{
 "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": "plate-cam-parabolic-flat-r20-h12",
 "name": "Plate cam, constant acceleration (parabolic) rise 12 mm, base circle R20, for a flat-faced follower",
 "kind": "modern",
 "category": "Hardware",
 "group": "Mechanism parts",
 "year": null,
 "question": "What profile does a constant acceleration (parabolic) plate cam have?",
 "tags": [
  "mechanism part",
  "507 mechanical movements"
 ],
 "aliases": [
  "parabolic cam",
  "plate cam",
  "disc cam",
  "flat-faced cam",
  "leva de disco",
  "Kurvenscheibe"
 ],
 "overall_mm": {
  "length": 52,
  "width": 52,
  "height": 6
 },
 "official_cad": false,
 "xem_status": "free-files",
 "les": false,
 "free_files": 1,
 "url": "https://xemstudio.com/objects/plate-cam-parabolic-flat-r20-h12/",
 "sheet_txt": "https://xemstudio.com/objects/plate-cam-parabolic-flat-r20-h12/sheet.txt",
 "sheet": {
  "basis": "Xem Studio design following Brown's figure (1868); true size, no printing allowance",
  "overall_mm": {
   "length": 52,
   "width": 52,
   "height": 6
  },
  "notes": [
   "Disc cam (6 mm, Ø5 bore) for a radial flat-faced follower on a 20 mm base circle: rise 12 mm over 120° with constant acceleration (parabolic) motion, dwell 60°, return over 120°, dwell 60°.",
   "Profile computed point by point (720 points) from the displacement law: envelope of the flat face: contact at x = ds/dθ from the follower's axis.",
   "Xem Studio design following Brown's figure; true size, no printing allowance (apply your own to the mating features)."
  ],
  "table": {
   "columns": [
    "dimension",
    "value"
   ],
   "rows": [
    [
     "base circle",
     "R20"
    ],
    [
     "rise",
     "12 mm over 120°"
    ],
    [
     "dwells",
     "60° high, 60° low"
    ],
    [
     "law",
     "constant acceleration (parabolic)"
    ],
    [
     "bore",
     "Ø5"
    ],
    [
     "thickness",
     "6 mm"
    ]
   ]
  }
 },
 "sheet_text": "Plate cam, constant acceleration (parabolic) rise 12 mm, base circle R20, for a flat-faced follower — dimension sheet\nSource: Xem Studio, https://xemstudio.com/objects/plate-cam-parabolic-flat-r20-h12/  (CC BY 4.0)\nBasis: Xem Studio design following Brown's figure (1868); true size, no printing allowance\nCatalog version: 2026-10-20\n\nOverall (mm): length 52.0, width 52.0, height 6.0\n- Disc cam (6 mm, Ø5 bore) for a radial flat-faced follower on a 20 mm base circle: rise 12 mm over 120° with constant acceleration (parabolic) motion, dwell 60°, return over 120°, dwell 60°.\n- Profile computed point by point (720 points) from the displacement law: envelope of the flat face: contact at x = ds/dθ from the follower's axis.\n- Xem Studio design following Brown's figure; true size, no printing allowance (apply your own to the mating features).\n\ndimension  value\nbase circle  R20\nrise  12 mm over 120°\ndwells  60° high, 60° low\nlaw  constant acceleration (parabolic)\nbore  Ø5\nthickness  6 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. 138: figure, his text and an animation — web — Publisher's page; dimensions are facts — https://507movements.com/mm_138.html\n- Xem Studio: drawing — web — Publisher's page; dimensions are facts — https://xemstudio.com/objects/plate-cam-flat-follower-mechanism/\n\nFree files (CC BY 4.0, Xem Studio; STEP + STL, 1 parts): https://xemstudio.com/files/hardware/plate-cam-parabolic-flat-r20-h12/index.json\nAPI: https://xemstudio.com/api/geometry?object=plate-cam-parabolic-flat-r20-h12\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. 138: figure, his text and an animation",
   "url": "https://507movements.com/mm_138.html",
   "formats": [
    "web"
   ],
   "license": "Publisher's page; dimensions are facts",
   "license_verified": true,
   "hosted": false
  },
  {
   "publisher": "Xem Studio",
   "title": "drawing",
   "url": "https://xemstudio.com/objects/plate-cam-flat-follower-mechanism/",
   "formats": [
    "web"
   ],
   "license": "Publisher's page; dimensions are facts",
   "license_verified": true,
   "hosted": false
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 ],
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  "mesh_price_usd": null,
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  "tolerance_mm": null
 },
 "related": [
  "plate-cam-flat-follower-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 profile does a constant acceleration (parabolic) plate cam have?",
   "a": "Disc cam (6 mm, Ø5 bore) for a radial flat-faced follower on a 20 mm base circle: rise 12 mm over 120° with constant acceleration (parabolic) motion, dwell 60°, return over 120°, dwell 60°."
  }
 ],
 "files_license": null,
 "offers": [
  {
   "file": "plate-cam-parabolic-flat-r20-h12",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "CC BY 4.0 (Xem Studio)",
   "step": "https://xemstudio.com/files/hardware/plate-cam-parabolic-flat-r20-h12/plate-cam-parabolic-flat-r20-h12.step",
   "stl": "https://xemstudio.com/files/hardware/plate-cam-parabolic-flat-r20-h12/plate-cam-parabolic-flat-r20-h12.stl",
   "note": "cam, z 0..6, follower on +Y at cam angle 0"
  }
 ],
 "markdown": "https://xemstudio.com/objects/plate-cam-parabolic-flat-r20-h12/index.md"
}