Tri-clamp displacer head: ISO 2852 cap with Ø3 rod bore and 4 mm barb, 1.5, 2 and 3 in — dimension sheet
Source: Xem Studio, https://xemstudio.com/objects/tri-clamp-displacer-head/  (CC BY 4.0)
Basis: ISO 2852 cap face (Ø50.5 / 64.0 / 91.0 flange, 6 mm cap) with a Ø3 run bore on centre and a 4 mm hose barb
Catalog version: 2026-10-20

Sizes: see table below
- An ISO 2852 end cap with the displacer-rod guide and a transfer port on its back, so a stock clamp and Type B gasket seal it to any ferrule of its size.
- On centre: a Ø3 bore straight through cap and boss for the Ø3 displacer rod (run fit). The bore is the rod guide and the clearance seal; nothing is pressed into it.
- Off centre: an integral 4 mm hose barb (Ø6.4 base, Ø3.2 bore) for the transfer tube to the power cylinder, at 13.75 / 20.25 / 33.75 mm from the axis on the 1.5 / 2 / 3 in head.
- Flange Ø50.5 (1.5 in, also fits 1 in ferrules), Ø64.0 (2 in), Ø91.0 (3 in).

size_in  flange_od_mm  rod_bore_mm  barb  barb_offset_mm
1.5  50.5  3  4 mm (Ø6.4, Ø3.2 bore)  13.75
2  64.0  3  4 mm (Ø6.4, Ø3.2 bore)  20.25
3  91.0  3  4 mm (Ø6.4, Ø3.2 bore)  33.75

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 Low Temperature Differential Stirling Engines (displacer and gap design) — book — Moriya Press [verify license at link] — https://www.stirlingengine.com/
- Wikipedia: Stirling engine — web — CC BY-SA 4.0 (text) — https://en.wikipedia.org/wiki/Stirling_engine

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