While I've done more than a few cobble jobs, using the right equipment for the job is always better. Since I've had a brake drum and rotor lathe in every shop I've run for the past 50 years, there's no reason to use a general purpose machine for those kinds of projects, especially when flat rate labor time is involved. Setting up a general purpose lathe to turn a rotor would eat up the profit margin on a brake job more or less instantly. Rotors must be machined with a carbide cutter bit on both sides simultaneously to hold the proper parallelism between the surfaces the pads contact, or there will be an annoying shudder in the brake pedal. That's impossible to do on most general purpose lathes without building a special fixture for every rotor.
Jerry
