I had some of the diamond stones for a Dremel but, they got misplaced in the shop and the local Lowes didn't stock them any more. They worked and lasted well. I used 'em in a cordless drill.
I tried the Oregon carborundum stones and went through three before I finished sharpening a 16in chain. They're just junk.
Pull a properly sized file from the handle and put it back in loosely, so it can rotate. Chuck the other end of the file in a cordless drill. Go to work controlling the long end with the file handle. Sharpening goes pretty quick. Works well for me.
