I ran into a problem Saturday, casting using some new-to-me
equipment. I bought a used Memco Electro-Vac and programmable kiln.
Earlier in the week I tried two small flasks in my old smaller kiln,
just to make sure I could make it work, which it did brilliantly.
Saturday I had six 4 x 6 flasks all hot and ready to cast and the
heating element in the caster burned out after the first flask.
So now there are 5 flasks, that represent a lot of work waxing, and
no chance of repairing the machine until Tuesday. Each casting was
about 300 grams of sterling deox. My question for the casting sages
on the list is what should I have done?
Let the flasks cool and reheat when the machine is fixed.
Keep the flasks at temp for the next 3 or 4 days. What would be a
good holding temperature?
Melt the metal in an open crucible with a torch and use the
vacuum chamber on the Elecro-Vac like you would a vacuum table.
I tried the last option. The second flask cast beautifully. Two of
the other four were probably not hot enough because the metal did not
flow into many of the smaller cross sections. I saved about 50% of
my work. Using my trusty centrifigal force caster I usually only melt
about 150 grams at a time, so my judgment for the bigger casting
under the torch was not so good.