Nylock Nut Knob

thingiverse

I've been using the Prusa Mendel Filament Spool Holder for a couple of years now (I should; I designed it!), but I've been using a box wrench whenever I needed to change out filament reels. I belatedly had the idea of making this knob (which press-fits onto a 5/16" nylock nut) to make it possible to do filament changes using just bare hands. It's a good refinement, and makes me a bit more willing to, e.g., change filament to get a different color. Instructions (1) Print the attached STL file. Sand as necessary; I spent a bit of time on this since it's something I'll be gripping with my bare hand. (2) Use a bench vise or diagonal pliers to press-fit the knob onto a standard 5/16 Nylock nut. The "top" of the nut (the end with the nylon insert) goes into the knob first. (Note: It may also fit an 8mm Nylock for those who have an all-metric Mendel; I didn't try it). (3) Screw the knob onto the shaft of the Filament Spool Holder in place of the original bare nut, adjusting as needed to allow the spool to feed easily but not unwind wildly. (4) Put that wrench that's been sitting next to your printer back in your tool box and leave it there.