Xem Studiomeasured geometryLibrary › Mechanisms › Intermittent motion ·
Geneva stop star: 5 positions, 4 slots and one convex stop tooth, Ø64.72, Ø5 bore
What is the star of a Geneva stop? · Modern device · basis: Xem Studio design following Brown's figure (1868); true size, no printing allowance
Also called: geneva star, maltese cross, stop work star, winding stop wheel, cruz de Malta con diente de tope, Malteserkreuz mit Sperrzahn
Exact dimensions. True size, with no printing tolerance added.
- length
- 60.13 mm
- width
- 63.14 mm
- height
- 6.0 mm
Notes
- Maltese cross of tip radius 32.36 (= a·cos(π/5)) with 5 positions 72° apart: 4 radial slots 4 wide (= the pin, no clearance) with round bottoms 17.87 mm deep, and one position left as a convex tooth of the full rim radius — the stop. Between positions the rim is a concave arc of radius 20.51 about the finger wheel's centre, which rests on the locking disc.
- Each turn of the finger wheel indexes the star one position; after four turns the pin arrives at the convex tooth, cannot enter, and the wheel is held: a four-turn stop. In a watch the finger wheel sits on the barrel arbor and the star on a stud — it limits the winding so the mainspring never reaches its stiffest, over-wound turns.
- Xem Studio design following Brown's figure; true size, no printing allowance (apply your own to the mating features).
Geneva stop star: 5 positions, 4 slots and one convex stop tooth… size chart
| dimension | value |
|---|---|
| positions | 5 (4 slots + 1 stop tooth) |
| tip radius | 32.36 mm |
| slot | 4 wide, 17.87 deep |
| locking arcs | r 20.51 about the wheel centre |
| thickness | 6 mm |
| bore | Ø5 |
| turns allowed | 4 |
Where the files are
Other publishers' files are linked, not hosted. "verify" = check the license at the link before commercial use.
| Henry T. Brown (1868, public domain) | Five Hundred and Seven Mechanical Movements — scan on archive.org | web | Publisher's page; dimensions are facts |
| 507movements.com | Brown's movement No. 212: figure, his text and an animation | web | Publisher's page; dimensions are facts |
| Xem Studio | drawing | web | Publisher's page; dimensions are facts |
Free files
★ Free files 1 parts. Xem Studio design: free to use, print and sell things from; not to be republished as files. Xem Studio Design License. index.json
| geneva-stop-star-5-positions-4-slots-r32-4 | star, axis Z, z 0..6, slot 0 on -X, stop tooth at 288° | STEP · STL |
https://xemstudio.com/mcp to Claude, ChatGPT, Cursor or any MCP client (free, no account, one minute) and it can look up exact sizes, mating fits and free STEP/STL from every chat.Plain text: sheet.txt · JSON: /api/geometry?object=geneva-stop-star-5-positions-4-slots-r32-4
Fits with
Questions
What is the star of a Geneva stop?
Maltese cross of tip radius 32.36 (= a·cos(π/5)) with 5 positions 72° apart: 4 radial slots 4 wide (= the pin, no clearance) with round bottoms 17.87 mm deep, and one position left as a convex tooth of the full rim radius — the stop. Between positions the rim is a concave arc of radius 20.51 about the finger wheel's centre, which rests on the locking disc.