My dad was at Lowe's a couple weeks ago and he picked up an electric chain sharpener. Oregon makes it. It's 12 volt with both a cigarette lighter plug and a set of clips to run right off an automotive battery. It's basically a little router with a guide on it to maintain proper angle and depth. It came with 3 bits-3/16, 5/32, and I forget what the last one was. It was big. Anyway, it spins at 20,000RPM and seems to do a nice job. The motor case is red plastic. I think it cost about $20.00. I've seen replacement bits for like $5 a set. I like it so far. I like the 12 volt because (obviously) you can use it in the woods. So far, so good.