Spool holder with ball bearings

I made this spool holder to print TPU. The problem I had was that traditional spool holders stretch the TPU filament due to friction. As the result, the extruder extrudes less filament volume per linear unit. Even worse, the stretching varies and with it the extrusion coefficient.

This spool holder uses 609 bearings and has minimal friction. I suppose it can also be useful to print brittle filaments with carbon or glass fibers.

The holder is designed to mount on Ender 3, but can also be mounted on other mounting hardware.

609 ball bearings: https://www.amazon.com/dp/B07XVPGMXQ?ref_=ppx_hzsearch_conn_dt_b_fed_asin_title_6&th=1

Reality filament bracket (if you want to use the same mount as I did): https://www.amazon.com/dp/B08XQGWXKP?ref=ppx_yo2ov_dt_b_fed_asin_title

Also you will need 5/16" x 3.5" (or M8 x 10mm) screw, one normal nut (goes inside of part 3), one wing nut, and one washer. See the pictures for the assembly.

The 609 ball bearings are hold by spring-like tongs. Use non-brittle filament. PLA is fine. Not sure if filaments with high percentage of carbon or glass fibers would work.

I used 0.4 mm nozzle. I used 5 walls (maybe an overkill).

The two halves of the holder are screwed around the filament spool. First time it may be difficult to screw in, but it will be easier after screwing in and out a few times.

To make the holder compatible with different sizes of the filament spool hole, the center part is made narrow. When fixing the spool, try to center it before tightening.