Rack guide base 170 × 20 with side rail and spring seat — dimension sheet
Source: Xem Studio, https://xemstudio.com/objects/rack-guide-base-170-spring-seat/  (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 170.0, width 20.0, height 16.0
- 4 mm base plate with a 6 mm side rail the rack slides against and a 10 mm end wall the return spring bears on, 30 mm from the rack's end.
- Xem Studio design following Brown's figure; true size, no printing allowance (apply your own to the mating features).

dimension  value
base  170 × 20 × 4
rail  6 × 8
spring seat  10 × 20 × 12

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. 81: figure, his text and an animation — web — Publisher's page; dimensions are facts — https://507movements.com/mm_081.html
- Xem Studio: drawing — web — Publisher's page; dimensions are facts — https://xemstudio.com/objects/mutilated-gear-spring-rack-mechanism/

Free files (Xem Studio Design License, Xem Studio; STEP + STL, 1 parts): https://xemstudio.com/files/hardware/rack-guide-base-170-spring-seat/index.json
API: https://xemstudio.com/api/geometry?object=rack-guide-base-170-spring-seat