Picked up a tired Simpson 260 VOM that was missing the function knob and didn't want pay $9+ with shipping. Also none of the parts I found looked like the original Simpsons knob. Not having the original part to measure my design is all from interpretation of photos.

Snug fit for 1/4" diameter "D" shaped shaft. Allows for #4-40tpi locking screw without any tapping. A normal 4-40 screw will self-tap.

Version 2 is for a 4-40 set-screw (no head)
Version 3 accepts a half-inch long 4-40 screw with a pan or flat head

Snug enough, you may not need locking screw.

Bambu Lab

A1

Doesn't Matter

No

0.175mm

20%

Hand chamfer d-shaped hole to clear any 1st layer mushrooming.

A recess for the pointer line can be filled with white paint for added authenticity.