Gear rack, module 1, 120 mm, full-depth 20° teeth — dimension sheet
Source: Xem Studio, https://xemstudio.com/objects/gear-rack-m1-120-full-depth/  (CC BY 4.0)
Basis: Xem Studio design following Brown's figure (1868); true size, no printing allowance
Catalog version: 2026-10-20

Overall (mm): length 120.0, width 11.0, height 8.0
- Module 1 basic rack (ISO 53): straight 20° flanks, pitch π = 3.1416 mm, addendum 1 mm above the pitch line, dedendum 1.25 mm below it, tooth thickness π/2 on the pitch line; 120 × 8 mm, body to 10 mm below the pitch line, three Ø3.4 (M3 clearance) holes across it.
- A module 1 pinion of N teeth sits with its axis N/2 mm above the pitch line and moves the rack πN mm per turn.
- Xem Studio design following Brown's figure; true size, no printing allowance (apply your own to the mating features).

dimension  value
module  1
pressure angle  20°
pitch  3.1416 mm
addendum / dedendum  1 / 1.25 mm
length × width  120 × 8 mm
pitch line to back  10 mm
holes  3 × Ø3.4 at x = −45, 0, 45

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. 113: figure, his text and an animation — web — Publisher's page; dimensions are facts — https://507movements.com/mm_113.html
- Xem Studio: drawing — web — Publisher's page; dimensions are facts — https://xemstudio.com/objects/rack-and-pinion-mechanism/

Free files (CC BY 4.0, Xem Studio; STEP + STL, 1 parts): https://xemstudio.com/files/hardware/gear-rack-m1-120-full-depth/index.json
API: https://xemstudio.com/api/geometry?object=gear-rack-m1-120-full-depth