A simple but stylish knob for 6 mm D-shaft rotary encoders and potentiometers.

Look, I know I'm not inventing the wheel for the first time here, there are hundreds of these knobs out there already. However, I tried something like ten different knobs found on Printables and Thingiverse and not one of them would fit my encoders (the tactile EC11 ALPs encoders sold by e.g. splitkb.com). Either they were too large and rattled around and fell off or they were too snug or tapered and wouldn't slide all the way onto the shaft. While this could be solved by scaling up or down a percentage point or two, it was a lot of wasted resin for things that were all made to fit the same specification.

Thus, I decided to “solve” the problem by making yet another knob that uses a way of holding onto the shaft that I believe is a bit more flexible (literally, unless you print them in some insanely non-flexible material). I'm neither an engineer nor an industrial designer though, so it might be a really stupid and fragile design, but it's a knob, it shouldn't have to deal with a lot of mechanical forces and mine haven't broken thus far.

I've provided the stl for my original design and an f3d file for Autodesk Fusion (I wonder how long it will take me to stop writing Fusion 360 before correcting myself). The design is parametric but I will freely admit that the parameterization could probably be improved. If you want to play around with it and can't work out the parameterization please just send me a message and I will try to help. 

The design should be easily adaptable to other sizes of D-shafts just by changing the shaft parameters, though you might have to repair the initial extrude for the gripper component.

This is a new model but the general outline and the concept for the gripper were inspired by this knob by Dampmaskin.