Tri-clamp instrument head: ISO 2852 cap with Ø6, Ø3 and Ø4 probe ports, 1.5, 2 and 3 in — dimension sheet
Source: Xem Studio, https://xemstudio.com/objects/tri-clamp-instrument-head/  (CC BY 4.0)
Basis: ISO 2852 cap face with three ported bosses on the C2 − 16 circle, each with an M3 pinch hole (Ø2.5)
Catalog version: 2026-10-20

Sizes: see table below
- An ISO 2852 end cap with three probe ports, so a cylinder can be instrumented without drilling a flat cap.
- Ports: Ø6 (a DS18B20 sleeve), Ø3 (a K-type sheath) and Ø4 (a 4 mm tube), 120° apart on a circle of radius C2/2 − 8 (13.75 / 20.25 / 33.75 mm for 1.5 / 2 / 3 in).
- Each port has a boss 6 mm larger than its bore, 10 mm tall on the back of the 6 mm cap, and an Ø2.5 radial hole at 11 mm for an M3 pinch screw that holds the probe.

size_in  flange_od_mm  port_circle_r_mm  ports_mm  pinch
1.5  50.5  13.75  Ø6 / Ø3 / Ø4  M3 (Ø2.5)
2  64.0  20.25  Ø6 / Ø3 / Ø4  M3 (Ø2.5)
3  91.0  33.75  Ø6 / Ø3 / Ø4  M3 (Ø2.5)

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-instrument-head/index.json
API: https://xemstudio.com/api/geometry?object=tri-clamp-instrument-head