Here is a parameterized model for knobs on a Iwatsu DS-8812 oscilloscope based on measurements by user Artag (See thread "Need a knob" in repair.
The posted model generates the following knob.

But by adjusting parameters a wide variety of useful knobs can be created. Two examples are shown. One has just 1 rib and is suitable as an indicator. The other has two extended size ribs and is appropriate for a hard to turn multi-position switch.
The shaft attachment can be resized for various D type shafts or adapted to a friction fit on a round shaft.
The model is in FreeCAD (Version 1.0.1) format. Number of ribs can be set from 1 to 12. The only things that can't be changed in the Params spreadsheet are the flllets on various edges. Changing these requires diving into the model.
Have fun.