Can-engine diaphragm: membrane, clamp rings and centre disc, Ø40 / 50 / 60 — dimension sheet
Source: Xem Studio, https://xemstudio.com/objects/can-engine-diaphragm/  (CC BY 4.0)
Basis: Ring bore = diaphragm working diameter; centre disc at half the bore; 6 × M3 clearance (ISO 273) on the ring
Catalog version: 2026-10-20

Sizes: see table below
- The diaphragm power piston of the can engine: a 0.2 mm membrane clamped round its edge between two identical rings, with a stiff centre disc the con-rod screws to.
- Rings come in Ø40, Ø50 and Ø60 bores, each 3 thick with an outside of bore + 16 (Ø56 / 66 / 76) and 6 × Ø3.4 holes on a bore + 8 circle (Ø48 / 58 / 68).
- Each ring size has its own centre disc at half the bore: Ø20, Ø25 or Ø30 × 2 with a Ø3.2 hole for the M3 con-rod screw.
- Each membrane is the rings' outside diameter (Ø56 / 66 / 76) × 0.2 with the same six Ø3.4 holes and a Ø3.2 centre hole; its free span is the ring bore. One membrane, two rings and one disc of the same size make one diaphragm.

size  ring bore  ring outside  screw circle  ring thickness  disc  disc hole
40  40  56  48  3  Ø20 × 2  3.2
50  50  66  58  3  Ø25 × 2  3.2
60  60  76  68  3  Ø30 × 2  3.2

Files elsewhere (not hosted by Xem Studio; license as stated by the publisher):
- Wikipedia: Stirling engine — web — CC BY-SA 4.0 (text) — https://en.wikipedia.org/wiki/Stirling_engine
- Long Earth Society: Can engine build — video, web — LES site — https://longearthsociety.com/engineering/
- Long Earth Society: Engine builds (videos and write-ups) — web, video — LES site — https://longearthsociety.com/engineering/

Free files (CC BY 4.0, Xem Studio; STEP + STL, 9 parts): https://xemstudio.com/files/hardware/can-engine-diaphragm/index.json
API: https://xemstudio.com/api/geometry?object=can-engine-diaphragm