Don Terrill’s Speed-Talk

Any wisdom you can give me about cutting slotted or drilled brake rotors? I never gave it a second thought until someone suggested that the cutting bit skips and jumps whenever it runs over a slot or a hole; leading to a poor finish.

My machine is an ancient Bear; but I can certainly make light passes if that would help. I'm aware of vibration dampening of the rotor and the cutting head--at least that part isn't a problem for me.

I have heard of people grinding them in a flywheel grinder but never tried it myself.

They do tend to want to skip a little bit depending on the rigidity of the brake lathe. I have a Winona Van Norman model 204 brake lathe that you can adjust the cutter feed rate as slow or fast as you want. I find that if I slow the feed rate way down to a snails pace it cuts very well. If your lathe has a fixed cutter speed I think light passes (.002"-.003") for the final cut would help.

I tried grinding a motorcycle rotor on my flywheel grinder because it had to big of an opening for any of my brake lathes centering cones and bells.