January 6, 2019
Description
Filament load/unload issues? MMU2 taking too much space? Not with this Universal Auto-Rewind spool holder! It keeps filament on the spool during unloading, up to four full revolutions. Video compilation
This is a remake of the Original and Parametric Auto-Rewind Spool Holder, but with significant enhancements:
Spring should be printed with 0.2 mm layer thickness to match the gaps in the structures (see assembly instructions). All other parts can be printed in any layer thickness, 0.2 mm is default.
GCode for Prusa i3 MK2/S and MK3(S) /MM(S) can be downloaded here: single color and multi-material.
The MM version uses two colors for most parts (three for the stand). First color is the base color (silver grey in shown examples), second color is for decals and markers (vibrant color), third color is for the characters on the stand (white). The parts are designed such that missing layers in the 2nd and 3rd color do not affect the structural strength of all parts, also the number of color changes is kept to a minimum.
Four spring styles are available: SpringFlat is to be used with a 3-D printed axle with flat side. SpringRound (available in zip file) is used with a round axle (e.g. metal rod). SpringRound has an anti-rotation block which aligns with the frame, so it is not needed to immobilize the round axle. Both SpringFlat and SpringRound come in two different stiffnesses. The soft version is recommended to start with and the stiff version can be used when more torque is needed.
The hub thread length can be customized with the Parametric Auto-Rewind Spool Holder customizer. Use output="hub", hubThreaded="yes", set hubThreadLength to the desired length and leave all other parameters at its default settings.
At Robotics and Mechatronics (RaM), University of Twente some research is done on variable stiffness actuators. Certain mechanisms in this Auto-Rewind Spool Holder were (loosely) inspired by our research there. One side of the stand reads "It's Rewind Time" while the other side reads "University of Twente". A stand with no text (blank) is also available.
A list of (mostly) compatible stands are on the Parametric Auto-Rewind Spool Holder page.
Table/wall/ceiling
AutoRewind Spool Stand Hanging Screw Mount (table/wall/ceiling, use SpringRound)
Screw-down tabletop, wall, and ceiling mounted stands (table/wall/ceiling, needs different axle)
Wall Mount Spool Rewinder Adapter (wall)
Wall mount (wall)
Strong wall mount (wall)
The MMU2s Prusa Final Filament Rewind Solution (wall)
Numbered filament stands (table)
Multiple Mechanism stand (table)
Ceiling or under shelf hanging mount (ceiling)
Stand and hub for 3kg spools (table)
Fast print stand (table)
Wall-mount XXL (wall)
Vertical mount (wall)
Spool screw down mount (table)
Autorewind Hanger
Hanging bracket
Hanging holder
Wire shelving mount
Hanger for 1x2 wood shelves
2020 Top mount, high
2020 Top mount, low
2020 Side mount
2020 Side mount alternative
Longer axle, for 2020 Top mount
Under table setup
A10M Dual auto-rewind spool holder
Auto-Rewind Spool Top Mount for Ender 3/Pro
Ikea Lack table sliding spooler stand
MMU Spoolholder for Stuva / Besta (for parametric rewinder, check size)
MMU V2 Autorewind Spoolholder for IKEA Samla BOX (for parametric rewinder, check size)
Brackets for Securing Auto-rewinders on Ikea Lack enclosure
MMU2 PTFE Tube Guide for Ikea Lack enclosure
Adapter for Spannerhands Spool System
SpannerHands dual-color hub
Individual-Spool Dry-box Inserts for Rubbermaid container
Modified Axle for Dry-box Insert for Universal Auto-Rewind Spool Holder
Prusa i3 MK3 top stand, narrow
Prusa i3 MK3 top stand, 1 mm bigger In case the narrow one does not fit
Another Prusa i3 MK3 top stand
Stand for Wanhao Duplicator i3
Anet A8 top stand
FLSUN QQ-S
AM8 Modified Anet A8
Vincent's Auto-Rewind Spool Holders
Original Auto-Rewind Spool Holder
Parametric Auto-Rewind Spool Holder
Universal Auto-Rewind Spool Holder (this thing)
Sisyphus Auto-Rewind Spool Holder (gravity-based)
Integrated Auto-Rewind Spool Holder
Yet another rewinding spoolholder Uses rubber O-rings
Remixed spoolholder Narrower, new tube holder
Universal Auto-Rewind Spindle Parametric rewinder with threaded rod and nuts
RepRewind Fits inside the RepBox container
Wall-mount Auto-rewind Spool Thing
Parametric Hangable Any-Direction Continuous Slip Clutch
Circular Gravity-based Auto-Rewind Spool Holder
Linear Gravity-based Auto-Rewind Spool Holder
Prusa i3 top mount roller-style gravity rewinder
Rewinder upgrade for Quick Change Universal Spool Holder
Name Badge Reel Remix or here
Gravity spoolholders Re-uses original Prusa MMU2 spool holders
Snapmaker 2 universal rewind spool holder Minimalistic design
4-lobe NutCurved Fits spools with thumbscrews
Spool hub spacer Helps in centering spools
Three-pointed dial Idea now included in V3.3
3d printed 608 bearing
Better 3d printed 608 bearing
Remix with 3 sizes filament rings For centering spools
Plain dial Dial with four simple spokes
Round hub springs with endstops To re-use the just-too-short Prusa MMU2S axles
Sample filament adapter
Universal Spool Holder Non-rewind
PTFE tube adapter Snaps into base of frame
Tube holder assembly for Replicator Mini+
Sisyphus Clutch Mod
Modular spring customizer See instructions for correct settings
Spring One Way for Prusament spool
PTFE adapter (PC4-M6) shelf edge
PTFE Tube adapter for Universal Auto-Rewind Stand (PC4-M6)
Spring One Way for Prusament Spool
Horizontal Rewind Spool Holder
One way spring A.R.S.H. (Auto-Rewind Spool Holder)
Instructions
Below are the captions for the pictures. (At the moment, Thingiverse is no longer showing captions under the pictures.)
