Polydryer Auto-Rewinder - Complete Solution

I wanted an auto-rewinder for my Polydryer boxes and while all the pieces and parts existed to make it work exactly the way I wanted, it was scattered across numerous uploads, chains of remixes, etc. This is largely a compilation of parts, with a couple minor tweaks, to make a complete working system as a 1-stop download for others that want to do the same.

If you're looking to also add more desiccant to your polydryer boxes, check out my Polydryer In-Lid Desiccant Container which is compatible with the auto-rewinder for at least all the spools I have on hand.

Important Note:

• Ensure you print this with filament that has similar or higher melting temperatures than the filament you will be drying. 

  • If you print this in PLA, but are drying ABS, you will end up melting the re-winder.

Preperation:

Bill of Materials:

A few additional non-printed pieces are needed for the auto-rewinder to function

• 4x 608 Bearing

  • Any standard 608 bearing should work perfectly fine. I've used these ones specifically in the past. They're not particularly good bearings, but they're cheap and work well enough for this specific use-case.

• 1x Flat Coil Spring from a Badge Reel

  • I've used both this badge reel from Amazon as well as this much cheaper option from AliExpress depending on how quickly I needed them

  • If you want to try and source the spring directly, the dimensions are 4mm x 550mm x 0.1mm (LxWxD)

    • Realistically anything between 500-600mm, potentially even a little longer should work

    • I've not found anywhere to source the springs directly myself, if you find one, please let me know

Tools:

While tools generally aren't required a few things may make your life easier

• A pair of needle-nose pliers can help in manipulating and bending the spring

• A screwdriver may be needed to disassemble the badge reel depending on which exact model you get.

Assembly:

1. Slide a bearing onto longer segment of the axle until it reaches the stop

   

2. Insert the notched end of your badge real spring into the spring holder as shown, then rotate it 90° so the notches lock it into place

   

   

3. Coil the spring into the inside of the spring holder leaving an inch or so loose, then slide the assembly onto the axle and bearing

   

   

4. Insert the loose end of the spring through the slot in the axle and then make a bend in the loose end so it can be pulled back through. You may need needle nose pliers to assist you with straitening and bending the spring.

   

   

5. Insert the spring cover onto the axle, notched side first, alight the notches in the cover with with ridges in the spring holder and clip it into place

   

6. Slide another bearing down the axle and it should seat into the spring cover

   

7. Slide one of the C-Clips down the axle to lock the bearing into place

   

   

8. Insert the dial into the clutch as shown

   

9. Slide this assembly down the axle and over the spring module you assembled until it comes to a rest

   

10. Rotate the dial and clutch to tighten them. If you are having difficulty tightening it by hand, you can use the included dial wrench for the dial, and the backside of the bolt can be used as a handle for the clutch.
    Be aware that depending on your print settings, filament, etc, it can be possible to over-tighten the clutch. In the case you have over-tightened it's possible the spring holder or spring may break. You need to find the right balance of making it tight enough that you get an adequate number of rewind rotations without being so tight that things break.

    

    After tightening, it should look something like the below, but yours may need to be in a slightly different position based on your filament and needs

    

11. Insert the entire assembly you've made into the open end of the bolt

    

12. Insert the outer bearing holder into the remaining space of the bolt, then insert a bearing, and lock it into place with another one of the C-Clips

    

    

    

13. Insert one more bearing into the other end of the bolt, and lock it into place with the remaining C-Clip

    

    

14. Insert the bolt into your spool and secure it with the nut. Make sure the arrows on the bolt and nut are facing the direction the spool will spin as it dispenses filament

    

    

15. Add the polydryer adapters to each end of the axle, making sure to line up the indents in the adapter with the C-Clips on the ends of the axle

    

    

16. Slide the spool into the polydryer box. The open end of the notch in the adapters needs to be facing down, and the notch will rest on the ridges built into the box

    

    

17. Pull the filament out through one of the ports in the polydryer box, insert the loose end of the filament into the plug, then insert the plug into the port

    

    

    

Acknowledgements:

• The vast majority of the parts included on this are from @rans_1668459's  Stronger Compact Spool Auto-Rewinder

  • This itself is based on @OleksiiMoroz_538346's Compact Spool Auto-Rewinder

• A modified version of the axle, as well as the adapters to interface with the polydryer are from @DrinkyCrow_3210453's Polydryer Adapter

• I remixed the spring holder myself, but my version is largely inspired by two other modified spring holders, I just combined both idea's into a single spring holder

  • Removed 1 hole to make it single direction like @Wolftousen_3585401's version in Single Direction Bolt

  • Made some various walls thicker like in @electrodraco_3135885's Stronger spring holder for compact spool auto-rewinder

• Also uses @Wolftousen_3585401's single direction bolt and nut from Single Direction Bolt

• @ParasitKegel's Polydryer Filament Holding Drybox Plug is used to stop the rewinder from completely sucking in the filament and ensure it's still easy to access and pull out when needed

• The Dial Wrench that can be used to assist with assembly comes from @Name_Too_Long_495397

Version History

• 1.1.0 - 2026-07-06

  • Modified the mounting bracket from @DrinkyCrow_3210453's Polydryer Adapter so that spools now sit 4mm lower. This improves spool compatibility when also using my Polydryer In-Lid Desiccant Container

• 1.0.0 - 2026-07-05

  • Initial Upload