# Geneva drive: 4 and 6 station wheels, R30, with drive discs

> How do I make a Geneva drive with 3D printed parts?

- Category: Stirling engines › Drives & mechanisms
- Kind: Hardware
- Basis: Geneva geometry: centre distance c = R / cos(π/n), drive pin radius R·tan(π/n); Ø5 pin, Ø5 shafts
- Page: https://xemstudio.com/objects/geneva-drive/ · JSON: https://xemstudio.com/api/geometry?object=geneva-drive · Plain text: https://xemstudio.com/objects/geneva-drive/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

- Turns continuous rotation into steps: the wheel indexes 360/n degrees once per turn of the drive, then is held by the drive's locking disc until the next index.
- Wheels are R30 × 6 with 5 mm slots for the Ø5 drive pin. The drive is a 3 mm base plate carrying the locking disc and the pin; the wheel runs in the plane of the disc and pin, 3 mm above the base.
- The locking arcs on the wheel are 0.3 mm larger than the locking disc: a designed gap, keep it.
- Checked over a full turn of the drive for both wheels: pin, disc and wheel never overlap.

## 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 |
|---|---|---|---|---|
| wheel and drive bores | Ø5 | Ø5 shafts | press | all |
| wheel slots | 5 | Ø5 drive pin (slides in them) | slide | geneva-* |
| locking arc gap | 0.3 | drive disc | designed | geneva-* |

## Sizes

| stations | index angle | centre distance | drive pin radius | locking disc radius |
|---|---|---|---|---|
| 4 | 90° | 42.4 mm | 30.0 mm | 26.0 mm |
| 6 | 60° | 34.6 mm | 17.3 mm | 13.3 mm |

## Where the files are

- Wikipedia: [Geneva drive](https://en.wikipedia.org/wiki/Geneva_drive) — web — CC BY-SA 4.0 (text)
- Long Earth Society: [Engine and rig builds on extrusion frames](https://longearthsociety.com/engineering/) — web, video — LES site

## Free STEP/STL (4 parts, CC BY 4.0, Xem Studio)

Index: https://xemstudio.com/files/hardware/geneva-drive/index.json

- geneva-4-wheel-r30: [STEP](https://xemstudio.com/files/hardware/geneva-drive/geneva-4-wheel-r30.step) · [STL](https://xemstudio.com/files/hardware/geneva-drive/geneva-4-wheel-r30.stl) — Geneva wheel, 4 stations, R30, 5 mm slots, Ø5 bore
- geneva-4-drive-r30: [STEP](https://xemstudio.com/files/hardware/geneva-drive/geneva-4-drive-r30.step) · [STL](https://xemstudio.com/files/hardware/geneva-drive/geneva-4-drive-r30.stl) — Geneva drive for the 4-station wheel: 3 mm base with arm, R26.0 locking disc and Ø5 pin at R30.0 in the wheel's plane, Ø5 bore (centre distance 42.4 mm)
- geneva-6-wheel-r30: [STEP](https://xemstudio.com/files/hardware/geneva-drive/geneva-6-wheel-r30.step) · [STL](https://xemstudio.com/files/hardware/geneva-drive/geneva-6-wheel-r30.stl) — Geneva wheel, 6 stations, R30, 5 mm slots, Ø5 bore
- geneva-6-drive-r30: [STEP](https://xemstudio.com/files/hardware/geneva-drive/geneva-6-drive-r30.step) · [STL](https://xemstudio.com/files/hardware/geneva-drive/geneva-6-drive-r30.stl) — Geneva drive for the 6-station wheel: 3 mm base with arm, R13.3 locking disc and Ø5 pin at R17.3 in the wheel's plane, Ø5 bore (centre distance 34.6 mm)

## How it fits

### Goes in or on
- [Stirling shafts and rods: Ø3 rods, Ø5 / Ø8 D-flat crankshafts, Ø5 tube rods, Ø3 pins, thrust spacers](https://xemstudio.com/objects/stirling-shafts-and-rods/): Ø5 shafts for wheel and drive

### Alternatives
- [Ratchet wheels and pawl (anti-reverse / one-way drive)](https://xemstudio.com/objects/ratchet-and-pawl/): step motion driven by a rocker

### Also needed
- [Ball bearings, 683 to 6210 and flanged F6xx (ISO 15)](https://xemstudio.com/objects/ball-bearings-metric/): 625 bearings for the Ø5 shafts

## Questions

**What centre distance does a Geneva mechanism need?**

C = R / cos(π/n): for a 6-station wheel of R30, 34.6 mm; the drive pin sits at R·tan(π/n) = 17.3 mm from the drive centre.

**How long does the wheel stay still?**

For n stations it moves during (180 − 360/n)° of each drive turn: 90° of 360 for 4 stations, 120° for 6.

## Fits with

- [Stirling shafts and rods: Ø3 rods, Ø5 / Ø8 D-flat crankshafts, Ø5 tube rods, Ø3 pins, thrust spacers](https://xemstudio.com/objects/stirling-shafts-and-rods/)
- [Ball bearings, 683 to 6210 and flanged F6xx (ISO 15)](https://xemstudio.com/objects/ball-bearings-metric/)
- [Spur gears, involute 20°: module 0.5, 1 and 2, 12–60 teeth](https://xemstudio.com/objects/spur-gears-involute/)
- [Ratchet wheels and pawl (anti-reverse / one-way drive)](https://xemstudio.com/objects/ratchet-and-pawl/)