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Parallel ruler with two swinging arms (parallelogram)
How does a two-arm parallel ruler work? · Hardware · basis: Xem Studio design following Brown No. 325 (1868)
Also called: parallel ruler, parallel rule, parallelogram ruler, regla paralela, Parallellineal
Exact dimensions. True size, with no printing tolerance added.
- sizes
- 4 in table
Notes
- Two straight-edges joined by two equal arms pivoted 100 mm apart on each: the four pivots always form a parallelogram, so the upper bar stays parallel to the lower one while it swings sideways and away from it.
- Drawn with the 60 mm catalog links at 60°: the upper bar is offset 30 mm along and 51.96 mm across; the opening ranges from 0 to 60 mm (arms square to the bars).
- Brown's No. 325 — the common drawing-office parallel ruler; the arms must be exactly equal and the pivot spacings identical or the bars twist.
- Parts (each has its own page): parallel-ruler-bar-200-h100, four-bar-links, dowel-pins-metric.
- Brown's movement No. 325 (1868) shows it; this model is a Xem Studio design following his figure, every part at true size.
Parallel ruler with two swinging arms size chart
| parameter | value |
|---|---|
| bars | 2 × 200 × 20 × 5 mm |
| arms | 2 × 60 mm (four-bar link) |
| pivot spacing | 100 mm |
| opening drawn | 51.96 mm (60°) |
Where the files are
Other publishers' files are linked, not hosted. "verify" = check the license at the link before commercial use.
| Henry T. Brown (1868, public domain) | Five Hundred and Seven Mechanical Movements — scan on archive.org | web | Publisher's page; dimensions are facts |
| 507movements.com | Brown's movement No. 325: figure, his text and an animation | web | Publisher's page; dimensions are facts |
Free files
★ Free files 1 parts. Xem Studio design: free to use, print and sell things from; not to be republished as files. Xem Studio Design License. index.json
| swinging-arm-parallel-ruler-mechanism-assembly | Assembled mechanism, all parts placed at one pose (STEP keeps each part separate) | STEP · STL |
https://xemstudio.com/mcp to Claude, ChatGPT, Cursor or any MCP client (free, no account, one minute) and it can look up exact sizes, mating fits and free STEP/STL from every chat.Plain text: sheet.txt · JSON: /api/geometry?object=swinging-arm-parallel-ruler-mechanism
Fits with
Questions
How does a two-arm parallel ruler work?
Two straight-edges joined by two equal arms pivoted 100 mm apart on each: the four pivots always form a parallelogram, so the upper bar stays parallel to the lower one while it swings sideways and away from it.