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HTD displacers: Ø240 flat hollow displacers for a 10 in chamber

Name: HTD displacers: Ø240 flat hollow displacers for a 10 in chamber dimension sheet
Creator: Xem Studio
License: https://creativecommons.org/licenses/by/4.0/

How do I make a large light displacer for a flat Stirling engine? · Hardware · basis: Exact geometry: Ø240 shells in the 10 in bore (Ø247.19), 3.6 radial gap

Long Earth Society build part. Parts of the HTD engines. The engines

Exact dimensions. Every file is drawn at true size with no printing tolerance. The holes and pins that meet another part are listed below under Mating features, with the fit each joint needs; open those by your printer's or process's clearance before making the part. Mating features

sizes: 1 in table

Notes

A thin closed shell: 0.5 skins top and bottom and a 0.5 rim, a Ø20 hub through the middle with the rod socket, a Ø1 hole in the top skin so the inside follows the mean pressure (the skins never carry the charge pressure, only the flow's few pascals).
Mass about 0.57 kg at a density of 7.9 g/cm³ (a lighter shell material scales it). Gap to the bore 3.6 radial: the annulus is the only passage between hot and cold space and the shuttle-loss path (0.5 W air, 2.4 W helium, Martini).
Heat leaks through the displacer: the rim skin about 44 W and radiation between the skins about 71 W (ε 0.3, no shield); a foil shield inside cuts the radiation.

Sizes

part	diameter_mm	thickness_mm	stroke_mm	socket_mm
displacer-240x40-rod6	240.0	40.0	8.0	30.0

Mating features

Drawn at the exact size. Open press, slide, run and socket features by your process's clearance; leave designed gaps and clamp fits as drawn.

feature	exact	mates with	fit	files
OD	Ø240 in the Ø247.19 bore	hot cup bore (3.6 radial, no contact)	designed	all
rod socket	Ø6 × 30 (M6 as the major diameter)	displacer rod, M6 thread	press	all
end clearance	1.5 to floor and ceiling at the stroke ends	cup floor, cap	designed	all
equalising hole	Ø1	gas (no contact)	designed	all

Where the files are

Other publishers' files are linked, not hosted. "verify" = check the license at the link before commercial use.

NASA (NTRS, public domain)	W. R. Martini, Stirling Engine Design Manual, NASA CR-168088 (1983): shuttle loss	PDF	US Government work, public domain
Long Earth Society	Engine builds	web, video	LES site