Crank discs Ø30 for a Ø3 crankshaft, 10 to 20 mm stroke — dimension sheet
Source: Xem Studio, https://xemstudio.com/objects/crank-discs-3mm-bore/  (CC BY 4.0)
Basis: Ø30 × 6 disc, Ø3 bore, Ø3 pin hole at stroke / 2, M3 grub
Catalog version: 2026-10-20

Sizes: see table below
- A Ø30 × 6 disc with a Ø3 bore for the crank head's Ø3 crankshaft (623 towers) or the can engine's Ø3 shaft.
- A Ø3 pin hole at 5.0, 7.5 or 10.0 mm from the axis gives 10, 15 or 20 mm stroke.
- A radial Ø2.5 hole (M3 tap drill) at mid-thickness locks it to the shaft.

file  stroke  pin offset  disc  bore
crank-disc-b3-stroke10  10  5.0  Ø30 × 6  3
crank-disc-b3-stroke15  15  7.5  Ø30 × 6  3
crank-disc-b3-stroke20  20  10.0  Ø30 × 6  3

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

Free files (CC BY 4.0, Xem Studio; STEP + STL, 3 parts): https://xemstudio.com/files/hardware/crank-discs-3mm-bore/index.json
API: https://xemstudio.com/api/geometry?object=crank-discs-3mm-bore