Built-up crank webs for Ø8 shafts and Ø6 crank pins (two-throw cranks at 90°) — dimension sheet
Source: Xem Studio, https://xemstudio.com/objects/stirling-built-up-crank-webs/  (CC BY 4.0)
Basis: Design values; Ø6 dowel crank pins (ISO 8734)
Catalog version: 2026-10-20

Sizes: see table below
- Discs pressed on Ø8 shafts with Ø6 dowel crank pins pressed through them: the horizontal gamma's crank has four webs (two throws, 76.2 mm apart, a shaft between) and the beta's has two webs and a link web between the two con-rods (the shaft does not pass the con-rods).
- Pin radius 15 for the displacer (30 stroke) and 18 for the piston (36 stroke); the pins are a quarter turn apart, the displacer leading.

part  thickness  pin radius
crank-web-56x10-r15  10  15
crank-web-56x11-r15  11  15
crank-web-56x11-r18  11  18
crank-web-56x10-r18  10  18
crank-web-56x8-r18  8  18
crank-web-56x8-r15  8  15
link-web-14-r18-r15-90  14  18 / 15

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, 8 parts): https://xemstudio.com/files/hardware/stirling-built-up-crank-webs/index.json
API: https://xemstudio.com/api/geometry?object=stirling-built-up-crank-webs