I designed these spool weight adaptors to fit inside the CFS units to add weight. I found I was getting a lot of retraction and feed errors and after trying almost everything, I made a prototype after reading that other people had found success adding weight to the spools.

I already have the CFS lid bumpers to help keep smaller spools in place (like Sunlu, Jayo, etc), but it wasn't enough. I have to say that since adding these, I've had no errors at all - which could be pure coincidence!

I've added odd nuts and bolts to the insides of mine, which now each weigh circa 300g. The cap simply glues in place with superglue once you've added your weight. I also thought about adding sand as an alternative, but haven't tried it yet.

I've tried to design them to fit multiple spool brands as they all seem to have different centre bore openings. The smallest I have is creality and elegoo cardboard (52mm) and the largest I have are Sunlu and Jayo (74mm).

I've used PLA+ and have added the correct tolerances so the threads work very easily.

My settings are:

Max volumetric speed 14mm3/s

220c nozzle

60c bed

15% gyroid infill

3 walls

4 top layers

4 bottom layers

Normal snug supports - top z distance 0.22

Support blocker on the knurled retaining nut outer profile (Torus in cp6.xx)

Filament spool weights

0.2mm layer, 2 walls, 15% infill