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VincentGroenhuis

Universal Auto-Rewind Spool Holder

by VincentGroenhuis Jan 6, 2019
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Is there a dual extrusion version so I can generate my own MMU GCODE? I want to print dual color in an MMU printer that actually works reliably, my trusty MMU 1.0. For the life of me I cannot comprehend how the 2.0 was released as the 1.0 works so well with everything except for flex materials and the 2.0 version doesn't even work with the simplest materials like PLA.

@vincent, would you be open to make a couple of screw holes in the base of the model and rotate the mount ing hole for the hub 90 degrees like attached images. i can make the holes, just the rotating i cant get worked out.

There are several wall-mounted holders for this rewinder, what is wrong with them?

I like this one more stengt and shape and it's dutch

Would be a lot of work for me. Best if you do it yourself using the STEP files.

I've printed several of the v1.0 (or around there) designs from the .3mf full plate, and some of them work correctly and some don't. The ones that don't work seem like the spring works backwards... when loading filament forward, the spool keeps spinning forward so extra filament leaps off the spool, and on retracts, they barely rewind. I've tried every clutch setting from 1 to 15 with no difference. I'm sure they're assembled correctly, as the spring only fits one way on the 1.0 design. Any idea why and how to fix it? Are the springs broken? Can I just replace the springs with the new v3 ones? Thanks.

The v3.3 version is definitely an improvement over v1.0 and also backwards compatible. I recommend printing a new spring, clutch, dial and axle, and closely watch the video to test the characteristics. Let me know if you still have issues getting it work correctly.

Thank you very much, here are some pictures of the prototype for a 90 mm wide spool, I was going to just make 5 of these for the MMU but they do not fit very well under the lack table so I was thinking 2 90mm wide ones for the rear and 3 narrower ones at the front (esun 1kg spool is only 60mm wide and a 750g spool is only 55mm)
its been a labour of love, need to rethink the front catch, but overall I'm happy with the box and quick release

Hi Vincent, I love your work, any chance you could do me a step file with a 60mm long hub instead of a the standard 90mm one that is in the step file, so I can add it to my smaller dry box I am designing.. I tried to duplicate the hub but can not find the thread

Thanks

Sure. Attached a STEP file of a 60 mm hub. Good luck with your drybox!

Dear Sir,
thanks for your magnificent work.
It is possible to find a wider stand with longer shaft? The original it does't fit the Prusa spools (not prusament) because it's 87.5mm wide and it touchs the stand.
thanks

The default stand was designed to fit 87.5 mm wide spools. I have some of these as well. Use exactly one curved nut and it should fit, no second nut is needed. If it does not fit then please measure the inner diameter of the spool and take a picture so that we can see what goes wrong and how to fix it.

I've tried half a dozen prints of the version 3.3 soft spring and have yet to get a print that actually separates as pictured in the video, is there some secret for getting it to print right? I'm using a mk3s and settings that have been durable and dimensionally accurate in the past, with 0.2mm layer height and PETG filament, I can see the gap in the model on the slicer, but the spring is pretty stuck to the bottom plate and the hub is entirely fused to it.

You are not the only one, there are many comments about too much too little adhesion of those interface layers. In general, try: a) different filament type (e.g. PLA), b) lower temp, c) higher speed, d) more cooling fan, e) disable Z hop on retract, f) start with a different profile, etc. Also note that the bottom half of the hub is to remain fused to the bottom plate, only the top half breaks free. Good luck!!

I appreciate the tips. Several tries later I managed to get two springs to print fine and breakaway as expected, here's what I did to fix it:
Switched from my own slower print settings to PrusaSlicer's 0.20mm Fast settings
Raised my print fan base and bridge speed by about 35%
Lowered my nozzle temperature just a few degrees

From the couple of experiments I did before getting the good print, I think the biggest difference was speed settings.

what type of filament should I use for the spring? I think PLA is too brittle for its application

I use PLA and PETG, both work fine. Just experiment. Good luck!!

I seem to be having a really hard time printing the dual spring... I had to turn off the part cooling fan for the first layer of the bottom spring and the first layer of the top spring to get it to work. I'm not a big fan of having to babysit the print. I've tried the 0.1mm version... increasing extrusion multiplier, increasing the flow rate, etc...

I'm honestly not sure what I have to do in order to get it to print correctly without babysitting it. Anyone else having this problem? Is there a version that does not have the dual spring? I have everything printed buy this specific piece for 2 more spools so it kind of stinks that I can't seem to get it to print to finish my setup.

Try the 0.1 gap version of the spring, printing at 0.1 mm layer height. If this doesn't work either then print the classic v1.01 version which does not have gaps at all.

one other question. On the 3.3 is the center of the spring supposed to break free from the bottom plate? in the few that i've got to print half of the spring (where it fails when trying to print the top spring) I can't get that center collar to break free. It ends up breaking the bottom plate.

Just so you know, I am running the version of the spring that has the top half and bottom half running in different directions. So, I've been able to print a similar spring in the past, not sure exactly what has changed to be honest... it's wierd. Unfortunately, I no longer have that STL file to try and print it.

No, it is not supposed to break free. The video explains it well, also check the post-printing pictures.
You probably refer to one of the experimental v1.02 springs. These designs are still available in a zip file. Hope this helps!

Ah I see... just the top half of that hub breaks free. I didn't pay close enough attention to that video to see that.

yea, that didn't work either. I'll go back to the 1.01 spring. I may also try to add a modifier in the middle of the print that shuts off the fan... if I can figure that out in PrusaSlicer.

Also try increasing extrusion temperature and lowering speed. Switching to a different type of filament could also help (PLA or PETG).
You are not the only one with gap layer adhesion issues. On the other hand, there are also users having trouble separating the gaps for being fused too tightly. It is hard to come up with a design which solves both issues, so I leave it as it is now.

You could just turn off the fan during the entire spring print.

I'll give that a try too.

So, i printed off the "Screw-down tabletop, wall, and ceiling mounted axle stands" and was starting to do a test fit and realised that one end of the axle is squared and doesnt fit into the slot on the holder. Do you have another version of the axle that's rounded to that it will fit in that specific mount?

That's specifically why I made my version, it is the second one on the list.
Edit: Sorry, thought you were having a different problem.

You can try generating a matching axle using the Parametric Auto-Rewind Spool Holder customizer. Will also look into it myself later to give the right parameters and make instructions more clear.

It doesn't look like the "Customizer" app is enabled for this object.

The parametric auto-rewind spool holder is a different object: https://www.thingiverse.com/thing:3252111
Set Output=axle and define Axle Set Length to the appropriate value.

Parametric Auto-Rewind Spool Holder

Sorry, I misunderstood you. I thought you were saying I could use the customizer to change the shape of the universal shaft.
You're just saying use the other shaft and make it longer.

Thanks for your help!!!

While we're on the topic - can you change my description to also include walls? My one piece works on horizontal or vertical surfaces.

Done! Any more suggestions?

Looks like you didn't like the dual-springs afterall? Too many broke?

I've had an issue with the round-spring's locating tab breaking off. Could it be made with a little more material there?

My dual-springs work much better than the first generation! The new photo I added in instructions uses two random springs, both new and old.

If the tab breaks off in yours then I'd first look at layer bonding strength. Try increasing temp, lower speed, turn off fan. Hard to add more material the as it has to fit through the dial etc, but the current design should be strong enough for sure.

The dual spring I'm printing right now (3.3 soft&round) has two stacked springs.... wound the same direction. The earlier ones were counter-rotated (to make the symmetric?), the new ones are effectively one big spring with a missing layer..... Or am I missing something?

The breaking tab has so far only happened once, it's because in my stand it goes in last. I had somehow convinced myself that putting it plastic side down would be too heavy (LOL), so it's possible to get strain when changing rolls. I should update my stands to flip it the other way..... And maybe to accept the plastic rod version. I guess you've never had issues with the plastic shaft version?

Nice improvement on an already nice set up. I had a little more trouble breaking it loose, but no actual trouble - I got a pick into the central bit to get the split started I really like how it's looking!

Also, if the little allignment bump doesn't line up I suppose the part could get torqued on insert. It does look like there's room to widen the tab up till it is tangent with the metal pole?

Good you figured it out already! Nice to hear you were able to break it loose correctly.
About the alignment bumps: yes these are thin, the idea was that it would also fit in stands of other users that do not have grooves for these alignment bumps (in that case it is just a friction fit). What exactly do you mean with "get torqued on insert": torque in which direction? A picture would clarify that.

As the rod tilts/pushes into the hole, the black spring can catch on the brown holder's edge of the slot.

Putting them in upside down would lead to needing a "left" and a "right" or else the axles wouldn't sit parallel to surface.

It's probably not worth changing.

Ah, I see! You could cut or file away the small alignment bumps. The tab will then slide easily into the slot.

The reason for using two springs in series and not parallel is that series spring has more rewinding revolutions: the sum of each individual spring's number of revolutions. This gives more possibilities in tuning the rewinder.

I just sent you a tip. Thank you for your design. It is a lifesaver!!! Hopefully others will do the same.
Please continue to design and share. :P

Thank you so much for the tip!!! Highly appreciated! This surely gives me motivation to continue with creating and uploading awesome designs!

What an innovative design! I have MakerBot Replicator Mini+ printers, so is there a file for the Stand and the TubeHolder that can be printed in parts on a smaller build plate (101mm x 126mm)?

Message by @anttix:

There are quite a few community contributed stand designs linked from the details page that come in multiple pieces. However given the spool itself is already 200mm across, the "arms" would need to be cut and glued together. The shortest arms I've seen so far were around 152mm (Final Filament Rewind Solution. The "short" arm is also included in Ikea Lack table sliding spooler stand but it's still 157mm.

It should be possible to use the "cut" functionality in slicer to print these in multiple pieces.

Alternatively one can use one of the "mounts" that attach to a larger structure. These 2020 mounts can be placed on top of a pair of aluminum extrusions. There's also a Side mount which is essentially a block that can be screw mounted onto any vertical surface.

There are quite a few community contributed stand designs linked from the details page that come in multiple pieces. However given the spool itself is already 200mm across, the "arms" would need to be cut and glued together. The shortest arms I've seen so far were around 152mm (Final Filament Rewind Solution). The "short" arm is also included in Ikea Lack table sliding spooler stand but it's still 157mm.

It should be possible to use the "cut" functionality in slicer to print these in multiple pieces.

Alternatively one can use one of the mounts that attach to a larger structure. These 2020 mounts can be placed on top of a pair of aluminum extrusions. There's also a Side mount which is essentially a block that can be screw mounted onto any vertical surface.

The MMU2s Prusa Final Filament Rewind Solution
Lack sliding spooler stand
2020 mount for Universal Auto-Rewind Spool Holder
by iamgnat
2020 Side Mount for Universal Auto-Rewind Spool

Hi Vincent,

Just want to say Big Thanks to your effort! You are our hero!
Printed two holders in single color and then printed my third holder with 2 colors, all by PETG.

For the spring, I do think printing in PETG is better than PLA. It is stronger but also more elastic.

Nice to hear that your rewinder works well! PETG is of course a great material, I use both PETG and PLA without issues.

I'm new to this but given my experience with the micro catapult I suspect ABS may be even better material. The catapults I printed out of ABS are stiffer and shoot farther while having the same amount of plastic deformation as PETG ones in their torsion bar. PLA catapults do work but suffer noticeably more plastic deformation.

https://www.thingiverse.com/make:668875

Micro Catapult
by anttix

Hi Vincent, to mount the Universal Auto-Rewind Spool on the side of my Bear Upgraded Prusa Printers, I modified the Spool Holder Mount 2020 by butchja to mate with the SpringRound parts. https://www.thingiverse.com/thing:3686332

2020 Side Mount for Universal Auto-Rewind Spool

Nice! Just added it to the list. Cheers!

Hi Vincent!

First of all thanx a million for relieving the world of the filament buffer pain. I've successfully printed my first test rewinder with one PETG soft and one PLA+ stiff spring.

I'm running into a problem where the spring loses too much tension after the clutch slips. I'm able to get less than half of the available rewinding revolutions immediately after the clutch breaks. Unlike nice continuous slipping seen at 2:58 in your video, my spring just goes woooosh and spins down most of its tension before the clutch "catches" it again. Looks like there is too wide of a difference between static and dynamic friction.

Any idea what may be causing this behavior?

Thank you!

Good question! I am not sure how to solve your issue. What material did you print the clutch with, and what is the dial setting?

Clutch is multicolor PLA. However I printed one single color version from ABS today to test if the material may be an issue. Doesn't seem to matter, it behaves the same way.

The soft spring needs clutch setting of 10 to allow for about three revolutions before the clutch slips. The stiff one needs 12 to get to 1.5 revolutions, I didn't dare to test above 14 with the stiff nor above 12 with the soft.

There is a comment by slyice from Apr 8: "Making the clutch tighter allowed it to slip a few times and not slip as much (meaning it didn't slip very far) and kept the tension."

I'm wondering if I'm seeing the same problem but in my case I haven't found a setting that would result in consistent short slips.

Here are some videos.

https://youtu.be/AfkR2Zvtp3s
https://youtu.be/Z36OxZ5Ledc
https://youtu.be/eauItNNDE2Y

Hard to say, honestly! Spinning 2.5 turns in your 2nd video is exceptional. The odd thing is that it first slips over (exactly?) 1/5 turn and then is wound up for another full turn before doing woooosh. Which implies that the static friction after the first slip is significantly much higher than at the start of that video. The increased torque then probably lets it pick up more angular speed, travelling a longer angular distance before it brakes to standstill.

