# Build list: Thermoacoustic standing-wave engine, 2 in spools

> What parts do I need to build a Thermoacoustic standing-wave engine, 2 in spools?

- Category: Stirling engines › Guide
- Kind: List / guide
- Basis: Every printed part is a free file on this site; bought items named with quantities
- Page: https://xemstudio.com/objects/list-thermoacoustic-2in/ · JSON: https://xemstudio.com/api/geometry?object=list-thermoacoustic-2in · Plain text: https://xemstudio.com/objects/list-thermoacoustic-2in/sheet.txt
- License: dimension sheet CC BY 4.0 (Xem Studio); linked files under their publishers' licenses

## Notes

- No pistons: a printed stack in a λ/4 tube of spools; a speaker turns the sound into electricity.
- Numbers: 2 in × 6 in + 2 in × 12 in spools ≈ 470 mm closed-open → ~180 Hz · stack 40 mm at ~60 mm from the hot end · 1.3 mm cells (60% honeycomb infill)

## Sizes

| subsystem | object | parts | qty | print_or_buy | note |
|---|---|---|---|---|---|
| Hot end | tri-clamp-end-cap | tc-cap-2in-flat | 1 | print | flame or nichrome coil |
| Spools | tri-clamp-spool | tc-spool-2in-6in, tc-spool-2in-12in | 2 | buy | stainless |
| Joints | tri-clamp-end-cap | tc-gasket-2in | 3 | buy | ISO 2852 Type B gaskets on the cold joints |
| Clamps | tri-clamp-clamps | clamp-half-2in | 6 | print | two halves per joint; stainless clamp at the flame side |
| Stack | thermoacoustic-stacks-and-resonators | stack-blank-2in-40 | 1 | print | honeycomb infill = the stack |
| Heat exchangers | copper-pipe-type-l-m | copper-2in-typeL-50mm | 2 | buy | copper stubs / mesh on both stack faces |
| Cold side | regenerator-and-heat-materials | ceramic-standoff-10x20 | 2 | print | standoffs + water jacket or fins |
| Driver / load | thermoacoustic-stacks-and-resonators | driver-cap-2in-40mm-speaker | 1 | buy | 40 mm speaker |
| Speaker | adafruit-audio-speakers-mics | 3968-speaker-40mm | 1 | buy | 40 mm 4 Ω |
| Instruments | instrument-mounts | probe-clamp-k-type-3mm, probe-clamp-ds18b20-6mm | 2 | print | hot / cold temperatures |
| Insulation | regenerator-and-heat-materials | firebrick-230x114x64 | 1 | buy | under the burner |
| Stand | spool-hanger-collars | hanger-2in-tab, hanger-2in-plain | 2 | print | two collars on the resonator, cold side |
| Frame rails | t-slot-extrusions | 2020-100 | 3 | buy | uprights + crossbar |

## Where the files are

- Long Earth Society: [Engine builds](https://longearthsociety.com/engineering/) — web, video — LES site

## Build order

1. Print the stack blank with 1 perimeter, 0 top/bottom, honeycomb infill 60%.
2. Copper heat-exchanger stubs on each face of the stack (or copper mesh discs).
3. Hot cap on the 6 in spool; stack + exchangers 60 mm from it; 12 in spool; driver cap with the speaker at the open end.
4. Heat the cap (flame or coil); it sings when the gradient is enough; load the speaker with LEDs through a rectifier.

All printed STLs: https://xemstudio.com/objects/list-thermoacoustic-2in/stl-list.txt

## Questions

**What parts do I need to build a Thermoacoustic standing-wave engine, 2 in spools?**

8 printed parts (all free here) and 7 bought items; see the table and build order on this page.

**How do I download every STL for this build at once?**

The stl-list.txt on this page lists every printed part's STL URL; paste it into a download script or your slicer's import.

## Fits with

- [Tri-clamp end cap and gasket, 1.5 and 2 inch](https://xemstudio.com/objects/tri-clamp-end-cap/)
- [Tri-clamp spool (two ferrules on a tube), 1.5 and 2 inch](https://xemstudio.com/objects/tri-clamp-spool/)
- [Tri-clamp clamps (printable two-bolt), hot-joint gaskets and heat shields: 1.5, 2 and 3 in](https://xemstudio.com/objects/tri-clamp-clamps/)
- [Thermoacoustic stacks (slicer-infill blanks, spiral), resonator lengths and a speaker driver cap for tri-clamp spools](https://xemstudio.com/objects/thermoacoustic-stacks-and-resonators/)
- [Copper pipe (ASTM B88 Type L and M), 1/4 to 2 inch](https://xemstudio.com/objects/copper-pipe-type-l-m/)
- [Regenerator and heat materials: stainless mesh counts, steel wool, scrubbers, mica, fiberglass, ceramic, firebrick](https://xemstudio.com/objects/regenerator-and-heat-materials/)
- [Speakers, amplifiers and microphones: 3 in, 40 mm, enclosed, STEMMA speaker, MAX98357, I2S/PDM mics](https://xemstudio.com/objects/adafruit-audio-speakers-mics/)
- [Instrumentation: DS18B20 and K-type probes, hall sensor, encoder disc, dial-indicator stems](https://xemstudio.com/objects/instrument-mounts/)
- [Spool hanger collars: clamp a tri-clamp spool to 2020 extrusion over the flame (1.5, 2, 3 in)](https://xemstudio.com/objects/spool-hanger-collars/)
- [Aluminium T-slot extrusion: 2020, 2040, 2060, 2080, V-slot, 3030, 3060, 4040, 4080, 1010, 1515](https://xemstudio.com/objects/t-slot-extrusions/)