Nothing in here has an axle

A rim with 48 teeth facing in, a 24-tooth sun with a dish for your thumb, and six 12-tooth planets between them. No pins, no carrier, no bearings: every planet stays on its circle because the sun pushes it out and the rim pushes it back.

Eight printed parts, meshed before you touch them.

Thumb in the dish. The sun turns.

24 teeth driving 12: one turn of the sun is one turn of every planet, the other way.

Six planets on one circle, and nothing at the centre of any of them.

Lift them out. No pins, no carrier, nothing underneath.

Back down flat — the shape it printed in.

Drag the drawing to turn it

Turn the sun once,
count the rim

Hold the rim and give the sun one full turn. Every planet turns exactly once the other way, and the six of them together drift a third of a turn around the middle. Nothing here is approximate: 48 teeth around the rim is exactly twice the 24 in the middle, so the ring of planets needs 3 turns of the sun to come back to where it started.

The outline you are turning is the part itself — the printed face of the shipped mesh, traced tooth by tooth, not an illustration of it.

Sun
0.00
Each planet
0.00
Ring of six
0.00
  • Sun 24 teeth, 39 mm across, dished 1.2 mm deep for a thumb
  • Planets 12 teeth each, six of them, seated on a 27 mm circle
  • Rim 48 teeth facing inward, behind a 3.5 mm wall

One plate, one job,
no assembly step

Every part is 10 mm tall with a flat bottom, so the whole train prints lying down, no supports, nothing to glue afterwards. It comes off the plate as one stiff disc and takes a first firm twist to break the parts free of each other.

Close view of the meshing teeth, showing the chevron of the herringbone flanks and the layer lines of the print.
Herringbone: two opposed 20° helices meeting at an apex halfway up the face. Opposed hands cancel the sideways push a single helix would make, which is what keeps a planet sitting flat with nothing holding it down.
The printed disc seen from above at an angle: a peach rim, a lavender sun gear and six pastel planet gears, all meshed.
Eight parts, and the seams between them are the only gaps: tooth tip to tooth root measures 0.375 mm at every one of the 12 meshes.
The disc almost edge on, showing the rounded outer bead of the rim and the gears sitting inside it.
The outer edge is a 2 mm roundover top and bottom, so the part you pinch has no printed corner on it.

The part

Overall
3.2 × 3.2 × 0.4 in
Weight
0.9 oz
Printed parts
8, in one job
Material
PETG
On the plate
2.7 h
Gear set
24 / 12 × 6 / 48 teeth
Module
1.5 mm
Teeth
20° herringbone, 10 mm face
Mesh clearance
0.375 mm, tip to root
Ratio
3 sun turns per turn of the ring of six

Eight pieces come off one plate as a single stiff disc. The first twist frees them, and nothing after that needs a tool.