# Slip-on fin sleeve for a 2 in closed hot end (nine Ø76 ring fins)

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

- Category: Hardware › Stirling & thermoacoustic
- Kind: Hardware
- Basis: Design values; fin set as the finned hot head on this site so the same burner shroud fits
- Page: https://xemstudio.com/objects/tri-clamp-ring-fin-sleeve/ · JSON: https://xemstudio.com/api/geometry?object=tri-clamp-ring-fin-sleeve · Plain text: https://xemstudio.com/objects/tri-clamp-ring-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

- A separate part: a finned cup that slides over the closed end of a 2 in hot spool and sits on it. Bore Ø50.8 (the tube's OD) and an inside bottom shaped to the closed end, so the heat crosses where they touch. Nine Ø76 × 1.5 ring fins at 5 mm pitch take the flame's heat in the burner shroud.
- Optional: the engine runs without it at a lower hot-wall temperature for the same 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 with a 1.5 inner round at the bottom | 2 in tube OD and closed end | slide | all |
| fins | 9 × Ø76 × 1.5, 5 pitch | burner shroud Ø88 bore (gas annulus) | designed | all |

## Sizes

| feature | value |
|---|---|
| bore | Ø50.8 |
| depth | 45.0 |
| fins | 9 × Ø76 × 1.5, 5 pitch |

## 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-ring-fin-sleeve/index.json

- fin-sleeve-2in-9x76: [STEP](https://xemstudio.com/files/hardware/tri-clamp-ring-fin-sleeve/fin-sleeve-2in-9x76.step) · [STL](https://xemstudio.com/files/hardware/tri-clamp-ring-fin-sleeve/fin-sleeve-2in-9x76.stl) — slip-on hot-end fin sleeve for a 2 in closed end: cup, bore Ø50.8 with the closed end's 1.5 round inside its bottom, wall 2, bottom 2, 45.0 deep; 9 ring fins Ø76 × 1.5 at 5 pitch

## Questions

**Does it have to be a press fit?**

No: it slides on and sits on the closed end; at temperature the fit closes up if the sleeve grows less than the tube.

## Fits with

- [2 in × 152.4 mm closed-end hot spool, bore finished Ø48.00](https://xemstudio.com/objects/tri-clamp-closed-hot-spool-bored/)
- [Burner shroud for a 2 in tri-clamp hot end](https://xemstudio.com/objects/tri-clamp-burner-shroud/)
- [Burner shroud for a horizontal finned 2 in hot spool](https://xemstudio.com/objects/tri-clamp-horizontal-burner-shroud/)
- [Build list: Tri-clamp horizontal gamma generator, 2 in, chargeable](https://xemstudio.com/objects/list-tri-clamp-horizontal-gamma/)
- [Build list: Tri-clamp charged beta, 2 in](https://xemstudio.com/objects/list-tri-clamp-charged-beta/)