KRAKEN FOR THE BAMBU LAB AMS · CARDBOARD AND HARD PLASTIC SPOOLS

Kraken spool rings, nut and gear generator

Remixed by Repro from Kraken by humebeam

Repro's Kraken tools: centering rings that seat a spool on the Kraken spool holder, sized to the spool's centre hole from 45 to 95 mm in 0.1 mm steps, with pentagon points for cardboard hubs or spring fingers for hard plastic hubs; a Kraken spool nut with a thicker flange; and a spool gear with your own spoke pattern. The STL files are generated in your browser.

Generate a ring pair Download a ready-made size Thicken the nut flange Spoke a gear

Repro's remix of humebeam's Kraken: an eight-spoke tapered spool gear, a 53.4 mm pentagon ring pair for cardboard spools and a 52.1 mm spring-finger ring pair for hard plastic spools, both with 2.2 mm gear-side flanges and 0.6 mm cap-side lips, and a spool nut with a 3.5 mm flange, rendered from the generated STL files — r54t12 spoked gear, 53.4 mm pentagon pair (cardboard), 52.1 mm spring pair (hard plastic) and 3.5 mm flange nut, rendered from this page's generated STL files. Remixed by Repro; holder core, nut, teeth and hub from humebeam's Kraken.

01 / WHICH SIZE TO PRINT

Cardboard spool: print a pentagon pair. Hard plastic spool: print a spring pair. Measure the spool's centre hole with calipers in a few directions, take the smallest reading, and print that size or up to 0.9 mm below it.

The round support surface sits 0.1 mm inside the nominal radius, so a ring larger than the hole will not enter. The five pentagon points stand 0.7 mm proud of the nominal radius, so they still grip a hole up to about 1 mm wider than the nominal size. Print one gear-side ring and one cap-side ring per spool.

Cardboard spool centre holes for popular brands
Cardboard spool	Centre hole	Ring to print	Where the figure comes from
Polymaker	55.5 mm	55.5 mm pair	Measured for this remix
Elegoo Rapid PETG	53.4 mm	53.4 mm pair	Measured for this remix
Bambu Lab cardboard spool	about 55 mm	55 mm	Community report
eSun	52–54.3 mm, varies	Measure; 52 or 54 mm	Community reports disagree (52 mm, 54.3 mm)
Overture, Duramic	about 53.5 mm	53 mm or the 53.4 mm pair	Inferred from a bushing designed for them
Other brands	52–58 mm is typical	Measure first, then generate	—

Spool makers change cores between batches. Treat the brand column as a starting point and the caliper reading as the deciding figure. Physical fit has been checked only where the table says measured.

02 / READY-MADE SIZES

Pairs published in Repro's kraken-remix-ogAMS repository. The generator below produces the same geometry for these sizes. 3MF and STL hold geometry only, flange or lip on Z0; STEP files are gzip-compressed faceted solids.

Cardboard spools: pentagon rings. Five points stand 0.7 mm past the hole and bite into the cardboard.

Hard plastic spools: spring rings. A plastic hub does not give, so the spigot is round at 0.2 mm under the hole and four spring fingers bow 0.2 mm past it. They hold the ring in the hub when the gear shaft comes out.

Flange sets. Normal: 2.2 mm gear-side flange and 0.6 mm cap-side lip. Skinny: 0.4 mm on both sides, for holders where the extra 2.0 mm of stack does not fit. humebeam's original 0.4 mm cap lip is fragile: it tends to break during bed removal and handling.

Cardboard spools · brand sizes

Brand-specific pentagon pairs for cardboard spools
Spool hole	Gear side · 2.2 mm flange	Cap side · 0.6 mm lip
55.5 mm · Polymaker	3MF · STL · STEP.gz	3MF · STL · STEP.gz
53.4 mm · Elegoo Rapid PETG	3MF · STL · STEP.gz	3MF · STL · STEP.gz

Cardboard spools · stock sizes, 45–95 mm

Each stock pair keeps the holder core of humebeam's ring of the same size. The last column lists the measured holes each ring suits.

