Rope sheave for Ø3 rope, pitch Ø80 (rope centre), Ø84.4 rim, Ø4 bore — dimension sheet
Source: Xem Studio, https://xemstudio.com/objects/rope-sheave-3mm-pitch-80/  (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 84.4, width 8.0, height 84.4
- Sheave 8 mm wide with a round-bottomed groove of radius 1.6 mm (1.07 × the Ø3 rope, the usual 6–10 % oversize) opening into 30° flanks; the rope rests on the groove bottom with its centre on a Ø80 circle, so a turn moves the rope 251.33 mm. Rim Ø84.4, Ø4 bore for a Ø4 pin.
- Xem Studio design following Brown's figure; true size, no printing allowance (apply your own to the mating features).

dimension  value
rope  Ø3
pitch Ø (rope centre)  80 mm
groove  R1.6, 30° flanks
rim  Ø84.4 × 8 mm
bore  Ø4

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. 12: figure, his text and an animation — web — Publisher's page; dimensions are facts — https://507movements.com/mm_012.html
- Xem Studio: drawing — web — Publisher's page; dimensions are facts — https://xemstudio.com/objects/single-fixed-pulley-mechanism/

Free files (Xem Studio Design License, Xem Studio; STEP + STL, 1 parts): https://xemstudio.com/files/hardware/rope-sheave-3mm-pitch-80/index.json
API: https://xemstudio.com/api/geometry?object=rope-sheave-3mm-pitch-80