{
 "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": "rope-sheave-3mm-pitch-20",
 "name": "Rope sheave for Ø3 rope, pitch Ø20 (rope centre), Ø24.4 rim, Ø4 bore",
 "kind": "modern",
 "category": "Hardware",
 "group": "Mechanism parts",
 "year": null,
 "question": "What groove does a rope sheave need?",
 "tags": [
  "mechanism part",
  "507 mechanical movements"
 ],
 "aliases": [
  "rope sheave",
  "pulley wheel",
  "block sheave",
  "pulley 24.4 mm",
  "roldana (garrucha) para cuerda",
  "Seilrolle"
 ],
 "overall_mm": {
  "length": 24.4,
  "width": 8,
  "height": 24.4
 },
 "official_cad": false,
 "xem_status": "free-files",
 "les": false,
 "free_files": 1,
 "url": "https://xemstudio.com/objects/rope-sheave-3mm-pitch-20/",
 "sheet_txt": "https://xemstudio.com/objects/rope-sheave-3mm-pitch-20/sheet.txt",
 "sheet": {
  "basis": "Xem Studio design following Brown's figure (1868); true size, no printing allowance",
  "overall_mm": {
   "length": 24.4,
   "width": 8,
   "height": 24.4
  },
  "notes": [
   "Sheave 8 mm wide with a round-bottomed groove of radius 1.6 mm (1.07 × the Ø3 rope, the usual 6–10 % oversize) opening into 30° flanks; the rope rests on the groove bottom with its centre on a Ø20 circle, so a turn moves the rope 62.83 mm. Rim Ø24.4, Ø4 bore for a Ø4 pin.",
   "Xem Studio design following Brown's figure; true size, no printing allowance (apply your own to the mating features)."
  ],
  "table": {
   "columns": [
    "dimension",
    "value"
   ],
   "rows": [
    [
     "rope",
     "Ø3"
    ],
    [
     "pitch Ø (rope centre)",
     "20 mm"
    ],
    [
     "groove",
     "R1.6, 30° flanks"
    ],
    [
     "rim",
     "Ø24.4 × 8 mm"
    ],
    [
     "bore",
     "Ø4"
    ]
   ]
  }
 },
 "sheet_text": "Rope sheave for Ø3 rope, pitch Ø20 (rope centre), Ø24.4 rim, Ø4 bore — dimension sheet\nSource: Xem Studio, https://xemstudio.com/objects/rope-sheave-3mm-pitch-20/  (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 24.4, width 8.0, height 24.4\n- Sheave 8 mm wide with a round-bottomed groove of radius 1.6 mm (1.07 × the Ø3 rope, the usual 6–10 % oversize) opening into 30° flanks; the rope rests on the groove bottom with its centre on a Ø20 circle, so a turn moves the rope 62.83 mm. Rim Ø24.4, Ø4 bore for a Ø4 pin.\n- Xem Studio design following Brown's figure; true size, no printing allowance (apply your own to the mating features).\n\ndimension  value\nrope  Ø3\npitch Ø (rope centre)  20 mm\ngroove  R1.6, 30° flanks\nrim  Ø24.4 × 8 mm\nbore  Ø4\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. 12: figure, his text and an animation — web — Publisher's page; dimensions are facts — https://507movements.com/mm_012.html\n- Xem Studio: drawing — web — Publisher's page; dimensions are facts — https://xemstudio.com/objects/single-fixed-pulley-mechanism/\n\nFree files (Xem Studio Design License, Xem Studio; STEP + STL, 1 parts): https://xemstudio.com/files/hardware/rope-sheave-3mm-pitch-20/index.json\nAPI: https://xemstudio.com/api/geometry?object=rope-sheave-3mm-pitch-20\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. 12: figure, his text and an animation",
   "url": "https://507movements.com/mm_012.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/single-fixed-pulley-mechanism/",
   "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": [
  "single-fixed-pulley-mechanism",
  "spanish-burton-single-mechanism",
  "spanish-burton-with-lower-block-mechanism",
  "third-system-pulleys-7-to-1-mechanism",
  "tackle-rove-to-advantage-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 groove does a rope sheave need?",
   "a": "Sheave 8 mm wide with a round-bottomed groove of radius 1.6 mm (1.07 × the Ø3 rope, the usual 6–10 % oversize) opening into 30° flanks; the rope rests on the groove bottom with its centre on a Ø20 circle, so a turn moves the rope 62.83 mm. Rim Ø24.4, Ø4 bore for a Ø4 pin."
  }
 ],
 "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": "rope-sheave-3mm-pitch-20",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "Xem Studio Design License",
   "step": "https://xemstudio.com/files/hardware/rope-sheave-3mm-pitch-20/rope-sheave-3mm-pitch-20.step",
   "stl": "https://xemstudio.com/files/hardware/rope-sheave-3mm-pitch-20/rope-sheave-3mm-pitch-20.stl",
   "note": "sheave, axis Y, centred on the origin"
  }
 ],
 "markdown": "https://xemstudio.com/objects/rope-sheave-3mm-pitch-20/index.md"
}