Pentagon pairs for cardboard spools, every whole-millimetre stock size
Ring	Gear side · 2.2 mm flange	Cap side · 0.6 mm lip	Smallest hole reading
45 mm	3MF · STL · STEP.gz	3MF · STL · STEP.gz	45.0–45.9 mm
46 mm	3MF · STL · STEP.gz	3MF · STL · STEP.gz	46.0–46.9 mm
47 mm	3MF · STL · STEP.gz	3MF · STL · STEP.gz	47.0–47.9 mm
48 mm	3MF · STL · STEP.gz	3MF · STL · STEP.gz	48.0–48.9 mm
49 mm	3MF · STL · STEP.gz	3MF · STL · STEP.gz	49.0–49.9 mm
50 mm	3MF · STL · STEP.gz	3MF · STL · STEP.gz	50.0–50.9 mm
51 mm	3MF · STL · STEP.gz	3MF · STL · STEP.gz	51.0–51.9 mm
52 mm	3MF · STL · STEP.gz	3MF · STL · STEP.gz	52.0–52.9 mm
53 mm	3MF · STL · STEP.gz	3MF · STL · STEP.gz	53.0–53.9 mm
54 mm	3MF · STL · STEP.gz	3MF · STL · STEP.gz	54.0–54.9 mm
55 mm	3MF · STL · STEP.gz	3MF · STL · STEP.gz	55.0–55.9 mm
56 mm	3MF · STL · STEP.gz	3MF · STL · STEP.gz	56.0–56.9 mm
57 mm	3MF · STL · STEP.gz	3MF · STL · STEP.gz	57.0–57.9 mm
58 mm	3MF · STL · STEP.gz	3MF · STL · STEP.gz	58.0–58.9 mm
59 mm	3MF · STL · STEP.gz	3MF · STL · STEP.gz	59.0–59.9 mm
60 mm	3MF · STL · STEP.gz	3MF · STL · STEP.gz	60.0–60.9 mm
61 mm	3MF · STL · STEP.gz	3MF · STL · STEP.gz	61.0–61.9 mm
62 mm	3MF · STL · STEP.gz	3MF · STL · STEP.gz	62.0–62.9 mm
63 mm	3MF · STL · STEP.gz	3MF · STL · STEP.gz	63.0–63.9 mm
64 mm	3MF · STL · STEP.gz	3MF · STL · STEP.gz	64.0–64.9 mm
65 mm	3MF · STL · STEP.gz	3MF · STL · STEP.gz	65.0–65.9 mm
66 mm	3MF · STL · STEP.gz	3MF · STL · STEP.gz	66.0–66.9 mm
67 mm	3MF · STL · STEP.gz	3MF · STL · STEP.gz	67.0–67.9 mm
68 mm	3MF · STL · STEP.gz	3MF · STL · STEP.gz	68.0–68.9 mm
69 mm	3MF · STL · STEP.gz	3MF · STL · STEP.gz	69.0–69.9 mm
70 mm	3MF · STL · STEP.gz	3MF · STL · STEP.gz	70.0–70.9 mm
71 mm	3MF · STL · STEP.gz	3MF · STL · STEP.gz	71.0–71.9 mm
72 mm	3MF · STL · STEP.gz	3MF · STL · STEP.gz	72.0–72.9 mm
73 mm	3MF · STL · STEP.gz	3MF · STL · STEP.gz	73.0–73.9 mm
74 mm	3MF · STL · STEP.gz	3MF · STL · STEP.gz	74.0–74.9 mm
75 mm	3MF · STL · STEP.gz	3MF · STL · STEP.gz	75.0–75.9 mm
76 mm	3MF · STL · STEP.gz	3MF · STL · STEP.gz	76.0–76.9 mm
77 mm	3MF · STL · STEP.gz	3MF · STL · STEP.gz	77.0–77.9 mm
78 mm	3MF · STL · STEP.gz	3MF · STL · STEP.gz	78.0–78.9 mm
79 mm	3MF · STL · STEP.gz	3MF · STL · STEP.gz	79.0–79.9 mm
80 mm	3MF · STL · STEP.gz	3MF · STL · STEP.gz	80.0–80.9 mm
81 mm	3MF · STL · STEP.gz	3MF · STL · STEP.gz	81.0–81.9 mm
82 mm	3MF · STL · STEP.gz	3MF · STL · STEP.gz	82.0–82.9 mm
83 mm	3MF · STL · STEP.gz	3MF · STL · STEP.gz	83.0–83.9 mm
84 mm	3MF · STL · STEP.gz	3MF · STL · STEP.gz	84.0–84.9 mm
85 mm	3MF · STL · STEP.gz	3MF · STL · STEP.gz	85.0–85.9 mm
86 mm	3MF · STL · STEP.gz	3MF · STL · STEP.gz	86.0–86.9 mm
87 mm	3MF · STL · STEP.gz	3MF · STL · STEP.gz	87.0–87.9 mm
88 mm	3MF · STL · STEP.gz	3MF · STL · STEP.gz	88.0–88.9 mm
89 mm	3MF · STL · STEP.gz	3MF · STL · STEP.gz	89.0–89.9 mm
90 mm	3MF · STL · STEP.gz	3MF · STL · STEP.gz	90.0–90.9 mm
91 mm	3MF · STL · STEP.gz	3MF · STL · STEP.gz	91.0–91.9 mm
92 mm	3MF · STL · STEP.gz	3MF · STL · STEP.gz	92.0–92.9 mm
93 mm	3MF · STL · STEP.gz	3MF · STL · STEP.gz	93.0–93.9 mm
94 mm	3MF · STL · STEP.gz	3MF · STL · STEP.gz	94.0–94.9 mm
95 mm	3MF · STL · STEP.gz	3MF · STL · STEP.gz	95.0–95.9 mm

