# Built-up crank webs for Ø8 shafts and Ø6 crank pins (two-throw cranks at 90°)

> How do I build a two-throw crankshaft with ball-bearing con-rods?

- Category: Hardware › Stirling & thermoacoustic
- Kind: Hardware
- Basis: Design values; Ø6 dowel crank pins (ISO 8734)
- Page: https://xemstudio.com/objects/stirling-built-up-crank-webs/ · JSON: https://xemstudio.com/api/geometry?object=stirling-built-up-crank-webs · Plain text: https://xemstudio.com/objects/stirling-built-up-crank-webs/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

- Discs pressed on Ø8 shafts with Ø6 dowel crank pins pressed through them: the horizontal gamma's crank has four webs (two throws, 76.2 mm apart, a shaft between) and the beta's has two webs and a link web between the two con-rods (the shaft does not pass the con-rods).
- Pin radius 15 for the displacer (30 stroke) and 18 for the piston (36 stroke); the pins are a quarter turn apart, the displacer leading.

## 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 |
|---|---|---|---|---|
| shaft hole | Ø8 | Ø8 crank shaft | press | crank-web* |
| pin holes | Ø6 | Ø6 dowel crank pins | press | all |

## Sizes

| part | thickness | pin radius |
|---|---|---|
| crank-web-56x10-r15 | 10 | 15 |
| crank-web-56x11-r15 | 11 | 15 |
| crank-web-56x11-r18 | 11 | 18 |
| crank-web-56x10-r18 | 10 | 18 |
| crank-web-56x8-r18 | 8 | 18 |
| crank-web-56x8-r15 | 8 | 15 |
| link-web-14-r18-r15-90 | 14 | 18 / 15 |

## Where the files are

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

## Free STEP/STL (8 parts, CC BY 4.0, Xem Studio)

Index: https://xemstudio.com/files/hardware/stirling-built-up-crank-webs/index.json

- crank-web-56x10-r15: [STEP](https://xemstudio.com/files/hardware/stirling-built-up-crank-webs/crank-web-56x10-r15.step) · [STL](https://xemstudio.com/files/hardware/stirling-built-up-crank-webs/crank-web-56x10-r15.stl) — crank web Ø56 × 10: Ø8 shaft hole, Ø6 pin hole at r 15 (both press), two Ø11 lightening holes beside the pin (counterweight)
- crank-web-56x11-r15: [STEP](https://xemstudio.com/files/hardware/stirling-built-up-crank-webs/crank-web-56x11-r15.step) · [STL](https://xemstudio.com/files/hardware/stirling-built-up-crank-webs/crank-web-56x11-r15.stl) — crank web Ø56 × 11: Ø8 shaft hole, Ø6 pin hole at r 15 (both press), two Ø11 lightening holes beside the pin (counterweight)
- crank-web-56x11-r18: [STEP](https://xemstudio.com/files/hardware/stirling-built-up-crank-webs/crank-web-56x11-r18.step) · [STL](https://xemstudio.com/files/hardware/stirling-built-up-crank-webs/crank-web-56x11-r18.stl) — crank web Ø56 × 11: Ø8 shaft hole, Ø6 pin hole at r 18 (both press), two Ø11 lightening holes beside the pin (counterweight)
- crank-web-56x10-r18: [STEP](https://xemstudio.com/files/hardware/stirling-built-up-crank-webs/crank-web-56x10-r18.step) · [STL](https://xemstudio.com/files/hardware/stirling-built-up-crank-webs/crank-web-56x10-r18.stl) — crank web Ø56 × 10: Ø8 shaft hole, Ø6 pin hole at r 18 (both press), two Ø11 lightening holes beside the pin (counterweight)
- crank-web-56x8-r18: [STEP](https://xemstudio.com/files/hardware/stirling-built-up-crank-webs/crank-web-56x8-r18.step) · [STL](https://xemstudio.com/files/hardware/stirling-built-up-crank-webs/crank-web-56x8-r18.stl) — crank web Ø56 × 8: Ø8 shaft hole, Ø6 pin hole at r 18 (both press), two Ø11 lightening holes beside the pin (counterweight)
- crank-web-56x8-r15: [STEP](https://xemstudio.com/files/hardware/stirling-built-up-crank-webs/crank-web-56x8-r15.step) · [STL](https://xemstudio.com/files/hardware/stirling-built-up-crank-webs/crank-web-56x8-r15.stl) — crank web Ø56 × 8: Ø8 shaft hole, Ø6 pin hole at r 15 (both press), two Ø11 lightening holes beside the pin (counterweight)
- crank-web-56x12-r15: [STEP](https://xemstudio.com/files/hardware/stirling-built-up-crank-webs/crank-web-56x12-r15.step) · [STL](https://xemstudio.com/files/hardware/stirling-built-up-crank-webs/crank-web-56x12-r15.stl) — crank web Ø56 × 12: Ø8 shaft hole, Ø6 pin hole at r 15 (both press), two Ø11 lightening holes beside the pin (counterweight)
- link-web-14-r18-r15-90: [STEP](https://xemstudio.com/files/hardware/stirling-built-up-crank-webs/link-web-14-r18-r15-90.step) · [STL](https://xemstudio.com/files/hardware/stirling-built-up-crank-webs/link-web-14-r18-r15-90.stl) — link web 14 thick: Ø6 press holes for the piston pin (r 18) and the displacer pin (r 15, 90° on)

## Questions

**Which way does it turn?**

The way that brings the displacer pin to each point a quarter turn before the piston pin.

## Fits with

- [Con-rods and links with a 626 big end and a 625 small end: 55 to 488 mm](https://xemstudio.com/objects/stirling-conrods-626-625/)
- [Ground rods, hollow piston rod and crank shafts for the performance engines (Ø6, Ø8, Ø10 / 7)](https://xemstudio.com/objects/stirling-precision-rods/)
- [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/)