At House of Reloader. We (meaning he) used his new-to-him and new-in-box On Vehicle brake lathe. My AC Delco rotors, with only 10K miles, had a warp in them. (I think they were the middle of the 3 different ACD quality levels). The lathe uses the vehicle's drivetrain to turn the rotors while the cutting blades cut the rotor. The blades are moved from center to outside of the rotor by turning the wheel on the lathe.

The finished product, with a non-directional finish applied via a grinding wheel

Lots of filings

And we can't do this work without finding more issues. This boot is pushing grease out of the end but it also has a crack in the boot. Finally going back to AC Delco CVs now that I have a front locker and will test the strength of the CV axles. Preferred Chassis Fabrication diff mount in picture as well.