Originally Posted by My name is Mudd
What's the shaft diameter?
lol, I can't help it....that question has my juvenile mind literally laughing out loud.
Anyway, avoiding the cheap jokes (which isn't easy for me, believe me!)....I always hated geometry so I'm not sure I can give you an exact answer but let me first ask - which shaft are you talking about? The shaft of the tuning peg or the shaft of pole which slides through the hole in the headstock? I'll post some additional pics below which may or may not be helpful.