I have a small vacuum caster from Rio. It has a single table used
for investing and casting. Usually I just use it for investing and do
my casting with my Neycraft centrifuge. A friend suggested that I
use my vacuum for casting rather than the centrifuge. He told me that
when he does it, he puts the heated flask on the vacuum table, set
for casting, melts his metal in the sprue hole of the flask, rather
than in a melting furnace, or crucible, and when it is all molten,
turns on the vacuum pump, still keeping the torch on the metal so
that there is no danger of it freezing.
That is the first time I ever heard of that method, and it seems
that it would be a very efficient way of doing casting.
Have any of you tried melting your metal directly in the flask, and
if so, have you had good dense castings?