Drybox filament spool holder (no ball bearings needed)

For this filament spool holder, I wanted to avoid using ball bearings because I did not have any at home. Honestly, using bearings for this purpose would also be a bit of overkill. Another goal was to fit the widest possible spools. In this box, that maximum width is about 70 mm.

This spool holder was designed for this box from Amazon:
https://www.amazon.de/dp/B0C1N9C3T7/ref=cm_sw_r_as_gl_apa_gl_i_YVFM1DQNNPM62AJ2PH2J?linkCode=ml1&tag=valrc07-21&linkId=619ef14718f123c92c7843d8171b6645&th=1
However, it may also fit other boxes. There are many similar listings for this type of box, and it would not be surprising if some of them are actually the exact same product sold under different names.

Instead of bearings, I used small nails as axles. Because the contact surface is very small, friction is minimal and the rollers work perfectly.

To fit wide filament spools, one roller is placed on top of two others. This allows the top roller to use the maximum width available inside the box. The other corner of the box is slightly wider, so a roll can be mounted there normally.

Assembly
You will need:

• 6 nails (diameter about 1 mm, length about 13 mm)

• 1 box (from Amazon)

Print the base plate and the rollers. Make sure to print them one at a time to avoid shrink lines. In PrusaSlicer, use sequential printing. For a smoother surface, I recommend using a scarf seam on all rollers, but not on the base plate.

Cut off the head of each nail and lightly sand the cut ends. Insert a nail into the hole of a roller and gently tap it in with a hammer. Leave about 3 mm sticking out so it can act as an axle. Repeat this for all holes.

Snap the rollers into place. Note that the two small rollers are not the same length. Finally, place the last roller on top of the two small ones.

When installing the PTFE tube, make sure the spool rotates in the correct direction. It should turn so that the loose roller is pulled under the spool rather than pushed away from it (look at picture 5). For this purpose, I specifically designed a guard that prevents the roller from falling out. However, even with this guard, it is still better to use the rotation direction where the roller is pulled underneath.