# Ross yoke alpha frame for two 10 mL syringes

> What frame holds two parallel syringes and a crank for a Ross yoke Stirling engine?

- Category: Stirling engines › Drives & mechanisms
- Kind: Hardware
- Basis: Solved Ross linkage: barrel axes 40 apart, socket inner faces 63 above the crank axis, rocking-link post at (−40, 20); 625 pockets at the bearing OD
- Page: https://xemstudio.com/objects/ross-yoke-frame/ · JSON: https://xemstudio.com/api/geometry?object=ross-yoke-frame · Plain text: https://xemstudio.com/objects/ross-yoke-frame/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 one-piece frame of the Ross yoke alpha: 83 × 53.45 × 148. A Ø24 boss carries the Ø5 crankshaft in two 625 bearings (Ø16 pockets, fit: press) with a Ø5.6 passage between them.
- Two Ø15.9 barrel sockets (fit: socket) on parallel axes 40 mm apart; their inner faces sit 63 mm above the crank axis, where the syringe finger flanges seat. The lowest piston skirt comes to 62.1 mm, so the pistons never leave the barrels; M3 pinch screws in Ø2.5 holes.
- A post at (−40, 20) has a Ø3 hole (fit: press) for the rocking-link pin. The foot has 2 × Ø5.5 at 50 mm for M5 into a 2020 rail.

## 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 |
|---|---|---|---|---|
| barrel sockets | Ø15.9 | 10 mL syringe barrel | socket | ross-frame-* |
| bearing pockets | Ø16 | 625 bearing | press | ross-frame-* |
| frame-post pin hole | Ø3 | Ø3 × 20 pin | press | ross-frame-* |
| shaft passage between pockets | Ø5.6 | Ø5 shaft (no contact) | designed | ross-frame-* |
| pinch-screw holes | Ø2.5 | M3 tap drill | designed | ross-frame-* |
| foot holes | Ø5.5 | M5 clearance (ISO 273) | designed | ross-frame-* |

## Sizes

| parameter | value |
|---|---|
| outline | 83 × 53.45 × 148 |
| barrel sockets | 2 × Ø15.9, axes 40 apart |
| socket inner face | 63 above crank axis |
| bearing pockets | 2 × Ø16 (625) |
| rocking-link post | Ø3 at (−40, 20) |
| foot | 2 × Ø5.5 at 50 |

## Where the files are

- Wikipedia: [Ross yoke](https://en.wikipedia.org/wiki/Ross_yoke) — web — CC BY-SA 4.0 (text)
- 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/ross-yoke-frame/index.json

- ross-frame-2x-10ml: [STEP](https://xemstudio.com/files/hardware/ross-yoke-kit/ross-frame-2x-10ml.step) · [STL](https://xemstudio.com/files/hardware/ross-yoke-kit/ross-frame-2x-10ml.stl) — Ross alpha frame: Ø5 shaft in two 625s, two 10 mL barrel sockets on parallel axes 2 × 20 = 40 mm apart (inner faces 63 mm above the crank axis), rocking-link post at (-40, 20), foot 2 × M5 at 50 mm for 2020

## How it fits

### Parts that fit it
- [Transfer tee for 4 × 6 mm tube](https://xemstudio.com/objects/transfer-tee-4mm/): between the Ross alpha's syringe tips

### Goes in or on
- [Plastic syringes 1–60 mL as pistons and cylinders](https://xemstudio.com/objects/plastic-syringes/): two 10 mL barrels in the Ø15.9 sockets
- [Aluminium T-slot extrusion: 2020, 2040, 2060, 2080, V-slot, 3030, 3060, 4040, 4080, 1010, 1515](https://xemstudio.com/objects/t-slot-extrusions/): 2 × M5 into 2020

### Connects to
- [Ross yoke rocking link, 40 mm](https://xemstudio.com/objects/ross-rocking-link/): Ø3 × 20 pin in the post
- [Ross yoke crank disc Ø24, 6 mm throw](https://xemstudio.com/objects/ross-crank-disc/): on the Ø5 shaft in the boss

### Alternatives
- [Alpha V-twin frame for two 10 mL syringes at 90°](https://xemstudio.com/objects/alpha-v-twin-syringe-frame/): V-twin alpha on one crank pin

### Also needed
- [Ball bearings, 683 to 6210 and flanged F6xx (ISO 15)](https://xemstudio.com/objects/ball-bearings-metric/): 2 × 625

## Questions

**How far apart are the syringes on the Ross yoke frame?**

40 mm between parallel axes; turn both finger flanges front-to-back so they do not touch.

**How does the Ross frame mount?**

Two M5 screws through the Ø5.5 foot holes, 50 mm apart, into 2020 extrusion.

## Fits with

- [Ross yoke a = h = 20 for two parallel syringes](https://xemstudio.com/objects/ross-yoke/)
- [Ross yoke crank disc Ø24, 6 mm throw](https://xemstudio.com/objects/ross-crank-disc/)
- [Ross yoke rocking link, 40 mm](https://xemstudio.com/objects/ross-rocking-link/)
- [Plastic syringes 1–60 mL as pistons and cylinders](https://xemstudio.com/objects/plastic-syringes/)
- [Aluminium T-slot extrusion: 2020, 2040, 2060, 2080, V-slot, 3030, 3060, 4040, 4080, 1010, 1515](https://xemstudio.com/objects/t-slot-extrusions/)
- [Build list: Ross yoke alpha, two parallel 10 mL syringes](https://xemstudio.com/objects/list-ross-yoke-alpha/)