Commutator Test
- Ensure continuity exists between any 2 commutator segments. If continuity does not exist, replace armature.
- Clean commutator segment surfaces with emery cloth and polish with No. 400 grit sandpaper (if necessary). If surface is scored, out-of-round, or pitted, turn commutator/armature assembly on a lathe.
- Using "V" blocks and dial indicator, ensure maximum commutator runout and minimum commutator diameter does not exceed specification after lathe turning. See STARTER SPECIFICATIONS .
- Standard undercut depth for insulating mica should be .016-.024" (.40-.60 mm). Minimum mica undercut depth is .008" (.20 mm). If depth is not within specification, undercut to specified depth using hacksaw or replace armature.