Thermoacoustic bore spacers and liners for 2 in tri-clamp spools: 8.4, 60 and 61.7 mm — dimension sheet
Source: Xem Studio, https://xemstudio.com/objects/thermoacoustic-bore-spacer/  (CC BY 4.0)
Basis: ASME BPE 2 in bore Ø47.5; ISO 2852 Type B lip 1.95 past the face; inside Ø44 = the regenerator cage bore; lengths from the engine layouts in tools/gen_ta_family.py
Catalog version: 2026-10-20

Sizes: see table below
- Thin tubes at the spool bore (Ø47.5 outside, Ø44 inside) that stand between the parts of a thermoacoustic core and hold each one where the acoustic design wants it. Their ends bear on the exchangers' 1.0 mm outer ring and on the gasket lip, so the whole stack is held between the two gasket lips of the spool with nothing loose.
- 8.4: from a gasket lip to an exchanger at 10.35 mm from the face, so the exchanger sits under a 14 mm water jacket that starts 9.35 mm from the face (clear of the clamp).
- 61.7: the loop core's thermal buffer tube liner. In a 6 in spool the stack of parts is lip, 8.4 spacer, exchanger 10, buffer tube 61.7, hot exchanger 10, regenerator 40, exchanger 10, 8.4 spacer, lip: exactly the 148.5 mm between the two lips.
- 60: the hot-cavity liner of the standing-wave engines' closed hot end; it holds the hot exchanger 60 mm off the closed end, which in the model lowers the half-wave engine's onset from about 680 °C (exchanger on the closed end) to about 271 °C.
- Fits: outside slide in the bore; inside is gas passage; the end faces are flat rings.

file  outside_mm  inside_mm  length_mm  use
ta-spacer-2in-8.4  47.5  44.0  8.4  end spacer
ta-spacer-2in-60  47.5  44.0  60.0  hot-cavity liner
ta-spacer-2in-61.7  47.5  44.0  61.7  thermal buffer tube

Files elsewhere (not hosted by Xem Studio; license as stated by the publisher):
- Long Earth Society: Engine builds — web, video — LES site — https://longearthsociety.com/engineering/

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