Minimal Material Dry Box/Cereal Box Spool Holder

Design Benefits:

This design uses a center roller for the filament spool, compared to most other dry box designs that use 2 bottom rollers to hold the outer edge of the spool.

This design has several advantages:

• Less friction, useful for TPU.

• Works with different spool sizes

• Works better with cardboard spools.

• Significantly less filament use

Compatibility:

Cereal Box:

There are two models of the most common cereal boxes: ones with 3 shallow grooves (as shown in picture), and ones with 1 deep groove.

The 3-groove version is better because the inner dimension is wider. From my testing, the version with 1 deep groove doesn't quite fit Bambu spools (55mm wide).

They are probably available on your local Amazon, make sure you have the right version.

Filament Spool:

Compatible with almost all 0.5/0.75/1kg spools, cardboard or plastic.

Tested with:

• Bambulab (1kg plastic)

• Eryone (1kg cardboard)

• Overture (1kg cardboard)

• Elegoo (1kg cardboard)

(If you have different brand spools, please let me know if they work, so I can expand this list for more people to see.)

Assembly & Usage Guide:

Print settings:

• Any rigid filament works. PLA or ABS recommended (non-hygroscopic).

• print the spool roller with support. You can use thick layers to save time and it won't matter.

• print the hex shaft with at least 1.2mm walls for strength.

BOM:

• 2x 608 bearings (printed ones also work)

• 8x M3x6mm screws

Tools:

• 3mm or 1/8" drill bit (optionally glue)

Assembly of Roller:

1. insert 608 bearings into both sides of the roller. (there are crush ribs, so this should be a press fit.

2. insert hex shaft through both bearings

3. press the hex locking rings on both ends of the hex shaft. This should be a press fit. Make sure they are fully seated so there's no axial play between the roller and shaft

assembled roller:

Assembly of Wall Mount pieces (requires drilling the box):

1. Take off the lid of the box. Use a ruler to mark the horizontal center of the two walls with a marker. (roughly 105mm from either end)

2. Use the printed drill guide to align the notch with the center mark, and mark the 4 hole locations on each side of the wall.

3. drill the 4 holes. (you can use a slightly larger drill bit like 4mm to allow for some misalignment)

4. use the M3x6 screws to mount the two wall pieces. Optionally if you don't want to drill, you can glue the pieces to the box. (I tested with hot glue)

assembled side wall mount:

Usage:

To put the spool in, first put the roller through the hole in the spool, then drop the spool into the box, making sure to align the roller with the locking pieces on the wall.

Top view of roller locking in place

Related Accessories:

To feed the filament to the printer, I drill a 6mm hole on the front/top of the box and use this PC4-M6 coupler adapter