Crankshafts Ø3, Ø5 and Ø8 with full-length D-flat — dimension sheet
Source: Xem Studio, https://xemstudio.com/objects/stirling-crankshafts/  (CC BY 4.0)
Basis: Solid shafts at the 623 / 625 / 608 bore Ø; Ø5 and Ø8 with a 0.5 mm D-flat along the whole length
Catalog version: 2026-10-20

Sizes: see table below
- Solid round shafts with 0.3 chamfers on both ends. Ø3 × 40, 44, 60 and 80 are plain round; Ø5 × 80, 100, 120, 150 and Ø8 × 80, 100, 120 have a D-flat 0.5 deep along the whole length (4.5 and 7.5 across the flat).
- The flat is where the M3 grubs in crank discs, webs and flywheel hubs bear, so the hubs cannot turn on the shaft. It also gives the shaft a flat face to lie on.
- Ø3: the crank head's 623 towers and the Ø3-bore crank discs. Ø5: the 625 crank stands, rhombic gears, crank discs and Ø5 flywheel hubs. Ø8: the tri-clamp crank frame's 608s, crank webs and Ø8 flywheel hubs.
- Lengths on the engines here: 2 in gamma Ø5 × 100 between two 625 stands with the flywheel outside; tri-clamp crank frame Ø8 × 80; rhombic gear shafts Ø5 × 80, one × 120 to carry the flywheel; can engine Ø3 × 44 and LTD Ø3 × 40 (a crank disc at each end, bearings and flywheel between).

file  Ø  length  D-flat  fits
crankshaft-3x40  3  40  —  623; crank-disc-b3
crankshaft-3x44  3  44  —  623; crank-disc-b3
crankshaft-3x60  3  60  —  623; crank-disc-b3
crankshaft-3x80  3  80  —  623; crank-disc-b3
crankshaft-5x80-dflat  5  80  0.5 full length (4.5)  625; crank discs; Ø5 hubs
crankshaft-5x100-dflat  5  100  0.5 full length (4.5)  625; crank discs; Ø5 hubs
crankshaft-5x120-dflat  5  120  0.5 full length (4.5)  625; crank discs; Ø5 hubs
crankshaft-5x150-dflat  5  150  0.5 full length (4.5)  625; crank discs; Ø5 hubs
crankshaft-8x80-dflat  8  80  0.5 full length (7.5)  608; crank webs; Ø8 hubs
crankshaft-8x100-dflat  8  100  0.5 full length (7.5)  608; crank webs; Ø8 hubs
crankshaft-8x120-dflat  8  120  0.5 full length (7.5)  608; crank webs; Ø8 hubs

Files elsewhere (not hosted by Xem Studio; license as stated by the publisher):
- Long Earth Society: Engine builds — web, video — LES site — https://longearthsociety.com/engineering/

Free files (CC BY 4.0, Xem Studio; STEP + STL, 11 parts): https://xemstudio.com/files/hardware/stirling-crankshafts/index.json
API: https://xemstudio.com/api/geometry?object=stirling-crankshafts