# Single-tooth pinion: module 1, 20-tooth gear with one tooth left

> What is a single-tooth 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/single-tooth-pinion-m1-20t/ · JSON: https://xemstudio.com/api/geometry?object=single-tooth-pinion-m1-20t · Plain text: https://xemstudio.com/objects/single-tooth-pinion-m1-20t/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 |
|---|---|---|
| 19.74 | 17.5 | 8.0 |

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

## Notes

- The catalog module 1, 20-tooth gear (Ø6 bore, 8 face) cut down to its root circle (Ø17.5) everywhere except one involute tooth (±9.5° about +X): every turn it engages the driven wheel and advances it exactly one tooth.
- 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 | 1 of 20 |
| root Ø | 17.5 mm |
| bore | Ø6 |
| 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. 241: figure, his text and an animation](https://507movements.com/mm_241.html) — web — Publisher's page; dimensions are facts
- Xem Studio: [drawing](https://xemstudio.com/objects/single-tooth-intermittent-gear-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/single-tooth-pinion-m1-20t/index.json · license: https://xemstudio.com/files/hardware/single-tooth-pinion-m1-20t/LICENSE.md

- single-tooth-pinion-m1-20t: [STEP](https://xemstudio.com/files/hardware/single-tooth-pinion-m1-20t/single-tooth-pinion-m1-20t.step) · [STL](https://xemstudio.com/files/hardware/single-tooth-pinion-m1-20t/single-tooth-pinion-m1-20t.stl) — pinion, tooth on +X, z 0..8

## Questions

**What is a single-tooth gear?**

The catalog module 1, 20-tooth gear (Ø6 bore, 8 face) cut down to its root circle (Ø17.5) everywhere except one involute tooth (±9.5° about +X): every turn it engages the driven wheel and advances it exactly one tooth.

## Fits with

- [Single-tooth pinion driving a 40-tooth wheel (one tooth per turn)](https://xemstudio.com/objects/single-tooth-intermittent-gear-mechanism/)