Prusa CORE One Bearing Spool Holder

🛠 Core One Bearing Spool Holder – Assembly Instructions

Parts Required:

2x 608 bearings

1x M8 bolt (recommended: 80mm length no cutting required, if longer then cut to fit) 
👉 Example bolt

2x M8 nuts an optional third M8 nut can be added and tightened against the second nut, effectively acting as a lock nut. 

Spacer (adjusted to nut thickness – see step 4)

Hacksaw (for trimming bolt)

4x screws (to mount the holder to the printer)

Assembly Steps:

1.Prepare the Centre Piece

Remove any support material.

Push one 608 bearing into each side of the center part.

2. Mount the Bolt into the Base

Screw the M8 bolt into the base until it stops.

Use two nuts locked together on the thread to grip and turn the bolt until the head sits flush or recessed in the base.

3. Secure the Bolt

Thread a single M8 nut down to the base and tighten it firmly.

4. Add the First Spacer

Place a spacer on next.

Spacer length = 9mm – thickness of the nut (e.g., if nut is 6mm thick, use a 3mm spacer).

5. Install the Centre with Bearings

Slide the assembled center piece onto the threaded bolt.

Add another spacer and then a nut.

6. Mark and Cut the Bolt

Mark the bolt at the point where the thread is protruding from the final nut by around 10mm.

Remove the nut, spacer, and center.

Cut the bolt at the mark using a hacksaw.

7. Reassemble

Reinstall everything in the same order.

Do not fully tighten the final nut yet.

8. Mount to Printer

Attach the spool holder base to the printer using the 4 screws.

9. Adjust Tension

Tighten the final nut until the spool spins smoothly but has resistance so it does not spin freely.

10. Finish Up

Press the center cap into place. (Removal of center cap I use double sided tape and attach it to something hard and flat and use that to pull the cap off)