Power cylinder liners, piston blanks, crosshead and guide (the non-syringe power piston) — dimension sheet Source: Xem Studio, https://xemstudio.com/objects/power-cylinder-piston-crosshead/ (CC BY 4.0) Basis: Trunk piston and crosshead practice for model engines: clearance-seal piston lapped into a honed liner (10–25 µm radial), or a graphite piston in a glass tube; crosshead takes the con-rod side load so the piston only moves axially Catalog version: 2026-10-20 Sizes: see table below - Two ways to seal: (1) lapped fit: brass or aluminium piston turned 0.05 under, lapped with fine compound into a honed brass/stainless liner until it falls through slowly under its own weight; (2) graphite piston in a borosilicate glass tube (16 or 20 mm test tube / tube): self-lubricating, near-zero friction, the premium option. Printed liners and pistons here are for prototyping the layout; a printed piston will not seal. - Sizes: Ø16 (1.65 mL per 12 mm stroke... see table), Ø20, Ø25, Ø30. For the 2 in tri-clamp gamma with the Ø46 × 90 displacer at 20 mm stroke, a Ø20 × 12 mm stroke piston (3.8 mL) is in the right range; Ø16 at 15 mm for the 1.5 in. - Crosshead: a Ø8 slider on the Ø3 piston rod running in a guide bushing; the con-rod's angle pushes sideways on the crosshead, not the piston, so the lapped seal stays round. Trunk alternative: wrist pin in the piston boss, con-rod directly on it; fine for short rods (L ≥ 4 × stroke). - Flange: 4 × M3 on a Ø(D + 16) circle, matches the power head's socket pattern when drilled; seal with a paper or silicone gasket. bore_mm liner_len_mm piston_len_mm ml_per_12mm_stroke 16 40 14 2.41 20 45 18 3.77 25 50 22 5.89 30 55 27 8.48 Files elsewhere (not hosted by Xem Studio; license as stated by the publisher): - Wikipedia: Crosshead — web — CC BY-SA 4.0 (text) — https://en.wikipedia.org/wiki/Crosshead - Wikipedia: Piston — web — CC BY-SA 4.0 (text) — https://en.wikipedia.org/wiki/Piston - James R. Senft: Miniature Stirling engine piston fits (LTD book) — book — reference [verify license at link] — https://www.stirlingengine.com/ - 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/power-cylinder-piston-crosshead/index.json API: https://xemstudio.com/api/geometry?object=power-cylinder-piston-crosshead