Print-in-Place Herringbone Planetary Fidget | Keychain

A satisfying planetary-gear fidget with herringbone teeth: the V-shaped teeth lock every gear in place vertically, so nothing falls out — no pins, no carrier, no glue, no supports.

Features

• ✅ Print-in-place — comes off the bed as one working mechanism

• ✅ No supports, no assembly

• ✅ Herringbone gears = smooth, quiet, can't fall apart

• ✅ Thumb dimple on the sun gear, grip ridges on the ring, keyring loop

• ✅ Multi-color ready — separate STLs for ring / sun / planets (same coordinates)

• ✅ Fully parametric OpenSCAD source — open it in the Customizer to change size, teeth, clearance, thickness

Specs (default)

• Ø 49 mm (58 mm with keyring loop), 10 mm thick

• Sun 16T, 4 × planet 12T, ring 40T — gear ratio 3.5 : 1

• ~14 g PLA, ~45–60 min on a modern printer

Print settings

First layer is critical — a squished first layer will fuse the gears. Level/calibrate first, keep the first-layer flow at 100 %.

Freeing it up

Right after printing, hold the ring and twist the sun firmly (pliers through the keyring hole help). It may click once or twice — that's the first-layer skin breaking. After 20–30 turns it runs smooth.

Doesn't turn? Customize!

Open the .scad in Customizer and adjust:

• clearance — 0.25 for tuned printers, 0.3 default, 0.35 if it fuses

• first_layer_relief — raise to 0.2–0.25 if only the bottom is stuck

• module_mm — bigger = bigger gears, larger desk toy

• thickness, keyring, grip_scallops, planet_holes, sun_dimple