Robo 3D Knurled Extruder Knob

SummaryUpdate: One of the very few flaws in the Robo3D is the rather onerous filament changing interface. I switched to a single knob to see if I would have slippage problems and have had none, so I made a larger version. Now I can easily remove it one-handed and change filament from in front with the use of an added mirror. This saves a lot of time and stress, especially when you have to change mid-print. I also use a weaker spring and a ninjaflex grommet so it doesn't go shooting off across the room anymore. This is a simple upgrade, but wow, what a difference it makes in ease and convenience. It employs 2 replacement bolts (M4 Hex head, 50mm) which I was able to source at a True Value store. It is a bit snug, but I found that I could tap it in without cracking the plastic. Scale up a tiny bit if you want it to be easily removable.