A 6-pointed disc cuts more effectively, with less pressure than a round one. The corners dig in and dislodge the paint, primer, and surface rust better than a rounded edge, with less down pressure exerted on the metal. I can skin the paint down to bare metal and barely leave any scratches in the surface with a high speed hex disc and a little careful sweeping motion.
The same procedure works for rough-shaping body filler before going to a D-A sander and 80-grit paper.
Jerry
