Pimp My Prusa

January 19, 2019

This Filament Guide and Spool Enclosure is my submission to the Pimp My Prusa design competition. It gets the filament spool off the top of the printer frame and provides a bit of humidity protection if you leave your filament loaded for a few days. It consists of the following three main assemblies.

  • PTFE Tube Guide. The PTFE tube guide consists of a Guide Bracket, which snap fits into the MK3’s z-axis-top part hexagonal opening and extends a threaded opening over the build plate. The opening accommodates the PTFE Tube Lock, which is a slotted, tapered tube through which the PTFE guide tube is passed. An integrated thumb screw provides the means to adjust the locking force preventing axial movement of the PTFE tube. The PTFE tube terminates at the Threaded Filament Sensor Cover, which accommodates a PC4-M6 push fitting to lock the PTFE tube to the filament sensor cover. The push fitting and 77 cm length of PTFE tube are the only non-printed components required.
  • Spool Case. This 3D printed enclosed spool holder is assembled from a foldable Hex Panel component with “permanent” snap-fit joinery. Assembly is nearly toolless (pliers are likely required to snap some of the joints together unless you have fantastic finger strength). The two case halves are finished with a set of Rails and Stiles. The rails feature a light, snap-fit closure between the two case halves and the lower set of rails also provides an integrated spool axle cradle. In order to allow the filament to pass through the case, a Hex Panel Port receives a snap-fit, threaded Tube Flange through which another adjustable PTFE Tube Lock is installed. Finally, there is a Gel Cover and associated Plug that allows loose silica gel desiccant to be contained in a hex panel. Though not air-tight, the fit of the case parts is close enough to allow silica gel to maintain an internal humidity lower than than the external environment for at least a couple days.
  • Spool Hub. Also fully 3D printed, the adjustable axle assembly accommodates various filament spool widths with two threaded Spool Flanges, each of which incorporates a print-in-place gear bearing. The Spring Axle, which is printed in vase mode, has an integrated spring design to reduce axial movement of the spool flanges. The assembly nominally handles filament spools with through-hole diameters of 48 to 75 mm and widths from 40 to 70 mm, but is dependent on a spool’s specific combination of hole diameter and width.

All the stl files are available for free at MyMiniFactory. I’ll be posting more on the design details of these components, but for now this quick video shows how the Spool Case and Axle work together.

William Dutcher  


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