While I wait to get the garage back from the
Jetta repair, I've re-thought my shaft attachment method. The old way was more complex and didn't hold the pulley perpendicular to the shaft as well as I had hoped. The new way is simpler and works better from my little bit of testing thus far.
The new attachment method uses a tapered bushing that squeezes down on the shaft as its tightened. Its a common industrial method that works quite well.
The pulley will have a female shaped tapered bore.
The bushing has a male tapered bore.
You put screws through the bushing that engage into the pulley. The tighter it goes, the more it squeezes the shaft.
I'll be printing new parts soon, but I need my garage back to work on the Metro...