1 All rewinder's parts (except stand and XL curved nut) fit on a single buildplate with size 250x210 mm. Example GCode can be downloaded from https://www.prusaprinters.org/prints/168-universal-auto-rewind-spool-holder-mm. The spring and clutch are printed concentrically and need to be separated as the spring is assembled upside-down.
2 Align the pointer of the dial with the highest marker of the clutch (without spring). There are three pointers but only one alignment is correct (check tabs). Carefully insert dial in clutch. After that, rotate dial back to zero. If this is difficult then you can use the spool hub to have a better grip on the clutch.
3 The v3.3 springs require a bit of work to separate the layers properly (see video). The object is split into three parts: the base with outer rim and two separate springs. The three parts are connected at the axle and/or the secondary rim. Check surfaces and grind if necessary after splitting to ensure smooth operation. There are two stypes: a stiff version (left) and a soft version (right). The soft version only works if friction is small and the spool is properly balanced (see video), in that case it is recommended to use the soft spring. If the spool is not balanced or friction is higher than in the video or the soft spring breaks then use the stiff one instead. Both springs come with flat axle hub by default, but round axle hub versions are also available in the zip files.
4 This is a schematic cross-section of the spring showing the connectivity of the shafts, spring blades, rims and base. The yellow sections are to be broken free, the red parts remain connected.
5 From v3.4 a modular and improved spring design is available. This is printed in three parts and assembled together by aligning the tabs and pressing them in. Use this design if you experience issues in printing the monolithic spring, and to replace broken older version springs.
6 The v3.4 modular spring is relatively dense with thick blades and small gaps, resulting in a robust spring. Make sure that the springs wind up around the axle when installing the rewinder and not against the rim. Alternative modular springs can be generated using the scad file of the Integrated Auto-Rewind Spool Holder: https://www.thingiverse.com/thing:3781815
7 If your clutch slips too much during actual use then it is a good idea to put adhesive tape on the outer rim of the spring to increase the clutch friction. Ducttape, electrical tape and any other tape with a not-too-slippery surface should help. The endpoints of the tape should overlap in the same direction as the spool rotation so that it cannot be caught and pulled loose by the clutch fingers.
8 Insert spring. This is an older photo showing the original spring. If you use the new dual spring then the top looks different. The spring shaft goes through the dial.
9 Insert two 608 bearings (e.g. 608ZZ or 608RS) in the spool hub. The bearings are more or less necessary, if you leave them out then there is in principle too much friction to rewind the spool properly. 3D printed bearings generally also have too much friction due to surface irregularities, although you can always try in combination with a stiff spring of course. If the 608 bearings do not roll smoothly then consider de-greasing it with IPA (isporopylalcohol) and re-lubricating it with light oil (see video). Lower the friction in the bearings means that you can use lower settings of the dial, reducing material stresses in the spring and increasing its lifetime.
10 Attach the spool hub on the clutch. Make sure that all clips are fully pressed in.
11 Insert the axle. The axle must be able to slide easily through the spring and bearing holes; grind axle if necessary. Place the clip as shown. There should be a small gap between clip and bearing.
12 The filament guide tube (if used) can be inserted in the tube holder. This photo shows an older version, from v3.3 the tube holder has ten holes at different angles and positions. If you do not use a filament guide then do not use the holder. If insertion is difficult then you can wiggle a flat screwdriver in the slot to open it up a bit. Alternatively, you can use a 4 mm drill to enlarge the hole. On the other hand, if the tube is loose then you can use some tape to prevent it from falling out.
13 The hub, stand, tube holder and curved nut can be put together as shown. The other end of the filament guide tube is typically attached to the extruder or the MMU (which also stabilizes the tube holder), so it should be longer than pictured here. You can now adjust the tension of the clutch using the dial to get a proper rewinding and slipping action. Ideally you would aim for a minimum of 1.5 full rewinding revolutions consistently (also right after the clutch slips). But do not set the dial too high, otherwise the spring will get overloaded and eventually break due to material fatigue. If the dial gets stuck at a high setting then wind up the spring towards the outer rim as far as possible, this makes it easier to dial back down. In the photographed configuration the filament guide is above the spool and leads the filament to the left. Different positions and filament directions are also possible, the spring works both ways. After flipping the direction you may to recalibrate the clutch tension (not needed for v1.02 and beyond), as it will be different due to the changed spring behaviour. The hub should be able to spin with very little friction: give it a twist and it should oscillate a few times before coming to a halt (see video).
14 From v3.2.2 a redesigned tube holder is included which allows to mount the filament tube at different angles (0, 10, 20, 30 and 40 degrees) and lateral positions (two positions per angle). This helps in reducing the risk of the filament jumping off the spool.
15 In this configuration the tue tube holder is positioned below the spool. Again, the filament tube must run all way to the extruder or MMU, and if you are not using the tube then you must leave the tube holder out.
16 Due to the spool rotation direction (counterclockwise as seen from this side) you need two nuts to secure it. The lips of the tube holder can be opened to make a snap-on style attachment which makes it easier to change spools in this configuration.
License:
Creative Commons - Attribution - Share Alike
VincentGroenhuis
