Parametric Auto-Rewind Spool Holder  

Re: Parametric Auto-Rewind Spool Holder

Um, that's on backwards, isn't it?

I super like the idea. Do you have a feeling for how long it holds up (have you emptied any rolls of filament yet)?

I worry a bit about the load of rotating the whole kg quickly on load/unloads. Actually, thinking about it, it's only loads - the spring does some/most of the pushing on rewind, but you might have to slow loads down.

I'll try to give this a shot.

Have you checked into designing something using metal springs? I would GLADLY spend a dollar or two to have a flawless rewinder, but don't know if it's needed.

Re: Parametric Auto-Rewind Spool Holder

What do you mean with backwards? I've been happily using the original spool rewinders which have much smaller springs, and yes I've almost emptied a few rolls without issues. No need to worry about loads, there are two 608zz bearings to transfer the weight to the axle. Metal springs are not needed, PLA or PETG is perfectly fine. 100mm springs are a massive overkill for a typical MMU2 setup, but it is fun to have and play with it!

Re: Parametric Auto-Rewind Spool Holder

Backwards because the filament comes off the top of the roll, and the spring is set up to wind with the filament coming off the roll, not towards the little "outlet" hole at the bottom of the holder/stand, or is that hole not used? I assumed it was similar to the Prusa setup with a PTFE tube coming into the bottom of that stand.

Qibbles over the picture aside, what would you recommend someone use? I would *really* like to get the set up to be close to as narrow as the spool for putting them in enclosed boxes, it seems like you're pretty close to that with the smaller springs?

Re: Parametric Auto-Rewind Spool Holder

Hi Vincent,

I'm missing something ? what appens when during a long print the spring reaches is maximun tension, how did you manage the constant filament feed ?

Re: Parametric Auto-Rewind Spool Holder

It's a balance between the spring tension, and the friction between the spool and the holder. Once the spring gets enough tension, the spoolholder "axle" stays fairly stationary, like a normal spoolholder, and the spool rotates around that.

Re: Parametric Auto-Rewind Spool Holder

I'll admit to being a bit skeptical when I first saw this as I did not see how the friction would work out correctly to accomplish three separate goals.

It has to have high enough friction between the spool and hub to wind the spring as the printer is pulling filament.
But, the friction has to be low enough to allow the spool to slip on the hub once the spring is completely wound.
Finally, once the printer kicks ejects filament, the hub has to have enough of a grip on the spool to allow the stored energy in the spring to wind the filament back in.

But, the appeal of this solution is so high, I had to give it a try and printed on instance overnight last night.

It works amazingly well! I would strongly recommend this solution to others.

I have not tried the adapter for my larger diameter spools yet, but cannot see a reason that will not work also.

This is great work Vincent.

Re: Parametric Auto-Rewind Spool Holder

Just wanted to tell you that I find your design really ingenious. I am limited in space so this will really come in handy. I already printed one holder set and lasercut a holder for it and it seems to work well.

Thanks for sharing!

Re: Parametric Auto-Rewind Spool Holder

Thanks for all the positive feedback! Good to hear that it does work as intended.

About first question ("backwards"): I do not use the small hole at the bottom. An earlier photo of my setup is shown in attachment, using old style compact spool holders.

I also printed a bunch of new style spool holders but do not have matching stands for many of them yet, so I guess someone has to design a parametric stand generator!

Re: Parametric Auto-Rewind Spool Holder

I might add that it works "backwards" just fine. I.e., unwinding the spring instead of winding it while feeding. It might be beneficial to swap them around from time to time to re-tension the spring.

Re: Parametric Auto-Rewind Spool Holder

Great idea.

Re: Parametric Auto-Rewind Spool Holder

well i took the time to print one out for testing. for me it didn't work. It caused problems I didn't have with the pmeyer spool holders so i went back to them. there are many factors i can see that may of contributed to my problems a big issue is the large amount of time required to output these and if there is a problem then you have to start all over.

Re: Parametric Auto-Rewind Spool Holder

What issues did you encounter? If Paul Meyer's setup is working fine for you, then it is of course most logical to stick to that setup anyway! (If it works, don't change it =) )

Re: Parametric Auto-Rewind Spool Holder

some issues.

related to the spool holders: which are not related to the Auto-rewind spool. (these are separate items)

i had to custom create the spool holder as the wide version in the link for it was still about 12mm too narrow and caused binding on the hub. The pivot for the TPFE tube kept falling out. The spool design was very weak had wobble, i wasn't happy with them, again these are made by a different person from the auto rewind spool holders.

