Originally Posted by rwtalbot
Interesting, so you have an O-ring seal at the top or is that grove for bearing retention?
How are you attaching the gear to the shaft? Loctite 638 might be an option with interference fit, or is there still room for a grub screw? There must be a secure solution involving a minimum of machining. It looks like Dan may have used grub screws.
The groove at the top of mine is for a snap ring to retain the bearing.
The spacer between the bearings is retained to the shaft by a dog-type grub screw. The tip of the screw has an unthreaded portion that fits into a matching hole on the shaft. The tip extends about 3/8' into the shaft and is 3/16 diameter of grade 12.9.
The top gear is held on in a similar fashion. However, since my gear position lined up perfectly with the existing rivet holes in the shaft (from where the magneto was cast on) that pin passes all the way through the shaft. There is also a regular grub-screw on the gear as well. I just left that since there was already a second threaded hole from the gear manufacturer, so why not. According to the spec for Grade 12.9, that little 3/16 dog should have a shear strength close to 19k pound.
In my case, the bottom bearing is pressed in. and everything else is assembled on top of that.