Spool roller with brake

This system is intended to automatically roll a spool of filament.
If you want to use a motor it is difficult to program the right rotation speed to roll you spool as the effective diameter of the spool will change as the filament is rolled. This design includes a brake to allow the spool to not turn if the tension on the filament is to high.
The system is designed for an M8 threaded rod and nuts, two ball bearings and M3 bolts with 3D printer bed holder springs.
The spool holder part is compatible with 50 to 55 mm hole diameter.

Look here to see this design at work:
https://www.youtube.com/watch?v=0awgUET8cA0