# Sun-and-planet arm, 30 mm centres, Ø10 holes

> What does the arm in a sun-and-planet gear do?

- Category: Hardware › Mechanism parts
- Kind: Modern device
- Basis: Xem Studio design following Brown's figure (1868); true size, no printing allowance
- Page: https://xemstudio.com/objects/sun-and-planet-arm-30/ · JSON: https://xemstudio.com/api/geometry?object=sun-and-planet-arm-30 · Plain text: https://xemstudio.com/objects/sun-and-planet-arm-30/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/)

## Overall (mm)

| length | width | height |
|---|---|---|
| 48.0 | 18.0 | 5.0 |

**Exact dimensions.** True size, with no printing tolerance added.

## Notes

- 18 × 5 mm arm with two Ø10 holes 30 mm apart: it turns on the sun's Ø10 shaft and on the planet's boss and only keeps the two gears in mesh (centre distance 30 mm for two module 1, 30-tooth gears).
- Xem Studio design following Brown's figure; true size, no printing allowance (apply your own to the mating features).

## Sizes

| dimension | value |
|---|---|
| centres | 30 mm |
| holes | 2 × Ø10 |
| section | 18 × 5 mm |

## Where the files are

- Henry T. Brown (1868, public domain): [Five Hundred and Seven Mechanical Movements — scan on archive.org](https://archive.org/details/fivehundredseven00browiala) — web — Publisher's page; dimensions are facts
- 507movements.com: [Brown's movement No. 39: figure, his text and an animation](https://507movements.com/mm_039.html) — web — Publisher's page; dimensions are facts
- Xem Studio: [drawing](https://xemstudio.com/objects/sun-and-planet-gear-mechanism/) — web — Publisher's page; dimensions are facts

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

Index: https://xemstudio.com/files/hardware/sun-and-planet-arm-30/index.json

- sun-and-planet-arm-30: [STEP](https://xemstudio.com/files/hardware/sun-and-planet-arm-30/sun-and-planet-arm-30.step) · [STL](https://xemstudio.com/files/hardware/sun-and-planet-arm-30/sun-and-planet-arm-30.stl) — arm, z 0..5

## Questions

**What does the arm in a sun-and-planet gear do?**

18 × 5 mm arm with two Ø10 holes 30 mm apart: it turns on the sun's Ø10 shaft and on the planet's boss and only keeps the two gears in mesh (centre distance 30 mm for two module 1, 30-tooth gears).

## Fits with

- [Sun-and-planet gear (Watt's crank substitute), 30 : 30](https://xemstudio.com/objects/sun-and-planet-gear-mechanism/)