A simple solution to solving the filament spool drag on the rear spool holder. Great for printing with TPU or cardboard spools as this reduces the strain on the extruder.

UPDATE: I have tweaked the model dimensions of the roller to allow for some more tolerance with different spool holders. Some people reported it not fitting. These have been added as v2 parts. The originals are still there for people who liked the tighter fit.

3 parts to print:

1. Thin spacer which inverts the keying of the rear spool holder allowing you to bolt it in upside down. Uses exactly the same bolts as are currently fitted, no need to find extras.
2. The cradle which rests in the now upside down spool holder.
3. The spindle which is designed to combine with 2x standard 608 bearings and then rests in the cradle.

Extra parts needed:

2x 608 bearings (22x7mm w 8mm hole)

It's been designed so the spindle is a few mm smaller than the bearings which provide a stop point so your filament roll won't make a run for it. Due to the space the bearings take up, it will only fit spools up to 72mm in width.