PrintrBot Zero Friction Spool Holder

thingiverse

I've taken a look at another design by Emmett for a horizontal spool holder that fits onto the Z-bars of my PrintrBot, but I found the friction on the spool was a bit too strong and produced artefacts on the print as the filament was being pulled out. I think mounting the spool horizontally offers a neat and stable design, so I created one with a built-in bearing to minimize friction - okay, describing it as "zero friction" might be a slight exaggeration. I could have used real ball bearings here, but picking up some marbles from my last visit to the local toy store seemed more in line with the DIY spirit of 3D printing. The result is an extremely smooth action... really, you should try it! I'm also quite pleased with the threaded spool retainer. Not only was this my first attempt at printing a thread and it worked perfectly, but the conical design allows me to fit all the spool sizes I've encountered so far without any wobble (see photos). Just remember not to tighten the knurled top too much or you'll lose the "zero-friction" action. The spool holder was designed in Moi3D, which is a great CSG modeler although it does cost some money. For those of you who have or want to try out Moi3D, I've included the 3DM file here. Instructions Print all three parts: Main, Upper, and Top. I printed these in ABS and PLA (the photos show PLA) at a 0.3mm layer height, and Support isn't needed. Assemble by attaching the main part to the PrintrBot bars with the filament guide facing forward and left. Put the marbles into the bearing - eleven 16mm ones fit well for me - then add the Upper bearing cover with the cone facing upward. Mount your spool on top - the filament must unwind counterclockwise when viewed from above, or else the screw will tighten up and lock up the movement. Attach the Top part and leave it barely tightened to allow the spool to rotate freely.