I'd suggest to closely inspect all surfaces of the spring for artifacts. E.g. elephant feet, aligned seams, loose filament strands, the surfaces around the two gaps of the spring, the bottom hub surface, any odd things on the clutch elements.

If still nothing improves then try the following:

  • Grind the outer spring surface with coarse sand paper. This increases friction (both static and dynamic) resulting in altered behaviour.
  • Grease outer spring surface with some lubricant. This decreases friction (both staic and dynamic) resulting in altered behaviour.
  • Print spring at 101% or 102% scale. Never tried it myself, but it should increase clutch tension at same dial setting allowing to use lower dial settings which make the clutch arms longer and behaviour different.

Figuring this out has been way more fun than I anticipated :)

I was thinking about the same thing that maybe it's not the clutch that the spring is sticking to and did quite a bit of cleanup, even sanded the inside of the dial to make sure it's smooth and has no chance of catching any of the coils. No significant change. Then I checked the spring housings for roundness in case there is large X/Y skew that I'm not aware of. Calipers are not the most accurate instrument in the world for this, but I was not able to measure a difference over 0.15mm which falls into the the ballpark of "standard" 3D printing tolerance. I'm not sure if skew would even matter given the clutch has five arms.

Finally I printed another soft spring out of ABS. With this one I had the guts to bump the clutch up to 14 and voila! Nice consistent short slips :) Did the same with PETG spring and got a similar although not as a consistent result.

Here's a video of the ABS version: https://youtu.be/uRr2F8C8uh0

The spring is almost completely wound up when the clutch gives. I think what's going on here is that at the end, the torque curve of the spring becomes steeper so once the clutch breaks, the torque will fall off quickly and the spring housing can't pick up enough momentum to continue spinning.

I'm going to print another stiff spring from ABS to see if I can get that to work as well.

While this combination resolves my immediate issue, I'm wondering if it's possible to improve the design to have a wider range of settings that result in a consistent clutch action. I've looked at a clutch design of https://www.thingiverse.com/thing:3406725 and he uses a variation of a ratcheting clutch. I'm wondering if this has already been tried. E.g. a spring that looks like an attached image with a clutch featuring matching spring loaded half-cylinders that drop into the holes.

Parametric Hangable Any-Direction Continuous Slip Clutch with optional Auto-Rewind Universal Spool Holder

Nice that you are having fun with it! Sounds perfectly reasonable that the spring won't pick up as much momentum at a high dial setting. But I am afraid that the tension in your spring is way too high, it won't last long under these circumstances and soon crack or bend the other way round. At least it gives a hint where to look for. Still, we don't know why there is so much variation in the static friction. I was thinking about this experiment: put tape all around the outer rim of the spring, like in the original auto-rewind spool holder. This significantly increases the friction coefficient and I guess that the static and dynamic coefficients are more close to each other.

The ratcheting idea: I actually did model that kind of spring in the earlier versions of this rewinder, but hey, that was noisy! Did not intend to re-invent the musical rattle instrument, so quickly ditched that design. Could be that I added too many notches in the outside rim, using just ten (or five) of them seems to be a good idea. Might be worth a try...

Printed a spring with five notches, doesn't work. The spring has too much momentum and drive straight through the notches.
What we need is a damper with friction proportional to velocity, so that the momentum is dissipated and the spring moves only slowly. This is hard to construct with 3D printed materials...

Hi Vincent!

First of all, I'm very impressed how responsive you are on the forums. This must be taking up quite a bit of your time and it's highly appreciated.

Thanx for testing the ratcheting spring idea. Too bad it didn't work. I guess linear speed (kinetic energy) would be lower near the center but moving the clutch there would be a more invasive redesign.

I looked into why I'm seeing slips of different lengths and by rotating slowly I was able to get slightly more consistent results ( https://youtu.be/PM7iMekw6r4 ) although I'd still see a shorter slip once in a while. I may need to drive the hub with a motor and not by hand: It's quite easy to break the clutch with jerky movements like here https://youtu.be/ohY_GJlinOA this is of-course extreme but indicates that hand-driven tests may be inconsistent due to the jerkiness introduced by my sloppy hands.

Thank you for suggesting a tape test. Tested four different tapes.

  • Blue painters tape
  • Scotch "magic" tape
  • Duct tape (MacGyver's favorite)
  • Electrical tape (black vinyl)

The tape was applied only to the outer rim, I used a thin breakaway knife blade to cut it flush with the side surfaces.

Blue painters tape dropped the max clutch setting from 14 to 12 but behavioral differences were almost unnoticeable.

Scotch magic tape made the response a little quieter (probably because it's smoother than 3D printed surface) but still about the same.

The softer tapes are were where the fun began.

First the Duct tape. This seems to drop static friction coefficient either very close or even below the dynamic one. When spun slowly, the response is excellent. I got nice smooth slipping for all settings from 5 to 10. However when spun quickly it allows excess tension to build up in the spring. Here's a video that shows this effect: https://youtu.be/zD9dwhMV3Fc In a way this is the dampening effect that's needed although it's not fully 3D printed :(

The electrical tape also gave a nice smooth response for a range of settings but did not build up too much tension when spun quickly. Here's a video: https://youtu.be/o3z6TWpYbyw

Finally I put some painters tape on top of the electrical tape to see if the difference may be just because of the increase in the diameter. Didn't seem so. The action changed back to what it was of-course at lower clutch setting.

This is where my background hits its limit so I can only speculate what could be going on here. My wild guess is that softer tapes will deform slowly when statically loaded and that's why static friction is reduced while dynamic is not. I know PETG has somewhat similar properties e.g. it deforms when loaded slowly but shatters on impact however I have no idea what the coefficients are or if this even applies to elastic deformation.

For now the electrical tape route seems most promising. I'll do some more testing to see how it fares and if anything changes after it's fully burned in. I've yet to print an oversized spring but I don't expect this to change much given the results I've seen so far.

Whoa! I like your soft tape videos. Will add a note in the assembly instructions. I am not an expert in tribology either (=science and engineering of interacting surfaces in relative motion) but we know that rubber-like materials have a high friction coefficient and duct tape / electrical tape have a more rubber-like feel than the other two tapes you tested. To study this further scientifically we would have to measure the friction coefficients of the material combinations involved with a different setup. The classic setup is moving a block with known mass over a flat surface and measuring the required force and with this information we can probably explain better what is going on.

Did you try the old v1.01 style spring yet? I often hear (and feel) high-frequency vibrations when this type of spring slips, but I don't known yet what the resonating element is.

Another attempt with a ratchet spring. Failed miserably, picks up way too much momentum between the notches.

Thank you for the ideas Vincent!

I'm printing the v1 spring out of PETG as I write this. I tried to print it out of ABS but it curled off the bed. PrusaSlicer doesn't have a concept of internal brim that would support the coils and I'm too lazy to set up the original Slic3r or Cura right now.

I remember doing a friction experiment in a physics class a looong time ago so I took a look into my waste plastic bin and found a few pieces that would work for the setup. 3lb diving weight on top of a calibration cube seems to be a good match to a stiffness of a pen spring. Now all I need is a bit of free time to calibrate the spring with a scale and a bunch of weights (I have a pack of large bearing balls that probably work well for this), camera to film the action in slow-mo and some string to tie all of it together.

Here's a snapshot of the setup I was thinking about. The string with a weight will go over the end where a piece of PTFE tube is taped at pulling on a pen spring that will pull the moving block (cube). A camera will catch the length changes of the spring against a backdrop of a measuring tape. The accuracy will probably be quite poor as the spring is short and the tape has only 1mm graduation but it should be enough to gauge the differences in static and dynamic friction and how they change when tape is applied.

Please let me know if you have suggestions how to improve the setup.

Comments deleted.

Nice, even a quick and dirty setup can give valuable insights! Recording with a camera allows you to take many precise measurements.

What exactly is the PTFE tube on the left used for? If you are using weights of known mass to pull the string and using PTFE as a pulley then you have to take the friction coefficient of PTFE/string into account. Even though ptfe is quite slippery, a bearing as pulley will roll smoother.

Yeah, I was thinking about using the PTFE tube as a pulley to reduce friction as the string is going over the side, but I do have some GT2 belt pulleys laying around so I'll use a proper pulley instead. The friction there shouldn't matter much though as the force measurement device is the spring not the weights pulling it.

Good! Looking forward to see some results!

Okay, I'm frustrated, I've tried printing too many versions of the "spring with shell" and breaking it when separating. What's the most recent "simple spring" version that doesn't have the full shell?

Where exactly does it break? v1.01 is a simple spring.

Vincent, here are two recent ones. You can see the white one (which started out at too high of a speed, hence the rough 'disk') is still attached at the outer ring and I'm not sure if the center is splitting at the right spot. Should it split at that plane, leaving the rest attached to the disk?

In the red one I got the entire spring loose, including the outer part of it (which is correct, right?) but the center wouldn't separate.

The center should split in the middle. For the flat version, the plane is slightly below the place where the notch for the flat part of the shaft starts. I had the same problem with my ABS spring that the center didn't want to separate. I ended up using two shafts inserted from both sides to carefully break it apart. This way there was no force that could rip the lower half from the housing. Hope this helps.

The spring should stay a single piece, only partly separated in two planes. I've tried to make this point as clear as possible in the instructions, both the pictures and in the video compilation. You are not the first one to have (probably) missed these. If anything is unclear then please let me know!

I have a large filament storage box containing spools from 600g to 8kg. The box sits near my large delta printer, so the path to the extruder is in the range of 1-2m. I would love to use this awesome design to rewind that distance as soon as I use another filament. I've printed and tried a soft spring for a half empty 2.2kg spool and it works decently well with the clutch at 15, yet ideally the retraction would be even further and stronger, especially for the larger spools.
My question, is it possible to upscale the spool/dial/clutch design so the diameter increases (one could theoretically go as large as a spool diameter) and hopefully increasing stiffness while maintaining or improving 'windup length'?

Of course you can! Have a look at the Parametric Auto-Rewind Spool Holder. Set spring diameter to 200 mm and adjust other parameters to your liking. You can print separate adapters for each spool size, or use a long threaded rod and make the spool slip on the nuts.

I've been drowning around in all the settings there for a while but as I understand there is no way to make the springs it generates compatible with the new clutch style system. Same for the actual clutch and dial.

Correct, the parametric rewinder uses a different clutch mechanism. The new clutch system is currently only available in 80 mm diameter. Do you really need (or just want) this clutch system?

Since I planned on using quite stiff springs to accommodate the heavy spools, having the clutch adjustable for the lighter spools would be preferable yeah. But define 'need' hehe, I do plan on actually using them if that is what you mean.

Why not make two rewinders? One heavy duty for the 8kg spools and a standard one for lighter ones?

An alternative approach is to make the existing clutch system thicker. So keep radius at 80 mm, but scale Z by 200% and see how it turns out.

I think I am going to experiment with scaling the new design and see how it goes

Universal Threaded Spindle for Auto-Rewind Spool Holder

I would really like to incorporate this on top of my delta printer horizontally. Would this work in a horizontal configuration?

Don't know, probably yes. Just try :-)

Put spring on top, the weight of the spool then pushes the bottom bearing on the clip which should be fine. If there is friction somewhere in the system then figure out yourself how to eliminate it

for prints that are very large and use only one filament, is there a point where the spool holder slips or could the spring continue to tighten until it snaps?

It will slip if the dial is correctly set.

Can't seem to print the spring, regardless of if I use the SOFT or HARD version! I'm using a Prusa Mk3s w/ MMU2S and after about 6 attempts to print the spring part, it fails every time. The first 1 or 2 layers AFTER the (apparently) random filament (the layer between the solid base at the bottom and the first layer of the spring) seems to pop free and cause the spring layers to come loose and catch in the printhead which basically rips them off the previous layer. I've tried different filaments (cheap PLA vs. Prusament), different nozzle heat settings (+- 5 degrees from optimal for the filament type), different speeds, cooling fan on, and cooling fan off. Any suggestions on how to get the spring printed???

Might be an underextrusion issue? Try 110% filament flow (extrusion multiplier) and also increase temp by 10 deg, turn off fan and lower speed to 20% just to be sure. If this doesn't work then I'll upload an adjusted spring with 0.1 mm air gaps.

Thanks, I'll give those suggestions a try tonight after work and report back.

Just added a new version of the stiff spring, with 0.1 mm gap and to be printed with 0.1 mm layer height. Good luck!

Here is my thoughts with using nylon for the spring. The soft spring will print out nice and look nice, but nylon is too flexible for this use. it tends to twist and deform when in use. Will try the hard spring next.

Quick update, the nylon spring came out great. I can be more aggressive with this part and it has separated perfectly.

Cool! I will remember this. We have nylon here in the lab at work, might be worth a try and then I'll make a note in the instructions.

Vince. I did get it assembled and was playing with the assembly, making it reverse. then I was wondering how it worked after feeding a fare amount of filament, at what point does it slip and start retensioning. that is when I broke the ABS spring. I cranked it too much.

I use S3D. Not Cura. I printed out the lower half of the spring with Taulman Alloy 910 Nylon. and it came off the bed just fine. I created two disks, the bottom at 0.25mm and the other at 0.22mm. moved them into position and then merged them into one piece with tinkercad. For me this works perfect. I am using a Geeetech A10M printer.

I ccan't find @IAndrade's cura settings? Do you know where they are posted

You could send him a message to ask his settings, but that aside: try lower speed, higher temp, lower part cooling fan (turn it off?), increase top infill extrusion (or infill/gap overlap) to have some "anchors" sticking out vertically. If none works then try importing the step file CAD software to decrease the gaps manually and then print it with smaller layer height.

