Hey! This thing is still a Work in Progress. Files, instructions, and other stuff might change!

RepRewind - Auto-Rewind Spool Holder for The Repbox and Repbox 2

by jterranella Mar 27, 2019
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I was able to make a stiffer spring using version 5_3 of Vincent's Integrated rewinder scad using the following settings:

universalRewinderSpring = true;
rewinderDiameter = 88;
rewinderLength = 6;
springBladeThickness = 1.4;
springBladeCount = 2;
axleConnectionDiameter = 11.8;
springFlatShaftLength = 2.75;
springAlternate = true;
reverseSprings = true;
axleClearance = .2;

I did have to use supports on the build plate when printing the spring, but they were relatively easy to remove.

With this version, my 1 kilo roll of prusament can do 3 rewind revolutions!

I've printed the 75mm width version out, and it's only able to auto-rewind maybe 1/4th revolution. I used prusament pla for the spring, it's a pretty clean print, with 80% infill and 3 perimeters, and rectalinear infill.

Has anyone had better luck with either the stiff spring from the universal winder, or using the integrated rewinder listed below, but modified to fit with the reprewind stand so it can fit inside a repbox 2?

Also, bumping this to the top: Don't use the textured plate to print the cover, it makes the friction too high. And the clutch listed below by mikekscholz is a better fit than the provided one.

Comments deleted.

Integrated rewinder is now available: https://www.thingiverse.com/thing:3781815
You can tune the parameters in the SCAD file to make a compact and powerful rewinder with efficient use of the available space.

Integrated Auto-Rewind Spool Holder

There's one little problem. I've printed this out and I think your integrated rewinder is perfect. However, the RepRewind stand uses a different axle...one with smaller diameter (in both the circular and the flattened dimensions, smaller by about .75mm-.85mm). One of my axles barely grips...the other doesn't at all. @jterranella was there a reason to use a smaller diameter axle (and also to change the grooves?

cmmtchll, did you figure out what the fix was for the small axle? Did you size the supplied one up, or did you adjust the hole dimensions in the scad?

It is easy to adjust the axle hole dimensions in the scad file of the integrated rewinder. There are parameters for axle diameter (default 8.0) and axle clearance (default 0.3). If you need to change the position of the flat side then you have to adjust line 573 of the code. I haven't printed the RepRewind myself so can't give more specific instructions here.

Interestingly, I was coming back here to ask the same question of JMT. I ended up just using JMT's spool axle bumped up a few % in two dimensions, keeping the total length the same, and using a knife to work on the notch. I'd like to get the CAD file and edit it for my other 4 spool holders. But this might be helpful to start if you can read a 3mf file. This was generated from PrusaSlicer, but current not set for a Prusa printer, but my RailCore.

Those who've printed this: Are you printing the crossbeams standing up? Or do you lay them down on the flat side? If standing up, do you find you need a brim?

Print them laying down w/support. Do not print them standing up. Not very strong when printed that way and WAY more support/bridging required.

I fixed your clutch and added the tapered edge back that you lost by doing a simple cut. the dial fits properly now,

Has anyone used the new files for having this rewinder in a Repbox 2 with the wider Prusament roles? The tolerances is on the axle are WAY too tight, not to mention under diameter. The clutch hub cover rubs against the inside of the stand and is too much friction for it to return.

So, couple issues. First, if you have a textured bed, DO NOT use it for the clutch cover piece. That added thickness, plus texture, equal non-useable friction. Second, I did have the nut a touch too tight.

Request, the axle does need to be increased in diameter. There is so much play in it that it can turn and wedge itself in at about 45 degrees.

Yea I thought I was going nuts, person below made a thicker one, I'm printing now.

His works, but not long enough for Repbox2 and the Prusa rolls. I made some edits to it last night, printing today and if it works I will put it up.

Whats the recommended layer height?

Whatever you like. I used 0.2

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Do NOT print standing up. The support is for the counter sunk bolt holes.

For the bearings, why Remove the guards & grease?

