Hi SilverBear, long time, no talk! When I was first prototyping the Silent power drive, I could not easily get a small piece of 5/8 keyed shaft, and I spun the set screws on the flats i had ground into the shaft. My solution then was to use a Dremel with the new style quick-release stones, the type with the fiber-glass grid on it so it doesn't explode so easily.
I cut a key-way into the shaft, problem solved!
(Later i did get shafting, but learned a valuable lesson about being more inventive)
Mike