LockSpool V3: Parametric, reusable (1 part printed twice)

Reusable filament spool made from a single part printed twice. Fully parametric and customizable.
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updated September 24, 2024

Description

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LockSpool V3 is a reusable filament spool made from a single part printed twice, and joined together with a quick twist, with a snap-lock to hold it in place. The design can be customized to fit any spool-less filament refill coil by adjusting just six parameters.

V1/V2 was on Thingiverse, but a glitch made it inaccessible, so I had no choice but to upload a new version.

This is a good print for combining small lengths of leftover filament. I printed the parts in the photographs with a nearly-empty spool of silver-gray Prusament. You can see where I had to switch over to my blue PLA. The photographs are from V1.

These designs include channels in the hub to accommodate tie wraps. The channels deliberately do not line up in the open and closed positions. Instead, they overlap enough in each position to clear the tie-wraps. I based the designs on examples and dimensions that I could find (linked in the list below), but have not tested all designs with all refills. In some cases (like SUNLU), the LockSpool needs no channels because the manufacturer's own reusable spool is designed to be loose.

This design produces spools compatible with these filament coils, and any others for which dimensions can be found:

Why so many? Well, xkcd said it best:

Parameter values are shown below and in the OpenSCAD code comments.

Improvements over original MasterSpool and similar designs:

  • Both halves are the same. Print just one part as many times as you need.
  • Quick twist to connect the halves, no multiple turns of a threaded part.

Improvements over SlantSpool:

  • Snap-lock mechanism to keep the two halves in place.
  • Tie-wrap slots to aid removing and installing refill coils.
  • No large gaps in the hub, the better to wind your own spool if needed.
  • Parametric design. OpenSCAD file included.
  • Better CC-BY-SA license (SlantSpool has a "no derivatives" restriction).

Other improvements:

  • Lighter weight, less material, and faster printing: 41% faster than original MasterSpool, 24% faster than SlantSpool, both of which use about 1/4 kg of filament just to print one spool! The MasterSpool-compatible LockSpool is only 130 grams.
  • Designed for printing without top or bottom layers, improving print speed while remaining strong.
  • Multiple parts stack together neatly on a shelf!
  • You can customize this for replacing worn-out flanges of cardboard spools for use in an AMS (using only the cardboard hub).

500 g MasterSpool refills:

750 - 850 g MasterSpool refills:

1 kg refills for other spools:

Spool dimensions in the OpenSCAD code:

The STL files provided were made using the following settings in the OpenSCAD code for the different types of spools.

DimensionMaster SpoolSlant Spool / KOILEcono FilFusionSUNLUInland / eSunPara mount 3DLee Fung
1kg / 800g
PrusamentMatter Hackers
spool_dia198200200198200200200200200175
hub_dia10210074.576799010090(b) / 1039382
bearing_dia52.55247(a)48(a)525252535252
inner_width46.76258675755.5 / 57.6(c)7057(b) / 466562
numslots344334334(e)4
hubindent33220(d)33332
hubwall101077610109 / 10107

(a) EconoFil and Fusion Filaments bearing diameter is made smaller here to compensate for internal structure of LockSpool hub design.

(b) Lee Fung dimensions based on manufacturer's spool dimensions modified by their comments on https://www.thingiverse.com/thing:3582542/comments

(c) Inland and eSun spools are nearly identical. The eSun settings should work for both.

(d) The reusable spool provided by SUNLU is designed to be loose so that tie-wrap channels are not needed. So it is here. If you want channels, use values bearing_dia=50, hubindent=2, hubwall=7.

(e) Slots are not needed for Prusament unless you want to remove the coil from the spool.

Version history

V1, early January 2022

V2, January 2022

  • Increased latch spring thickness in OpenSCAD file.
  • Widened tie-wrap slot so that the tie wrap has clearance at any twist angle of the spool halves.
  • Updated and simplified input parameters.
  • Added parameters for SUNLU, Inland, eSun, and Paramount3D refills.
  • Moved dimension label from bottom to side, making more room for a larger bearing diameter on narrow-hub spools.
  • Version 2.1: Updated SUNLU spool parameters based on this make by mjomalley

V3, February 2022

  • Lock spring no longer interferes with bearing hole volume in SUNLU and EconoFil designs.
  • Loosened up clearance of bayonet pins with entry holes for stacking.
  • Removed tie-wrap channels from SUNLU design because the spool provided by SUNLU doesn't need them either. This allowed the bearing diameter to be 52mm.
  • Added parameters for Lee Fung spools.
  • Removed separate KOIL design - KVP KOIL is compatible with SlantSpool, and provides a SlantSpool STL on their website.
  • V3.1 (April 2022): Updated Inland/eSun inner width, thanks to measurements provided by cjlee89.
  • V3.2 (November 2022): Updated Paramount spool for 3 slots instead of 4.
  • V3.3 (December 2022): Added spool for Prusament refills. Added Prusa Mini support (Prusament STL provided).
  • V3.4 (January 2023): Increased Prusament spool width from 60 to 65 mm.
  • V3.5 (April 2023): Fixed small locking pin interference in SUNLU and Fusion spools.
  • V3.6 (June 2023): More general fix for locking pin interference for small hub diameters.
  • V3.7 (September 2024): Added MatterHackers AMS refill parameters thanks to generic0000, code cleanup and label centering thanks to Roblue, idea to replace worn-out flanges for cardboard spools for use in an AMS thanks to jeffgolden.

Print settings

Resolution: 0.20-0.30mm layers, 0.4mm nozzle

Infill: 20% cubic (recommended) or 15% gyroid

Filament: Generic PLA

Notes:

Set top and bottom layers to 0 in the slicer, which exposes the infill in the final print. It's still strong but saves material. You can use 2 perimeters.

If you need narrower flanges, you can reduce them to 3mm but then you should print top and bottom layers also, to keep them stiff. 4mm without top and bottom still works well.

Use 0.30 mm layer height ("DRAFT" preset in Slic3r / PrusaSlicer), with these values in "Print Settings":

  • Layers and perimeters > Solid layers = 0 for top and bottom
  • Layers and perimeters > Detect bridging perimeters = ON
  • Advanced > Elephant's foot compensation = 0

If you find the perimeters separating on negative-slope inside curves (like the bearing hole the first few layers in), then re-slice with a 0.20mm height profile, and you can use the variable height setting to increase the layers without negative-sloped surfaces to 0.25mm. The print takes longer but the perimeters behave. The 45° rule barely works at 0.30mm.

Post-printing

After printing, I suggest:

  • Take a flat file and gently smooth the top surface of the spool hub (the surface that has the locking pins sticking out of it). This ensures that the locking pin has has enough depth to get into the locking groove on the other half-spool.
  • Important: Rub some candle wax or a crayon on the angled surfaces of the locking pin and the corresponding groove, to lubricate them. PLA tends to have a lot of friction with itself. Waxing sliding plastic surfaces makes a big difference.

How I designed this

Designed completely in OpenSCAD. Particular challenges were figuring out the beveled bezier-curve holes in the reel and getting the locking mechanism working. There were also several test prints to work out the best clearance settings.

 

Category: 3D Printer Accessories

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Model origin

The author marked this model as their own original creation. Imported from Thingiverse.

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