Starter armature may need to turn three areas that need a machine that can make the turning of commutator OD,commutator raisor and the area next to OD which might need strengthen ring after turning lathing the surface
If so, you need two kinds of cutter to turn the OD surface of commutator, one is wide cutter, one is sharp cutter as below
There are different types armatures which were turned in commutator OD, riser and strengthen ring area,
Pearl
Emily