Upper fiddle block: pitch-Ø80 and pitch-Ø30 sheaves one above the other, with becket — dimension sheet
Source: Xem Studio, https://xemstudio.com/objects/tackle-block-fiddle-upper-80-30/  (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 90.4, width 13.0, height 140.2
- Block frame: two 2 mm cheeks either side of the sheaves (Ø4 pin holes), joined by bridges that carry Ø3 stems (into the beam, the floor plate or a weight's socket) and Ø3 rope-end sockets; every bridge sits clear of the rope's path. Both sheaves turn in one plane, so every rope strand hangs vertical in that plane.
- Xem Studio design following Brown's figure; true size, no printing allowance (apply your own to the mating features).

dimension  value
sheaves  pitch Ø80 at (0, 0), pitch Ø30 at (0, -62)
cheeks  2 mm, 9 mm apart (8 mm sheaves)
pins  Ø4
stems  Ø3 × 8 at x = 0 up
rope sockets  Ø3 × 5 at x = -34

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/blocks-and-tackle-mechanism/

Free files (Xem Studio Design License, Xem Studio; STEP + STL, 1 parts): https://xemstudio.com/files/hardware/tackle-block-fiddle-upper-80-30/index.json
API: https://xemstudio.com/api/geometry?object=tackle-block-fiddle-upper-80-30