Sunlu S4 Dryer - Secure Spool Stand (Anti-Slip)

I own a SUNLU Filament Dryer S4 and while it's great it has a known flaw. When a spool gets light or is half-empty it tends to jump off the original track and block itself. This risks failing the print and is just generally frustrating.

I designed this spool organizer and stand to prevent spools from getting off-axis. It keeps the spool secure so it can't jump or block itself, even when it's running low.

The design features supports on the sides and a blocker on top to keep the "spool pipe" (the axle) inside. The supports are wide enough to ensure the spool doesn't jump on top of them while rotating.

This model uses 688zz bearings for smooth rotation.

• 1 Spool: 4 bearings

• 2 Spools (one half of dryer): 8 bearings

• 4 Spools (full dryer): 16 bearings

I didn't use the original bearings from the Sunlu S4 because they were too small for the mechanism I wanted.

• Bearings I used: 688zz Bearings (AliExpress)

No Bearings? No Problem :)

If you don't have the bearings yet, you can still print the "spool pipe" and use it as-is. It will slide well on the plastic (just with a bit more friction), but it's a perfectly functional temporary solution while you wait for hardware to arrive.

Print Settings and Materials

• Material: You must use heat-resistant filament. The dryer gets hot and PLA will deform.

  • I used Overture ABS White.

  • Filament Link: Overture ABS (Amazon Canada)

• Infill: I printed with 15% infill, which is strong enough for ABS.

• Profile: I used a 0.25mm Balanced profile on my Prusa CoreOne, but standard 0.20mm settings should work fine too.

Optional Parts

1. 4-Spool Setup: If you are filling the dryer, print the "bases connector" (you'll need 3 of them). This connects the two platforms so they don't move around or hit each other inside the dryer.

2. Sag Prevention: Depending on your filament type, the base might sag slightly in the middle. I designed a "base bottom support" that clicks into the place where the original dryer bearings used to be. It acts as a "ground" for the base and keeps everything level.