The odd thing is that the previous comment (by IAndrade) was about having the spring stick too much to the base plate, breaking the spring in his attempts to free it. So you might want to copy @IAndrade's settings to get better layer adhesion between 4 and 6, and IAndrade can use your settings to make separation easier!

I can't print the SpringFlat_Soft_v3.3 on a Prusa MK3. I am print with PLA, and when I get to layer 6-7, the filament doesn't stick anymore, and strings of filament come out. I am using Cura 4 with 30% infill, generating supports, brim. Is there any other settings that need to be set in Cura specifically for this to print?

First thing to check is that there is a gap of exactly one layer between the base and the bottom of the spring. You can verify this by inspecting the preview window and scrolling layer by layer.

If it breaks again, I will try nylon.

I think i finally got a spring that will work. I made the first one out of ABS, and it broke. Then I have tried 3 times making it out of PETG. I broke them attempting to free the spring. I increase the space between the spring and also the base and I think it will release the spring when done. (4th attempt). What do you normally use as a filament for the spring?

I mostly use PLA, sometimes PETG just for testing. It is challenging to make a design that works for most users, considering that the floating parts are all curves which are harder to support. Some users report insufficient gap adhesion while others like you report too strong adhesion. Good to hear that you are able to adjust the spacing yourself, hope this works well for you!

Hi Vincent,

Im having some problems with the tabs on the dial, it is the one with 3 arrow markers. everytime i print it the tabs break they are too thin and they snap then the clutch no longer works properly.

I am printing in pla on a prusa mk3, tried changing number of perimeters and detect thin walls option on and off in prusa slicer 2.0 but still snap

I have tried slowing the print on the lcd screen down to 35% during print but still the same thing, also when i load the part into slicer it shows errors so I run it through 3d builder for windows 10 and when it fixes the errors the hole in the centre is closed up. should i try printing the closed one and just drill the hole for the metal axle

I need the hole for the axle to slot through to fit on my wall mounted spool holder, is there a way to thicken just the tabs slightly please but still work with the rest of the parts

Seems you have a layer adhesion issue. Things to try: increase nozzle temperature, decrease fan speed, change (or dry) filament, increase flow (or extrusion multipler).

The design of the tabs is fine, I can squeeze it pretty hard as shown in this picture: https://cdn.thingiverse.com/assets/7e/f1/9b/84/b4/dial_bent_by_pulling_tabs.jpg

I don't see errors in slicing, are you sure you downloaded the latest version (v3.3, single-material)? Could you please post a screenshot of the error in slic3r?

Hi Vincent,

My apologies it was the slicer at fault with the errors, i changed some settings and it needed a restart and the increase in temperature printed the tabs fine.

Sorry for any trouble

Thank you Kerry

Good to hear, thanks for letting it know!

Thanks for the spoolholder design - I wouldn't have space for my MMU2s without it.

I found the metal tubes supplied from Prusa to be a little short for the holder. I've just added a minor remix of the springs with an endstop that makes them a little easier to handle.

Fab! love it! great in tight spaces

So many downloads, so less likes - shame :)

You can download multiple times, but like only once! I don't care these statistics, a single click is too cheap. Remixes are much more interesting, that's why I list every single of them!

I mean new generation, takes and didn't says thank you :)
Remixes shows new ideas and improvements - right

Have nice day

Hi, possibly I've missed a step here, but the spring in my 3.3 print doesn't seem to be increasing in tension on any of the settings, but on the higher settings, it does prevent the axis from spinning. Any thoughts as to what the issue might be?

No idea, could you share a video?

Video should be attached

Umm, I don't see a video?

This is brilliant but I'm not too keen on the new bidirectional spring design (see the attached image) ... Printed with PETG. Gone back to a v1.01 spring which seems to work better for me.

Did you break the bottom half of the spring free as well?

Umm, what stand did you use? And how high was the dial setting?

Hi Vincent. The bottom half did stay attached. I'm using a metal rod axle. The dial was set to just under 15. I needed it that high to keep the tension on a full 1kg spool, otherwise the clutch would slip too easily and it prevented the spool from reversing and maintaining tension on the filament.

The bottom half of the spring should be broken free from the bottom plate, as described in instructions and video. The v1.02 spring is indeed much simpler to prepare and install. If that one works for you then it is great already!

Vincent, I think I misunderstood what you meant. The bottom half of the spring is/was loose (I did break it free after I printed it). I am experimenting with the tension on the v1.01 spring and so far I am getting good results on 10. I do think the mass of a full 1kg spool was what caused my other spring to fail. Too much mass + too much tension. Spring too thin perhaps?. I am going to have to print a longer hub. I need one about 120mm to use with some spools of ABS that I have. Anyway I'm happy with the way I've got it now, so thank you for a great design.

Thanks for the details! I myself don't think it has to do with your 1 kg spool, I use the same rewinder hardware on 3 kg spools which have much more mass and inertia. If bearings are good and no other parts are rubbing then even heavy spools can be set to motion with little torque.

Did you do the oscillation test (see video)? How often does it oscillate back and forth away most before coming to a halt? This may give a clue for finding the root cause. A picture of your setup may also help. In any case a dial setting of 15 is way too tight for a long spring life.

It will spin freely a couple of full turns in either direction. But anyway, I can't find any mention of printing parameters for any of the parts. What infill percentage should I be using for the spring? I have a feeling that could be why my bidirectional spring failed. But it was working fine. I only noticed it was bent after a long print, when I went to change the filament spool. I'm not using an MMU (yet!) so I don't need multiple revolutions of rewind, just enough tension to prevent knots and tangles on the spool.

The spring blade just consists of perimeters, making it more or less solid if you use a standard profile. You can check in the output view in your slicer software.
Things you could try: print spring and clutch in PLA, print slightly oversized (101%-102%) to get dial in range 5-10.

Thanks for all your help Vincent. I've currently got it working on a dial setting of 10. This is still with the old style spring. I'll print another bidirectional one and give that another go. Happy it's working anyway. Thanks again.

Do you still have a metal-axle version, where you reuse the Prusa metal tubes for spool holding?

My mount utilizes those and people are asking where to get them. If everything's printed now, I could/should tweak my design to work with the plastic parts.

So far, I'm SUPER happy with the metal ones, they pop in and out of my mount both positively and effortlessly and are super strong. :-)

Yes: check SpringRound in the zip!

The latest Zip? Thanks, I'll update my description.

Yes, should I add those to the files section itself?

I would like it if you would, yes. Thanks!

Vincent- I haven't seen it mentioned in the comments, but have you tried printing the spring from nylon? It seems like this might be a better (more durable) choice vs PLA or PETG for that component.

If you have a weedeater you have nylon. My weedeater line prints on my printer. Nylon adsorbs a lot of water. It is very flexible and cool to print with.

Never tried that. I don't have nylon here and I guess very few people use that exotic material. So I would rather focus on improving the design to make the spring unbreakable in common materials (PLA/PETG).

Thanks so much, what an excellent effort and works so well.

You're a genius Vincent.
I've tried several different mechanisms to take up the filament slack on my MMU2S.
Nothing worked to my liking!
I printed one of your Rewind Spoolers and it works perfectly!
I'm going to print 4 more.
Thanks!!

Nice to hear, thanks!!

Vincent, thanks for this. I believe running off a couple of these was part of the source of finally getting my first successful MMU print (I don't have space for the factory buffer setup).

For me the PTFE holder seems rather useless as it kinda flops around in and when pulled forward binds up the filament enough to cause issues. I tried on top and it had about 2 inches of play either direction and also mounting it underneath where it would pull forward about 2 inches (the vertical brace on the base prevented it from moving backwards).

As far as I can tell I have it attached like in your examples. Am I missing something? Is there something else I need to do?

Did you run the filament tube all way to the MMU or extruder? The picture with the short tube is not connected to a printer. Good examples are at the end of the video compilation.

Or do you mean that the filament tube sits too loose in the tube holder? In that case try the v3.2 version (just added it to the files) which has one single hole and sits much tighter, and I'll update the v3.3 version to make it tigher as well.

Did you run the filament tube all way to the MMU or extruder?

I did initially, but to get my successful print I removed the long PTFE tube, used short tubes in the back of the MMU, and skipped the arm altogether.

Or do you mean that the filament tube sits too loose in the tube holder?

No the PTFE tube fits in the holder perfectly. It's the arm itself that moves around.

It is hard to imagine how a moving filament tube holder could possibly bind up the filament rewinder. Do you have a picture of this specific situation? Apart from that, it makes perfect sense to leave the tube holder out if the rewinder is positioned directly behind the printer.

It is hard to imagine how a moving filament tube holder could possibly bind up the filament rewinder.

Not the rewinder itself, the filament going to the MMU. Basically as the MMU starts loading the movement of the filament is causing the arm to move forward. This is most noticeable during the "fast load" to the nozzle. When the arm is holding the tube above the rewinder a similar issue occurs during the unload process (pushes the arm backwards and slows things down) which prevents complete unloads.

The movement is just enough to take it out of optimal alignment for the filament and adds enough friction to irritate the MMU's sensitive nature ;-)

The impact I am seeing from the "floppy" arm could simply be that due to the current lack of space for my setup (there is only 6" between the spool holder bases and the back plate of my MK3) it is super sensitive due to the angles involved.

I see, then I don't know. My own MMU2 is not sensitive at all to additional friction in the filament path. As you see in the video compilation I can install very short or very long tubes, all original with I.D. 2 mm. For me it is normal that the tube holder moves a bit during fast loading/unloading and it is never a problem here. But I have read about other user's comments that they have a MMU2 very sensitive to tube friction so I understand your issue. Hope you can work around it. What about 3D printing a stiff guide for the filament tube guide to maintain the desired curvature?

Yeah for now simply skipping the arm and only using the short tube on the MMU seems to be working.

Someone pointed me to this MMU mod: https://www.thingiverse.com/thing:3233579

I'm going to do that in the near future and at the same time I'll whip up an adapter to fit a PTFE holder on the base of the spool holder. I think that should work pretty well.

Prusa MMU2 PTFE Holder M10 Passthrough Adapter

Good idea! I'm also considering this mod, but don't have M10x4mm sockets (yet).

Yeah I'm waiting until I get a few more successful prints before spending MMU specific money :-D

Anyway, thanks again for this great spool holder. Works a treat and helped get things working for me.

Vincent, let me say these things are a work of pure genius... This plus my incoming RepBox, it is going to be a nice setup. A few months back, I did a prototype quick print of one, just to try it out and it worked flawless. I decided to print a batch of 8 of them, but started with two to test out your 3.3 design.

My prototype one I made forever ago has does print after print, no issue. The new one on 3.3, the light springs seem quite weak with a 1Kg spool. I had to crank it all the way to 15 to get it to rewind decently with the MMU. About an hour into the first print with it, I noticed this picture below. You can see the lower half of the spring broke (probably because of running on 15) and is all bound up. This was printed with Prusament PLA in .2mm layers.

Is this just a case of needing to use the stiffer spring?

Thank you for the nice words! I'd recommend investigating why you needed to dial it so high. Did you compare the behaviour with the video? With/without spool, with/without spring (four combinations in total). Maybe there was a rough surface or the clip was too tight or the spool was not balanced or one bearings not fully pressed in etc. Any cause can be solved, let me know if a part could be improved. If it is rolling smoothly again then the light spring should be able to do its job at a relatively low dial setting. If the spool itself is out of balance and you don't want to use a counterweight then it is a good idea to consider the stiff spring. And the old 1.0x springs are also compatible with the 3.3 version.

Yeah I went through all of those, bearings seated well, spool is balanced, no rough spots. The only odd thing is the dial is very tight within the clutch as well, but cannot figure out why. Any thoughts on what could cause that? I will mess with it some once the current print is finished.

Something must be wrong with the dimensions then. Like the dial was accidentally printed at 102% scale. Did you use pre-sliced gcode? It is perfectly possible that there is an error in it as I have not yet actually printed the latest version yet. Or did you slice it yourself?
You could try one of your older dials as the dimensions as the dial-clutch interfaces are identical.
If the spool is rotating in clockwise direction (as seen from the spring side) then setting the dial very high potentially allows the clutch to "bind up" by bending the clutch blades outwards. This is more an issue of older springs which tend to be deformed into elliptical shapes, but might also happen with the newer ones. That's why we have to figure out why a lower setting slips too much in your case.

HI, can you give more detail on what has changed in 3.3? If anything? Does it include the 3.2 filament guide?

I barely got done printing 5 x of v3.02 with springs from 3.1. Everything works good. What am I missing? Trying to determine if I want to reprint everything again. Thank you!!

Great that it works fine! The filament guide (=tube holder) has been redesigned, from 3.3 there are ten slots at different angles instead of just one. Other recent changes (besides the reworked spring) are slightly thinner dial and adjusted axle to give the spring more space and reduce friction. Hub and frame are basically the same. Clutch now has three scales instead of one.

wow amazing it work flawlessly! thanks for this design :)

My available print area is only 200x180. How can I print the stand without deforming the notches the axle fits into?

The stand has a 200x123 footprint, you should be able to print it upright if you leave out the skirt. The notches won't be at the very edges of your build area so these should be fine.

Even with skirt disabled it still tells me it's outside the print area. I could scale it in one axis only to make it fit, but that will make the notches narrower too.

I'll check.

Is the stand you linked to in the first version of the auto-rewind hub, and which is pictured but not mentioned in the parametric version, compatible with this version?

If you use a different stand then you would have to check the width to make sure it fits.

