LTD Stirling top plate with syringe socket, Ø120 and Ø170 — dimension sheet
Source: Xem Studio, https://xemstudio.com/objects/ltd-top-plate/  (CC BY 4.0)
Basis: Senft LTD gamma layout, sized in the assembled Ø100 engine on this site; syringe socket at the 10 mL barrel OD Ø15.9; rod bore at the 2 mm rod; M3 clearance Ø3.4 (ISO 273), M3 tap drill Ø2.5
Catalog version: 2026-10-20

Sizes: see table below
- The cold plate of the LTD engine and its power cylinder mount. Ø120 (for the 100 chamber) or Ø170 (for the 150 chamber), 3 thick, with 6 × Ø3.4 on a Ø112 / Ø162 circle (at 30°, 90°, …) matching the chamber ring.
- At x −5 a Ø20 boss, 13 tall with the plate, has a Ø2 bore straight through for the 2 mm displacer rod (fit: run); the bore is the rod guide.
- At x 40 (45 from the rod guide, so the two con-rods can sit at the two ends of the crankshaft) a Ø21.9 boss rises to 20 mm with a Ø15.9 socket from 8 to 20 for a 10 mL syringe barrel (fit: socket) and a Ø10 port under it into the chamber: the barrel's closed end sits on the socket floor and its Luer tip ends flush with the plate's underside.
- Four Ø9 × 4 pads at (7.5, ±27) and (27.5, ±27) carry the two crank stands, each with an M3 tapped hole (Ø2.5) 6 deep.

file  plate  screw circle  rod guide  syringe socket  height
ltd-100-top-plate-syringe  Ø120 × 3  112  Ø2 × 13 at x −5  Ø15.9 × 12 at x 40  20
ltd-150-top-plate-syringe  Ø170 × 3  162  Ø2 × 13 at x −5  Ø15.9 × 12 at x 40  20

Files elsewhere (not hosted by Xem Studio; license as stated by the publisher):
- Wikipedia: Stirling engine — web — CC BY-SA 4.0 (text) — https://en.wikipedia.org/wiki/Stirling_engine
- James R. Senft: An Introduction to Low Temperature Differential Stirling Engines — book — Moriya Press [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, 2 parts): https://xemstudio.com/files/hardware/ltd-top-plate/index.json
API: https://xemstudio.com/api/geometry?object=ltd-top-plate