Elliptic trammel (trammel of Archimedes, ellipsograph) — dimension sheet
Source: Xem Studio, https://xemstudio.com/objects/elliptic-trammel-mechanism/  (CC BY 4.0)
Basis: Xem Studio design following Brown No. 152 (1868)
Catalog version: 2026-10-20

Sizes: see table below
- Two blocks slide in crossed grooves and carry a bar; a point on the bar a distance a from one block and b from the other draws an ellipse with semi-axes a and b.
- Here the blocks are 40 mm apart on an 80 mm centre-hole link and the pen hole is 40 mm beyond: semi-axes 80 and 40 mm. At 50° the pen is at (51.42, 30.64); x²/80² + y²/40² = 1.
- Brown's No. 152 (ellipsograph: traverse bar with two studs sliding in grooves of a cross).
- Parts (each has its own page): trammel-cross-plate-140, slide-block-12x6, centre-hole-link-80, dowel-pins-metric.
- Brown's movement No. 152 (1868) shows it; this model is a Xem Studio design following his figure, every part at true size.

parameter  value
semi-axis a  80 mm
semi-axis b  40 mm
blocks  2 × 12 × 6.2 × 5
grooves  6.2 × 5 deep, crossed

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. 152: figure, his text and an animation — web — Publisher's page; dimensions are facts — https://507movements.com/mm_152.html

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