This is an update (v2) for the Sunlu S1 dryer filament spool roller smooth mod v1 (<link>). The SUNLU S1 dryer is a nice little tool. However, spools inside do not rotate freely and I had sporadic print fails due to the spool being stuck, specially with small spools and cardboard spools when the filament is running out. The v1 version was rolling so smooth that if not properly centered the spool could roll backwards when full.

This mod solves all the above problems and as it keeps the spool secure and able to roll and provide filament even when full or with almost empty cardboard spools with very low weight. It is completely reversible and you do not need to modify anything of the dryer.

Origins

This mod stands in the shoulder of giants, as it is adapted/inspired from other mods to the S1 and S2 dryers:

• SUNLU S2 Dryer Spool Mod - Thin/Wider spool, larger hole sizes - Sensor free by Flx_Mark.
• Sunlu S1 filament roller and binding fix by luma.
• SUNLU Dryer S2 Mod by Kim, Kyoung-Joong.
• Creality (Ender 3) Filament holder 80mm spools by mjoaris.

Many thanks to them for their work and contribution.

Alternatives

This mod comes in three alternatives. Use whatever you like, they work equally well:

1. Use the original bearing that comes with the Sunlu Dryer. In this case, use the provided profile “Original bearings".
2. Use two 608zz bearings. In this case, use the provided profile "608zz bearings".
3. Use two 624zz bearings. In this case, use the provided profile “624zz bearings”.

IMPORTANT: As it goes inside the dryer when hot. Use PETG, ASA or ABS for all the parts (avoid PLA).

Assembly Instructions

Assembly is straightforward. First of all assembly the pillars in the sunlu dryer:

1. First you need to remove the original axis and bearings at the bottom of the dryer. You do not need any special tools. Just force them a little up into the foam and they will go out:

2. Attach the two pillars printed parts vertically where the bearings used to sit. You need to force a little the printed part to fit in. You will hear a click when the printed part is properly inserted. If properly inserted, you will notice that the part really stays upward by itself.

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Now depending on the alternative that you have chosen:

3a. If you use the original bearings, just pass the spool through the bearing and put the bearing sitting on the vertical pillars. You only need one axis/bearing from the two that you just remove so keep the other one in a safe place.

3b. If you use the 608zz or the 624zz bearings, glue the axis and the axis_final part together (they are separated so it can be printed without support). And then attach the two bearings at the end. You can now rest it on top of the pillars.

4. Just rest the spool on top and close the door of the dryer.

Disclaimer/Drawbacks

This mod works very well for me and I am happy to share so it might help others. Let me know if there is a problem and I will try to correct it in updates. I have only tried “standard” spools of 1kg and small ones of 250gr. Big spools might not fit, and the distance between the sides of the dryer is reduced. You may fit filament spools of 75mm maximum, I would say. As always, take care with the dryer, this mod is completely reversible and you can go back as long as you don't break anything in the process.