{
 "version": "2026-10-20",
 "license": "Dimension sheets are written by Xem Studio from the cited sources and are free to use (CC BY 4.0, attribute 'Xem Studio'). Linked files belong to their publishers under the license shown; Xem Studio does not host them. 'license_verified: false' means the license shown is from memory or the publisher's page as last read and should be confirmed at the link before commercial use.",
 "slug": "elliptic-trammel-mechanism",
 "name": "Elliptic trammel (trammel of Archimedes, ellipsograph)",
 "kind": "hardware",
 "category": "Mechanisms",
 "group": "Linkages",
 "year": null,
 "question": "How does an elliptic trammel draw an ellipse?",
 "tags": [
  "mechanism",
  "linkages",
  "kinematics",
  "507 mechanical movements"
 ],
 "aliases": [
  "elliptic trammel",
  "trammel of archimedes",
  "ellipsograph",
  "ellipse drawing tool",
  "trasmallo de Arquímedes (elipsógrafo)",
  "Ellipsenzirkel"
 ],
 "overall_mm": {
  "length": null,
  "width": null,
  "height": null
 },
 "official_cad": false,
 "xem_status": "free-files",
 "les": false,
 "free_files": 1,
 "url": "https://xemstudio.com/objects/elliptic-trammel-mechanism/",
 "sheet_txt": "https://xemstudio.com/objects/elliptic-trammel-mechanism/sheet.txt",
 "sheet": {
  "basis": "Xem Studio design following Brown No. 152 (1868)",
  "overall_mm": {
   "length": null,
   "width": null,
   "height": null
  },
  "notes": [
   "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."
  ],
  "table": {
   "columns": [
    "parameter",
    "value"
   ],
   "rows": [
    [
     "semi-axis a",
     "80 mm"
    ],
    [
     "semi-axis b",
     "40 mm"
    ],
    [
     "blocks",
     "2 × 12 × 6.2 × 5"
    ],
    [
     "grooves",
     "6.2 × 5 deep, crossed"
    ]
   ]
  }
 },
 "sheet_text": "Elliptic trammel (trammel of Archimedes, ellipsograph) — dimension sheet\nSource: Xem Studio, https://xemstudio.com/objects/elliptic-trammel-mechanism/  (CC BY 4.0)\nBasis: Xem Studio design following Brown No. 152 (1868)\nCatalog version: 2026-10-20\n\nSizes: see table below\n- 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.\n- 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.\n- Brown's No. 152 (ellipsograph: traverse bar with two studs sliding in grooves of a cross).\n- Parts (each has its own page): trammel-cross-plate-140, slide-block-12x6, centre-hole-link-80, dowel-pins-metric.\n- Brown's movement No. 152 (1868) shows it; this model is a Xem Studio design following his figure, every part at true size.\n\nparameter  value\nsemi-axis a  80 mm\nsemi-axis b  40 mm\nblocks  2 × 12 × 6.2 × 5\ngrooves  6.2 × 5 deep, crossed\n\nFiles elsewhere (not hosted by Xem Studio; license as stated by the publisher):\n- 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\n- 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\n\nFree files (CC BY 4.0, Xem Studio; STEP + STL, 1 parts): https://xemstudio.com/files/hardware/elliptic-trammel-mechanism/index.json\nAPI: https://xemstudio.com/api/geometry?object=elliptic-trammel-mechanism\n",
 "sources": [
  {
   "publisher": "Henry T. Brown (1868, public domain)",
   "title": "Five Hundred and Seven Mechanical Movements — scan on archive.org",
   "url": "https://archive.org/details/fivehundredseven00browiala",
   "formats": [
    "web"
   ],
   "license": "Publisher's page; dimensions are facts",
   "license_verified": true,
   "hosted": false
  },
  {
   "publisher": "507movements.com",
   "title": "Brown's movement No. 152: figure, his text and an animation",
   "url": "https://507movements.com/mm_152.html",
   "formats": [
    "web"
   ],
   "license": "Publisher's page; dimensions are facts",
   "license_verified": true,
   "hosted": false
  }
 ],
 "xem": {
  "status": "free-files",
  "sheet_free": true,
  "mesh_price_usd": null,
  "step_price_usd": null,
  "tolerance_mm": null
 },
 "related": [
  "trammel-cross-plate-140",
  "slide-block-12x6",
  "centre-hole-link-80",
  "dowel-pins-metric"
 ],
 "fits": [],
 "dimensions": "exact (nominal, no printing tolerance)",
 "dimension_rule": "All geometry on Xem Studio is exact (nominal, true size) with no printing tolerance. Where a part meets another part, the object lists its mating features (feature, exact size, what it mates with, fit class: press, slide, run, socket, clamp or designed). Apply your process's allowance to those features only; 'designed' gaps are part of the design and stay as drawn.",
 "mating": [],
 "faq": [
  {
   "q": "How does an elliptic trammel draw an ellipse?",
   "a": "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."
  },
  {
   "q": "Which point draws a circle?",
   "a": "The midpoint between the two blocks (a = b) draws a circle of radius half their spacing."
  }
 ],
 "files_license": null,
 "offers": [
  {
   "file": "elliptic-trammel-mechanism-assembly",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "CC BY 4.0 (Xem Studio)",
   "step": "https://xemstudio.com/files/hardware/elliptic-trammel-mechanism/elliptic-trammel-mechanism-assembly.step",
   "stl": "https://xemstudio.com/files/hardware/elliptic-trammel-mechanism/elliptic-trammel-mechanism-assembly.stl",
   "note": "Assembled mechanism, all parts placed at one pose (STEP keeps each part separate)"
  }
 ],
 "markdown": "https://xemstudio.com/objects/elliptic-trammel-mechanism/index.md"
}