went well so I cut up a
couple of ingots snd fired the furnace back up . I'm going to have
to address the hydrogen porosity I'm seeing with some of my stock .
I've tried chlorine pool granules and that works well enough , but
the fumes are dangerous so I'm thinking about bubbling some CO2 in
the melt to degas . Anyway , the pour came out well too other than
the H2 microbubbles , and that piece is in the lathe now for
machining .
--
Snag
As soon as I get the rest of my sand up here
I'll be ready to start casting shaper parts ...

The clerk at MG Stevens told me the porosity meant my sand was too
damp, though he gave me a small bag of broken degassing pellets.
http://www.mgstevens.com/

I might take my patterns to a local art foundry:
http://www.granitestatefoundry.com/

So far I've built up machine parts that could be candidates for
casting by welding, annealing and forging/jacking out the shrinkage
distortions. Unlike casting all the metal doesn't have to be heated
red-hot at the same time, and it gives the tensile strength of steel
rather than aluminum.
-jsw