Sliding-triangle parallel ruler — dimension sheet
Source: Xem Studio, https://xemstudio.com/objects/sliding-triangle-parallel-ruler-mechanism/  (CC BY 4.0)
Basis: Xem Studio design following Brown No. 322 (1868)
Catalog version: 2026-10-20

Sizes: see table below
- Two equal right triangles laid together on their hypotenuses make a rectangle; holding one and sliding the other along the shared hypotenuse moves its outer edge to a parallel position, offset by s·sin of the hypotenuse angle.
- Here 120 × 40 mm triangles slid 25 mm along the hypotenuse: the far edge moves 25 × 40/126.49 = 7.91 mm across (and 23.72 mm along).
- Brown's No. 322, the simplest parallel ruler.
- Parts (each has its own page): parallel-ruler-triangle-120x40.
- Brown's movement No. 322 (1868) shows it; this model is a Xem Studio design following his figure, every part at true size.

parameter  value
triangles  2 × 120 × 40 × 4 mm
slide drawn  25 mm
offset  7.91 mm

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. 322: figure, his text and an animation — web — Publisher's page; dimensions are facts — https://507movements.com/mm_322.html

Free files (CC BY 4.0, Xem Studio; STEP + STL, 1 parts): https://xemstudio.com/files/hardware/sliding-triangle-parallel-ruler-mechanism/index.json
API: https://xemstudio.com/api/geometry?object=sliding-triangle-parallel-ruler-mechanism