# Alpha V-twin frame for two 10 mL syringes at 90°

> What frame holds two syringes in a 90° V for an alpha Stirling engine?

- Category: Stirling engines › Drives & mechanisms
- Kind: Hardware
- Basis: Computed in the generator: crank throw 8, rod 60, 10 mL barrel 15.9 OD / 14.5 ID; checked over a full turn
- Page: https://xemstudio.com/objects/alpha-v-twin-syringe-frame/ · JSON: https://xemstudio.com/api/geometry?object=alpha-v-twin-syringe-frame · Plain text: https://xemstudio.com/objects/alpha-v-twin-syringe-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 two-syringe alpha: 140 × 52.45 × 128. A Ø24 boss holds the Ø5 crankshaft in two 625 bearings (Ø16 pockets at both ends, fit: press) with a Ø5.6 passage between.
- Two Ø15.9 barrel sockets (fit: socket) at ±45°, their axes meeting at the crank axis; the 90° between them is the alpha phase, with both con-rods on one crank pin.
- Socket inner faces at R45 from the crank axis: the piston skirt comes no closer than R43.4, so it never leaves the barrel. M3 pinch screws in Ø2.5 holes; foot with 2 × Ø5.5 at 50 mm for M5 into 2020.

## 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 | alpha-frame-* |
| bearing pockets | Ø16 | 625 bearing | press | alpha-frame-* |
| shaft passage between pockets | Ø5.6 | Ø5 shaft (no contact) | designed | alpha-frame-* |
| pinch-screw holes | Ø2.5 | M3 tap drill | designed | alpha-frame-* |
| foot holes | Ø5.5 | M5 clearance (ISO 273) | designed | alpha-frame-* |

## Sizes

| parameter | value |
|---|---|
| outline | 140 × 52.45 × 128 |
| V angle | 90° |
| barrel sockets | 2 × Ø15.9 at ±45° |
| socket inner face | R45 |
| min skirt radius | 43.4 |
| bearing pockets | 2 × Ø16 (625) |
| foot | 2 × Ø5.5 at 50 |

## Where the files are

- Long Earth Society: [Engine builds](https://longearthsociety.com/engineering/) — web, video — LES site
- Wikipedia: [Stirling engine (alpha configuration)](https://en.wikipedia.org/wiki/Stirling_engine) — web — CC BY-SA 4.0 (text)

## Free STEP/STL (1 parts, CC BY 4.0, Xem Studio)

Index: https://xemstudio.com/files/hardware/alpha-v-twin-syringe-frame/index.json

- alpha-frame-10ml: [STEP](https://xemstudio.com/files/hardware/alpha-v-twin-frame/alpha-frame-10ml.step) · [STL](https://xemstudio.com/files/hardware/alpha-v-twin-frame/alpha-frame-10ml.stl) — alpha V-twin frame: Ø5 shaft in two 625s (pockets both ends of the Ø24 boss), two 10 mL barrel sockets at ±45° whose axes meet the crank axis, inner faces at R45, M3 pinch screws, foot with 2 × M5 at 50 mm for 2020

## How it fits

### 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
- [Alpha V-twin crank disc Ø26, one pin, 16 mm stroke](https://xemstudio.com/objects/alpha-v-twin-crank-disc/): on the Ø5 shaft beside the boss

### Alternatives
- [Ross yoke alpha frame for two 10 mL syringes](https://xemstudio.com/objects/ross-yoke-frame/): parallel-cylinder alpha

### Also needed
- [Ball bearings, 683 to 6210 and flanged F6xx (ISO 15)](https://xemstudio.com/objects/ball-bearings-metric/): 2 × 625
- [Transfer tee for 4 × 6 mm tube](https://xemstudio.com/objects/transfer-tee-4mm/): joins the two syringe tips

## Questions

**How do I get 90° phase on a two-syringe alpha Stirling?**

Put the barrels in a 90° V with both con-rods on one crank pin; the V angle is the phase. This frame holds them at ±45°.

**Why do the barrel sockets start 45 mm from the crank?**

At bottom dead centre the piston skirt is 43.4 mm from the axis, so with the socket face at R45 the piston stays inside the barrel.

## Fits with

- [Alpha V-twin crank disc Ø26, one pin, 16 mm stroke](https://xemstudio.com/objects/alpha-v-twin-crank-disc/)
- [Con-rods with Ø3 pin ends, 45 and 60 mm, 8 × 5](https://xemstudio.com/objects/pin-end-con-rods/)
- [Transfer tee for 4 × 6 mm tube](https://xemstudio.com/objects/transfer-tee-4mm/)
- [Plastic syringes 1–60 mL as pistons and cylinders](https://xemstudio.com/objects/plastic-syringes/)
- [Build list: Alpha V-twin, two 10 mL syringes](https://xemstudio.com/objects/list-alpha-v-twin-syringe/)