A prop shaft company I dealt with advised me to use steel cup point grub screws centered in a slight dimple on the shaft.
Michael Brown Windburn C&C 30-1 Four years ago I put a new Universal M3-20B in our club launch, and new shaft as well. Drilled pretty deep holes in the shaft for the set screws, tightened them and wired them in place. After about two months the shaft slipped out, with no apparent damage to the shaft. I think what happened was the threads on the end of the screws compressed in the holes allowing enough play to release the shaft. I then put the set screws in a lathe and cut the bottom of the threads off, so it was just a solid tip, and tapered the end. It's held since then. Neil Gallagher Weatherly, 35-1 Glen Cove, NY
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