To: Doug1
I am considering making a "barrel" type of commutator.
I believe that the centrifugal outward pressure along
with your suggested anti-spark recommendations would
help keep the brush from sparking. I have a metal lathe
to do the final internal cutting and polishing.
Shadow

This type or style.

WOW!
Is that the one you ground the flat space on?
The only one I had similar to that was this one.
This one was good to 20 amps but the mechanism
was slow as molasses in winter. I thought I would
be able to speed it up, but gave up on it.
Shadow

No that is just a picture of an old style might even be home made. Certainly easier to wind and change out the winding. It would just take a big enough core which is dimension-ally different from a mot or a step transformer. I would venture a guess the core came out of an old mag amp for radio work. Was then converted to this or that. There is what looks to be some type of flat insulator under the windings that is larger then the center leg itself. to help support the wound conductor.

After fooling around with designs for class A amplifiers to power exciter electromagnets for a 16 KW generator, I found them to be  impractical due to excessive heating and heat sink requirements. Attached are block diagram and schematic drawings for a preliminary design which uses a crystal controlled 60 Hz frequency standard that can be synchronized with the incoming power line, an optional 3 phase signal source, a digital 10 stage (20 step) sine wave generator,and a PWM approach to powering the exciter electromagnets. A spreadsheet with applicable calculations is also attached.

I have not yet built this contraption, and would appreciate suggestions for improvements, corrections, and especially those pointing out mistakes.

Thanks in advance for your help.
Sam6
Note:
The drawings show a VCO with a 0/1 KHz sine wave output. The design calculations are for a 360/360000 Hz square wave output from that VCO.