hey, i was about to fly planes, but the touring bug got me again. I don't own a lathe, because i'm 15(no job), and a lathe costs in the 200 dollar range. Many compaines make them, like integy, cobra, and a few others. I never counted how many times a comm can be cut, mostly because something else brakes or happens to my motor, so i throw it away, and get a new one. I think a motor should last a season, and still be running good, as long as you maintain it well with oil, brushes, springs, a little dremel work on the bushings(i do it). For more info about motors, just go the stock motor forum, it says stock motors, but your questions are general enough.