# Clamp-on hot-end fin sleeve for a 2 in tri-clamp tube (optional)

> How do I add fins to a plain tri-clamp hot end?

- Category: Hardware › Stirling & thermoacoustic
- Kind: Hardware
- Basis: Design values: ring fins Ø76 × 1.5 at 5 pitch, two halves clamping the Ø50.8 tube
- Page: https://xemstudio.com/objects/tri-clamp-hot-end-fin-sleeve/ · JSON: https://xemstudio.com/api/geometry?object=tri-clamp-hot-end-fin-sleeve · Plain text: https://xemstudio.com/objects/tri-clamp-hot-end-fin-sleeve/sheet.txt
- License: dimension sheet CC BY 4.0 (Xem Studio); linked files under their publishers' licenses
- Use in every chat: add https://xemstudio.com/mcp as a connector (https://xemstudio.com/use-with-ai/)

**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.

## Notes

- Two halves with 14 ring fins that clamp onto the lower 66 mm of the closed-end spool with 4 × M4 × 16: the flame passes between the fins inside the shroud. The spool itself stays plain.
- Optional: without it the flame heats the bare tube; the analysis on the performance page assumes the inside wall at 800 K either way, and the sleeve is how a burner gets there with less flame.

## Mating features (exact size; open press / slide / run / socket by your process clearance, leave designed and clamp as drawn)

| feature | exact | mates with | fit | files |
|---|---|---|---|---|
| bore | Ø50.8 | hot spool tube OD | clamp | all |
| split | 1.0 total (0.5 per half) | the other half | clamp | all |
| ear holes | Ø4.5 | M4 clearance (ISO 273 medium) | designed | all |

## Sizes

| feature | value |
|---|---|
| fins | 14 × Ø76 × 1.5, pitch 5 |
| bore | Ø50.8 (clamp) |
| height | 2–68.5 |

## Where the files are

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

## Free STEP/STL (1 parts, CC BY 4.0, Xem Studio)

Index: https://xemstudio.com/files/hardware/tri-clamp-hot-end-fin-sleeve/index.json

- fin-sleeve-half-2in-76: [STEP](https://xemstudio.com/files/hardware/tri-clamp-hot-end-fin-sleeve/fin-sleeve-half-2in-76.step) · [STL](https://xemstudio.com/files/hardware/tri-clamp-hot-end-fin-sleeve/fin-sleeve-half-2in-76.stl) — fin sleeve half (optional): bore Ø50.8 from 2 to 68.5 above the hot end, 14 ring fins Ø76 × 1.5 at 5 pitch, ears with 2 × M4 each side

## Questions

**Is it required?**

No; it is a heat exchanger and every heat exchanger on this engine is optional.

## Fits with

- [Tri-clamp closed-end spool: 2 in × 152.4 mm (6 in) with a welded closed end, the hot end of a pressurised Stirling](https://xemstudio.com/objects/tri-clamp-closed-end-spool/)
- [Split burner shroud for a vertical 2 in tri-clamp hot end](https://xemstudio.com/objects/tri-clamp-split-burner-shroud/)
- [Build list: Free-piston Stirling generator, 2 in tri-clamp (pressurised, linear alternator)](https://xemstudio.com/objects/list-fpse-generator-2in/)