{
 "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": "crank-discs-5mm-bore",
 "name": "Crank discs for a Ø5 shaft, 10 to 30 mm stroke",
 "kind": "hardware",
 "category": "Stirling engines",
 "group": "Drives & mechanisms",
 "year": null,
 "question": "What crank disc gives a 10–30 mm stroke on a 5 mm shaft?",
 "tags": [
  "crank disc",
  "crank",
  "stroke",
  "5 mm shaft",
  "stirling",
  "long earth society"
 ],
 "aliases": [
  "crank disc stl",
  "crank disc 5mm bore",
  "model engine crank disc",
  "crank stroke disc"
 ],
 "overall_mm": {
  "length": null,
  "width": null,
  "height": null
 },
 "official_cad": false,
 "xem_status": "free-files",
 "les": true,
 "free_files": 5,
 "url": "https://xemstudio.com/objects/crank-discs-5mm-bore/",
 "sheet_txt": "https://xemstudio.com/objects/crank-discs-5mm-bore/sheet.txt",
 "sheet": {
  "basis": "Disc 6 thick, Ø5 bore, Ø3 pin hole at stroke / 2, M3 grub; disc Ø = max(30, stroke + 12)",
  "overall_mm": {
   "length": null,
   "width": null,
   "height": null
  },
  "notes": [
   "A 6 mm disc with a Ø5 bore and a Ø3 crank-pin hole at half the stroke from the axis: 5.0, 7.5, 10.0, 12.5, 15.0 mm for 10–30 mm stroke.",
   "Disc Ø grows with the stroke: Ø30 (10 and 15), Ø32 (20), Ø37 (25), Ø42 (30).",
   "A radial Ø2.5 hole (M3 tap drill) at mid-thickness locks the disc to the shaft's D-flat.",
   "The crank pin is fixed in the disc and the con-rod's 623 turns on it; fits are under Mating features."
  ],
  "table": {
   "columns": [
    "file",
    "stroke",
    "pin offset",
    "disc Ø × t",
    "bore"
   ],
   "rows": [
    [
     "crank-disc-stroke10",
     10,
     5,
     "30 × 6",
     5
    ],
    [
     "crank-disc-stroke15",
     15,
     7.5,
     "30 × 6",
     5
    ],
    [
     "crank-disc-stroke20",
     20,
     10,
     "32 × 6",
     5
    ],
    [
     "crank-disc-stroke25",
     25,
     12.5,
     "37 × 6",
     5
    ],
    [
     "crank-disc-stroke30",
     30,
     15,
     "42 × 6",
     5
    ]
   ]
  }
 },
 "sheet_text": "Crank discs for a Ø5 shaft, 10 to 30 mm stroke — dimension sheet\nSource: Xem Studio, https://xemstudio.com/objects/crank-discs-5mm-bore/  (CC BY 4.0)\nBasis: Disc 6 thick, Ø5 bore, Ø3 pin hole at stroke / 2, M3 grub; disc Ø = max(30, stroke + 12)\nCatalog version: 2026-10-20\n\nSizes: see table below\n- A 6 mm disc with a Ø5 bore and a Ø3 crank-pin hole at half the stroke from the axis: 5.0, 7.5, 10.0, 12.5, 15.0 mm for 10–30 mm stroke.\n- Disc Ø grows with the stroke: Ø30 (10 and 15), Ø32 (20), Ø37 (25), Ø42 (30).\n- A radial Ø2.5 hole (M3 tap drill) at mid-thickness locks the disc to the shaft's D-flat.\n- The crank pin is fixed in the disc and the con-rod's 623 turns on it; fits are under Mating features.\n\nfile  stroke  pin offset  disc Ø × t  bore\ncrank-disc-stroke10  10  5.0  30 × 6  5\ncrank-disc-stroke15  15  7.5  30 × 6  5\ncrank-disc-stroke20  20  10.0  32 × 6  5\ncrank-disc-stroke25  25  12.5  37 × 6  5\ncrank-disc-stroke30  30  15.0  42 × 6  5\n\nFiles elsewhere (not hosted by Xem Studio; license as stated by the publisher):\n- Wikipedia: Crank (mechanism) — web — CC BY-SA 4.0 (text) — https://en.wikipedia.org/wiki/Crank_(mechanism)\n- Wikipedia: Flywheel — web — CC BY-SA 4.0 (text) — https://en.wikipedia.org/wiki/Flywheel\n- Wikipedia: Stirling engine — web — CC BY-SA 4.0 (text) — https://en.wikipedia.org/wiki/Stirling_engine\n- Long Earth Society: Engine builds that use these parts (videos and write-ups) — web, video — LES site — https://longearthsociety.com/engineering/\n\nFree files (CC BY 4.0, Xem Studio; STEP + STL, 5 parts): https://xemstudio.com/files/hardware/crank-discs-5mm-bore/index.json\nAPI: https://xemstudio.com/api/geometry?object=crank-discs-5mm-bore\n",
