Tri-clamp con-rod: 58, 70 and 95 mm centres with 623 pockets — dimension sheet
Source: Xem Studio, https://xemstudio.com/objects/tri-clamp-con-rod/  (CC BY 4.0)
Basis: Rod centres = wrist-pin height + crank height + stroke/2 (1.5 in 58, 2 in 70, 3 in 95 mm), keeping the rod angle under 11°
Catalog version: 2026-10-20

Sizes: see table below
- An I-section connecting rod with a Ø10 pocket for a 623 bearing at each end: the small end on the piston's Ø3 wrist pin, the big end on the Ø3 crank pin.
- Centres 58 / 70 / 95 mm for the 1.5 / 2 / 3 in piston and crank frame. 5 mm thick, Ø14 ends, 10 mm wide web recessed 1.2 mm each side (2.6 mm web).
- Overall 72 / 84 / 109 mm long. At bottom dead centre the piston skirt is flush with the ferrule face.

spool_in  centres_mm  overall_len_mm  thickness_mm  end_od_mm  pockets
1.5  58  72  5  14  623 (Ø10) both ends
2  70  84  5  14  623 (Ø10) both ends
3  95  109  5  14  623 (Ø10) both ends

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/
- James R. Senft: An Introduction to Stirling Engines (piston fit and leakage) — book — Moriya Press [verify license at link] — https://www.stirlingengine.com/
- ASME: BPE tube dimensions (16 ga sanitary tube) — standard — ASME [verify license at link] — https://www.asme.org/codes-standards/find-codes-standards/bpe-bioprocessing-equipment

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