I just chopped off the two "feet" that stick out on one side. That gives me plenty of room to work with.

I am trying to print the single color version and when I slice it in slic3r it says that the object excedes the build volume. It looks like the parts are in but the skirt doesn't fit. If I print this will anything bad happen?

You can simply disable the skirt.

Ok. I had to split the parts up anyway because I couldn’t run it that long. But thank you for responding.

I have created a Wall Mount Spool Rewinder Adapter that allows this to be used with the Prusa MMU2 Wall Mount Spool Holder if you would like to add it to the list of stands/mods.

Wall Mount Spool Rewinder Adapter
Prusa MMU2 Wall Mount Spool Holder
by Olef

Thanks for the useful mod! Just added it to the list.

Hi,
I have printed v3.2.1 and the alignment of the arrow and numbers seems not to be correct. I can move the dial from 8 to about 25. Did I miss something?
I also have the question,why the lower end of the "TubeHolder" has these hollow ends (below the shaft hole). Is this by intention?
Thank you for you great work!

Hi Sebi, try a different alignment, only one is correct. There are five tabs but only three dial markers, that's why the others are off.

The lower end of the TubeHolder can be broken away, the hollow ends make this easier. This way it can be "snapped" on the axle, which is actually needed when mounting it under the spool as in one of the pictures.

Of course it is working like a charm if I am assembling it correctly! I feel like being a bit dumb now :-) Thank you for your fast reply!

Good to hear that!

I have problems with the spring the tolarance is too small for the axle to fit. I have tried filing it and sanding it and 2 of the springs broke.
Do you have any suggestions/ model change maybe?

I've only just started printing this from Parts_MM_v1.01 and was seeing tolerance problems between the Hub and NutCurved parts - they would not mesh at all. In Ultimaker Cura I set C1/Extruder 1's Horizontal Expansion to -0.4mm and C2/E2's to 0.4mm. Now they fit together snugly and bonus: because the C2/E2 parts are thicker the secondary color is more apparent.

If your nut does not fit on the thread then it might be attributed to insufficient cooling, resulting in dimensional inaccuracies of the sloped surfaces. Besides your workaround, you can also scale the nut to e.g. 102% size in X/Y directions.

You could try the v3.02 designs (last zip file), but I will put more clearance in the next release.

Edit: just uploaded v3.2.1 in a zip file, this one has larger tolerances in the spring shaft (among some other improvements).

Comments deleted.

If anyone is interested in seeing this in action, I created a short video on YouTube of the filament switching process using this spool holder.

https://youtu.be/kNHsGkuzL_E

I have it working fairly well, so I'm kinda afraid to touch it. I've had the most luck with PLA+ for the springs, but PLA should work fine. PETG broke easily, but may try playing with that again eventually. Over tightened the clutch on a couple which deforms the spring eventually causing it to fail over time. I have it more loose at the moment and seems to be working so far.

NIce, thanks for sharing!

Is it possible that the clutch and the dial of V3.2 missmatch?

There are three pointers and five tabs. There is one correct way to assemble these together, and four wrong ones.

Align the "free standing" pointer with the dot above the rightmost marker (there is only one such dot) and it should match.

are you suppose to remove the bottom flat part of the spring after printing?

No. The bottommost two pictures in the instructions show how it is prepared.

The spring model does not slice with cura!

EDIT: I got it to slice but its 14HOURS to print just the spring 80% of the print is travel any settings to tune to make this faster?

Yes: turn combing mode off and printing time should drop to under 3 hours. You can find the "combing mode" setting in the Travel section.

I've tried a couple of materials for the R5 springs and this is what I've found so far:

1) PLA+ = Hard to separate the 2 springs from each other but doable. Broke one spring at the center where the spring connects to the hub after installing and using from over tension trying to get it not to slip as much.

2) PETG = Broke 3 out of 4 just trying to get them to release from the back plate. The one survivor is working great.

Getting the clutch to hold as tight as possible, but still allow it to give is most important from what I can tell. The one spring that is working is holding well and only slips about a half inch each time. The PLA+ spring I could get to hold, but would slip like 3 inches when it gave way.

Not sure how to help anyone with this info, but it's my observations.

Going to try a regular PLA spring to see how it does. Will not be trying ABS.

I'm wondering if a ridged outer ring on the spring would help it not to slip so much and still leave enough wiggle room to get past the ridge? I would like to redesign and test, but not sure how to modify the existing ones without just starting from scratch.

Just added a zip file with the v3.02 pre-release files which also include STEP files that can be imported in CAD software. Well, in theory at least, as importing the spring doesn't work with my software yet. Many other files also have been updated to give the double spring more room and reduce friction. Hope this helps!

Ridged outer ring: I tried it once and it turns the rewinder into a musical instrument (rattle)!

Awesome! I’ll check it out. Thanks for the reply.

Well, I have to say, this is pretty amazing.

I have had all kinds of trouble with the original components that came with my MMU2 to the point I had to babysit multi-color prints due to a couple of the original components not catching certain filaments in the front and allowing them to roll up when unloading like they were supposed to. This would cause the roll to get all tangled up with itself because the loose filament would just wrap around the roll and slide off sometimes.

I've printed one of these (took a long time) and it's now sitting on my most problematic position. It has worked well so far. Getting the clutch at the right tension is obviously very important. I'm now using it to print the rest of the Auto-Rewind spools. The spool holders next to it seem to know what's coming and morale is low. ;)

I'll post a make when they are all done. I'm also considering posting a video of how to get the spring loose (R2) as it took me a while to figure it out and I'm an engineer! Looking at the layers in slic3r as mentioned did help to see where they were "suppose" to separate, but it look some tempting to get them separated (and a hobby knife). Make sure you clean up all of the left over plastic that hangs around from the bridging so it doesn't get stuck when winding/unwinding the spring.

Great job on this. I know people have had issues and I get it. Luckily, my printer is tuned in very well (lots of trial and error over a year), so I haven't had issues like most, but I can definitely see where the slightest problems in the print could cause things not to work.

Currently printing them with eSun PLA+. May run out of the main color, so the stands may end up being Sunlu PETG.

Update: Found my first problem. When printing multiple colors and one of the colors is only a very small amount overall on the print, it's loosing too much tension on the spring because the clutch will let loose and it's not enough printing to wind it back up (e.g. printing the dials). Over time, it will loose basically all tension and can't wind it back up unless you do it manually between prints.

It has made me think of a new base with a new winder and axle. This would also solve peoples problem of holding the filament onto the roll while winding it up. You could wind it up after you load the filament! Off to Fusion 360!

I am having a hard time getting the spools to rewind. It starts to rewind but the MMU pauses for a second and the spool doesnt start rewinding again. I wonder if a taller spring would give more torque? Double with it is now. Or even bearings on the axle ?

I am using Hatchbox filament, kinda heavy.

Thank you for the XXL Nut and for this design.

I would say check these 3 things:

1) Make sure your clutch is as tight as it can go and still function properly. I originally had my clutch one less that where it is now because I didn't think my printer could pull the filament well at that strength. I noticed with smaller layer times on that color, it would slip the clutch only once which made it not very tight on the next run. In other words, the slip on the clutch was way too much movement. Making the clutch tighter allowed it to slip a few times and not slip as much (meaning it didn't slip very far) and kept the tension.

2) Make sure the spring is clear of any bridging material that held the spring to the back plate while printing. It can cause the spring to think it's tight if it gets caught and slip around when it tensions. Making sure it's all clean in there allows it to tighten smoothly.

3) Definitely use the R2 stiff spring (if you aren't already). It's just better and can go both ways for tension.

What version of the spring are you using? It should be possible, many users have 3 kg spools without problems.

@Vincent + @Slyice - I am using SpringFlat_Stiff_v1.02_RC5.

@Slyice Thanks for the suggestions.
1) I've noticed on this spring that the coil winds completely at about setting 11 before the clutch slips. So moving it to 12-15 would not really really give it any more pulling power.

2) Yeah, fragments on one of the clutch housings was making it hard for the whole mechanism to function as designed.

However, I have to say, I did not realize you were suppose to add bearings. lol Just added some. Looking forward to testing.
Now I see "bearings" in the details. Geeze.

Yeah, bearings are a must in this design! I updated the instructions to better reflect this and warn about too high friction in the axle.

What difference bearings make..!! hahaha
Rewind is working! -- reprinting using v3 with 2 colors (black/white).

/bow /bow /bow

Hi, just a quick question I haven’t been able to answer from the description and pictures. I printed the soft spring v1.02 RC 5. The spring and the hub in that STL, are we supposed to separate the spring snd the hub? Portions of the spring freed up on its own but the center portion remains connected on the hub.

Check the very bottom of the main page (https://www.thingiverse.com/thing:3338467), the last two pictures show how it is supposed to be separated. Center portion remains connected :)

Universal Auto-Rewind Spool Holder

Have you considered beveling the bottom of the spring where it meets the backer for easier removal like the depression to allow it to separate in two?

Yes, it is beveled, also to minimize the contact surface to avoid sticking too hard.

It doesn't look beveled? Is there a newer version?

You are right, the bottom is not beveled. I now remember the reason: reducing the surface may make it too loose. There is a huge variation in layer adhesion among different printers and materials, one user already reported insufficient adhesion with the RC5 design. In fact I added the curved slits to allow insertion of a flat screwdriver to release the bottom part of the spring. Hope this helps!

Huh, never thought to push up from the bottom. Worked much better. Also may have helped I printed at a .25 layer height. I didn't have any problems with the layers sticking, though I am using Amazon Basics PETG at 240 degrees.

hI VincentGroenhuis first thanks for your work ;)
I just want to know if i can use the spring only but nor the support because i have a threaded rod like support
thanks

Yes, you can use SpringRound which fits on your rod!

Thank you for your quick reply
Ok thanks i'm happy to learn it thanks again and very good job :)

You will also need some clamp or holder to keep the spring shaft from spinning. I remember someone else had the same issue and designed a clamp for it, but I don't know if he actually published it.

Just last night I was looking at the stl files and I saw a notch in the spring so I will pierce it too I think
I also watched if someone published the changes otherwise I would publish them myself as I have some time

Did you have a solution for keeping the shaft from spinning but do not tension it too much so that it is locked?

Comments deleted.

HI,

The file list is getting a bit long and it's not clear to me what I need to print. Can you bundle the last revision in a zip somewhere

Just cleaned up the files section, there are only three springs left (two in v1.01 and one experimental v1.02_RC5), the others are in a zip file. I'd use the experimental version, it definitely works much better than the older ones. Regarding the other files, either use an all-in-one plate or just print everything if you don't know what to print. Once you have one rewinder up and running, you will understand the differences between the different stands, springs and nuts. Use the multi-material version if you like to print it in two colors.

Just noticed you got pre sliced files on your website and that includes the spring, Though you also have a separate spring for PETG. My guess is that PETG will be a better solution right?

Also there a 3 nuts, Do you have a preferred one to print? Mainly use Esun, Prusament and PM Filament.

PLA should be fine if you don't stress the spring too much. With RC5 and 2-3 rewinding revolutions the PLA spring should retain its shape in the long term and you can always flip the spool holder around to load the spring in the other direction.

Nuts: use at least one curved nut. Add a second one if you have difficulties in centering the spool. If you unwind the spool in ccw direction (seen from the threaded side) then use a flat nut to avoid unscrewing the curved nut. If you big spools then use the XL curved nut. Hope this helps!

Thanks, I will start one tomorrow with the RC spring then.

First attempt with the spring ended in a spiderweb, Base went fine, though the springs printed too fast or toom much gap.

What settings did you use? Layer thickness, speed, material, cooling?

0.2mm layers
2 perimiters
25% infill
Cooling 100%
PETG
45mm/s
small and external 25mm/s

Tried again with 40% speed, Same mess

Could you check in your slicer that the gap is exactly one layer? If no: what is initial layer thickness? If yes, then how would your slicer normally support a spiral structure?

I'm using Slic3r PE with pretty petg for filament, Quality 0.2 for print and MMU2 single color for printer. The gap is 0.2mm and definitely 1 layer.
I managed to print it by dropping the speed after layer 5 is finished to 10% then after layer 8 I set it to 80%. (percentage of speeds mentioned earlier)

Now I'm not sure what part to cut loose, the spring is loose and I think I need to cut something else too right?

Insert axle halfway and wiggle the top half of the shaft free :)

Then the whole spring would be separated from the back isn't it?

Edit, It doesn't. I do think it's quite loose and not very springy even on 10

No, check last two images on the very bottom of the main page :)

Got it, now it's time to print the stand. Tried by holding the axel and walk backwards though it doesn't roll back very much. I'll see when it's in a stand.

Could be if the axle is too tight or the spring surfaces are still rough. Try grinding the spring smooth, remove the clip from the axle, identify problematic surfaces if there is still friction in the system.

Finished the stand now, the filament guide: is that supposed to drop down on its own? And with 10cm 4*2 ptfe there's too much friction to rewind.

There are instructions on the main page, the ptfe tube is supposed to be attached to the MMU unit (or extruder) at the other end.

Try PLA, or turn off fan with PETG? (PETG with fan results in poor layer bonding in my experience, and apparently almost no bonding if there is a 0.2 mm gap)

Hi Vincent,

First of all, thank you for your work in developing this system. I'm very keen on minimizing the space the MMU requires as I'm planning to enclose my printer for printing ABS.

