I got most of one of these yesterday:
A friend did some research and came up with the picture above.
He said it was a commutator cutter.
What is that?
It looks like something a sadistic dentist would enjoy.
I have two of them and some spare parts. They are used to undercut the mica insulators on armatures. You can still get the cutters for it from Martindale. You said that you got most of one, looks complete to me.
That is not a picture of the one I have. My friend found that photo on the net.