Skinny set for cardboard spools · 0.4 mm gear flange and cap lip

Brand-specific pentagon pairs for cardboard spools, skinny set
Spool hole	Gear side · 0.4 mm flange	Cap side · 0.4 mm lip
55.5 mm · Polymaker	3MF · STL · STEP.gz	3MF · STL · STEP.gz
53.4 mm · Elegoo Rapid PETG	3MF · STL · STEP.gz	3MF · STL · STEP.gz

Pentagon pairs for cardboard spools, every whole-millimetre stock size, skinny set
Ring	Gear side · 0.4 mm flange	Cap side · 0.4 mm lip	Smallest hole reading
45 mm	3MF · STL · STEP.gz	3MF · STL · STEP.gz	45.0–45.9 mm
46 mm	3MF · STL · STEP.gz	3MF · STL · STEP.gz	46.0–46.9 mm
47 mm	3MF · STL · STEP.gz	3MF · STL · STEP.gz	47.0–47.9 mm
48 mm	3MF · STL · STEP.gz	3MF · STL · STEP.gz	48.0–48.9 mm
49 mm	3MF · STL · STEP.gz	3MF · STL · STEP.gz	49.0–49.9 mm
50 mm	3MF · STL · STEP.gz	3MF · STL · STEP.gz	50.0–50.9 mm
51 mm	3MF · STL · STEP.gz	3MF · STL · STEP.gz	51.0–51.9 mm
52 mm	3MF · STL · STEP.gz	3MF · STL · STEP.gz	52.0–52.9 mm
53 mm	3MF · STL · STEP.gz	3MF · STL · STEP.gz	53.0–53.9 mm
54 mm	3MF · STL · STEP.gz	3MF · STL · STEP.gz	54.0–54.9 mm
55 mm	3MF · STL · STEP.gz	3MF · STL · STEP.gz	55.0–55.9 mm
56 mm	3MF · STL · STEP.gz	3MF · STL · STEP.gz	56.0–56.9 mm
57 mm	3MF · STL · STEP.gz	3MF · STL · STEP.gz	57.0–57.9 mm
58 mm	3MF · STL · STEP.gz	3MF · STL · STEP.gz	58.0–58.9 mm
59 mm	3MF · STL · STEP.gz	3MF · STL · STEP.gz	59.0–59.9 mm
60 mm	3MF · STL · STEP.gz	3MF · STL · STEP.gz	60.0–60.9 mm
61 mm	3MF · STL · STEP.gz	3MF · STL · STEP.gz	61.0–61.9 mm
62 mm	3MF · STL · STEP.gz	3MF · STL · STEP.gz	62.0–62.9 mm
63 mm	3MF · STL · STEP.gz	3MF · STL · STEP.gz	63.0–63.9 mm
64 mm	3MF · STL · STEP.gz	3MF · STL · STEP.gz	64.0–64.9 mm
65 mm	3MF · STL · STEP.gz	3MF · STL · STEP.gz	65.0–65.9 mm
66 mm	3MF · STL · STEP.gz	3MF · STL · STEP.gz	66.0–66.9 mm
67 mm	3MF · STL · STEP.gz	3MF · STL · STEP.gz	67.0–67.9 mm
68 mm	3MF · STL · STEP.gz	3MF · STL · STEP.gz	68.0–68.9 mm
69 mm	3MF · STL · STEP.gz	3MF · STL · STEP.gz	69.0–69.9 mm
70 mm	3MF · STL · STEP.gz	3MF · STL · STEP.gz	70.0–70.9 mm
71 mm	3MF · STL · STEP.gz	3MF · STL · STEP.gz	71.0–71.9 mm
72 mm	3MF · STL · STEP.gz	3MF · STL · STEP.gz	72.0–72.9 mm
73 mm	3MF · STL · STEP.gz	3MF · STL · STEP.gz	73.0–73.9 mm
74 mm	3MF · STL · STEP.gz	3MF · STL · STEP.gz	74.0–74.9 mm
75 mm	3MF · STL · STEP.gz	3MF · STL · STEP.gz	75.0–75.9 mm
76 mm	3MF · STL · STEP.gz	3MF · STL · STEP.gz	76.0–76.9 mm
77 mm	3MF · STL · STEP.gz	3MF · STL · STEP.gz	77.0–77.9 mm
78 mm	3MF · STL · STEP.gz	3MF · STL · STEP.gz	78.0–78.9 mm
79 mm	3MF · STL · STEP.gz	3MF · STL · STEP.gz	79.0–79.9 mm
80 mm	3MF · STL · STEP.gz	3MF · STL · STEP.gz	80.0–80.9 mm
81 mm	3MF · STL · STEP.gz	3MF · STL · STEP.gz	81.0–81.9 mm
82 mm	3MF · STL · STEP.gz	3MF · STL · STEP.gz	82.0–82.9 mm
83 mm	3MF · STL · STEP.gz	3MF · STL · STEP.gz	83.0–83.9 mm
84 mm	3MF · STL · STEP.gz	3MF · STL · STEP.gz	84.0–84.9 mm
85 mm	3MF · STL · STEP.gz	3MF · STL · STEP.gz	85.0–85.9 mm
86 mm	3MF · STL · STEP.gz	3MF · STL · STEP.gz	86.0–86.9 mm
87 mm	3MF · STL · STEP.gz	3MF · STL · STEP.gz	87.0–87.9 mm
88 mm	3MF · STL · STEP.gz	3MF · STL · STEP.gz	88.0–88.9 mm
89 mm	3MF · STL · STEP.gz	3MF · STL · STEP.gz	89.0–89.9 mm
90 mm	3MF · STL · STEP.gz	3MF · STL · STEP.gz	90.0–90.9 mm
91 mm	3MF · STL · STEP.gz	3MF · STL · STEP.gz	91.0–91.9 mm
92 mm	3MF · STL · STEP.gz	3MF · STL · STEP.gz	92.0–92.9 mm
93 mm	3MF · STL · STEP.gz	3MF · STL · STEP.gz	93.0–93.9 mm
94 mm	3MF · STL · STEP.gz	3MF · STL · STEP.gz	94.0–94.9 mm
95 mm	3MF · STL · STEP.gz	3MF · STL · STEP.gz	95.0–95.9 mm

