A Customizable knob that could go on a long coupling nut. The default settings work well for a missing knob on our lawn mower, and will fit a 5/16" nut. :-)

To customize, install freecad, (It's Free! ;-) and open the file. Then in the left you'll see a tree of operations that describe the knob. Double click on "Customize". There you will find the settings, the most important of which is the nut width. It's best to make small changes, and watch out for small red flecks on the operations icons, these indicate an error, like trying to make the minimum handle diameter less than the inner shaft size etc... Just go back to the last working setting and try again.

After you're happy with your changes, regenerate the mesh part, and export to STL. See:

https://wiki.freecadweb.org/Manual:Preparing_models_for_3D_printing#Converting_objects_to_meshes

The knob was loosely based on the basic sketcher tutorial here:

https://wiki.freecadweb.org/Basic_Sketcher_Tutorial

Prusa

I3 MK3S

No

No

0.3mm

40%