Eccentric spur gear, module 1, 40 T, Ø5 bore 5 mm off centre, Ø3 centre stud hole — dimension sheet
Source: Xem Studio, https://xemstudio.com/objects/eccentric-spur-gear-m1-40t-e5-b5/  (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 41.99, width 41.99, height 8.0
- Ordinary module 1, 40-tooth involute gear (pitch Ø40, face 8) whose Ø5 shaft bore is 5 mm off its geometric centre, with a Ø3 hole at the true centre for the stud that keeps the link to the pinion. On its shaft it turns at constant speed while its pitch circle wobbles ±5 mm.
- Xem Studio design following Brown's figure; true size, no printing allowance (apply your own to the mating features).

dimension  value
module  1
teeth  40
bore  Ø5 at 5 mm from centre
centre hole  Ø3
face  8 mm

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. 222: figure, his text and an animation — web — Publisher's page; dimensions are facts — https://507movements.com/mm_222.html
- Xem Studio: drawing — web — Publisher's page; dimensions are facts — https://xemstudio.com/objects/eccentric-gear-and-pinion-mechanism/

Free files (Xem Studio Design License, Xem Studio; STEP + STL, 1 parts): https://xemstudio.com/files/hardware/eccentric-spur-gear-m1-40t-e5-b5/index.json
API: https://xemstudio.com/api/geometry?object=eccentric-spur-gear-m1-40t-e5-b5