Simple^2 Anti-Tension Customizable Spool Holder for Printrbot Simple Metal 1403

thingiverse

Using other z-rod-mounted filament spool holders, I discovered that they created excessive tension on the filament when employing fast retraction. The ones attempting to resolve this issue relied either on metal bearings or overly complex (and large) solutions. Not finding a suitable one that I liked, I designed my own in OpenSCAD. The design allows the filament guide arm to flex during resume from fast retract, rather than having the full tension of the retract spinning the mass of the entire spool. In testing, it functions exceptionally well and also minimizes overall filament tension by pulling from the spool more orthogonal to the spin moment and normal force. There are a few other touches like an inverted cone over z-rod allowing for smoother pivoting, yet keeping as simple and minimalistic design as possible. A demonstration of retract flex is available here: http://www.youtube.com/watch?v=JVb58lKCKzM. To replicate the print settings used in this project, I sliced it using Cura with 4 shells and 6.8% infill (tweaked in Cura's layers view to achieve single-truss internal supports). If you prefer printing a smaller arm to accommodate spools such as Taulman's, etc., it is advisable to download the scad source and compile it in OpenSCAD instead of using Customizer. There are detailed comments in the SCAD file providing additional explanations. I recommend utilizing the printOnlyZrodBearing parameter to print just the z-rod bearing surface for calibration before printing the entire design. The 45-degree arm offset at the end poses almost an overhang torture test. It is suggested that you print a large 150mm tall cylinder adjacent to it in order to extend cooling time of the arm. Alternatively, consider printing without the guideHole and drilling it afterward; however, have it your way if you prefer the challenge! Good luck! A timelapse of the print can be found here: https://www.youtube.com/watch?v=mncNZO2ifYY.