# LTD Stirling chamber ring, Ø100 and Ø150 × 20

> What size is the chamber ring of a coffee-cup Stirling engine?

- Category: Stirling engines › Can & LTD engines
- Kind: Hardware
- Basis: Chamber height 20: an 8 mm displacer at 10 mm stroke (crank-disc-b3-stroke10) with 1 mm at each end; M3 tap drill Ø2.5
- Page: https://xemstudio.com/objects/ltd-chamber-ring/ · JSON: https://xemstudio.com/api/geometry?object=ltd-chamber-ring · Plain text: https://xemstudio.com/objects/ltd-chamber-ring/sheet.txt
- License: dimension sheet CC BY 4.0 (Xem Studio); linked files under their publishers' licenses

**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 wall of the LTD displacer chamber, between the bottom and top plates. Bore Ø100 or Ø150, 20 tall, 10 mm wall (outside Ø120 / Ø170).
- Six Ø2.5 holes (M3 tap drill) through its height on a Ø112 / Ø162 circle: an M3 × 12 comes in from each plate.
- The displacer runs inside with a 2 mm radial gap by design; nothing moving touches the ring.

## 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 |
|---|---|---|---|---|
| chamber-ring screw holes | Ø2.5 through | M3 tap drill (an M3 × 12 from each plate) | designed | ltd-100-chamber* |
| chamber-ring screw holes | Ø2.5 through | M3 tap drill (an M3 × 12 from each plate) | designed | ltd-150-chamber* |

## Sizes

| file | bore | outside | height | screw circle |
|---|---|---|---|---|
| ltd-100-chamber-ring-h20 | 100 | 120 | 20 | 112 |
| ltd-150-chamber-ring-h20 | 150 | 170 | 20 | 162 |

## Where the files are

- Wikipedia: [Stirling engine](https://en.wikipedia.org/wiki/Stirling_engine) — web — CC BY-SA 4.0 (text)
- James R. Senft: [An Introduction to Low Temperature Differential Stirling Engines](https://www.stirlingengine.com/) — book — Moriya Press (verify at link)
- Long Earth Society: [Engine builds](https://longearthsociety.com/engineering/) — web, video — LES site

## Free STEP/STL (2 parts, CC BY 4.0, Xem Studio)

Index: https://xemstudio.com/files/hardware/ltd-chamber-ring/index.json

- ltd-100-chamber-ring-h20: [STEP](https://xemstudio.com/files/hardware/ltd-coffee-cup-engine-kit/ltd-100-chamber-ring-h20.step) · [STL](https://xemstudio.com/files/hardware/ltd-coffee-cup-engine-kit/ltd-100-chamber-ring-h20.stl) — chamber ring Ø100 bore × 20 tall, 10 mm wall, 6 × Ø2.5 (M3 tapped) through on a Ø112 circle; the displacer runs inside
- ltd-150-chamber-ring-h20: [STEP](https://xemstudio.com/files/hardware/ltd-coffee-cup-engine-kit/ltd-150-chamber-ring-h20.step) · [STL](https://xemstudio.com/files/hardware/ltd-coffee-cup-engine-kit/ltd-150-chamber-ring-h20.stl) — chamber ring Ø150 bore × 20 tall, 10 mm wall, 6 × Ø2.5 (M3 tapped) through on a Ø162 circle; the displacer runs inside

## How it fits

### Connects to
- [LTD Stirling top plate with syringe socket, Ø120 and Ø170](https://xemstudio.com/objects/ltd-top-plate/): top face, 6 × M3
- [LTD Stirling bottom plate, Ø120 and Ø170](https://xemstudio.com/objects/ltd-bottom-plate/): bottom face, 6 × M3
- [LTD Stirling displacer Ø96 × 8 and Ø146 × 8](https://xemstudio.com/objects/ltd-displacer/): displacer inside, 2 mm radial gap

## Questions

**How tall is the chamber of the LTD Stirling engine here?**

20 mm, for an 8 mm thick displacer moving 10 mm: 1 mm to spare at each end.

**What displacer goes in the Ø100 chamber ring?**

The Ø96 × 8 LTD displacer: 2 mm radial gap, designed.

## Fits with

- [LTD Stirling top plate with syringe socket, Ø120 and Ø170](https://xemstudio.com/objects/ltd-top-plate/)
- [LTD Stirling bottom plate, Ø120 and Ø170](https://xemstudio.com/objects/ltd-bottom-plate/)
- [LTD Stirling displacer Ø96 × 8 and Ø146 × 8](https://xemstudio.com/objects/ltd-displacer/)
- [Build list: LTD coffee-cup engine](https://xemstudio.com/objects/list-ltd-coffee-cup/)