After weeks and weeks of searching to find a local source of vacuum pumps and pressure pots for the purpose of resin pressure casting, I needed to face the reality that it's really difficult to obtain the kind of equipment needed locally. I can't explain why, since it is completely stock equipment used in the automotive shop industry. Nevertheless, this weekend, I took the trip to Syracuse, the closest place in the States that carries the necessary hardware, and at good prices, too. It was a worthwhile trip.
I ended up going to a store chain called Harbor Freight, and getting a 2.5CFM vacuum pump. I constructed a simple vacuum chamber from a thick acrylic cocktail shaker. The pump manages to vacate the glass in less than five seconds, which makes it very easy to work with.
The compression chamber is a standard 2.5 gallon paint pressure tank. Again, difficult to source locally, but available for a decent price from Harbor Freight. With a very modest compressor, it reaches 40psi in under twenty seconds, and maintains it easily.
Hooking up the equipment and trying it for the first time today yielded better than expected results. There was not a bubble to be seen in the clear Alumilite resin, and the pressure forced the casting into all parts of the mold far more reliably than gravity alone.