Hard plastic spools · spring rings

Measured for a 52.1 mm hard plastic hub. Generate other holes from 51.6 to 95 mm below; under 51.6 mm the finger slots would reach humebeam's holder core. Physical fit of the spring fingers is being tested.

Spring-finger pairs for hard plastic spools
Spool hole · flange set	Gear side	Cap side
52.1 mm · Normal · 2.2 mm flange, 0.6 mm lip	3MF · STL · STEP.gz	3MF · STL · STEP.gz
52.1 mm · Skinny · 0.4 mm flange and lip	3MF · STL · STEP.gz	3MF · STL · STEP.gz

Repro's remixes of Kraken by humebeam · CC BY-NC 4.0 · holder core from humebeam's kraken-spool-ring-NN-mm-100.3mf.

03 / ANY SIZE TO 0.1 MM · RING GENERATOR

Spool core

Cardboard · pentagon points Hard plastic · spring fingers

Flange set

Normal · 2.2 mm gear flange, 0.6 mm cap lip Skinny · 0.4 mm both sides

Spool hole · smallest reading, mm

45.0–95.0 mm. Enter the size to print: your smallest reading, or up to 0.9 mm less.

Fit adjustments

Bite · pentagon points beyond the hole, mm radial Undersize · support circle inside the hole, mm radial

Defaults 0.7 and 0.1 mm match every published pair. A larger bite grips a looser hole harder; a larger undersize eases a tight hole. Diameters change by twice these values. File names record non-default values.

Loading the geometry engine…

Repro remix of Kraken by humebeam, CC BY-NC 4.0. The STL header and the ZIP's credits file say so too.

Top view to scale, a magnified pentagon point or spring finger, and half sections. Values update as you type.

Loading local geometry engine…

Print pose on the bed: gear-side ring left (flange down), cap-side ring right (lip down). Drag to orbit. Grid 10 mm.

04 / NUT REMIXER · THICKER FLANGE

Thickens the flange of humebeam's spool nut on its outer face. The bearing face, barrel, thread and grip outline keep their original facets, so the same wrench fits. The added slab continues the single-start 6 mm trapezoid thread exactly one pitch, and the thread lead-in chamfer and bed-edge chamfer are re-applied at the new outer face.

