From a chemical lab supply firm, you must obtain an “aspirator
filter pump”. This is a valve that attaches to a faucet. .
When water is run through this device, a venturi-effect pulls a
vacuum from a port protruding from its side. When I run my
faucet at a wide-open setting this port can pull 28" of mercury
vacuum (as read from a Sears Craftsmen vacuum gauge). The
particular valve I have, is one manufactured by Humboldt Mfg…
I had to order it through a Chemical/Scientific supply house.
I’ve been trying to find a bell-jar or other pressure-sealed
container that I can attach to this valve, to make a
"vacuum-chamber".This device, I hope, will enable me to
debubblize either mixed investment or pourable rubber molding
compound (in a container) .
I found two 70’s era jewelry books that illustrate casting
systems that use this valve as the centerpiece of the
vacuum-casting process. Hoben-Davis Ltd…, an English firm,
marketed this system at one time. I spoke with one of their
reps at the last MJSA /Providence show, but he had never seen or
heard of this system. I asked him to investigate this, but to
date, he’s never responded back to me. The last listing that I
could find for this system was in the '92 catalogue from Walsh &
Sons, Ltd…, a British jewelry supply firm. It cost almost $450
at that time. I decided that, at that price, I could afford a
mechanical Vacuum pump ! But a search through the Thomas
register at my local library,helped me to find the “aspirator
valve” . The price for this valve, including some adapters, was
a whopping $30!
So, I have been hoping to find a way to build my own system. If
you could help me find a source for, say, hoses and fittings and
any suitable “chamber” I’d greatly appreciate it. If you desire
more info, Just reply back and I’ll help with what I can…