Lewis (three-piece stone lifter in a dovetail hole) — dimension sheet
Source: Xem Studio, https://xemstudio.com/objects/lewis-stone-lifter-mechanism/  (sheet CC BY 4.0; files Xem Studio Design License, https://xemstudio.com/license/)
Basis: Xem Studio design following Brown No. 493 (1868)
Catalog version: 2026-10-20

Sizes: see table below
- 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.

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

Files elsewhere (not hosted by Xem Studio; license as stated by the publisher):
- Henry T. Brown (1868, public domain): Five Hundred and Seven Mechanical Movements — scan on archive.org — web — Publisher's page; dimensions are facts — https://archive.org/details/fivehundredseven00browiala
- 507movements.com: Brown's movement No. 493: figure, his text and an animation — web — Publisher's page; dimensions are facts — https://507movements.com/mm_493.html

Free files (Xem Studio Design License, Xem Studio; STEP + STL, 1 parts): https://xemstudio.com/files/hardware/lewis-stone-lifter-mechanism/index.json
API: https://xemstudio.com/api/geometry?object=lewis-stone-lifter-mechanism