Universal Spool Hub 51-55mm

This ball bearing spool hub sit on a 5/16 inch metal hex bolts, at least 4 inches long. This one is universally sized and the sides are slightly slanted so it can fit hubs from 51-55 mmi n diameter, which matches many widths of popular hubs such as Polymaker, Bambu, Inland, Sunlu, etc.

Fits the original Prusa MMU3 spool bearings (22mm outer diameter, 7mm thick and an 8mm center hole.)

Print instructions:

• .25mm structural settings

• Use PETG or PLA+

• 3 perimeter walls

• 25% infill

• Organic supports (easier to remove) (note V2 doesn't need supports)

Parts Needed

4 inch long 5/16 inch metal bolt goes through a half inch thick wooden board (drill a 5/16 hole). On the other side of the board in this order use:

1. 5/16 inch metal washer

2. 5/16 metal nut

3. printed spoolhub with bearing pushed in with bearing side facing the nut above

4. spool

5. printed spoolhub with bearing pushed in with bearing side facing the end of the bolt

6. 5/16 metal nut

I use these in my buffer and spool system for the MMU3 where you can get the PTFE PC4-M10 Bracket you see above the spools, both left and right oriented. 

New Version 2  - No Supports Needed

I recommend taking the effort to make the main version as that one ensures the bearings cannot get out of position as they are held in place by the nuts, but if you like V2 and don't want to deal with supports you might prefer v2.

Version 2 doesn't need supports but you need to push the bearing past a ridge that you need to slightly sand down. Do not sand it down too much though as it needs to lock the bearing in place once inserted. However, The last four photos are of V2 and it works fine as long as you use force to get it past the ridge at the top of the opening.