In article ,
Bruce L. Bergman wrote:

On Tue, 22 Dec 2009 20:28:55 -0700, "Bob La Londe"
wrote:

"Gunner Asch" wrote in message
.. .
On Mon, 21 Dec 2009 23:28:59 -0800, Bruce L. Bergman
wrote:

Do you have a diaphragm vacuum pump? Or a shop-air venturi pump?
Mill out your pocket a bit oversize to allow for rubber, make two big
holes for the vacuum, and drape a sheet of inner-tube rubber on top.

Get a decent seal and enough differential pressure built up, and It
Will Not Move. Until you turn off the pump. And if they are slightly
undersized the jig will compensate.

Don't raise the drawbridge, lower the river.

-- Bruce --


Very good suggestion


Well, I do have a brake bleeder hand pump, but I don't think that will cut
it.

Nope, not gonna do it. You need a small (1/6 to 1/2 HP) diaphragm
pump or carbon-vane pump rated to pull (guessing) around 20" of
vacuum. An oil-ballasted high vacuum pump would be overkill.

An air-venturi pump like they sell at Harbor Fright for doing car air
conditioners would work but they are massively inefficient with shop
air, you need a true 5 HP compressor to run one.

The hand pump would work if you sat there squeezing the handle every
few seconds, but any leakage and your workpiece is likely to pop out
of the tooling halfway through the process, which is bad.

Would a water aspirator work?

http://en.wikipedia.org/wiki/Water_aspirators

Joe Gwinn