These knobs fit a 6mm shaft (such as a rotary encoder or a potentiometer). Print them using a 0.25mm nozzle.

Small knob dimensions:
height = 15 mm
outer diameter = 20 mm
hole depth = 12.5 mm
hole diameter = 6mm (for 1/4" shaft)

Large knob dimensions:
height = 15 mm
outer diameter = 40 mm
hole depth = 12.5 mm
hole diameter = 6mm (for 1/4" shaft)

If you need to make changes to the dimensions and have Solidworks, the Solidworks part files are provided.