John K Jordan
>>>Drill and tap 2 holes at 180 then run in 2 set screws to lock the cap and shaft in place?

If I understand the problem, the shaft needs to fit into the hex hole in the top by friction but needs to be easily removed to fill the pepper grinder.

I've had one loosen up with age and use; others still fit nicely. But we never pick them up by the top but by the body of the grinder.

JKJ