I'm struggling a bit with the springs. So far I've printed the original spring and RC5 of the dual spring. The original spring works quite well but I've managed to break 3 of them at the hub. There seems to be a very narrow window of 'just enough' tension to provide the necessary rewind without breaking the spring. I'm currently using the latest version of the dual spring but I'm concerned as it just does not provide nearly the same level of tension in rewind as the single spring. I've tried both directions and all of the tension settings on the clutch but am just not getting an adequate amount of torque to wind the filament back onto the spool with any tension.

In your experience how much 'pre-loading' of the spool do you need to do before performing the filament load sequence on the MMU? In other words what do you find to be an adequate number of forward revolutions of the spool to provide at least two revolutions under tension in rewind?

Thanks very much for your consideration.

Sounds like you have significant friction in the spool holder. Try to find parts rubbing against each other, remove the clip, grind rough surfaces if necessary, de-grease the bearings (or buy new ones) etc
Then do this awesome test: https://www.youtube.com/watch?v=EfB9rarOsi4

STL on the support leg used in the video..? :-)

Thnks...I never printed those..I use another stand for my rewinders... :-)

Will do, thanks for the tips.

Hey Vincent, Can you explain why the dual spring is better? For some reason I thought the dual springs would be going in opposite directions, instead of just printed on top of each other. What makes this design better? Just looking to understand.

A single spring has up to 3-4 rewinding revolutions, when fully wound up there is a lot of material tension which eventually deforms the spring.
With two springs in series you have around 6 rewinding revolutions. Als you only need 2-3 actual revolutions the material stresses are much smaller.

Another advantage: the clutch rim can no longer twist or translate thanks to the connection to the base plate and axle shaft, solving a nasty lock-up issue.

Interesting, I was not thinking about them operating "in series", I just assumed it was a .5+.5=1. I clearly do not know much about spring mechanics :D

Ahhh I see what you are doing now, makes sense.

The 1.02_RC1 version has springs in parallel, based on that design you are right! RC2 and later have the springs in series.

Hi. I have printed the rouded versions of the spring. I can easily separate 1 part of the spring once printed it. But I cant separate the part of the spring that is on the base of the spring. I mean: I can see in the slicer (slic3r PE latest) the gap sparating 1 section of the spring (marked as a bridge), but at the bottom of the spring there is no gap separateing the spring from the base. is that ok?

See attached cross-section drawing, the yellow parts are to be broken free and the red parts stay connected.

Look at my pictures this is how i should look like when the springs are separated..

i printed the rc4 version in PLA 0.2 mk3 Quality PLA settings in slic3er latest version

now going to print 4 times the rc5 version.

Yes! Thanks for sharing these photos!

Which version did you print, and with which layer thickness?

0.2 layer thickness and SpringRound_Stiff_v1.02_RC2.STL

If by "base of spring" you mean the attachment in the center: you are correct, this is supposed to stay connected, the whole printed spring remains a single connected body. If not: do you have a photo of the spring showing the separation that you have now?

No, i meant the Spring part that is atached to the base
. There is no Gap between the base and the spring

Could you post a photo of your spring?

Sadly, I still had problems with getting the spools to keep the filament on unwind. No matter what tension I set, it would eventually slip right before an unload and the filament would fall off the spool and tangle.
Yes, I tried your new design. Yes, I tried every of the 17 tension settings and filament arrangement. No dice whatsoever. I'm just gonna have to go back to the stock setup until the MMU2S upgrade comes in.

Pity to hear that! But thanks for letting it know. Things that cross my mind: print a spring at 101% size to get more clutch torque at same settings, change spool locations so that filament path is as straight as possible (no sideways bends, or just very gently only), use stiff version of spring (I will upload stiff version of 1.02 RC5 soon). If you post a picture of your setup then I can take a look at it. It should be solvable, most users did not report any problems.

Hey Vincent, are you still planning on uploading a stiff version of 1.02 RC5?

Done! Check the files section.

Hello. I have printed a few of the 1.02 RC5 stiff spring designs. Unfortunately each spring has broken while in the process of unwinding it after it printed. No matter how careful I am they seem to break at the same location.

I looked carefully at the model in both Slic3r PE as well as S3D and I think I might see why they are breaking. In the stiff spring the "thick coil" that splits into 2 "thinner coils" only has 1 perimeter layer on the inner portion, but has 2 on the outer portion. The soft spring has multiple perimeter layers on both coils. I have attached pics to show what I am referring to.

Would it be possible to thicken the inner coil where it splits off on the stiff spring to reduce breaking?

The particular slices you are showing are at beveled slices which are specifically meant to make separation easier. The real strength of the spring blades are in different layers which have more perimeters. In RC5, stiff spring has at least four or five perimeters everywhere. If the spring breaks at that point just during unwinding after it printed then there must be a problem with the filament or the printer, what about doing some strength testing? Anyway, attached is RC6 which is thicker at the location you zoomed in, hopefully this helps!

Awesome.. thank you!

Also, did you try v1.02 RC3, RC4 or RC5? These springs have a special design which allow for many more rewinding revolutions (five or six) which gives more headroom right after slipping.

can you put in the description all settings you used or what is prefferred i am a newbie sort of speak but its also better for everyone to have a startpoint wich settings to print are used, especially the spring etc.

thanks in advance, i am going to print this later today too:)

Bedankt Vincent voor deze post heb er 5 nodig heb mij de mmu2 besteld duurt wel nog tot mei 2019 voordat die geleverd word:)

I myself use PLA, 0.2 mm layer thickness, 3 perimeters, 30% infill, no supports. I also experiment with PETG springs, both materials work fine.

Thank you! I had the same problems. Reprinting the spring right now with 0.2mm layer height. The .amf file had 0.15mm preconfigured.
Could you include these infos in the thing details?

I've added it in the main text! Thanks for noticing!

oke wil try that too and any special temperature settings for filament and the bed?

Just stock settings. I mostly use Fillamentum, Prusa and Colorfabb filament. The Genetic PLA profile in Slic3r PE works fine.

Thanks vincent printing now wish me luck:)

OK, I wish you luck now!

Is there any preferred, or required layer heights for the different bits?

I use 0.2 mm for al parts, but different layer heights should also work fine.

I'm pretty much confused about the SpringFlat_Stiff_v1.02_RC2... it is printed on a solid plate and the outer ring and the inner "nut" seems bonded to the plate. as I can see, the spring itself is seperated by a one layer space so I loosened it. But now I'm confused. Since the spring is loose in the shell and the Clutch presses on the outer shell-case, how does the spring work? the nut drives directly the outer shell... and if i break out the nut from the shell, the spring should be way too loose in the clutch?

i have the same problem

Did you watch the video?

Rycoviac,

I have the same question. First, Yes I have split the spring in two.

I agree, the solid plate connects the center ring, which connects to the axle, to the outer slip clutch ring. The center of the spring is also connected the center ring and the outer part of the spring is connected to nothing. Both SpringFlat_Stiff_v1.02_RC2 and SpringFlat_Soft_v1.02_RC2 have this problem. So I printed SpringFlat_V1.02_RC1 and that one works.

Obviously it was designed this way with a good reason ;)

OH, The center hub splits in half also. I split the spring in half but not the center hub. Now it makes sense.

And RC4 is available, in this one it is much easier to split the center hub.

Just uploaded RC3 which is much easier to split across both planes.

hmm. I printed two 'soft 1.02 rc4' springs. They seemed well-bonded. I sort of "cracked" one to see if that took the spring free, ended up breaking the whole base side (the side against the bed). But since I had the other one I thought I'd see if I could wiggle the center spinner free. I put a screwdriver in it, it started to split but was breaking the base too. I guess I'll print the old RC1 instead.

Here you go, Vincent. It broke when I tried flexing it to break the spring and especially the hub.

Hope things are okay in your country today.

Okay, printed RC5 and got it split successfully. I thought I was going to break it at a few points, the axle and the "inner wall" were the toughest parts. Here's how I managed to split it:

  • Put a flat blade screwdriver between each "loop", twisted the screwdriver to break the loop free from the base. I had to do it twice- eg working out at the 0 deg plane, then at the 180 deg plane. That loosened most of them.
  • Very carefully split the spring in its lengthwise parts, then used my finger to spread and break it.
  • The inner ring didn't want to break loose. Finally I put the screwdriver between the inner and outer rings and it split fairly easily- starting 180 degrees from the "Y" where the spring joins the inner ring, which was the most difficult spot in the inner ring.
  • I really thought I was going to break the axle. Finally I put a knife between the spring halves and carefully split the rings until I reached the axle. After wiggling it a bit it finally split in two.

A lot of work, really.

Here are the same images that I attached to the post, because I think the "uploaded images" are hard to view: https://imgur.com/a/pqpNqHO

This was printed in PLA- normally I print your stuff in PETG but PLA prints faster. I'm also on a MK3, I wonder if retraction settings have a lot to do with it. I think it's pretty difficult to do this operation, though it's the best spring design yet. Perhaps some of the "skeleton" you used to separate the planes in early RCs would help?

That's odd, I printed a lot of these springs in PLA on a MK3 with stock settings, no issues in separation by bare hands.
Skeleton/spiderweb: another user reported bridging issues. Also, the use of a spiderweb results in a bigger gap and an even smaller spring.
Did you consider breaking the central hub free by inserting an axle and wiggling it?

I was thinking of the spiderweb only on the axle and the inner ring, not across the full area of the springs. With the broken springs that I printed earlier, which were in PETG, I tried breaking the axle loose but was trying to do it assuming the axle needed to be split from the base.

Maybe it's just me that has these problems. We'll see.

In my experience it is very easy to break the central shaft loose by inserting an axle (not deeper than 8 mm) and wiggling it. But not by inserting a screwdriver all way through of course. I will make specific instructions for this later.

Thanks for the pics! Glad you managed to properly break it free now. Do you consider it "too hard" to be included in the next release? I could try further reducing the contact area of the split surfaces, but I am afraid that it might get loose during printing. A spring printed in PLA is already quite loose. Even when printed in PETG (on my Prusa i3 MK3) I do not need any tools to break the parts free. Of course every one's printer has different characteristics. So...?

Thanks for the schematic. I think that's what I did wrong- I assumed it was supposed to free up at entirely different points. I'm printing RC5 and will report back.

Good to hear that the schematic helped!

Thanks for sharing! Also thanks for the last remark.

It broke when I tried flexing it to break the spring and especially the hub.

Flex it to break the hub? This is not possible, the bottom part of the hub should connected to the base. I added a schematic drawing (see instructions) to make it more clear. I don't know how far you tried to flex it, if bent too far it will eventually break but I will consider making the splits in the base a bit shorter.

How exactly did you break the base? If you post a picture then I know which part needs to be reinforced. Which material did you use?
Meanwhile I uploaded RC5 with stronger connection between base and centre hub and easier splitting of the hub.
RC1 is a totally different design with two springs in parallel, while this works fine it does not have the special advantages of the serially connected springs in later experimental versions.

The spring itself should be split mid-plane!

Ahhh now we are talking. I diddn't saw that, the PETG was pretty well bonded together and I just thought, this tiny "gap" was a extruding-failure. Now I see how this works. I wish, thingiverse has a per-file-description.

So, I've spent wayyyy too much time designing/building an enclosure that I feel may be what everyone here is itching for with this parametric spool holder. I'm in the testing phase of it now and all is going well. I should have all the parts/pieces up on Thingiverse in a week or so. Crossed fingers.

BTW: I'm not sure why you have a cylindrical spool nut. I could imagine just a cone on the (as printed) "lower" end of the threaded shaft Unless I wanted to center the spool, there's not a lot of reason not to just have the cone at the end.... I printed two of the cone nuts and just ran one "permanently" down to the end.

I've had some issues with the clutch popping out a bit. With a more robust mounting, I've had fewer problems, for as little sense as that makes. :-)

Indeed, it is a good idea to have two cone nuts for optimal centering. The cylindrical nut can be useful to lock the outer curved nut in place. Just keep the goal in mind: rigidly attach the spool to the hub, well-centered, and use the nuts in the way you feel it is best to achieve the goal.

Alternate to your stands for using less plastic and fixing to surface: https://www.thingiverse.com/thing:3474307

Thanks for the spools, they are pretty cool!

AutoRewind Spool Stand Hanging Screw Mount
by AbeFM

Thanks!! Posted a link on the main page.

All FDM 3D printing filaments are hygroscopic. That’s a fancy way of saying that the material likes to absorb moisture.

This hygroscopicity can wreak havoc on 3D printing filaments. As plastic polymers, they’re made of chains of molecules strung together. Moisture introduces water molecules that break up these chains, ruining the plastic and causing a whole slew of problems while printing.
Source: https://all3dp.com/2/how-to-dry-filament-pla-abs-and-nylon/

Food dehydrators are often used for the purpose of drying filament. See: https://www.thingiverse.com/thing:1618037 and https://www.thingiverse.com/thing:1117970

The difference between "Dehydration" = "Dehumidifying" can be explained as follows:

Dehumidifying: The process of drying air using a device (air-conditioner) or desiccant material like Silica-Gel. This is done at a constant air temperature.

Dehydration simply means removing liquid by using a blast of air to cause removal of liquid from the part being dried. Evaporation of liquid is enhanced through the use of heat and the movement of air over the parts.
See: https://techblog.ctgclean.com/2013/05/drying-the-effect-of-temperature-on-relative-humidity

Filament Dryer / Dehydrator
Three Spool Filament Dryer (Dehydrator)

In the post printing image, you have multi-color parts laid out on the build plate, but there's no wipe tower. Is there really a way to print it with that arrangement?

Yes! There IS a wipe tower ;)

OK - I see it now. It's really tiny!

You also understand why? :)

Well, the two color portions are all at the bottom, which explains the height, but I don't know how you got the Y so small...