The auto rewind spools. I used 602 bearings.
The auto-rewind never seemed to have enough power to actually rewind the filament. It worked better when the spool was full verse half full or empty. It seemed to be worse with a lighter spool where the material was 1/2 used. the spool would slip on the hub and the spring would unwind. the hub was pretty tight on the spool but you still need some clearance to be able to remove the spool. so when it kind of worked it would have very little power (even when i tired to rewind it 5 times by hand) to pull the filament back to take up the slack.
so i could see you needed to figure out a delicate balance between everything to try and get the tension just right so it would suck back the extra filament but also stay weak on the retract because it could cause MMU issues.

Again i could sit there for a while fiddling with the creation settings but it was like over 20 hours on the printer between the spool holder and the hub. the design is cool but you just start adding in more and more possible issues that need to be tuned and the only issue with the pmeyer spools is do to the prusa 'L' lock and the clearance between the PTFE tube you can get a filament snap because the bend is a little too tight there. (i had the filament snap a few times now).

i figured i would try it and thanks for designing it and posting it for the community to use.

Re: Parametric Auto-Rewind Spool Holder

I made designed a holder for 5 Spools that fits my Ikea enclosure

Parametric Spool for 80 mm wide spools, Spring 120 x 8mm (should give more rotatations at lower force)

I changed the axle to 2 cone shaped hubs for easier install of the spools. Friction keeps them from rotating.

Width of each "unit" is 105 mm. Total width is 533 mm.

Re: Parametric Auto-Rewind Spool Holder

That's awesome Maximilian, im gonna follow this post because I think that would fit my needs perfectly for my Ikea Stuva enclosure.

Will you be uploading it to thingiverse or providing it to the community here in a zip file at later date

Thank you

Kerry

Re: Parametric Auto-Rewind Spool Holder

I will change some details and then post it on Thingiverse.

btw. i designed it for MY Stuva Cabinet.. 😎

Re: Parametric Auto-Rewind Spool Holder

I did something usable during my lunch brake:

https://shop.prusa3d.com/forum/user-mods-octoprint-enclosures-nozzles--f57/spoolholder-for-stuva-besta-enclosure-t26578.html

https://www.thingiverse.com/thing:3291542

Re: Parametric Auto-Rewind Spool Holder

The auto rewind spools. I used 602 bearings.

602 bearings have a 2mm inner diameter! What axle did you use? I'd love to learn more about its material!

i had to custom create the spool holder as the wide version in the link for it was still about 12mm too narrow and caused binding on the hub.

This one is larger, stronger, heavier: https://www.thingiverse.com/thing:3283045

The auto-rewind never seemed to have enough power to actually rewind the filament. It worked better when the spool was full verse half full or empty. It seemed to be worse with a lighter spool where the material was 1/2 used. the spool would slip on the hub and the spring would unwind. the hub was pretty tight on the spool but you still need some clearance to be able to remove the spool. so when it kind of worked it would have very little power (even when i tired to rewind it 5 times by hand) to pull the filament back to take up the slack.
so i could see you needed to figure out a delicate balance between everything to try and get the tension just right so it would suck back the extra filament but also stay weak on the retract because it could cause MMU issues.

The hub blade springs should press against the spool for some added friction (besides gravity alone). Even with a nearly empty spool the hub should rewind multiple revolutions. Did you enter the correct parameters (spool width and diameter) in the customizer? If not, then you should apply some tape around the hub to increase the friction like in the original version of the auto-rewind spool holder.

Re: Parametric Auto-Rewind Spool Holder

The auto rewind spools. I used 602 bearings.
The auto-rewind never seemed to have enough power to actually rewind the filament. It worked better when the spool was full verse half full or empty. It seemed to be worse with a lighter spool where the material was 1/2 used. the spool would slip on the hub and the spring would unwind. the hub was pretty tight on the spool but you still need some clearance to be able to remove the spool. so when it kind of worked it would have very little power (even when i tired to rewind it 5 times by hand) to pull the filament back to take up the slack.

I think a metal spring might help? There's a lot you can do with printing, but in my experience printed springs work but only barely.

Has anyone got a feeling on what spinning the spool up to speed on load does? That's one thing I notice on my printer, in calibrating the feed distance, if there's a lot of tension on the spool (or you're loading very fast), the tension matters. If I have slack on the line it loads a lot more easily,

The proof is in the pudding, if it's working, awesome, but I'm curious what folks' experiences have been.