I got them to use on my little Unimat. Turning mild steel was a simple task. It produced nice long curls of chips, much better than my other cutters. Finally I blunted the edge; No problem, I just turn the cutter. I used the included T6 screwdriver to loosen the screw and click! The tip of the screwdriver broke in the screw head. It's too small for one of my broken screw extractors, so this tool is now being thrown away. I had several T6 screwdrivers, so I decided to loosen one of the other screws. Well, the teeth didn't break, but they twisted like spaghetti. The screw didn't move. So I thought maybe these screws are reverse threaded. I grabbed another T6, spun it the opposite direction, and the same result: a tattered bat and a screw that wouldn't budge. So I have no way to replace blunt cutters. I think they're great until they lose their sharpness, when that happens I just have to throw them away.