JPG wrote
Yep! I have tried to get 5/8" shafting with a 1/8" keyway, but have not been successful.
Why double snap ring?
The idler sheave does bear against the front snap ring - that why double? If so I do not see a need for double at the aux shaft end.
Double snap ring at idler sheave end will cause displacement along the shaft axis.
Well, not sure if you will believe me, but a snap ring is designed to hold lateral or axial pressure against one direction, not both. I think there are snap rings which have a bi-lateral design and are setup for pressure in both directions, but I'm not going to find that at Granger or McMaster Carr, and would have to order it special. The end of the shaft that faces outward where the threads are on the eccentric could get away with a single snap ring, as it is squeezed by the pinch bolt and won't go anywhere as long as the inner race doesn't move, but the inner snap ring location was incorrectly designed using a C clip(mine was completely missing) to separate the bearing race from the sheave. It was under-sized, and over-stressed for that application, although given that they lasted many years, I guess it could have been considered acceptable.
In the same theme, my commentary on the vacuum system engineering shows up the same way on this shaft. Wrong bearings, wrong C clip, wrong captive method. This is not a complaint, as the entire system of the Mk VII has stood the test of time. But - it could be better in some respects. We've also seen this in the plastic cam follower. Small mistakes were made, and over time have been corrected. BTW, the added width offset will be taken up by moving the eccentric out 3/32" to maintain the sheave alignment.
