Tri-clamp cups: closed-end spools (ferrule on a capped tube), 1.5, 2 and 3 in — dimension sheet Source: Xem Studio, https://xemstudio.com/objects/tri-clamp-cups/ (CC BY 4.0) Basis: ISO 2852 ferrule face (C2/C3, 2.85 mm rim, 1.6 mm recess, 20° back) and 16 ga ASME BPE tube from the tri-clamp ferrule entry; 3 mm flat end plate standing in for a welded cap Catalog version: 2026-10-20 Sizes: see table below - A cup is a spool with one ferrule and the other end closed: in stainless it is a tube with a cap welded on (or a 'tri-clamp end cap spool', sold as such); here it is one printed part. The ferrule end takes a stock clamp and gasket against any head on this shelf. - What it is for: the hot end of a beta or gamma engine (the cup is the displacer cylinder, the open ferrule end gets the cold head with the rod guide), an alpha cylinder with the piston in it and the head carrying the con-rod gland, a cold-side water jacket cap, or a mock-up to check lengths before buying steel. - Printed cups are cold-side and mock-up parts: PETG is good to ~70 °C. For a burner-fired hot end buy a stainless capped spool and use the printed one to set the length. Inner diameter matches the steel (34.8 / 47.5 / 72.9), so the displacers and pistons on this shelf fit both. - Print closed end down, 0.2 mm layers, 3+ walls; the ferrule's 20° back cone needs no supports. Sand the face flat on a sheet of 400 grit on glass so the gasket seals. - Lengths: 1.5 in 50/75/100, 2 in 60/90/120/150, 3 in 80/120/160; the -rod3 version has a Ø3.2 centre hole in the end for a displacer rod gland on the closed end (beta engines with the drive on the hot side are rare; it is there for a cold-end cup). size od_mm id_mm length_mm end_plate_mm end 1.5 38.1 34.8 50 3.0 plain 1.5 38.1 34.8 75 3.0 plain 1.5 38.1 34.8 100 3.0 plain 1.5 38.1 34.8 75 3.0 Ø3.2 centre hole 2 50.8 47.5 60 3.0 plain 2 50.8 47.5 90 3.0 plain 2 50.8 47.5 120 3.0 plain 2 50.8 47.5 150 3.0 plain 2 50.8 47.5 90 3.0 Ø3.2 centre hole 3 76.2 72.9 80 3.0 plain 3 76.2 72.9 120 3.0 plain 3 76.2 72.9 160 3.0 plain 3 76.2 72.9 120 3.0 Ø3.2 centre hole Files elsewhere (not hosted by Xem Studio; license as stated by the publisher): - ISO: ISO 2852:1993 Stainless steel clamp pipe couplings for the food industry — standard — ISO [verify license at link] — https://www.iso.org/standard/7873.html - 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, 13 parts): https://xemstudio.com/files/hardware/tri-clamp-cups/index.json API: https://xemstudio.com/api/geometry?object=tri-clamp-cups