I have a commutator lathe, manually operated type.
You mount the lathe in a vise, mount the commutator in the lathe (it would have different collets for different size shafts.) Then start cranking.
I'll dig it up and get pics. It is used in the first operation, then you need to cut the mica down.
Now-a days you just replace the tool/motor. Brushless motors, advanced electronics, inexpensive manufacturing. Everything's changed.
I like fixing / repairing/ re-purposing. I like it when others do it too. It's part of the Boy Scout's Law to be Thrifty.
Chilly