Geneva stop (Maltese cross stop-work): finger wheel limited to four turns — dimension sheet
Source: Xem Studio, https://xemstudio.com/objects/geneva-stop-winding-stop-mechanism/  (sheet CC BY 4.0; files Xem Studio Design License, https://xemstudio.com/license/)
Basis: Xem Studio design following Brown No. 212 (1868)
Catalog version: 2026-10-20

Sizes: see table below
- Resize: multiply every length by one factor k and the motion stays identical: angles, ratios, timing and the formulas below do not change, because a mechanism's motion depends only on the ratios of its lengths. Here, scales with k: centres; stays the same: star, turns allowed, engagement; step to the nearest standard size (and redraw the hole or pocket it fits): pin.
- Resize: fit clearances stay in mm (a slide fit is the same gap at any size); keep every printed wall and pin at least two nozzle widths; mass grows with k³ but part strength only with k², so at k = 2 parts are about 8× heavier and 4× stronger: check pins and thin links when scaling up.
- A finger wheel with one pin indexes a five-position Maltese cross one position per turn, the locking disc holding the cross still in between (a Geneva drive). One of the five positions is not a slot but a convex tooth: when the pin comes round to it the tooth will not let it in, and the finger wheel is stopped — after four turns in one direction (and four back). Brown: used in Swiss watches to limit the winding; the convex curved portion of the star is the stop.
- Standard Geneva proportions on 40 mm centres: pin radius a·sin 36° = 23.51, star tip radius a·cos 36° = 32.36, so the pin enters and leaves each slot along the slot (no shock); Ø4 pin in 4 mm slots, locking disc Ø41.02 cut back by the star's exact sweep. Checked at ten wheel angles through an indexing and at the last slot before the stop: no overlap beyond contact; with the stop tooth in place of a slot the pin collides 6° past the entry angle (75.4 mm³), which is the stop.
- Drawn with the pin entering the second slot (-20° before the line of centres), the stop tooth three positions on.
- Parts (each has its own page): geneva-stop-finger-wheel-r23-5-pin4, geneva-stop-star-5-positions-4-slots-r32-4, linear-shafts-h6.
- Brown's movement No. 212 (1868) shows it; this model is a Xem Studio design following his figure, every part at true size.

parameter  value
centres  40 mm
star  5 positions: 4 slots + 1 stop tooth
pin  Ø4 at r 23.51
turns allowed  4
engagement  108° of the wheel's turn per index

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

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