# Eccentric spur gear, module 1, 40 T, Ø5 bore 5 mm off centre, Ø3 centre stud hole

> What is an eccentric gear?

- 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/eccentric-spur-gear-m1-40t-e5-b5/ · JSON: https://xemstudio.com/api/geometry?object=eccentric-spur-gear-m1-40t-e5-b5 · Plain text: https://xemstudio.com/objects/eccentric-spur-gear-m1-40t-e5-b5/sheet.txt
- License: dimension sheet CC BY 4.0 (Xem Studio); files Xem Studio Design License (free to use and sell from, not to redistribute as files: https://xemstudio.com/license/)
- Use in every chat: add https://xemstudio.com/mcp as a connector (https://xemstudio.com/use-with-ai/)

## Overall (mm)

| length | width | height |
|---|---|---|
| 41.99 | 41.99 | 8.0 |

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

## Notes

- Ordinary module 1, 40-tooth involute gear (pitch Ø40, face 8) whose Ø5 shaft bore is 5 mm off its geometric centre, with a Ø3 hole at the true centre for the stud that keeps the link to the pinion. On its shaft it turns at constant speed while its pitch circle wobbles ±5 mm.
- Xem Studio design following Brown's figure; true size, no printing allowance (apply your own to the mating features).

## Sizes

| dimension | value |
|---|---|
| module | 1 |
| teeth | 40 |
| bore | Ø5 at 5 mm from centre |
| centre hole | Ø3 |
| face | 8 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. 222: figure, his text and an animation](https://507movements.com/mm_222.html) — web — Publisher's page; dimensions are facts
- Xem Studio: [drawing](https://xemstudio.com/objects/eccentric-gear-and-pinion-mechanism/) — web — Publisher's page; dimensions are facts

## Free STEP/STL (1 parts, Xem Studio Design License, Xem Studio)

Index: https://xemstudio.com/files/hardware/eccentric-spur-gear-m1-40t-e5-b5/index.json · license: https://xemstudio.com/files/hardware/eccentric-spur-gear-m1-40t-e5-b5/LICENSE.md

- eccentric-spur-gear-m1-40t-e5: [STEP](https://xemstudio.com/files/hardware/eccentric-spur-gear-m1-40t-e5-b5/eccentric-spur-gear-m1-40t-e5.step) · [STL](https://xemstudio.com/files/hardware/eccentric-spur-gear-m1-40t-e5-b5/eccentric-spur-gear-m1-40t-e5.stl) — gear centred on the origin, bore at (−5, 0), a tooth on +X, z 0..8

## Questions

**What is an eccentric gear?**

Ordinary module 1, 40-tooth involute gear (pitch Ø40, face 8) whose Ø5 shaft bore is 5 mm off its geometric centre, with a Ø3 hole at the true centre for the stud that keeps the link to the pinion. On its shaft it turns at constant speed while its pitch circle wobbles ±5 mm.

## Fits with

- [Eccentric spur gear and pinion on a swinging arm (variable speed)](https://xemstudio.com/objects/eccentric-gear-and-pinion-mechanism/)