I can't remember where I saw this idea......pretty sure it was in my old 60s magazines but they are in storage right now...... :cry:
Anyway, here is a crude diagram (not to scale):

The left side shows a side view. It was a 2x2 post on a small (4x4?) plywood base. I drilled an 1/8" hole, bent some music wire axle stock, and had my crank. I am sure you could put a brass sleeve through there if desired.
The right side shows a front view of the plate on the end of the crank that actually held the armature. The top slot (thank you Dremel) and bottom hole are lined up with each other. They both have small (8/32?) screw eyes in them, held in place with two nuts (I used my Cox wrenches to tighten them). I think they came from a picture hanging kit, but I maybe the hardware store. The top one, when loose, can slide up and down to loosen or tighten the arm in the jig.
To use it, loosen the top screw eye, put one end of the arm through the bottom screw eye, then lower the top one down and tighten the nut to hold the arm firm. Wrap your wire and start cranking, spin the arm in the jig when it's time to move to the next pole.
Cheap and easy and functional.