Gast Vs Thomas
I wasn't able to get the specs up that Allen sent, but I have a Thomas-Riechle (sp?) rocking piston type pump in addition to a Gast rotary vane pump - the Gast is used for chucking on the lathe, the Thomas was originally used on my old Jet 1642 and worked well enough - I had no problems chucking up to 15" bowls with it. When I stepped up in lathe size (Robust AB) I started using the Gast for chucking on the lathe. The Thomas is now used for chucking on a carving stand primarily where it continues to work well.
I think these type of pumps (the rocking piston) are used extensively in irrigation and pond aeration. When I did my original search for specs - a few years ago - the company, or at least the design of these pumps had been through a few company changes, so they're known by several different names depending on who owns the manufacturer at any particular time.
I'm pretty close to sea level here, and both pull very decent vacuum - the Gast will peg my gauge most of the time (depending on the piece), the Thomas pulls about 23 - 24 inches. I use the same chucks on both applications, so the situation is pretty much the same for both pumps. The cfm was less on the Thomas-Reichle, but I really haven't notice a huge difference in overall performance in real time use.
The Thomas was bought on eBay for less than $35, the Gast was also bought on eBay as new surplussed equipment for $85 (it was truly brand new, unused equipment) - both were excellent deals.
For what it's worth, the Thomas, even though it continues to function well, looks to have been through a few wringers in its life, so I rely on the Gast for anything that could turn into a flying hazard.
