how about blue loctite

Hmmmm, the fit isn't very tight to begin with (empeg guys, is the axle spec'ed as x.y mm or 1/x inch?) with a 6 mm hole, and 5.5 was too small. How hard does blue loctite get - it might be a case of too loose a fit to make loctite work unless it hardens fully. And I would prefer to be able to remove the knob without destroying the rotary encoder...

I've been toying with the idea of making a small spring, shaped like a 'b' but with taller vertical top and without the lower part of the vertical. The vertical part would press-fit into a radially milled recess at the back of the knob and the bent part would occupy the space of the 'missing' part of the axle, inside the hole. See attachment. Spring is dark blue, D-shaped part of axle is red.

Comments?

/Michael