Dave W wrote:
From what I have been able to find, a vacuum of 10 inches should be
sufficient for a vacuum chuck.
What I can't seem to find is the minimum cfm needed.

Used pumps are fairly easy to find, but I'm not sure what is the minimum
size I need.

Dave in Cherrylog, GA



A smaller passage between the chuck and pump is better than a larger
one, since there's less air to evacuate and you don't have to take into
consideration air flow as with a compressor. With this in mind, cfm may
not be as important as you think--an efficient low cfm pump can be
better than an inefficient hi cfm one.
My 1/4 hp Gast pump has fairly low cfm rating, but it's only a matter of
waiting a few seconds more to reach max vacuum than say, a 3/4 hp pump.

BTW, a good source for closed-cell foam rubber seal material: 2 mm thick
craft foam in 9 x 12 sheets, with adhesive backing. Available at craft
stores and Walfart for about 60 cents each, many choices of colors. Also
great for jam chucks. Moldable around compound curves (doesn't buckle).


Ken Grunke
rural La Farge, WI
http://www.token.crwoodturner.com/

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