Those venturi vac pumps are real air hogs. You can use up to 10x the
energy to run a compressor to get the same vac as a tiny vac pump would
give you. Fine for occasional use but miserable on a continuous basis
like you would have for a vac chuck.

ff wrote:

Peter Grey wrote:

Hi all,

I want to build a vacuum chuck. I'd like to build one that can hold a
piece up to 10" square with the ability to block off some holes and
use it for smaller pieces. I'm trying to figure out what pump is
appropriate to try to find used. In looking at what's available from
MSC and others, it appears as though a pump that pulls at least 26" is
about right. How important is the CFM rating in this application?
I'm assuming that a pump's max CFM will influence how quickly the
chuck builds vacuum, and depending on how much leakage gets past the
item I'm machining and its contact with the chuck, how easily it'll
maintain its hold. Any suggestions about minimum specs I should be
considering.

Thoughts and suggestions welcome.

Peter




We have used the really inexpensive venturi type vacuum pumps when the
leakage was kept to
a minimum. These pumps work on shop compressed air and have no moving
parts.
CFM rating will depend on how much leakage there is in the setup. If
coolant is used in machining
a catch tank in the line will be necessary to keep it from getting to
the pump.