{
 "version": "2026-10-20",
 "license": "Dimension sheets: CC BY 4.0. Standard and published-size files: CC BY 4.0. Xem Studio's own designs (files_license = Xem Studio Design License): free to use and sell things from, not to redistribute as files — https://xemstudio.com/license/. Other publishers' files: their own license, linked beside them.",
 "slug": "elliptical-gear-m1-5-36t-centre-bore",
 "name": "Elliptical gear, module 1.5, 36 teeth, b/a = 0.75, bore at the centre",
 "kind": "modern",
 "category": "Mechanisms",
 "group": "Gears",
 "year": null,
 "question": "What is a centre-pivoted elliptical gear for?",
 "tags": [
  "mechanism part",
  "507 mechanical movements"
 ],
 "aliases": [
  "elliptical gear",
  "oval gear",
  "engranaje elíptico",
  "elliptisches Zahnrad"
 ],
 "overall_mm": {
  "length": 64.18,
  "width": 48.97,
  "height": 12
 },
 "official_cad": false,
 "xem_status": "free-files",
 "les": false,
 "free_files": 1,
 "url": "https://xemstudio.com/objects/elliptical-gear-m1-5-36t-centre-bore/",
 "sheet_txt": "https://xemstudio.com/objects/elliptical-gear-m1-5-36t-centre-bore/sheet.txt",
 "sheet": {
  "basis": "Xem Studio design following Brown's figure (1868); true size, no printing allowance",
  "overall_mm": {
   "length": 64.18,
   "width": 48.97,
   "height": 12
  },
  "notes": [
   "Pitch ellipse 61.4 × 46.05 mm (perimeter 36 × π × 1.5) with the Ø8 bore at its centre; teeth generated by a 20° basic rack rolled round the pitch curve (spline outline within 0.008 mm), so it meshes with any module 1.5 involute pinion whose centre is free to follow the curve.",
   "Turning on its centre, its pitch radius at the mesh swings between the semi-axes twice per turn; the pinion must be free to move in and out to stay in mesh. 12 mm face.",
   "Xem Studio design following Brown's figure; true size, no printing allowance (apply your own to the mating features)."
  ],
  "table": {
   "columns": [
    "dimension",
    "value"
   ],
   "rows": [
    [
     "module",
     "1.5"
    ],
    [
     "teeth",
     "36"
    ],
    [
     "pitch ellipse",
     "61.4 × 46.05 mm"
    ],
    [
     "bore",
     "Ø8 at the centre"
    ],
    [
     "face",
     "12 mm"
    ]
   ]
  }
 },
 "sheet_text": "Elliptical gear, module 1.5, 36 teeth, b/a = 0.75, bore at the centre — dimension sheet\nSource: Xem Studio, https://xemstudio.com/objects/elliptical-gear-m1-5-36t-centre-bore/  (sheet CC BY 4.0; files Xem Studio Design License, https://xemstudio.com/license/)\nBasis: Xem Studio design following Brown's figure (1868); true size, no printing allowance\nCatalog version: 2026-10-20\n\nOverall (mm): length 64.18, width 48.97, height 12.0\n- Pitch ellipse 61.4 × 46.05 mm (perimeter 36 × π × 1.5) with the Ø8 bore at its centre; teeth generated by a 20° basic rack rolled round the pitch curve (spline outline within 0.008 mm), so it meshes with any module 1.5 involute pinion whose centre is free to follow the curve.\n- Turning on its centre, its pitch radius at the mesh swings between the semi-axes twice per turn; the pinion must be free to move in and out to stay in mesh. 12 mm face.\n- Xem Studio design following Brown's figure; true size, no printing allowance (apply your own to the mating features).\n\ndimension  value\nmodule  1.5\nteeth  36\npitch ellipse  61.4 × 46.05 mm\nbore  Ø8 at the centre\nface  12 mm\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. 35: figure, his text and an animation — web — Publisher's page; dimensions are facts — https://507movements.com/mm_035.html\n- Xem Studio: drawing — web — Publisher's page; dimensions are facts — https://xemstudio.com/objects/elliptical-gear-pinion-slotted-bar-mechanism/\n\nFree files (Xem Studio Design License, Xem Studio; STEP + STL, 1 parts): https://xemstudio.com/files/hardware/elliptical-gear-m1-5-36t-centre-bore/index.json\nAPI: https://xemstudio.com/api/geometry?object=elliptical-gear-m1-5-36t-centre-bore\n",
 "sources": [
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   "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"
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   "license": "Publisher's page; dimensions are facts",
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   "hosted": false
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  {
   "publisher": "507movements.com",
   "title": "Brown's movement No. 35: figure, his text and an animation",
   "url": "https://507movements.com/mm_035.html",
   "formats": [
    "web"
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   "license": "Publisher's page; dimensions are facts",
   "license_verified": true,
   "hosted": false
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   "publisher": "Xem Studio",
   "title": "drawing",
   "url": "https://xemstudio.com/objects/elliptical-gear-pinion-slotted-bar-mechanism/",
   "formats": [
    "web"
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   "license": "Publisher's page; dimensions are facts",
   "license_verified": true,
   "hosted": false
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  "tolerance_mm": null
 },
 "related": [
  "elliptical-gear-pinion-slotted-bar-mechanism"
 ],
 "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": "What is a centre-pivoted elliptical gear for?",
   "a": "Pitch ellipse 61.4 × 46.05 mm (perimeter 36 × π × 1.5) with the Ø8 bore at its centre; teeth generated by a 20° basic rack rolled round the pitch curve (spline outline within 0.008 mm), so it meshes with any module 1.5 involute pinion whose centre is free to follow the curve."
  }
 ],
 "files_license": {
  "name": "Xem Studio Design License",
  "holder": "Xem Studio",
  "url": "https://xemstudio.com/license/",
  "note": "Xem Studio's own design: free to use, print, modify and sell things made from it; not to be republished or redistributed as files."
 },
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   "stl": "https://xemstudio.com/files/hardware/elliptical-gear-m1-5-36t-centre-bore/elliptical-gear-m1-5-36t-centre-bore.stl",
   "note": "gear, centre on the Z axis, major axis along X, z 0..12"
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 "markdown": "https://xemstudio.com/objects/elliptical-gear-m1-5-36t-centre-bore/index.md"
}