Every gear has the radius, thickness and tooth count measured in the CT scan; the distances between arbors are those imposed by meshing; the motion is the same computing engine as the two-dimensional pages. Drag to rotate, scroll to zoom, right-drag to pan.
The wheels move apart along the crank axis: in this model they sit on twelve different depths, from +3.0 mm for the big b1 down to −13.5 mm for the last plane. Turn the labels on and look for k1 and k2: two 50-tooth wheels on arbors that are not aligned, one carrying a pin that runs in the other’s slot — that is how the machine makes the Moon run faster near perigee and slower near apogee. The pale green wheels are the hypothetical ones: they are not in the artefact.
Drag to orbit · pinch or scroll to zoom · tap a wheel for its card, tap again for the one behind
The tooth counts and the measurements — radius, thickness — of the 30 surviving gears come from the computed tomography of the artefact held at the National Archaeological Museum in Athens: Freeth et al., Nature 2006, and Freeth et al., Scientific Reports 2021, Table S8. The distances between the arbors are the sum of the pitch radii: the only position at which two gears can actually mesh. The ratios that drive the pointers are those of the back dials published in Freeth, Jones, Steele & Bitsakis, Nature 2008. The design choices — the angular placement of the arbors the papers do not publish, the depths the wheels sit at (twelve distinct planes), the shape of the plates, the patina — are listed line by line in the table below and marked derived or approximate. Where the source is missing, the model says so instead of pretending to know.
That distinction is the substance of this model, so it is declared line by line.
| Element | Source | Status |
|---|---|---|
| Tooth count, outer/inner/pitch radius and thickness of the 30 surviving gears | Freeth et al. 2021, Table S8 | measured |
| Radii of the 7 hypothetical gears (m3, n1, n2, n3, p1, p2, q1c) | mean module 0.495 × teeth / 2 | derived |
| Centre distance of every meshing pair | sum of the pitch radii | imposed by the mechanics |
| Metonic arbor (n) on the vertical above b; Saros arbor (g) on the vertical below | position of the two back dials | real constraint |
| Angular placement of the other arbors (c, d, e, f, h, i, l, m, o, p, q) | solved numerically: exact meshing, no collision between gears on the same layer | design choice — TO BE VERIFIED against the CT coordinates |
| Order and depth of the layers (z) | order imposed by the trains; depths chosen here, 1.5 mm pitch | approximate |
| Dimensions of plates, dials and spirals; pointer shapes | front cover ≈128.8 mm; the rest sized to contain the train | approximate |
| Artefact patina (surface colour and roughness) | procedural noise calibrated on the documented colours of corroded bronze: verdigris, cuprite, calcareous deposits; not a photograph | evocative |
| Direction of rotation, ratios, pin and slot | engine of the 2D pages (tested) | computed |