I took this picture a few years ago of the chip bin of a brake lathe. The metal chips were covering the mounting surfaces of the adapters that mount the rotor the arbor. You may think, “SO FREAKING WHAT!”

Consider this: The average sheet of 20lb copier paper is 0.0038″ thick. This is 0.001″ more than some runout specs. If you look at the edge or the paper you can barely see it. If you look at the chip bin, you can see chips that are larger than the edge of a piece of paper.

If chips sticks to a mounting surface, you are cutting runout into the rotor.