Single-tooth pinion: module 1, 20-tooth gear with one tooth left — dimension sheet
Source: Xem Studio, https://xemstudio.com/objects/single-tooth-pinion-m1-20t/  (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 19.74, width 17.5, height 8.0
- The catalog module 1, 20-tooth gear (Ø6 bore, 8 face) cut down to its root circle (Ø17.5) everywhere except one involute tooth (±9.5° about +X): every turn it engages the driven wheel and advances it exactly one tooth.
- Xem Studio design following Brown's figure; true size, no printing allowance (apply your own to the mating features).

dimension  value
module  1
teeth  1 of 20
root Ø  17.5 mm
bore  Ø6
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. 241: figure, his text and an animation — web — Publisher's page; dimensions are facts — https://507movements.com/mm_241.html
- Xem Studio: drawing — web — Publisher's page; dimensions are facts — https://xemstudio.com/objects/single-tooth-intermittent-gear-mechanism/

Free files (Xem Studio Design License, Xem Studio; STEP + STL, 1 parts): https://xemstudio.com/files/hardware/single-tooth-pinion-m1-20t/index.json
API: https://xemstudio.com/api/geometry?object=single-tooth-pinion-m1-20t