Tracer arm, Ø10 hub, Ø3 pin at 15 mm — dimension sheet
Source: Xem Studio, https://xemstudio.com/objects/tusi-tracer-arm-15/  (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 33.0, width 18.0, height 5.0
- Fixed to the planet (same Ø10 axle), it puts a Ø3 pin exactly on the planet's pitch circle (15 mm out): that point runs on a straight line through the ring's centre.
- Xem Studio design following Brown's figure; true size, no printing allowance (apply your own to the mating features).

dimension  value
pin radius  15 mm
hub hole  Ø10
pin hole  Ø3

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. 329: figure, his text and an animation — web — Publisher's page; dimensions are facts — https://507movements.com/mm_329.html
- Xem Studio: drawing — web — Publisher's page; dimensions are facts — https://xemstudio.com/objects/tusi-couple-straight-line-mechanism/

Free files (CC BY 4.0, Xem Studio; STEP + STL, 1 parts): https://xemstudio.com/files/hardware/tusi-tracer-arm-15/index.json
API: https://xemstudio.com/api/geometry?object=tusi-tracer-arm-15