 "sources": [
  {
   "publisher": "Wikipedia",
   "title": "Crank (mechanism)",
   "url": "https://en.wikipedia.org/wiki/Crank_(mechanism)",
   "formats": [
    "web"
   ],
   "license": "CC BY-SA 4.0 (text)",
   "license_verified": true,
   "hosted": false
  },
  {
   "publisher": "Wikipedia",
   "title": "Flywheel",
   "url": "https://en.wikipedia.org/wiki/Flywheel",
   "formats": [
    "web"
   ],
   "license": "CC BY-SA 4.0 (text)",
   "license_verified": true,
   "hosted": false
  },
  {
   "publisher": "Wikipedia",
   "title": "Stirling engine",
   "url": "https://en.wikipedia.org/wiki/Stirling_engine",
   "formats": [
    "web"
   ],
   "license": "CC BY-SA 4.0 (text)",
   "license_verified": true,
   "hosted": false
  },
  {
   "publisher": "Long Earth Society",
   "title": "Engine builds that use these parts (videos and write-ups)",
   "url": "https://longearthsociety.com/engineering/",
   "formats": [
    "web",
    "video"
   ],
   "license": "LES site",
   "license_verified": true,
   "hosted": false
  }
 ],
 "xem": {
  "status": "free-files",
  "sheet_free": true,
  "mesh_price_usd": null,
  "step_price_usd": null,
  "tolerance_mm": null
 },
 "related": [
  "connecting-rods-623",
  "counterweighted-crank-discs",
  "crank-discs-3mm-bore",
  "stirling-crankshafts",
  "pins-3mm"
 ],
 "fits": [
  {
   "role": "Goes in or on",
   "items": [
    {
     "slug": "stirling-crankshafts",
     "why": "Ø5 bore on the D-flat, M3 grub"
    }
   ]
  },
  {
   "role": "Connects to",
   "items": [
    {
     "slug": "connecting-rods-623",
     "why": "623 end on the Ø3 crank pin"
    }
   ]
  },
  {
   "role": "Alternatives",
   "items": [
    {
     "slug": "counterweighted-crank-discs",
     "why": "same strokes with a counterweight"
    }
   ]
  },
  {
   "role": "Also needed",
   "items": [
    {
     "slug": "pins-3mm",
     "why": "Ø3 crank pin"
    }
   ]
  }
 ],
 "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": [
  {
   "feature": "crank-disc bore",
   "exact": "Ø5",
   "mates": "Ø5 crankshaft (M3 set screw)",
   "fit": "slide",
   "files": "crank-disc-"
  },
  {
   "feature": "crank-disc pin hole",
   "exact": "Ø3",
   "mates": "Ø3 crank pin",
   "fit": "press",
   "files": "crank-disc-"
  },
  {
   "feature": "crank-disc set-screw hole",
   "exact": "Ø2.5",
   "mates": "M3 tap drill",
   "fit": "designed",
   "files": "crank-disc-"
  }
 ],
 "fit_classes": {
  "press": "stays put: pin, tube, bearing or magnet held by interference. Typical FDM: hole +0.0 to +0.1 mm on diameter.",
  "slide": "assembles by hand and is held by a grub, pinch or clamp: shaft in a hub, rod in a socket, spigot in a bore. Typical FDM: +0.2 mm.",
  "run": "turns or slides in use: pin in a link, rod through a guide. Typical FDM: +0.3 mm.",
  "socket": "large sliding fit: syringe barrel, sleeve, bobbin in a bore. Typical FDM: +0.3 mm.",
  "clamp": "split part that closes on the mating part with screws: make it at size.",
  "designed": "a gap that is part of the design (piston fit option, displacer gap, air gap): do not change."
