# Bored 2 in power spool: 2 in × 5 in spool bored to Ø48.00

> How do I make a power cylinder from a 2 inch tri-clamp spool?

- Category: Stirling engines › Tri-clamp engine parts
- Kind: Hardware
- Basis: Fabrication spec: a 2 in spool (tube Ø50.8 × 1.65) 127 face to face, its bore finished to Ø48.00 end to end (a machinist bores and hones it); exact geometry
- Page: https://xemstudio.com/objects/htd-bored-power-spool/ · JSON: https://xemstudio.com/api/geometry?object=htd-bored-power-spool · Plain text: https://xemstudio.com/objects/htd-bored-power-spool/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

- The stock bore is Ø47.5; finished to Ø48.00 it leaves 1.40 of wall. The piston is drawn at Ø48.00 exactly: the running fit is the machinist's (see Mating features).
- Both faces stay standard ISO 2852 2 in faces: Type B gaskets and stock 2 in clamps at each end.

## 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 | Ø48.00 × 127 (finished) | power piston Ø48.00 | run | all |
| faces | ISO 2852 2 in | tc-gasket-2in + 2 in clamp | clamp | all |

## Sizes

| part | length_mm | bore_mm | wall_mm |
|---|---|---|---|
| spool-2in-5in-bored-48.00 | 127.0 | 48.0 | 1.4 |

## 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/htd-bored-power-spool/index.json

- spool-2in-5in-bored-48.00: [STEP](https://xemstudio.com/files/hardware/htd-bored-power-spool/spool-2in-5in-bored-48.00.step) · [STL](https://xemstudio.com/files/hardware/htd-bored-power-spool/spool-2in-5in-bored-48.00.stl) — 2 in spool, 127 face to face (5 in), bored through to Ø48.00 over its full length; ISO 2852 faces

## Questions

**Why 48.00?**

The smallest round number that cleans up the stock Ø47.5 bore along its whole length, faces included.

## Fits with

- [Build list: HTD engine, 10 in tri-clamp (high-temperature-differential flat engine)](https://xemstudio.com/objects/list-htd-10in/)
- [HTD power pistons: Ø48.00 × 72 for the bored 2 in spool](https://xemstudio.com/objects/htd-power-pistons/)