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.