Parts Replacement & Testing: Commutator

Clean contact surface and polish with fine sandpaper if required. If surface is scored, burned, out-of-round or pitted, dress in a lathe only enough to restore smooth concentric surface. Out-of-round should not exceed 0.004" (0.10 mm) and mica depth should be 0.008 - 0.032" (0.20 - 0.80 mm). Undercut to give correct depth of 0.020 - 0.032" (0.50 - 0.80 mm).