Hint: Wipe to Object

I'm using Prusa Slicer 2.0, using the .amf files provided. It appears wipe to object is already selected for the spring, but there's still a GIANT wipe tower. Any idea how to change this?

I apologize. I was looking at editer view, not preview.

Ahh yes, I see hints of blue in the spring. Is it really ok to print the spring in PLA?

Apparently yes, as long as you don't dial too high. The 1.02_RC2 versions should perform better though.

This design is brilliant! We have three in operation and the last two stands are printing.

Has anyone come up with a humidity controlled enclosure that works with this auto-rewind spool holder?

We found a remix for using the old version of the spool holder with a Rubbermaid container (very cool), but this new version of the spool holder is too wide to fit.

 - Brad

I was thinking of modifying the spannerhands dry box to accommodate this. It shouldn't be too much work.

Hello Brad,

I took some time to produce some drawings to explain an idea i have for exactly that where you are asking for. Please have a look at the thing I published. https://www.thingiverse.com/thing:3455378

IKEA LACK for Prusa MK3 with MMU2 and 5 spool Dehydrator

Thank you, nice to hear! I don't know about suitable remixes for dry boxes. The Rubbermaid question was asked earlier and I suggested a workaround by scaling the relevant parts along certain axes. It should work although the spring would be a bit weak. I don't know if the experimental spring versions (v1.02_RC2) can be scaled in the same way, but it might be worth a try.

Hey Vincent,

I took some time to produce some drawings to explain an idea i have for exactly that where you are asking for. Please have a look at the thing I published. https://www.thingiverse.com/thing:3455378

IKEA LACK for Prusa MK3 with MMU2 and 5 spool Dehydrator

wmeelberg,

That is a cool "Lack Stack." I really like how the filament tray slides out. The best builders know how to design before they build!

The dehydrator is an clever idea - haven't seen that before. My dad used to dehydrate fruit when I was a kid. Our dehydrator seemed to simply circulate hot air around the fruit and to dry it. I wonder if the concentrated hot air will be compatible with 3D printer filament. In other words, does "dehydrator" = "dehumidifier". Interested to hear how it works out.

Hunting around, I found another solution that uses the IKEA Metod cabinet.

https://shop.prusa3d.com/forum/user-mods-octoprint-enclosures-nozzles--f57/enclosure-with-mk3-mmu2-t27045.html

Wondering if a dehumidifier like this one on Amazon would work well inside the case.

https://www.amazon.com/Pro-Breeze-Electric-Dehumidifier-Portable/dp/B01DC5PPWM/

I printed the SpringFlat_Stiff_v1.02_RC2.STL, in PETG. 0.2mm layers. After looking at where the separation lines are, it's very difficult to get the sprints to separate from each other... RC1, had that web, which made it easier to separate.

While trying to separate the two springs, I ended up snapping the whole spring... I could be the only one... but seeing how RC1 was much easier... RC2 being difficult to get the springs to separate from each other, there just isn't enough room to work with.

First, thanks for sharing your valuable feedback! It is unfortunate that you have troubles in separating the spring parts. Another user had troubles with the bridging in RC1, that's why I made a version that required no bridging. I'll think about creating a version for RC2 with spiderweb support to fix your issue, but it has the drawback that we end up with more and more different versions of the same spring (flat&round, soft&stiff and now also with&without spiderweb support). A different approach might be to print the spring in separate parts and clip them togheter. I will think about it. If you have suggestions, let me know. Meanwhile you could try printing the RC2 spring in PLA, this is easier to separate. Or tweak your PETG printing settings around the interface layers.

Printed the last version yesterday...first thought was that the whole bottom plate and the side only are there for printing reasons and should be removed.. So I bent and cracked a little and the spring got loose...but the center part is still fastened to the bottom plate... Should I just use more force...or is the bottom plate and sides a part of design and supposed to stay in place?

All are part of the design. You can check the layers in your slicer software to find the gaps that are supposed to separate. Hope this helps!

So the center of the spring should remain fastened to the bottomplate while in use? Everything goes in there..? :-)

You are 50% correct! I know it is complicated, but I like to make complicated things. The "spring" in fact consists of two separate springs put in series, connected together at the outside (the next-to-outermost rim). See if you can find the gap to split the spring in two. As for your original qustion: the bottom 50% of the centre of the spring remains fastened to the bottomplate, but the top 50% should be set free.

Good thing to have your own 3D-printer when trying to break apart this..I can just print another one..
:-)

I´ll give it a try!!

Having said that...I really like your work! Thank´s a lot for sharing,,and having the patience with us while answering endless question...

It worked!! :-) I managed to separate it exactly as it was meant!! :-)

Yay! Hope it also works as intended! The clip may be too tight, in that case just leave the clip out to reduce friction.

Hi Vincent,
thanks for your work...
Is there a recommendation which spring to use with PLA - stiff or soft?

Thanks, Henrik

I'd try soft first, keep friction to a minimum and dial low to reduce tension on the spring.

I will test that - thanks for the quick response...

Hi Vincent,
I'm still printing parts for these but need to organise the bearings.

You mention ZZ type but in your pictures, looks like RS.

I understand ZZ type will spin easier so assume they are the best ones to get?

Both are fine! I am using the 608 bearings provided by Prusa.

Thanks Vincent.

First spool holder is now complete and assembled. I will be using these with my MK3 with MMU2 and currently have the spools on top of a cabinet with the festo mod in relation to feed path.

So I'm thinking I'll need to run an additional length of PTFE tube from the auto rewind spool to the end of the PTFE tube from the MMU. I can print out a couple of joiners; I'd rather not have to replace the existing PTFE tubes from the MMU with longer ones so am hoping the use of joiners would work.

In relation to the tube holder, is it just the PTFE tube that keeps it in place as I notice it falls from side to side if trying it in the upright (top of spool) position.

Thanks for your help with all my questions.

Yes, the PTFE tube keeps the tube holder in place. This makes it easier to reposition the spool holder if needed.

I like the design and the idea of your spool holder but I had an issue yesterday while tightening a spool on the hub. I tightened the nut and after some minutes the hub broke. As you can see in the attached picture the material is very thin between the thread and the plate. I think it is not necessary to have a thread until the end. In my opinion, it might be better the stop with the thread 5 to 10mm before the plate and chamfer with a 5 to 10mm radius.

Yes, those walls are quite thin. The thinnest side is approx. 1.6 mm, which still fits four to five standard perimeters. In theory the cross-sectional area and strength should be comparable to that of a solid 30 mm cylinder with three perimeters and maybe 5% infill. Most users (including me) have no problems with tightening spools by hand as tight as possible, so your issue might be related to suboptimal layer bonding. You are not the first one to report breakdown of the hub on that location though, so I will think about adding a reinfoced hub besides the standard one in v1.02. One user already published a remix which includes a reinforced hub: https://www.thingiverse.com/thing:3425043

Remixed spoolholder

Unfortunately I have a broken spring V1.02_RC1. I would say total printing time was 20-25 hours, I had it set at 10 on the dial. I printed the spring from Amazon PLA, I'm thinking next I should try to print in PETG?

Oops! Thanks a lot for sharing these pictures! So let's see, the spring is broken at two locations, first at the outer rim and secondly near the axle shaft. I see two possible causes: 1) the clutch was operating normally but the stresses were too high, or 2) the clutch jammed.

In case of 1) it definitely helps to print the spring in PETG as that material is stronger under stress. On the other hand, I have several very old PLA springs from the small original rewinder (diameter 50 mm) which are still operating fine. So if 1) was really the cause then the dial might have been set a bit too high.

In case of 2) we have to figure out how exactly the clutch jammed. I know that in the v1.0 and v1.01 versions of the spring the clutch can jam if the spring is wound around the axle and pulled too tight, while it should not happen when wound towards the outer rim. Another possibility is that the spring caught a piece of the dial, blocking further movement of the spring, but if it had been operating fine for 20 hours then it seems unlikely to me.

So my conclusion is: yes, try PETG, and set the dial a bit lower than normal (aim for 1.5 rewinding revolutions). Meanwhile we hope to receive feedback from other users as well to see how the spring design can be improved in the existing universal rewinder.

Here are my pics from my first 1.02 version spring showing the support. PETG.

I am currently printing 2 springs in PETG now, I will report back on how those springs work later this week. I was aiming for 2 rewinding revolutions to ensure it pulled all of the slack back from the MMU in order to minimize the possibility of tangles, but I will shoot for 1.5 going forward.

A question about case 2, if the spring jammed, wouldn't that cause the spool to temporarily lock up and then the entire filament stand would be pulled towards the printer until the spring fractured?

I have a feeling PETG will help the issue as they were working fantastic until the fracture, I love the design and functionality.

Are you using the tube holders? If yes then the stand cannot be pulled towards the printer in case of a spring/clutch jam (except if the tube holder itself got loose first). But I hope your PETG spring will work well, especially when dialed not too high.

Meanwhile I modified the instructions, which now mentions to aim for a minimum of 1.5 revolutions (instead 2) plus a warning not to dial it too high.

Yes, I am using the PTFE tube holder, and that makes sense what you've said.

The first 2 PETG springs did not turn out, the bottom half of the springs are beautiful, however the spider web support caused bridging issues on the upper halves of the springs.

I'm trying to print another with the fan turned on full right after layer 18 when the bridging needs to start.

I'll keep you posted.

Just added a new spring (1.02 RC2) which does not need supports or bridging and also performs much better. I printed it in PETG and it turns out fine. Might be worth a try.

Great, I’ll give it a try soon. Thanks!

I finished the first one.
Great construction. Thanks a lot for that.
I have one question though:
How is the tubeholder fixed to the stand?

it just goes onto the axle and is placed on when placing the spool.

Hi Vincent,

Just printing the new spring design now.

Is there an easy way of removing the divider or is it just a matter of going around the spring with a hobby knife to remove it?

Should be easy, no knife needed. Just bend the spring up&down and most part of the divider should pop off.

Thanks Vincent. It was easy to remove - I didn't realise the spring was in 2 sections.

I have a couple of minor imperfections in the print but I'm hoping it will be ok. I used Prusa PETG filament.

Those "imperfections" are normal, the divider is quite minimalistic and not fully supporting the top spring. It should not affect the functionality, but if it does then it should be easy to smoothen it.

I'll print the new spring in the next few days. Hooray!

Vincent, do you have a way that you notify people about designs or updates to designs?

You could try the "Watch" button on this page!

Is PLA OK for all the parts?

Short answer: yes. Long answer: the new spring (1.02_RC1) has not been extensively tested yet as it was uploaded just a few days ago, so I'm not sure. At least the new spring is symmetrical, so it is possible to flip the system around without issues.

Vincent, is the divider in the middle of the new spring supposed to be removed entirely, or just broken free?

The divider acts as support during printing and must be removed.

I printed spring out and getting support out makes spring split in two , is that the right outcome ?

The axle shaft and the outer rim should still be in one piece, connected together by two different springs. So yes the "spring" (actually two different springs) are split, but being connected to axle shaft and rim it should still be a single physical body.

Hi, just want to check that the bottom spring of 1.02_rc2 does not need to be connected to the base? When I was removing the support, the spring split (which is good), but the bottom spring closer to the base was also removed from said base. They're still both connected to the axle shaft and outside rim.

Correct! 1.02_RC2 consists of two springs connected in series. This way you have more rewinding rotations without stressing the material too much. Hope it works!

This design is great except for one little issue, which is that sometimes the filament will come off the spool, especially when the spool is new. I assume it happens when the printer unloads the filament right after the spring slides.
There are no bends in the PTFE but I think I was able to mitigate the issue was to rotate the PTFE holder back so that the filament was entering the tube upward and behind (instead of on top).
It would be nice to have a rail that essentially allowed any loose filament to stay contained within the bounds of the spool.

Thank you for the feedback! I fully acknowledge your issue. If you (or someone else) designs a custom stand with rail as you suggested, then I'll post a link to it here. I myself am currently focusing on the spring following multiple reports of broken springs, so there is a new design (v1.02_RC1) in the files section. This new spring design possibly allows for some extra tension without breaking stuff which might actually be sufficient to solve your issue.

This design should solve that problem:
https://www.thingiverse.com/thing:1940114

You can see it in combination with your auto-rewind spool holder:
https://www.thingiverse.com/thing:3342786

Prusa i3 MK2/S/3 Filament Guide ClipOn
by Area51
Prusa i3 Mk3 top stands for Universal Auto-Rewind Spool Holder by VincentGroenhuis
by Racx

I ran into this as well. The trick for me (on the new springs) was to carefully adjust the tension so that when it slips, it only slips a small amount and doesn't completely unwind. One click can make all the difference.

I find that I need a higher setting (12-13) with the new springs.

I have lots of trouble getting these to work reliably. The adjustments on the springs don't seem to make much difference. The slack falls off the spool then tightens around the axle. I'm using the bearings and I've tried adjustments from 0 to the max. Not sure what I could be doing wrong. Any help is appreciated.

I have lots of trouble getting these to work reliably. The adjustments on the springs don't seem to make much difference. The slack falls off the spool then tightens around the axle. I'm using the bearings and I've tried adjustments from 0 to the max. Not sure what I could be doing wrong. Any help is appreciated.

Do you have a photo of your setup? Sharp bends to the left and right are one possible cause of the problems. Also, did you pre-tension the springs?
I don't have a video of the universal rewinder design yet, but there is one of the original design. Did you do the experiment: https://youtu.be/1Cki6mBVA8s?t=28 ? If yes, how many rewinding revolutions do you get? Does it change at different settings of the dial?

