{
 "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": "constant-breadth-cam-s30-r5-bore5",
 "name": "Constant-breadth cam: rounded Reuleaux triangle, breadth 40, Ø5 bore at its centre",
 "kind": "modern",
 "category": "Hardware",
 "group": "Mechanism parts",
 "year": null,
 "question": "What is a constant-breadth cam?",
 "tags": [
  "mechanism part",
  "507 mechanical movements"
 ],
 "aliases": [
  "constant breadth cam",
  "rounded reuleaux triangle",
  "constant width cam",
  "leva de anchura constante",
  "Gleichdick (gerundetes Reuleaux-Dreieck)"
 ],
 "overall_mm": {
  "length": 40,
  "width": 40,
  "height": 8
 },
 "official_cad": false,
 "xem_status": "free-files",
 "les": false,
 "free_files": 1,
 "url": "https://xemstudio.com/objects/constant-breadth-cam-s30-r5-bore5/",
 "sheet_txt": "https://xemstudio.com/objects/constant-breadth-cam-s30-r5-bore5/sheet.txt",
 "sheet": {
  "basis": "Xem Studio design following Brown's figure (1868); true size, no printing allowance",
  "overall_mm": {
   "length": 40,
   "width": 40,
   "height": 8
  },
  "notes": [
   "Reuleaux triangle of side 30 (three arcs of R30 about the opposite corners) with every edge offset 5 mm, so the corners are R5 arcs: breadth 40 mm in every direction. Bored Ø5 at its centre: turning there inside a yoke 40 mm wide it always touches both faces and moves the yoke 4.64 mm, three times per turn.",
   "Corner (vertex arc centres) on a 17.32 mm circle; largest radius 22.32 mm, smallest 17.68 mm.",
   "Xem Studio design following Brown's figure; true size, no printing allowance (apply your own to the mating features)."
  ],
  "table": {
   "columns": [
    "dimension",
    "value"
   ],
   "rows": [
    [
     "breadth",
     "40 mm"
    ],
    [
     "Reuleaux side",
     "30 mm"
    ],
    [
     "corner radius",
     "5 mm"
    ],
    [
     "thickness",
     "8 mm"
    ],
    [
     "bore",
     "Ø5 at the centre"
    ]
   ]
  }
 },
 "sheet_text": "Constant-breadth cam: rounded Reuleaux triangle, breadth 40, Ø5 bore at its centre — dimension sheet\nSource: Xem Studio, https://xemstudio.com/objects/constant-breadth-cam-s30-r5-bore5/  (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 40.0, width 40.0, height 8.0\n- Reuleaux triangle of side 30 (three arcs of R30 about the opposite corners) with every edge offset 5 mm, so the corners are R5 arcs: breadth 40 mm in every direction. Bored Ø5 at its centre: turning there inside a yoke 40 mm wide it always touches both faces and moves the yoke 4.64 mm, three times per turn.\n- Corner (vertex arc centres) on a 17.32 mm circle; largest radius 22.32 mm, smallest 17.68 mm.\n- Xem Studio design following Brown's figure; true size, no printing allowance (apply your own to the mating features).\n\ndimension  value\nbreadth  40 mm\nReuleaux side  30 mm\ncorner radius  5 mm\nthickness  8 mm\nbore  Ø5 at the centre\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. 276: figure, his text and an animation — web — Publisher's page; dimensions are facts — https://507movements.com/mm_276.html\n- Xem Studio: drawing — web — Publisher's page; dimensions are facts — https://xemstudio.com/objects/constant-breadth-cam-yoke-mechanism/\n\nFree files (Xem Studio Design License, Xem Studio; STEP + STL, 1 parts): https://xemstudio.com/files/hardware/constant-breadth-cam-s30-r5-bore5/index.json\nAPI: https://xemstudio.com/api/geometry?object=constant-breadth-cam-s30-r5-bore5\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"
   ],
   "license": "Publisher's page; dimensions are facts",
   "license_verified": true,
   "hosted": false
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  {
   "publisher": "507movements.com",
   "title": "Brown's movement No. 276: figure, his text and an animation",
   "url": "https://507movements.com/mm_276.html",
   "formats": [
    "web"
   ],
   "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/constant-breadth-cam-yoke-mechanism/",
   "formats": [
    "web"
   ],
   "license": "Publisher's page; dimensions are facts",
   "license_verified": true,
   "hosted": false
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  "mesh_price_usd": null,
  "step_price_usd": null,
  "tolerance_mm": null
 },
 "related": [
  "constant-breadth-cam-yoke-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 constant-breadth cam?",
   "a": "Reuleaux triangle of side 30 (three arcs of R30 about the opposite corners) with every edge offset 5 mm, so the corners are R5 arcs: breadth 40 mm in every direction. Bored Ø5 at its centre: turning there inside a yoke 40 mm wide it always touches both faces and moves the yoke 4.64 mm, three times per turn."
  }
 ],
 "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."
 },
 "offers": [
  {
   "file": "constant-breadth-cam-s30-r5",
   "formats": [
    "step",
    "stl"
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   "price_usd": 0,
   "license": "Xem Studio Design License",
   "step": "https://xemstudio.com/files/hardware/constant-breadth-cam-s30-r5-bore5/constant-breadth-cam-s30-r5.step",
   "stl": "https://xemstudio.com/files/hardware/constant-breadth-cam-s30-r5-bore5/constant-breadth-cam-s30-r5.stl",
   "note": "cam, z 0..8, a corner on +Y"
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 "markdown": "https://xemstudio.com/objects/constant-breadth-cam-s30-r5-bore5/index.md"
}