I have been told that those little die grinders use more air than just about any other tool.
I don't have air so I use a Dremel rotary saw with a five amp motor. I use a 1/4 collet and carbide grinders for doing detail work on welds. I have to watch the speed because I can burn a tip really easily. It is also a good tool for taking out spot welds that aren't good candidates for the regular cutting tool.
