# Stamp lifter: half-toothed pinion raising a rack and letting it fall

> How does a stamp mill lift and drop its stamp?

- Category: Mechanisms › Intermittent motion
- Kind: Hardware
- Basis: Xem Studio design following Brown No. 351 (1868)
- Page: https://xemstudio.com/objects/stamp-lifter-mechanism/ · JSON: https://xemstudio.com/api/geometry?object=stamp-lifter-mechanism · Plain text: https://xemstudio.com/objects/stamp-lifter-mechanism/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/)

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

## Notes

- A pinion with teeth on only half its rim meshes with a rack on the vertical stamp rod: while the toothed half is engaged the rod is lifted (half a turn = 10 pitches = 31.4 mm), then the blank half comes round, the rack is free and the stamp drops under its own weight.
- Catalog parts: the module 1 pinion with 10 of 20 teeth and the 120 mm full-depth rack, pinion axis 10 mm from the rack's pitch line; drawn with the toothed half meshing and the rack in a guide block.
- Brown's No. 351 (stamp: shaft with a part-toothed wheel lifting a rack and letting it fall).
- Parts (each has its own page): mutilated-pinion-m1-20t-half, gear-rack-m1-120-full-depth, rack-guide-block-32x12-ch11-5x8, dowel-pins-metric.
- Brown's movement No. 351 (1868) shows it; this model is a Xem Studio design following his figure, every part at true size.

## Sizes

| parameter | value |
|---|---|
| pinion | module 1, 10 of 20 teeth |
| rack | 120 mm, module 1 |
| lift per turn | 31.42 mm, then free fall |
| guide | 11.5 × 8 channel |

## 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. 351: figure, his text and an animation](https://507movements.com/mm_351.html) — web — Publisher's page; dimensions are facts

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

Index: https://xemstudio.com/files/hardware/stamp-lifter-mechanism/index.json · license: https://xemstudio.com/files/hardware/stamp-lifter-mechanism/LICENSE.md

- stamp-lifter-mechanism-assembly: [STEP](https://xemstudio.com/files/hardware/stamp-lifter-mechanism/stamp-lifter-mechanism-assembly.step) · [STL](https://xemstudio.com/files/hardware/stamp-lifter-mechanism/stamp-lifter-mechanism-assembly.stl) — Assembled mechanism, all parts placed at one pose (STEP keeps each part separate)

## Questions

**How does a stamp mill lift and drop its stamp?**

A pinion with teeth on only half its rim meshes with a rack on the vertical stamp rod: while the toothed half is engaged the rod is lifted (half a turn = 10 pitches = 31.4 mm), then the blank half comes round, the rack is free and the stamp drops under its own weight.

## Fits with

- [Mutilated pinion, module 1, 20 T with 10 teeth kept (half)](https://xemstudio.com/objects/mutilated-pinion-m1-20t-half/)
- [Gear rack, module 1, 120 mm, full-depth 20° teeth](https://xemstudio.com/objects/gear-rack-m1-120-full-depth/)
- [Rack guide block 32 × 12 × 20 with an 11.5 × 8 through channel](https://xemstudio.com/objects/rack-guide-block-32x12-ch11-5x8/)
- [Dowel pins, 2–6 mm (ISO 2338 / DIN 6325)](https://xemstudio.com/objects/dowel-pins-metric/)