 },
 "faq": [
  {
   "q": "How do I set the stroke on a crank disc?",
   "a": "Stroke = 2 × pin offset; these discs have the Ø3 pin hole at 5, 7.5, 10, 12.5 and 15 mm."
  },
  {
   "q": "What stroke do the 2 in tri-clamp engines run?",
   "a": "20 mm: crank-disc-stroke20, Ø32 × 6."
  }
 ],
 "files_license": null,
 "offers": [
  {
   "file": "crank-disc-stroke10",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "CC BY 4.0 (Xem Studio)",
   "step": "https://xemstudio.com/files/hardware/crank-conrod-flywheel-kit/crank-disc-stroke10.step",
   "stl": "https://xemstudio.com/files/hardware/crank-conrod-flywheel-kit/crank-disc-stroke10.stl",
   "note": "crank disc for 10 mm stroke (pin at 5.0 mm), Ø5 bore, M3 set screw, Ø3 pin hole"
  },
  {
   "file": "crank-disc-stroke15",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "CC BY 4.0 (Xem Studio)",
   "step": "https://xemstudio.com/files/hardware/crank-conrod-flywheel-kit/crank-disc-stroke15.step",
   "stl": "https://xemstudio.com/files/hardware/crank-conrod-flywheel-kit/crank-disc-stroke15.stl",
   "note": "crank disc for 15 mm stroke (pin at 7.5 mm), Ø5 bore, M3 set screw, Ø3 pin hole"
  },
  {
   "file": "crank-disc-stroke20",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "CC BY 4.0 (Xem Studio)",
   "step": "https://xemstudio.com/files/hardware/crank-conrod-flywheel-kit/crank-disc-stroke20.step",
   "stl": "https://xemstudio.com/files/hardware/crank-conrod-flywheel-kit/crank-disc-stroke20.stl",
   "note": "crank disc for 20 mm stroke (pin at 10.0 mm), Ø5 bore, M3 set screw, Ø3 pin hole"
  },
  {
   "file": "crank-disc-stroke25",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "CC BY 4.0 (Xem Studio)",
   "step": "https://xemstudio.com/files/hardware/crank-conrod-flywheel-kit/crank-disc-stroke25.step",
   "stl": "https://xemstudio.com/files/hardware/crank-conrod-flywheel-kit/crank-disc-stroke25.stl",
   "note": "crank disc for 25 mm stroke (pin at 12.5 mm), Ø5 bore, M3 set screw, Ø3 pin hole"
  },
  {
   "file": "crank-disc-stroke30",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "CC BY 4.0 (Xem Studio)",
   "step": "https://xemstudio.com/files/hardware/crank-conrod-flywheel-kit/crank-disc-stroke30.step",
   "stl": "https://xemstudio.com/files/hardware/crank-conrod-flywheel-kit/crank-disc-stroke30.stl",
   "note": "crank disc for 30 mm stroke (pin at 15.0 mm), Ø5 bore, M3 set screw, Ø3 pin hole"
  }
 ],
 "markdown": "https://xemstudio.com/objects/crank-discs-5mm-bore/index.md"
}