Waiting for the geometry engine…

Print pose, outer face on the bed. Orange: the added material. Drag to orbit.

05 / GEAR SPOKER · CUSTOM SPOOL GEAR WEB

Cut your own spoke pattern into the Kraken spool gear. Spokes run straight from a root width at the hub pad to a tip width at the window radius; window corners are rounded. Everything outside the disc web stays exactly as humebeam modelled it. The gear geometry (474 kB) loads when you reach this section.

Start from

Spoke count Hub pad radius, mm Root width at the pad, mm Tip width at the window radius, mm Window outer radius, mm Window corner fillet, mm

Widths are chords across the spoke, measured square to its centre line. Limits: spokes at least 1.35 mm, window openings at least 4 mm at hub and rim, windows inside R90 (a solid rim of 5 mm or more inside the teeth).

Grams are for a fully solid part at PETG 1.26 g/cm³. A printed gear weighs less: the r54t12 gear sliced with P1S PETG profiles at 15% infill used 80.5 g, the published spokes gear at five walls and 50% infill about 103 g including purge.

Loads when this section comes into view.

Repro remix of humebeam's Kraken spool gear (Kraken by humebeam), CC BY-NC 4.0. The STL header carries the credit.

Spoke layout to scale, updated as you type. Window corners are drawn sharp; the model rounds them with the fillet.

Loads when this section comes into view.

Print pose, disc on the bed. Drag to orbit. Grid 10 mm.

Model-only stiffness of the presets (comparative linear model, not a physical test)
Preset	Torsion vs original web	Out-of-plane bending vs original web
Published 8 spokes	1.44×	1.45×
r54t12	1.71×	1.61×
n6r42t12	1.20× (minimum)	not computed

Minimum paired ratios from Repro's linear plate model with hypothetical PETG properties and a hub clamp at R18 (gear README). Custom layouts are not analysed. Strength, creep, fatigue and bearing fit need physical testing. The published eight-spoke gear sliced in about 19% less time than humebeam's original web in a controlled PETG comparison.

06 / HOW THE FILES ARE MADE

Rings

The browser repeats generate_family.py boolean for boolean with the vendored Manifold engine. The outside is a 256-segment support circle joined to a five-point pentagon (first point toward +Y), with a 2 mm lead-in that pulls the points in by 1.9 mm. Inside a cylinder of up to 22.5 mm radius, the ring is humebeam's original holder core for the next smaller whole size. The stock ring's 0.4 mm lip becomes the base of both sides: the normal set thickens it to 0.6 mm on the cap side and to a 2.2 mm flange reaching 10.25 mm past the hole radius on the gear side; the skinny set keeps 0.4 mm on both. The source-lip section, bore and snap ribs included, runs straight through the thicker base, and the spigot rises by the added thickness so it inserts as deep as the stock ring. Spring rings replace the pentagon with a round spigot 0.2 mm under the hole and cut four 30° fingers, 1.3 mm thick with 1.0 mm slots, that bow out to 0.2 mm past the hole.

Checked against the Python generator's own files on 2026-10-28: normal pentagon pairs at 45, 46, 50, 53.4, 55, 55.5, 60, 70, 80 and 95 mm, skinny pairs at 45, 53.4, 55, 55.5, 70 and 95 mm, and 52.1 mm spring pairs in both sets. The largest symmetric volume difference is 0.0058 mm³, on a 95 mm cap side of 63,500 mm³.

Gear

The gear starts from humebeam's gear with its web made solid, built by gear_web.py plain. The browser cuts N window prisms through the 4 mm disc. All 53,083 source facets outside R90 or above the disc come through unchanged. The published eight-spoke, r54t12 and n6r42t12 presets land within 0.16 mm³ of the analytic CAD volume. The Python meshes differ from the analytic volume by 0.8–1.2 mm³, the chord sag of their OCCT window arcs.

Nut

The nut follows the 3.0 mm stiff-nut builder with the added thickness as the input. Against that builder's 3.0 mm STL the symmetric volume difference is 1.5 × 10⁻⁴ mm³. Each extra millimetre of flange takes one millimetre from the widest spool the holder accepts, and adds about 7.3 g of PETG at full density.

Downloads are checked as one closed solid at their float32 STL coordinates before the buttons enable. A 53.4 mm pair, a 3.5 mm nut and the r54t12 gear sliced without supports or brim in OrcaSlicer with P1S PETG profiles. Physical fit of generated fractional sizes has not been measured.

Built by Repro (thereprocase). Page source and checks · Input file hashes