My experience, air powered rotary tools need a ton of air. My biggest compressor, which isn't that big but makes the lights dim when it starts ( from memory about 12cfm) will not run my 1/4 inch shank di grinder for very long. It will keep the 1/8 inch one going sort of ok but pretty much runs all the the time.
I found that maximizing air flow does help a lot. So run the air hose straight from the tank and keep the hose as short as you can.
Good luck.
For little stuff I just bought a Dremel.
Dave.
(sorry the boss is calling me to help with dinner![]()