Swing arm / link 30 mm, Ø3 hole one end, Ø6 the other — dimension sheet
Source: Xem Studio, https://xemstudio.com/objects/swing-arm-30-holes-3-and-6/  (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 40.0, width 10.0, height 5.0
- 10 × 5 mm bar with a Ø3 hole and, 30 mm away, a Ø6 hole: used twice in the eccentric gear drive, as the arm that swings the pinion's Ø6 axle about a fixed Ø3 pin and as the link from the gear's Ø3 centre stud to that axle.
- Xem Studio design following Brown's figure; true size, no printing allowance (apply your own to the mating features).

dimension  value
centres  30 mm
holes  Ø3 and Ø6
section  10 × 5 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/swing-arm-30-holes-3-and-6/index.json
API: https://xemstudio.com/api/geometry?object=swing-arm-30-holes-3-and-6