# Lewis (three-piece stone lifter in a dovetail hole)

> How does a lewis lift a stone?

- Category: Mechanisms › Linkages
- Kind: Hardware
- Basis: Xem Studio design following Brown No. 493 (1868)
- Page: https://xemstudio.com/objects/lewis-stone-lifter-mechanism/ · JSON: https://xemstudio.com/api/geometry?object=lewis-stone-lifter-mechanism · Plain text: https://xemstudio.com/objects/lewis-stone-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 dovetail hole is cut in the top of the stone; the two tapered side pieces go in first, then a parallel centre piece between them pushes them out into the undercut. A pin through all three takes the hoisting shackle: pulling up jams the wedges against the dovetail's sloping walls, so the stone cannot slip off.
- Hole 20 → 30 mm over 30 mm depth, 14 mm wide; centre piece 10 mm, side wedges 5 → 10 mm, so the three fill the dovetail exactly (contact on every face, no overlap); Ø6 pin 12 mm above the stone. To release, lift the centre piece out first.
- Brown's No. 493 (lewis, for raising stones); in use since Roman times.
- Parts (each has its own page): lewis-stone-block-80x60x50, lewis-centre-piece-10x14x50, lewis-side-wedge-5-10x14x50, dowel-pins-metric.
- Brown's movement No. 493 (1868) shows it; this model is a Xem Studio design following his figure, every part at true size.

## Sizes

| parameter | value |
|---|---|
| hole | 20 → 30 × 14, 30 deep |
| centre piece | 10 × 14 × 50 |
| side wedges | 2 × (5 → 10) × 14 × 50 |
| pin | Ø6 × 40 |

## 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. 493: figure, his text and an animation](https://507movements.com/mm_493.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/lewis-stone-lifter-mechanism/index.json · license: https://xemstudio.com/files/hardware/lewis-stone-lifter-mechanism/LICENSE.md

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

## Questions

**How does a lewis lift a stone?**

A dovetail hole is cut in the top of the stone; the two tapered side pieces go in first, then a parallel centre piece between them pushes them out into the undercut. A pin through all three takes the hoisting shackle: pulling up jams the wedges against the dovetail's sloping walls, so the stone cannot slip off.

## Fits with

- [Stone block 80 × 60 × 50 with a dovetail lewis hole 20 → 30 × 14, 30 deep](https://xemstudio.com/objects/lewis-stone-block-80x60x50/)
- [Lewis centre piece 10 × 14 × 50, Ø6 pin hole](https://xemstudio.com/objects/lewis-centre-piece-10x14x50/)
- [Lewis side wedge 5 → 10 × 14 × 50, Ø6 pin hole](https://xemstudio.com/objects/lewis-side-wedge-5-10x14x50/)
- [Dowel pins, 2–6 mm (ISO 2338 / DIN 6325)](https://xemstudio.com/objects/dowel-pins-metric/)