How do you pretension the springs with this design. I am finally using this design on 2 spools but one of the things I really liked about the old design was that I could hold the spool and twist the rewinder to pre-load the tension.

What I do is: put the loose end of the filament through a hole in the rim of the spool and then twist the rewinder (with spool) a few times before feeding the filament in the printer. An alternative way is to first install the spool+filament, next lift the axle from the slot, rotate the axle two turns and put it back in the slot.

i have to join the band of broken springs, it has worked fine and i only needed a tension setting of 7'ish

not sure where it broke but i will try and get it apart while printing and then post a pic

Could you please try one of these? It is a new design which hopefully solves the issue.

will do, it will be the round axle. but it will not be before tomorrow i can print them

pic attached

The new design should prevent this type of cracks.

1.02 RC2 is available in the files section, it is now a serial double spring with good performance.

Hi Vincent, just sharing my experience so far.
I have broken a couple of springs. what i noticed is that for some reason the spring get stuck and then the obvious result is that it fails. i tried to figureout why, but it's not clear to me so far. i tried both wounding in inner and outer direction, but still there is something missing.
I'm also trying another path, using the universal hub with the parametric spring and then add a couple of spacer, similar to what Cabbey did, but both sides so that i can make sure the spool is free to move when the spring goes to the end. it's an hybrid of the two models you created.
if interested i will share my results after some testing.
thanks again
ciao

I will do and give you a feedback.
thanks a lot
ciao

I see. Winding the spring in inner direction results in imbalanced forces and torques on the outer rim which then may get stuck if dialed too high. Winding in outer direction results in high stresses around the axle. I tried to mitigate this by making the spring thicker and by adding reinforcements around the axle, but apparently this is not enough in your case. Maybe grinding the axle, spring and dial might help so that the parts slide more easily; you could also try leaving out the clip to get it running more smoothly. We see from the comments that you are not the only one with this issue. I'd like to have the system fully working for everyone, but apart from some very minor tweaks it is a bit difficult to find the best way forward within the current design philosophy: many ideas require a lot of work and/or a total design overhaul. Your approach to use the 100mm parametric spring combined with a self-constructed slipping element is a good one, I myself tried it as well a week or two ago. Two curved nuts plus one flat nut make for a suitable wedge-shaped space with sufficient friction for the (free-rolling) spool. Make sure that the nuts are well tightened on the hub, otherwise it might again cause jamming and destruction of the parametric spring.

With this design, am I right that the Nut (curved or otherwise) that supports the spool only goes on the side away from the spring? What is supporting the spool on the spring side, just the pressure that the nut is providing?

You can put a nut on the other side as well. A few of my spools work great with a curved nut spun on flat side against the back of the clutch, then another curved nut facing the opposite direction from the far side. However that did not work well for several of my spools, so I've modeled out a set of spacer discs that go inside to support the weight of the spool.

(Note I'm not affiliated with @VincentGroenhuis or the University of Twente or RAM... just a happy user of these spools.)

Spool Hub Spacer
by cabbey

That is exactly what I was expecting would be needed.

On a side note, one thing I always had problems with was when changing a roll, if you rewind and accidental let go of the filament, it will loosen up and can get wound over itself when re tightening. I was envisioning a system that clamped the filament and stopped it flying loose, but don't know how it would work precisely.

There's a relatively cheap and easy solution to that: small binder clips from any office store. :) As soon as the filament comes out of the PTFE tube, it is immediately clipped to the side of the spool. The binder clip doesn't come off again until the spool is reinstalled in the holder and you're ready to insert the end into the PTFE. At which point the clip goes into a small dish of them near the spools... ready to go on the next spool to come out.

Good idea! I usually use the holes along the rim of the spools and have to work around the pieces of filament sticking out. The binder clips can also be printed of course.

Note to self:
Always have it so that the spring is tightening and not loosening. One broken spring later and I now know.

You mean the spring should be wound around the axle and not towards the outer rim? This makes sense as the torques are highest in the center. I read more reports about broken springs, so I guess I may have to adjust the instructions accordingly. The drawback is that winding the spring around the axle causes unbalanced forces on the outer rim which is then deformed to an elliptical shape. Setting the dial too high then leads to a lock-up with again a distaster as result.

I think it makes sense. I think my spring must have snagged somewhere but the extruder has enough power to keep the spool turning which meant that the spring only had one thing to do and it started doubling back on itself. Sorry not explaining it too well. Perhaps the tensioner could also be reversed not that I’ve noticed the tension setting changing. I will keep an eye on it.

Summed up experience's:

i can't dial to 0 nor can i get it to the max mark, the lowest i can get is 2 and the max 13

more number markings would be nice in case the ones you see point to where you cant see them

bearings are a perfect fit, no need for a clip to hold them in place

hub thread and nut thread was a VERY tight fit, PTFE grease from superlube helped

I have checked that my extruder feeds precise 100mm when told so
A single wall cube of 20mm in all directions messure precise 20mm and the wall is precise 0.4mm thick, same width as nozzle

The stop block on the spring is held in place by the friction of the nut on the 8mm threaded rod i use, there is another nut in the other end

in my case it seems that a tension setting right in the middle does the job fine for me

for me the scale is perfect and the threads are really nice. Absolutely no grease required. Maybe you need to check your printer settings.

there is only so many times that you can check and recheck settings before it would be called insanity

All I can say is that the threads are some of the best threads I've seen, the "nut" just spins straight onto the thread. I've printed 3 of these things now and they have all been perfect.

Good luck finding the answer.

I have the exact same experience..

i can say that i have tried a single wall cube and the wall comes out precise 0.4mm thick as they should
i have made sure extruder feeds precisely 100mm when asked to

i have checked everythig to the "fly fu**'ing" level as we say here in DK

and if you read some of my post i kind of hinted that i will replace the cooling fan to a 5020 that should push a lot more air than the current 5010

:-D

Try printing a 3DBenchy. Lots of overhangs to challenge your printer. Good chance that the result won't be as smooth as standard Prusa ones with its huge radial fan blowers.

hmmm i looked arround to see what prusa uses on the mk3

seems like they use a 75xx fan

i have a 7515 fan but the duct i use needs some modding and i'm not that good with 3d modelling, even thou my extruder has a step file for each of the fan duct options

i'm told its easy to mod a step file, but my brain do not agree at all

yep, allready done and what i found is that i can barely get by with 0.2mm layers, anything less and the overhangs suffer, the thinner the layers the more they suffer and i get a tiny amount of stringing

so yes the radial blower i have (5010) is not good enough so i'm hunting down a 5020 instead, and my extruder mount allready have a fan duct for that, i'm using this one for extruder mount: https://www.thingiverse.com/thing:2065461

Prusa i3 MK2 Upgrade kit for E3D Titan Extruder by S±E

Thank you for posting your make and it is good to hear that it works! So locking the spring to the axle is easier than I thought, with just a pair of nuts and nothing else.

At the moment I don't know exactly why your hub and nut are so tight. One possibility is the steep slope of the overhangs (60 deg) in the threads. If your printer has suboptimal part cooling then it causes these overhangs to sag a tiny little bit. Setting fan to max and some overhang printing optimizations might help here.

A workaround is to scale the nuts to 101-102% in X and Y directions, adding 0.15 mm of additional horizontal clearance all way around for each percent increase.

the ziptie can do the trick at low tension settings but will not hold the spring at higher settings, so settings are lowered

not so much rewind pull but i think it will do the trick

so if anything a version of the round spring with a small hole in the stop block, or a small dent so the drill bit will not walk away

well the fan is allready running at 100% so if anything the fan i have is just not blowing enough, its a 5010 and i do in fact plan to upgrade to a 5020 instead

i spoke to fast on fixing the sprint to the axle, the nuts compress the spring to the dial/clutch part and hence the whole thing rotates... i will try with a simple zip tie and if that does not do the trick i will drill a 2.5mm hole and use a 3mm bolt as a set screw

Prusa uses a radial blower fan which is much more powerful than a 5010, this could indeed make the difference in overhang quality.
Fixing the spring to the bolt: I think the best way is to make a part which interlocks with both the spring and the nut. Some solid object with 8mm hole through-all for the axle, a hexagonal cutout for the nut and a rectangular cutout for the stop block. Fixing the nut to the rod is the last step which is very easy.

give me a few days to thinker with the idea... for now the zip tie at low tension does the trick

not elegant but works :-D

yeah, it has to be thought through so that you dont end up pushing the pring towards the hub, it has to be able to rotate as freely as if i held the stop block with my finger, but your idea is food for thought, i might end up doing something similar

maybe a metal nut in the other end and a solid block with a cutout for the stop block and i think instead of a nut i will use a set screw of some sorts,

Sorry Vincent, I don't know WTF I'm doing wrong. The filament on the fuller spools is going everywhere except back onto the reel, it's just not rewinding sufficiently. Am I supposed to have it tighter (higher number) on full reels, or looser (low number)? I've tried both & neither seem to make much of a difference. At least the PETG springs haven't broken yet.

The system might work for a little while, then I come back to it & filament is everywhere! Any assistance would be great, thx.

Thanks guys, I understand what you're talking about Vincent, but as you can see, I'm rather limited for space.

I will experiment with different filament placement & go from there. Thanks again!

It is not your fault, it is because of the sharp 90 degree turn to the left which causes the filament to twist (to follow the bend). During rewinding the twisted filament is strong enough to push itself off the spool as you see. One solution is to rearrange the spool setup so that the paths are straight and you only have up/down bends and very little sideways bends. Another solution is to install very long filament tubes, so that these curve very gently. You could also experiment with stronger springs but I don't know if it would work for you.

All I did was move the spools to make an 'arc' around the MMU so the PTFE tubes are straight(ish) & so far so good. I can't believe something so simple can make such a difference, it makes so much sense now. Thank you!

also the direction that the spool rotates has a say in how it should be setup, look at end of instructions

have you tensioned the spring? when the printer pulls on the filament it tensions the spring, but if that is not done enough there is not enough tension to pull it back

Hi,
Thankyou for a great design & its working well.
I have a problem with the spools size as my new filament have wider spool openings. Can you create larger nuts or advise how to customize the nuts. The new spools i have a centre width of 73mm & the curved nut is cracking so not holding the spool securely.
Thanks

A curved XL nut is provided in the files section which easily fits your 73mm spool!

in the description you find a link where you can put in your own numbers

takes 10 sec to find :-D

https://www.thingiverse.com/thing:3252111

Parametric Auto-Rewind Spool Holder

I had already checked that link & as Vincent points out there is no customiser for the nut. Check your facts :-D

There is no customizer for the nut in this link...

Thankyou Vincent....
i missed that as i was using the gcodes you had supplied & had not downloaded all the files from this post.

Hi, has anyone made a Creality Ender 3 stand for this?

Thanks

Hey Vincent

This is amazing. Works perfect! Printed mmu in black and white petg and it looks pro! Thanks for sharing this.

Flynn

Thank you! I read that the universal rewinder is not a perfect solution yet as some users report issues like broken springs etc, so it is good to hear that it does work in most cases like yours!

Hey Vincent,

I am using five of this spoolholders and they work great! I've printed them in PLA+ and the springs in REAL PETG but today to of the springs snapped right in the center where the first rotation would start. What infill do you use to prevent this?

Thanks!

Did you check the functioning of the clutch? it should start slipping after about 2-3 rotations and not much higher, otherwise the material stresses get too high. You could also try reversing the rotation direction (and recalibrate) to let the spring rewind around the axle instead, just to try.

Pity that two springs broke down! I use three perimeters and 10% infill. You are not the only one with this issue. will look into it.

i would say that the infill does not matter much since most of the spring are perimiters anyway

maybe make the spring thicker? not sure if that would work well, but just a thought

Ciao Vincent, i'm trying to reproduce the thread in fusion 360 to create a different Nut. I'm struggling to find the right thread type. would be possible for you to share the exact hub diameter and thread type ? thanks again for sharing this. ciao

Of course! 30 mm diameter, 4 mm pitch, ISO type thread.

thanks. looks like Fusion doesn't have this option. max is M30x3.5. what do you use to model it ?
thanks again

If you model the part at half height, then thread a hole with M30x2, then apply a 2x resize on the axis the hole follows you'll get M30x4. I did that last night and left a part to print, this morning it spun on perfectly. (I'll be uploading a "remix" with a variety of spool centering rings sometime today I hope.)

Edit to note VincentGroenhuis points out this will put the bearing surfaces quite out of whack, see thread below for better numbers to plug into the above idea.

Good idea! The perfectionist might say that the angles as defined by the ISO thread profile (60 deg) are not preserved when scaling in Z only, but if it works then it works. A more accurate alternative (if needed) is to use M30x3.5 and scale Z by a factor 1.142857.

hmm... good point, I hadn't thought about the impact to the bearing surfaces last night, just did it in a way to make easy math. ;)

I just altered my drawing to use that approach (extrude at final height divided by 3.5/4, thread with M30x3.5, scale Z by 3.5/4) and the resulting threads still match the imported stl from the flat nut, so looks good!

Edit to add: they're live now

Spool Hub Spacer
by cabbey

I use Solidworks, create a 30 mm rod and make a 4 mm pitch ISO thread profile on it. It is not a typical thread size of course, hopefully you can find a workaround in Fusion!

thanks Cabbey, Vincent. i will try tonight!! ciao

Hey, i tried printing the spring but my printer wouldn't do it. I printed out the other parts that worked fine. But when printing the spring flat v1.01 he wouldn't go past the first layer. He kept repeating the same movements but he didn't go up a layer and did not printed out any fillament. So stuck in first layer. I imagine it is a slicer problem. I am using Cura 3.6.0. My printer is a Anet A6

also, the Spring is printing in an oval. I did some more research on this and found some answers but it still hapens. it apears that the model is just oval. since a other part i printed at the same time is perfect round

I'm having the exact same problem. Did you figure it out and, if yes, could you help me by telling us how? Thanks.

