I posted some rambling speculations about 01/06 or /07 about this
and may have started some of you thinking about possible economic
savings for casting vacuum sources. There have been several reponses
and it is certainly great to see imaginations stirred up! However,
for jewelry (or other) casting applications I recommend everyone
listen to the voices of experience that are posting - that is, the
people you know to have experience with your exact methods,
requirements and equipment. It now seems to me that a used
high-quality electric vacuum pump would be the best solution where
economy is desired, and a new one if your budget allows for it. The
venturi effect might best be left for applications where it has a
track record such as laboratory work, perfume/pesticide application,
aircraft instrument vacuum etc.
Anyway, that's my disclaimer and I'm sticking to it....