Master Spool

Caution: does not work with eSun filament refill.

What you'll need:

• approx. 200g of filament
• 1x M3x20 socket head screw (used for installation only, optional if you have a dialed printer or are very strong but still highly recommended)
• 12x M3 nuts
• 12x M3x12 socket head screws (minimum length to reliably engage nut, up to M3x20 possible)
• Hex key that fits your screws

Assembly guide:

Print one core and two sides (0.2mm layer height required for core and recommended for sides, 10% cubic infill recommended for all parts).

Take the core, the M3x20 screw and the nuts. Push the bolt into one of the holes until there are enough threads exposed in the center of the core to thread on one of the nuts. 

Thread on the nut and tighten it with your finger until it is touching the hexagonal hole and you can't get it any tighter by hand. Align the nut with the hole, take the hex key and start tightening the bolt. Once the nut bottoms out, remove the screw and repeat for other holes.

Tightening the bolt may leave a mark on the core. As long as there are no cracks, delaminations or big dents, the core is completely fine and usable. If you wish to avoid these marks, you may need to use a washer during the installation step.

You can now screw the sides and core together. You can use as few as 2 screws per side, but at least 3 are recommended.

Refill instructions:

Unscrew one of the sides from your spool. Take your refill spool. Thread the inner tail of the filament through one of the hexagonal holes and fold it over to lock it in. Drop the refill onto the core. Screw the side you took off back on. Remove the zip-ties/plastic holding your filament together. Thread the loose end through the holes at the edge of the spool.

Enjoy the spool!

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