I was drilling out a broken stud the other day with a very dull drill. My old grinder wheel is pretty worn and it is hard to do a good job sharpening a small bit on it. My 3" air cut off tool was handy so I gave it a try sharpening the bit. I think it did a great job and I had better control with it than the big grinder. Just thought I would mention this tip I never thought of doing before.
Bob