Integrated Auto-Rewind Spool Holder

Use V5.5 or newer, double-check version of your files! (zip download has issues)

Filament load/unload issues? MMU2 taking too much space? Not with this Integrated Auto-Rewind spool holder! It keeps filament on the spool during unloading, up to, a few full revolutions.

This integrated design is the fifth iteration in the Auto-Rewind Spool Holder series, after the Original, Parametric, Universal and Sisyphus iterations. It returns to the roots of the series with the spring wound up inside the cylindrical space of the hub, as opposed to the side-spring designs. While the diameter is relatively small (45 mm-ish), almost the full width of the spool holder can be utilized allowing to stack many small springs and obtain sufficient rewinding revolutions at a good torque profile.

From V5.5 the arrows on both caps indicate the preferred direction of rotation (may be the wrong way round). The preferred direction is the one that causes all springs to wind up around the axle, which is fairly robust (low material stress).

The default implementation does not include a dedicated clutch. The contact surface between rewinder and spool is used as slipping surface. The magnitude of the friction is determined by the combination of materials and its structure (roughness), plus the weight of the spool itself. Tape with a rubbery feel can be used to increase the friction if necessary and obtain more rewinding revolutions, but this should not be needed in more recent versions.

The design is entirely parametric. Use OpenSCAD software (latest version!) to edit the thing. Several parameters are available to specify the dimensions of the Integrated Auto-Rewind Spool Holder. Previewing the model is quick, but rendering usually takes a long time.

Axle, stand and clips are not included. You can use those of any of the other spring-based spool holders such as the Original, Parametric or Universal Auto-Rewind Spool Holder.

You also need two "608" bearings. Assembly is trivial, check the pictures.

If the spring stack assembly is loose then try setting springRadialTabClearance = -0.1 or some other value (default is 0.05).

Video of Halloween edition and details

The scad file can also generate modular springs for the Universal Auto-Rewind Spool holder. Use the following settings (v5.3 or newer) (you can also download the .json file and open it as preset in OpenSCAD):

output="print"
universalRewinderSpring=true
rewinderDiameter=88.6
rewinderLength=8
springAlternate=true
reverseSprings=true
springBladeCount=2
springBladeThickness=1.4
springBladePitch=2.5
$fn=100
axleConnectionDiameter=12
springFlatShaftLength=5

---

Community mods

Filament drybox
Prusa Printer Enclosure V2 Uses original stands
5 Spool integrated autorewind holder Uses different stands
Integrated rewinder for RepBox
Axle and Mount to use on RepWinder Stand
4 Big spool holder
Auto-rewinder for RepBox 2 mashup
Integrated Auto-Rewind Buffer
Drybox Ikea 365+ 10.6l & autorewind (and not) spoolholder
Spannerhands rewinder spool

---

Version history

V5.6 Nov 10, 2019
- Chamfered bottom of springs to eliminate effect of elephant feet
- Reduced radial tab clearance to 0.05 mm for snug fit

V5.5 Nov 6, 2019
- Set springAlternate = true, optimizing rewind in one direction only
- Changed top/down emboss characters to < and > to indicate correct rewind direction
- Redesigned hub-spring attachment
- Eliminated ribs
- Three default sizes: 60 mm (narrow), 75 mm (standard) and 95 mm (wide)
- Default output "print"
- Fixed rendering issue in hole for flat shaft
- Increased spring tab clearance
- Set intertwinedThreadCount to 1 as there is no need anymore to un-screw the cap; changed thread dimensions to set overhang to 45 degrees for easier printing
- Three STLs: small (60 mm), medium (75 mm), wide (95 mm).
- Chamfered tabs for easier spring stack assembly
- Reduced hub wall thickness
- Adjusted spring parameters to make it slightly more flexible

V5.4 Oct 9, 2019
- Different decal characters top/bottom possible
- Enable/disable decal character mirroring
- rewinderSetRimDiameter now takes grips into account
- Default rewinderSetRimDiameter set to 50 so that cap can stay in place when changing spools
- Setting hubRibDepth to 0 now completely hides ribs
- Added Halloween mode for Jack O'Lantern pattern cutout

V5.3 Sept 10, 2019
- Improved Universal Rewinder spring parameters
- Changed default size and shape of decals for easier printing
- Increased clearance in hub-spring attachment
- Check for compatible OpenSCAD version

V5.2 Sept 5, 2019
- Added possibility to create spring systems for Universal Auto-Rewind Spool Holder

V5.1 Aug 5, 2019
- Fixed bug in rib generation (wrong variable name)
- Changed default hub hole shape to square to make the overhang angle less steep, and also avoid floating rib segments
- Reduced default spring blade width (from 1.3) to 1.1 and reduced spring blade pitch (from 2.5) to 2.0 to make the spring a bit more flexible
- Two STLs: one for spools up to 55 mm (7 springs, hub length 60 mm), other for spools up to 90 mm (9 springs, hub length 95 mm)

V5.0 Aug 1, 2019
- First version