[cncadmin]

http://alltronics.com/download/04T017.pdf

[DAB_Design]

Personally I wouldn't go with anything less than 15-20in hg. The ones we use at work pull between 25-30in hg. We have several parts that we run roughing operations on with no other means of holding the part. At 10in, you can usually push the parts around.

But I guess it depends on what you're doing also.

[sol]

It used to be a common cobble but we got richer I guess...Old A.C and refrigerator compressors make decent air compressors and can be used as vac pumps as well; if it exhales it has to inhale... I have one that pulls well over 25 in Hg without bogging down.... they are frequently free for the asking.

[bertvk]

There's a description on my site on how to build one yourself. I have built one using new parts, except for the freezer compressor. It works very well. I can get down to -0.95 bar. I have no idea how much HG this is.
Here a link : http://www.dream-models.com/eco/vacuumpump.html

[sol]

Bertvk

Thanks for the link, I like your vac diaphragm switch assembly...

Also... instead of a ping pong ball I use a sponge crammed in a pipe...

[bertvk]

It is the most popular page on my site. Aparently many people need a vacuum pump for all kinds of purposes, not just CNC.

I have used a Bosh car part for the switch. If you want I can get the part number. It's made from platic for Mercedes cars. Sealing is absolutely perfect and the movement of the pin is about 1/2", plenty to move a switch.

If any of you need more info, let me know.