Try the RC5 design, this is easier to slice and works better than the original one.

That is very strange. Could you try a different slicer?

Do you have any slicer recommendations?

Slic3r, both stock and the Prusa Edition, slice the springs fine, just slowly. (On a 4 year old mac book pro it takes about 10 minutes to slice the spring and clutch.)

Do you have any slicer reconmondations?

I just installed Ultimaker Cura 3.6.0 and the spring slices just fine at default settings. You can check the projected output in the layer view, does it look circular or oval-shaped?

Just wanted to give you an update. I finally got all the parts printed & gave a MMU print a go. Everything was going great & then about 25% into the print, two of the springs (printed in PLA) broke around the centre axle. I am reprinting all the springs in PETG instead which should hopefully be much stronger.

The one's that broke had relatively full spools of filament on them if that makes any difference.

What was the setting of the dials? Do you think lowering them would have preserved the springs and still give sufficient rewinding revolutions?

IIRC, it was set at around 10. Any less than that & it wouldn't rewind much at all.

Apparently the centre of the axle has too high stress. What about flipping the stand so that the spring is in the other side and rewinds around the axle?

In your case I'd also do a filament strength test, to narrow down the search for possible causes.

you can replace the spring with a propper metal spring and you could a heck of alot more then 4 full rotations

not needed, the spring included is plenty good enough and you dont need 4 rewind rotations

What to do with all those extra rotations?!

@VincentGroenhuis , great job thanks. i'm using this on a different stand an i would like to use the dual knob also with 88mm spools, but i cannot due to the actual length of the hub. are you planning a 100mm length version ? thanks

The 3 kg spool stand thing has a longer hub (over 100 mm). You can also generate your own hubs with the customizer of the parametric rewinder thing.

Found!! thanks a lot. ciao

Hi Vincent, i printed the 107mm hub from the large spool, but the clutch and also the spring size , taken from the universal, don't fit.Both are too small in diameter. In the large spool i don't see those elements. am i missing something? thanks again

Never mind..my fault. i tried to assemble too early in the morning..) ciao

@VincentGroenhuis i wonder if this could be modded to work on other spoolholders also?

on my Mendel90 i have an 8mm threaded rod and i use this one: https://www.thingiverse.com/thing:767317

problem is that when the nozzle goes down to the bed it pulls filament off the spool fine, but after print i home the Z up to get it out of the way, but the spool does not rewind automatic and over time it becomes a mess

so i'm looking for something that can rewind a bit automatic but still be on a 8mm rod

EDIT: you said this 2 days ago: "All rewinding spool holders designs use the same axle size (8 mm) and accept both round metal axles and 3d printed flat axles."

so i guess i'm good, just wanted to be sure before i start printing out parts :-D

Parametric universal spool holder
by rowokii

Yes it should be possible. Print SpringRound and see if you can fix the stop block somehow. All other parts are used in the same way as the normal spool holder.

i guess the "stop block" is the part of the spring that is highest when printing?

are the parts as step files inside on of the zip's? if so i could pull them in F360 and figure how to solve it before print

1) yes, 2) no I did not include STEP files, only STL and .AMF. If you need a STEP file of SpringRound then I can export it for you.

think i got it

where the assembly instructions say insert axle that mens i slide in my 8mm metal/threaded rod

but what is the purpose of the clip? to hold in the bearing?

i think i have a few ideas on how to fix the stop block, make a 2.5mm hole in it and make threads for a small 3mm bolt

but i will thinker with the idea, i might also get a plastic storage box and just place the spool holder as you made them inside so i can keep it try

its funny how one idea can make other idea's pop up

at any rate if you are going to make new versions of this one that can sit on a metal rod by itself could be usefull, not for me alone but also for others

Clip: yes, it is to keep the bearing in place! Looking forward to see your solution. Others also combined this rewinder with storage boxes, see the parametric rewinder page.

will give this a go tomorrow, to be sure i need to print these parts right?

clutch
dial
hub
nut curved xl
spring round

thanks, will give it a go tomorrow :-D
i assume that i use to of the curved xl nuts? or does one side have to be the normal nut?

Depends on your spool dimensions and rotation direction (CCW as seen from nut/open side needs an additional locking nut). Just experiment what works best.

i got a tube of ptfe grease from superlube, that and carefully turned on the nut made it go fine

i guess there was a blob in the nut threaded that made it go tight

after half of the nut was on it got better and only at the end of the hub thread it got tight again

will check if i need a nut more and then i will write a combined post of my findings, but the clutch works but with limited range on the dial

no broken spring

so first curved nut xl printed, the hub is from https://www.thingiverse.com/thing:3369189 Hub_107mm_A7.stl

the nut goes on about 1 turn before it locks up completely

are there a way to "fiddle" with the parametric one so its just a fraction more loose?

Large stand for 3 kg spools on Universal Auto-Rewind Spool Holder

So got the clutch, dial, spring and hub printed

the only "bad" experience is that i can't dial to 0 nor can i get it to the max mark

the lowest i can get is 2 and the max 13

and i would agree with another that said it would be better with 2 set of number markings on the dial so the numbers can be more easy seen
if possible have 4 set of marking spaced evenly on the dial

the good thing is that the bearings are a perfect fit, no need for a clip to hold them in place

i will try and see if i cant picture it in my head first

Sounds all good! If nut is too tight: you may be overextruding or having difficulties in printing the steep overhangs of the thread (try increased cooling). You could try grinding down the threads with some coarse sand paper if you know the difficult spots.
If you cannot dial lower than 2 or higher than 13 then it is another sign that you may be overextruding. I'd print a calibration cube or equivalent and measure the actual dimensions as precisely as possible, this will also improve your future prints.

hehe, funnt you mention the cube thing, that is the first thing after i have done anything to the printer

or if i change filament or change slicer settings

i just hope that things work as they are

now i just need to figure how to fix it to the threaded rod, most likely i will drill a 2.5mm hole and tap threads for M3 and use a small 3mm bolt as a set screw

Having worked with these awesome spools for a few days of non-stop printing now, I'd like to suggest an edit for whenever you do a new version. Please replicate the tension indicator 2 or 3 times around the diameter of the clutch and the pointer around the dial. It seems like every time I need to adjust the tension setting the dial is on the opposite side of the spool from where I'm working. I think once or twice maybe it's been in the right place to see it.

In order to maintain symmetry I would have to replicate it four more times (five total). Not sure if I will do that, it would get a bit cluttered. Adding just one at opposite side would make assembly ambigious, also not sure if this is a good idea.

4 indicators spaced evenly on the dial would be ok, not sure why there should be 5?

Because of the 5 fins on the dial that insert into the clutches. In order for the indicator to work correctly you need the fin to be a the correct spot in the clutch when the indicator pin on the dial is aligned with the correct number on the clutch. If there are 5 then you can rotate it however you want, they'll all align correctly all the time. With only 1 pin it's also easy, only 1 of the 5 ways you can put the fins into the clutch will result in the indicator pin even on the number range on the clutch, making it very easy to see if it's correct before you snap things together. But if you have any other number of arrangements, then you have a 4 in 5 (80%) chance of not getting it aligned correctly and the indicator pointing to an incorrect number, or possibly not even being in a number range. With 4 indicators there's a very high likelihood of putting it on wrong. With 2 indicators there's a reasonable chance you'll be able to tell it's not right to begin with... but it would make the directions much more complex.

But the position of the fin is in relation to the number on the scale. It doesn’t matter how many scales you have, they will all read the same number and therefore the fin will be in the same place no matter which scale you set it with.

It's not the position of the 5 fins that engage the clutch that is the problem, it's the position of the 1 pointer that is. The ratio of pointers to fins being other than 1:1 or 1:5 is problematic.

I can't see how that makes any difference either. The pointer bears no relation to the tabs that engage the clutch. You could have 100 pointers if you wanted.

Actually the pointer has a very direct bearing on the tabs that engage the clutch... it is indicating what position in the clutch slot the tab is at.

100 is divisible by 5, yes, but the adjustment range of one dial is larger than 1/100th of a full circle. So you would end up with multiple pointers on the same dial. The technology may be advanced, but it is still no quantum mechanics... :)

of course.... did not think of that :-/ had a washing machine blow out smoke from the electronics so have had my mind another place

3 Pointed dial and clutch

Those are very good points. I didn't think about what having 3 indicators and 5 tabs would do to the assembly instructions. In the end I just used a fine point sharpie to transfer one set of markings 180º around the clutch plate. (well, more like 175º, I put the indicator in the flat bit between two of the bumps.)

I cant find the multi color stl's for use with mmu2 or palette2. Are you only releasing multi color gcodes only?

Check Parts_MM_v1.01.zip to get the multicolor STLs for each part.
Or use UniversalAutoRewinder_v1.01_MM.zip.amf , you should be able to open this in Slic3r (PE) and see the individual multicolor objects. Same for Stand_RewindTime_MM_v1.01.zip.amf . Does this work for you?

zip within a zip.....missed that sorry....

Just a quick question , is the tube holder suppose to be open ? I seen you did two version and there was a blue strip in the middle of fork ..

Is optional, it makes swapping spools easier if tube holder is installed under the spool.

Any tricks to get more tension , I load spring , but it doesn't want to backwind when MMU unloads, any Ideals ? With spool on it it will spin back and forth ..

Could you send a photo of your setup?

Thanks for uploading the pictures! Very easy now to spot the issues.
1) The tube holder causes problems if you do not use a tube at all. So leave the tube holder out.
2) Spring/clutch system works better if wound in the other direction. So rotate the setup 180 degrees. Do not set dial too high, otherwise the clutch cannot slip.

Just to clarify your point 2 here... the spring/clutch works best if the spring is pushing to the outer diameter when under tension?

I took tube off to see if that was causing a issue , not sure what you mean 180 deg (having it pull from top ?) Can you send picture on way you think it should be .. Thank you

I just mean, put the spring on the other side of the spool.

I just made assembly instructions a bit clearer on point 1.

Hi! This is a great design. Any chance of you doing a wall mount holder so I can bolt these to the wall?

There are a number of wall mount stands on the parametric rewinder page. Look at https://www.thingiverse.com/thing:3227387 , https://www.thingiverse.com/thing:3268015 and https://www.thingiverse.com/thing:3291542

Screw-down tabletop, wall, and ceiling mounted axle stands for MMU2 Auto Rewind Spool Holder
Hanging Holder for Parametric Auto-Rewind Spool Holder
MMU Spoolholder for Stuva / Besta

Oh Ok. Sorry about that. I wasn't sure if the axle/pin would fit these.

Which axle to use depends on the specific stand. Just check the designs, print and experiment. All rewinding spool holders designs use the same axle size (8 mm) and accept both round metal axles and 3d printed flat axles.

Thanks for helping us to solve space issue with MMU2, great job!

In your “Post-Printing” Summary, under Pict #3, you mention: “Insert spring, note the correct orientation (spring shaft pointing down)”

If you use a 608zz bearing as mentioned under Pict #4, there is no space for extra spring axe size?

I think we should have the same spring shaft height as the spring itself to fit in the space remaining when the bearing is inserted.

Am I wrong?

andsta

You have to turn the spring upside-down! Yes, the instructions were a bit unclear so I changed the last sentence to "Insert spring, note the correct orientation (spring shaft going through the dial)".

Feedback:

1) Excellent
2) Spool shaft needs strengthening have attached -- patch in slic3r
3) First layer, it would print easier if the numbers started on the next layer (if you have mediocre adhesion this whole part will fail) -- I was not able to patch in slic3r
4) A lot of thin parts that can break easily. Another place that could use reinforcement is the tabs that go into the clutch.

1) Thanks!
2) Could you upload it as a new model (remix), then I'll link to it from the main page! I cannot replace the original hub as some users use a curved nut adjacent to the hub backplate to keep a large spool centered.
3) You are right, I will consider your suggestion in a next revision.
4) Did those parts break off during actual use, or before/during assembly? Together with 2) I guess that your printer's layer bonding is suboptimal and could be improved (slower speed, more heat, lower fan, new/dry filament etc). You are not the first to report this issue, but in my printed parts the tabs are quite strong.

(2) I don't have an actual model, just a patch. I made a small torus (40mm tall 10mm thick, inner radius 22.5mm I believe) and then put a chamfer on it. I placed that as an extra object for the slicer to handle. It's not perfect, but it's practical. The space it patches is very thin, just a mm or two, it has broken on pretty much every model if I am not careful by either dropping the part, or either tightening the spool moderately.

(4) The tabs break when handling them during assembly, they are fine in actual use. But I have had several of them break. They are thin in the direction they do not receive stress, but they pop right off if they do. They are only about 1mm thick, even a bump of 0.5mm would improve strength substantially. (My understanding is that it varies as a cube, so 50% thicker is more than 3 times stronger).

Is it possible to export these as step? I can more likely make the edits you request then. I can't edit STL in my cad software (which is why I went for the cheap patch in slic3r). I see what you mean if you have a really heavy spool you'd want the thread to go all the way to the end. However, you have some other options to make sure that the bearing hole doesn't cut so close to the threading. (One is to make the thread even larger inner diameter). I'm sure you'd know better, since you've gotten this far with the design. Once again, kudos!

p.s. the stand is also a bit thin near the top and has been a breaking p