"Dave W" wrote: (clip)What I can't seem to find is the minimum cfm
needed.(clip)
^^^^^^^^^^^^^^
The capacity of the pump affects two things:
1.) How fast does the system reach a usable vacuum?
b.) How much leakage will the system tolerate, and still work?

If you use a pump with more than enough capacity, you will be able to turn
wood without spending lots of time sealing leaks. You will have a bleed
valve, which will usually be partly open, so you don't get TOO MUCH vacuum.

If you go for a pump with very little volume flow, the slightest leak will
get you in trouble. I say there is no lower limit, but I advise you to get
the biggest pump you can find and afford. Mine is a 3/4 HP Gast, and I am
very happy. (It's a bit noisy, though.)