Lower fiddle block: pitch-Ø19 and pitch-Ø25 sheaves side by side — dimension sheet
Source: Xem Studio, https://xemstudio.com/objects/tackle-block-fiddle-lower-19-25/  (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 13.0, height 45.7
- 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. The stem sits on the line of the four supporting strands' resultant (x = 1.5).
- Xem Studio design following Brown's figure; true size, no printing allowance (apply your own to the mating features).

dimension  value
sheaves  pitch Ø19 at (-24.5, 0), pitch Ø25 at (27.5, 0)
cheeks  2 mm, 9 mm apart (8 mm sheaves)
pins  Ø4
stems  Ø3 × 8 at x = 1.5 down

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-lower-19-25/index.json
API: https://xemstudio.com/api/geometry?object=tackle-block-fiddle-lower-19-25