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.
This is a remake of the Original and Parametric Auto-Rewind Spool Holder, but with significant enhancements:
- Slipping point of the clutch can be adjusted in about 15 steps using the dial.
- One size fits almost all spools up to 1kg. Inner diameter 30-75 mm, max outer diameter 200 mm, max width 88 mm. Hubs for wider spools can be created with the customizer, same for hubs with narrow diameters. Stand for 3kg spools available here.
- Spring (v1 and v1.01) works both ways around: towards the axle and towards the outer rim. Note: flipping the direction requires re-calibration of the clutch tension!
- Spring v1.02+ is direction independent, can be flipped around without changes in clutch tension. This version might also be better protected against spring overloading.
GCode for Prusa i3 MK2/S and MK3 /MM can be downloaded here.
The MM version uses two colors for most parts (three for the stand). First color is the base color (silver grey), 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.
Two spring styles are available: SpringFlat is to be used with a 3-D printed axle with flat side. SpringRound 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.
The spring may take a long time (>5 min) to slice in Slic3r PE 1.41.2. This is caused by the 1.1 mm thick spring blade which apparently slows down generation of perimeters. Please be patient and it is also wise to set all print settings right before importing the spring.
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.
Additional stands and other mods designed specifically for this Universal Auto-Rewinder by the awesome community:
Prusa i3 MK3 top stand
Stand for 3kg spools
Yet another rewinding spoolholder
Lack sliding spooler stand
Spool hub spacer
Numbered filament stands
- v1.02 RC2 (springs only) Feb 17, 2019
- Redesigned experimental spring: symmetric dual serial spring system, direction independent and less prone to clutch jams; stiff and soft versions (flat and round) available
- v1.02 RC1 (springs only) Feb 4, 2019
- New experimental spring design: symmetric dual parallel spring system, direction independent and better guarded against overloading
- v1.01 Jan 12, 2019
- Added CurvedNutXL for mounting spools with large inner diameter
- Changed text on one stand to "It's Rewind Time!"
- Slightly decreased notch size in clutch to make dialing easier
- Modified single-material gcode for better cross-compatibility
- Re-exported all STLs (should no longer show errors in Slic3r)
- v1.0 Jan 6, 2019
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 http://www.vincentgroenhuis.nl/projects/universalautorewinder/ in single-color and multi-color versions. The spring and clutch are printed concentrically and need to be separated as the spring is assembled upside-down. The provided gcode files use spring v1.01, an experimental new version (v1.02) is available in the Files section. Spring v1.02 contains a spiderweb between the blades which has to be taken out, please be careful not to damage the spring itself.
Align the pointer of the dial with the highest marker of the clutch (without spring) and 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.
Insert spring, note the correct orientation (spring shaft going through the dial).
Insert two 608 bearings (e.g. 608ZZ or 608RS) in the spool hub if you have them. (The auto-rewinder may also work without bearings at reduced performance.)
Attach the spool hub on the clutch. Make sure that all clips are fully pressed in.
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.
The filament guide tube (if used) can be inserted in the tube holder. 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.
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 may 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.
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.
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.