Geneva stop star: 5 positions, 4 slots and one convex stop tooth, Ø64.72, Ø5 bore — dimension sheet
Source: Xem Studio, https://xemstudio.com/objects/geneva-stop-star-5-positions-4-slots-r32-4/  (sheet CC BY 4.0; files Xem Studio Design License, https://xemstudio.com/license/)
Basis: Xem Studio design following Brown's figure (1868); true size, no printing allowance
Catalog version: 2026-10-20

Overall (mm): length 60.13, width 63.14, height 6.0
- 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).

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

Files elsewhere (not hosted by Xem Studio; license as stated by the publisher):
- Henry T. Brown (1868, public domain): Five Hundred and Seven Mechanical Movements — scan on archive.org — web — Publisher's page; dimensions are facts — https://archive.org/details/fivehundredseven00browiala
- 507movements.com: Brown's movement No. 212: figure, his text and an animation — web — Publisher's page; dimensions are facts — https://507movements.com/mm_212.html
- Xem Studio: drawing — web — Publisher's page; dimensions are facts — https://xemstudio.com/objects/geneva-stop-winding-stop-mechanism/

Free files (Xem Studio Design License, Xem Studio; STEP + STL, 1 parts): https://xemstudio.com/files/hardware/geneva-stop-star-5-positions-4-slots-r32-4/index.json
API: https://xemstudio.com/api/geometry?object=geneva-stop-star-5-positions-4-slots-r32-4