Rectangular (oblong) gear, module 1.5, 40 teeth, driver — dimension sheet
Source: Xem Studio, https://xemstudio.com/objects/rectangular-gear-m1-5-40t-driver/  (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 65.62, width 49.39, height 12.0
- Pitch curve a rounded rectangle (superellipse |x/1.35|^3.5 + |y|^3.5 = 1, scaled to a perimeter of 40 × π × 1.5 mm) pivoted at its centre.
- Teeth generated by a 20° basic rack rolled round the pitch curve (spline outline within 0.008 mm of the generated curve); Ø8 bore at the pivot, 12 mm face.
- Xem Studio design following Brown's figure; true size, no printing allowance (apply your own to the mating features).

dimension  value
module  1.5
teeth  40
size  65.62 × 49.38 mm over tips
bore  Ø8
face  12 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. 30: figure, his text and an animation — web — Publisher's page; dimensions are facts — https://507movements.com/mm_030.html
- Xem Studio: drawing — web — Publisher's page; dimensions are facts — https://xemstudio.com/objects/rectangular-gears-oblong-mechanism/

Free files (Xem Studio Design License, Xem Studio; STEP + STL, 1 parts): https://xemstudio.com/files/hardware/rectangular-gear-m1-5-40t-driver/index.json
API: https://xemstudio.com/api/geometry?object=rectangular-gear-m1-5-40t-driver