Made the original model for my wife. She made a few suggestions for a different look. The result was a redesign for looks with a few tweaks for functionality.

The knob file here is the original. I simply adjusted the height of it in my slicer. I reduced the height by 50% and was still able to clip it on to the wheel. 

All of the files print with no supports. I used 10% infill, but the OP of the model suggests 20%. All the pieces press fit together, but depending on your settings tolerances may vary. Nothing a few dabs of Crazy Glue cant fix.