MMU3 / MMU2S 5 Spools auto rewinder adapter for (un)original Prusa drybox / Repbox
5 Spools rewinder adapter for MMU2S / MMU3 in (un)original Prusa drybox or Repbox. Could be used without drybox
615
1859
100
15 k
updated February 3, 2025
I have a MK4 and recently got the MMU3, yet to be assembled. In addition I am in the process of building the (un)original drybox including the heating mod. Hence, I am scouting for potential upgrades and modifications and found this interesting design.
As far as I can tell, the original auto rewind design has fixed connection between the barrel and the spool and an adjustable clutch to control the slip.
( https://www.printables.com/model/168-universal-auto-rewind-spool-holder-mm)
What worries me about the mod proposed here, from an engineer's view, is that, as far as I understand it, the slip occurs between the barrel and the spool. So I am worried that the slip (and therefore the tension of the springs) is affected by
* the roughness of the barrel
* the material and design of the spool (plastic, cardboard, solid or hollow inside)
* the weight of the spool (different sizes, full vs. close to empty)
* spring tension affected by temperature
Don't get me wrong, I have not yet build it. So these are only hypothetical issues, which crossed my mind when scouting for modifications.
* Can anyone comment on the performance of this design regarding the above mentioned point?
* Does anyone have this mod in action with the heated drybox and is willing to share their experience?
@maximweb_1466211
Hi, I can answer some of your questions.
About the heater, that work with according to the feedback but print the spring with a kind of plastics like ASA or ABS.
For your worry about that the spool slip around the barrel you are right but it's not an issue but the normal functioning of the rewinder. When the spring is full charged the spool start to turn around the barrel like that we can't brake the spring system. Even with light spool ( almost empty) the system works.
I use it since the release of the MMU3 and I have never experienced issues.
I have learn a lot with my mmu2 before.
Some advice :
- use PTFE tubes 2,5/4 mm
- avoid to bend to much PTFE tubes
- find the shorter way for the PTFE tubes.
Understand in this statements that the frictions between the filament and the guide tube is the more common problems that people encounter. If you have a good setup at the start you never experiment any trouble.
Have a good print
Don't hesitate if you have some other questions 😉
@Sanka @maximweb_1466211 Not to necro a response, but I HAVE ran into a few spools with thicker cardboard, that DO actually have issues with the winder, in that it produces too much friction. Once the winder reaches the end of the springs, it WILL lead to jams, due to the spool being no longer turning freely.
SunLu Elite PETG, for example, has a VERY thick cardboard spool, and it often binds.
Might look into some inserts for the spools, so there's less friction, so the spools DO freely spin, still, after the winder reaches the end of the spring.