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Steve Mathews
08-05-2019, 10:45 PM
Is the vacuum pump shown in the link below suitable for a vacuum chuck? It's not the Gast pump typically used by woodturners but a used one was given to me and I would like to make use of it.

https://gastmfg.com/products/compressors-and-pumps/rotary-vanes-motor-mounted/1531

Brice Rogers
08-06-2019, 12:41 AM
I think that it'll work okay in most situations with a couple of minor caveats/comments:
1. It is a little on the lower side for volume - - but if you have a decent seal and aren't working with highly porous wood it should do okay. If using porous wood causes a problem, just apply enough finish to reduce the leakage.
2.. It's max vacuum is a little low. A perfect vacuum at sea level is around 29.9 Hg. So, if you had a perfect vacuum and seal, you'd get 14.7 pounds of pressure per square inch. So - - say your seal is 10 square inches in diameter >> that translates to 147 pounds of force. But if you only can draw 20 mm Hg, you'll have roughly 100 pounds of force. For most things that should be fine . Also, if you used a larger vacuum chuck - - cross section at the seal - - (and your piece was large enough) you could largely compensate for that.

I love my vacuum chuck but I'm careful to take light cuts, ensure good seals, avoid catches, etc.

I'd recommend that you give it a try. I think that you'll get a lot of utility out of it. You have nothing to lose.

BTW, make sure that the seals that you use a very good sealed bearings. Some bearings are referred to as being sealed but are actually "non-contact" seals - - and they leak like a sieve. Some people use good sealed bearings and some use secondary seals. As long as they don't leak, you should be in good shape.

William C Rogers
08-06-2019, 9:41 AM
I think it is too small. I have the Thomas pump (same as what Frugal sells) and dead head will pull 28” vacuum. However with wood and other leakages I get about 22-24” when in use. So to me 16” would be marginal. Also the flow rate is on the small side.