Here is a picture of a little toolpost grinder I made for my old shoptask. Its just a Harbor freight air grinder that I zip tied the throttle open and used a paint gun regulator to adjust the speed. It has a 1/4 collet, so it holds a whole variety of little stones and burrs. When my chuck jaws started getting worn I was looking for a way to clean them up and the grinder idea came to me. I found a drill holder at Lowes that was used to clamp a drill motor and make a low budget bench grinder. The diameter was almost exactly the same as the HF air grinder and it had a swivel as well. I just made a plate for a couple of T nuts and mounted it to my table. To true up the jaws, I used a bearing race on the outside of the jaws, figuring that opening against this round part would set the inner jaws at center. I then turned the chuck slowly and ground the jaws with my HF special- came out nice. I have used it on some other shafts, and with a little WD 40 while grinding you can get a real nice finish. On my patriot machine it is a bit above center due to the thicker table on the new machine, so I will have to mill down the plate a bit.