Gear bearing, customized as an Prusa Mk3 spool holder improvement.
This parts fits on the 2018/2019 T-shape spool holders from Prusa Mk3 (for two spools).
Printing this so that the gear bearing has less friction ratio than the spool directly on the bar is difficult. So far the bearing seems to be a tiny bit better.
While the extruder motor does not care about the difference,
those two problems can be reduced.
1. Swivelling of the spool, which is caused by small alternating movements of the filament, when the spool does not advance, but keeps the same contact point due to static friction.
2. Filament on the spool builing 'knots' due to chaotic winded filament on the spool (Prusament does not have this issue, but some cheap ones do). In theory, less force on the filament for rotation should mean less force tightening those knots.
I got the original gear bearing from here: https://www.thingiverse.com/thing:53451