Qidi Box jam resistant filament guide

I found that my new Qidi Box was prone to jamming when changing filaments.  The jams consistently occurred when the filamant was about mid-way through the 4-into-1 manifold in the filament hub.  After some experimentation, I discovered that a solution was to ensure that the bowden tubes leading into this hub were straight, so the filament ends within each bowden tube were positioned for storage without a curve in them.  The straightened filament ends pass through the hub and load into the extruder very consistently without jams and errors.

This modification adds long bowden tube supports to ensure the filament path into the filament hub is straight.  The modification also includes a new hub enclosure that aligns and centers the bowden tube supports relative to the manifold.

The design is a little crude, but worked perfectly on the first try, so I probably won't bother refining it.

I used ABS for the prototype, but I believe PLA would work fine.  The prints were successful using standard speeds and temperatures for ABS, .4mm nozzle, .2mm layer height, and the textured PEI plate without adhesive.  I set the infill to 30% and used 5 wall loops.

I also bypassed the filament tangle sensor by replacing the bowden tubes going into and out of that sensor with a single long bowden tube (purchased on Amazon and trimmed to length) that connects to the hub on one end and the extruder on the other.  There was enough of a gap between the tangle sensor and the printer enclosure that I was able to route the bowden tube into the enclosure without modifying or disassembling anything.

I have completed numerous multi-color prints in ABS since making these mods, and through hundreds of color changes, I have not had a single filament misfeed.

To implement the mod, do the following:

Print 1 each of the Manifold Enclosure Inner and Outer halves.

Print 4 of the Bowden Tube Support Long.

Unplug the sensor cable from the manifold

Remove the hub from the back of the printer cabinet.  Leave all bowden tubes connected.

Remove the hub from the mounting arm by removing 4 screws.  Note that two screws of the plastic box are hidden behind the decal.  Keep the screws for reuse with the new parts.

Disassemble the plastic hub enclosure by removing 4 more screws located on the rear face.  Remove the manifold module and the exit bowden tube (with the quick connector still on the bowden tube).

Install the 4 Bowden Tube Support Long pieces on the 4 infeed bowden tubes, with the first support installed as close to the manifold as possible.  Optionally, insert a 1/8 inch or 3mm rod into the stack of supports to provide additional rigidity.

Install the Manifold Enclosure Inner Half (the side with the 4 tall posts) to the mounting arm using 4 of the screws.

Place the manifold and exit bowden tube with quick connector into the Manifold Enclosure Inner Half.

Install the Manifold Enclosure Outer half and secure using the remaining screws.

Mount the assembly back on the printer.

Use zip ties as necessary to tidy up the installation.