Will allow spinning with less torque. These bearings are designed to have a good amount of weight on them, hence the grease and guards. We are not putting over a kilo and a half on them so removing the grease allows the bearing to spin more freely for our purposes. You can use a very light machine oil instead of the grease.

After soaking them for 48 hours do we just leave the guards off?

Got one printed and assembled. The axle is very loose in the 608 bearings and the spring center. So loose it spins in the spring center. The axle diameter is only 7mm. Would you mind releasing the CAD files so I don't have to redraw it? Side note: have you thought about going to a electronic driven system for the repbox? Like a driven roller system?

Edit: I made it anyway, this one fits a lot better. STL and fusion 360 files attached.

Is there a rough estimate for a holder that will support wider spools? Many of my spools are too wide for this holder, and I don't think any other solutions currently available fits the Repbox

No estimate. Still working on a design that works reliably with at least 98% repeatability. But I am still working on it actively. I hope to have something within the month.

Sounds good. Thanks for the update

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For the spring, have you tested different infill patterns to see what impact they have on durability and... springiness? My gut says concentric may be better, but I'm no engineer.

The spring is so thin that if you print it with the proper amount of perimeters it should be relatively solid.

Good point, I should've realized that.

I'm pretty limited on space. So, I have to have my RepBox installed above my printer. I've actually modified my RepBox to have holes for the filament on the bottom, one set near the front and another set near the back of the box. Already printed everything and set them up outside the box. I'm unsure of how I should run the filament... Should I run PTFE tubes directly from my MMUv2 to the RepBox?

I do. I have the PTFE running out of the box straight to the back of the MMU2. I also printed the pass though adaptor that uses the M10 push fittings to make it easier to connect and disconnect from the MMU2.

I found the files I downloaded, the axle is about 2MM too small in diameter to fit the springs slot. I have to resize it to about 105% to get it to fit.

It intentionally fits loosely, but shouldn't cause any issues at 100%

Why have the bearing in the design if they are not engaged? Insert a plastic replacement instead.

The bearings are engaged

Awesome work! Will your setup work with RepBox Ver.1 and five spools? Just checking before I start printing 5 sets for my MMU2.

It works with V1 and V1.5 with five spools under 67mm width per spool.

what are the merits, that set this design apart from https://www.thingiverse.com/thing:3252111 and https://www.thingiverse.com/thing:3338467 ?

Parametric Auto-Rewind Spool Holder
Universal Auto-Rewind Spool Holder

The design of the rewinder mechanism is much thinner to be able to go in the repbox. Changed the axel design, added brackets, etc. It's a derivative of the ones you listed and listed as such.

would you be able to make one that would fit a 68mm spool (though preferably 74mm). I dont have a box and just want to test this design on my mmu2 but all my spools are to wide.

You can use the universal auto-rewinder: https://www.thingiverse.com/thing:3338467

Universal Auto-Rewind Spool Holder

Unless using with the Repbox, in that case it won't fit in the box :(

Otherwise the The original is a great one

We have a design in the works to accommodate larger spools. It's a little tricky, but we're on top of it.

Was looking for a solution with my MMU2 and RepBox.
Can you estimate when you are expecting this design to be described as "final"? Or would you recommend to use it with the current version?

This design works well for spools that have a total width of 67mm and below. It's still marked in progress because I'm working on a version that will accommodate wider spools.

I'm using this current iteration in my box with my MMU2 with great results.

thanks. it was nice to meet you at MRRF2019 will try this in my box. Hope to see a remake for the 60mm spools like prusament

What kind of voodoo magic are you investigating? I myself was thinking about multiplicating the spring of the original auto-rewinder (50 mm diameter) several times along the axis, to construct a long spring with many rewinding revolutions inside the hole of the spool. This would only work with spools >= 50 mm internal diameter, which is the case for the vast majority of commercial filaments.

That is a stellar idea! We were thinking along those lines, but integrating the rewind system in a different way within the box. Still ironing out those details though.

Awesome! Link to here is added on the universal rewinder's page.