{
 "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": "stirling-built-up-crank-webs",
 "name": "Built-up crank webs for Ø8 shafts and Ø6 crank pins (two-throw cranks at 90°)",
 "kind": "hardware",
 "category": "Hardware",
 "group": "Stirling & thermoacoustic",
 "year": null,
 "question": "How do I build a two-throw crankshaft with ball-bearing con-rods?",
 "tags": [
  "crank",
  "crank web",
  "crankshaft",
  "tri-clamp",
  "stirling",
  "long earth society"
 ],
 "aliases": [
  "built up crankshaft",
  "crank web 8 mm shaft"
 ],
 "overall_mm": {
  "length": null,
  "width": null,
  "height": null
 },
 "official_cad": false,
 "xem_status": "free-files",
 "les": true,
 "free_files": 8,
 "url": "https://xemstudio.com/objects/stirling-built-up-crank-webs/",
 "sheet_txt": "https://xemstudio.com/objects/stirling-built-up-crank-webs/sheet.txt",
 "sheet": {
  "basis": "Design values; Ø6 dowel crank pins (ISO 8734)",
  "overall_mm": {
   "length": null,
   "width": null,
   "height": null
  },
  "notes": [
   "Discs pressed on Ø8 shafts with Ø6 dowel crank pins pressed through them: the horizontal gamma's crank has four webs (two throws, 76.2 mm apart, a shaft between) and the beta's has two webs and a link web between the two con-rods (the shaft does not pass the con-rods).",
   "Pin radius 15 for the displacer (30 stroke) and 18 for the piston (36 stroke); the pins are a quarter turn apart, the displacer leading."
  ],
  "table": {
   "columns": [
    "part",
    "thickness",
    "pin radius"
   ],
   "rows": [
    [
     "crank-web-56x10-r15",
     "10",
     15
    ],
    [
     "crank-web-56x11-r15",
     "11",
     15
    ],
    [
     "crank-web-56x11-r18",
     "11",
     18
    ],
    [
     "crank-web-56x10-r18",
     "10",
     18
    ],
    [
     "crank-web-56x8-r18",
     "8",
     18
    ],
    [
     "crank-web-56x8-r15",
     "8",
     15
    ],
    [
     "link-web-14-r18-r15-90",
     14,
     "18 / 15"
    ]
   ]
  }
 },
 "sheet_text": "Built-up crank webs for Ø8 shafts and Ø6 crank pins (two-throw cranks at 90°) — dimension sheet\nSource: Xem Studio, https://xemstudio.com/objects/stirling-built-up-crank-webs/  (CC BY 4.0)\nBasis: Design values; Ø6 dowel crank pins (ISO 8734)\nCatalog version: 2026-10-20\n\nSizes: see table below\n- Discs pressed on Ø8 shafts with Ø6 dowel crank pins pressed through them: the horizontal gamma's crank has four webs (two throws, 76.2 mm apart, a shaft between) and the beta's has two webs and a link web between the two con-rods (the shaft does not pass the con-rods).\n- Pin radius 15 for the displacer (30 stroke) and 18 for the piston (36 stroke); the pins are a quarter turn apart, the displacer leading.\n\npart  thickness  pin radius\ncrank-web-56x10-r15  10  15\ncrank-web-56x11-r15  11  15\ncrank-web-56x11-r18  11  18\ncrank-web-56x10-r18  10  18\ncrank-web-56x8-r18  8  18\ncrank-web-56x8-r15  8  15\nlink-web-14-r18-r15-90  14  18 / 15\n\nFiles elsewhere (not hosted by Xem Studio; license as stated by the publisher):\n- Long Earth Society: Engine builds — web, video — LES site — https://longearthsociety.com/engineering/\n\nFree files (CC BY 4.0, Xem Studio; STEP + STL, 8 parts): https://xemstudio.com/files/hardware/stirling-built-up-crank-webs/index.json\nAPI: https://xemstudio.com/api/geometry?object=stirling-built-up-crank-webs\n",
 "sources": [
  {
   "publisher": "Long Earth Society",
   "title": "Engine builds",
   "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": [
  "stirling-conrods-626-625",
  "stirling-precision-rods",
  "list-tri-clamp-horizontal-gamma",
  "list-tri-clamp-charged-beta"
 ],
 "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": [
  {
   "feature": "shaft hole",
   "exact": "Ø8",
   "mates": "Ø8 crank shaft",
   "fit": "press",
   "files": "crank-web"
  },
  {
   "feature": "pin holes",
   "exact": "Ø6",
   "mates": "Ø6 dowel crank pins",
   "fit": "press",
   "files": "all"
  }
 ],
 "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": "Which way does it turn?",
   "a": "The way that brings the displacer pin to each point a quarter turn before the piston pin."
  }
 ],
 "files_license": null,
 "offers": [
  {
   "file": "crank-web-56x10-r15",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "CC BY 4.0 (Xem Studio)",
   "step": "https://xemstudio.com/files/hardware/stirling-built-up-crank-webs/crank-web-56x10-r15.step",
   "stl": "https://xemstudio.com/files/hardware/stirling-built-up-crank-webs/crank-web-56x10-r15.stl",
   "note": "crank web Ø56 × 10: Ø8 shaft hole, Ø6 pin hole at r 15 (both press), two Ø11 lightening holes beside the pin (counterweight)"
  },
  {
   "file": "crank-web-56x11-r15",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "CC BY 4.0 (Xem Studio)",
   "step": "https://xemstudio.com/files/hardware/stirling-built-up-crank-webs/crank-web-56x11-r15.step",
   "stl": "https://xemstudio.com/files/hardware/stirling-built-up-crank-webs/crank-web-56x11-r15.stl",
   "note": "crank web Ø56 × 11: Ø8 shaft hole, Ø6 pin hole at r 15 (both press), two Ø11 lightening holes beside the pin (counterweight)"
  },
  {
   "file": "crank-web-56x11-r18",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "CC BY 4.0 (Xem Studio)",
   "step": "https://xemstudio.com/files/hardware/stirling-built-up-crank-webs/crank-web-56x11-r18.step",
   "stl": "https://xemstudio.com/files/hardware/stirling-built-up-crank-webs/crank-web-56x11-r18.stl",
   "note": "crank web Ø56 × 11: Ø8 shaft hole, Ø6 pin hole at r 18 (both press), two Ø11 lightening holes beside the pin (counterweight)"
  },
  {
   "file": "crank-web-56x10-r18",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "CC BY 4.0 (Xem Studio)",
   "step": "https://xemstudio.com/files/hardware/stirling-built-up-crank-webs/crank-web-56x10-r18.step",
   "stl": "https://xemstudio.com/files/hardware/stirling-built-up-crank-webs/crank-web-56x10-r18.stl",
   "note": "crank web Ø56 × 10: Ø8 shaft hole, Ø6 pin hole at r 18 (both press), two Ø11 lightening holes beside the pin (counterweight)"
  },
  {
   "file": "crank-web-56x8-r18",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "CC BY 4.0 (Xem Studio)",
   "step": "https://xemstudio.com/files/hardware/stirling-built-up-crank-webs/crank-web-56x8-r18.step",
   "stl": "https://xemstudio.com/files/hardware/stirling-built-up-crank-webs/crank-web-56x8-r18.stl",
   "note": "crank web Ø56 × 8: Ø8 shaft hole, Ø6 pin hole at r 18 (both press), two Ø11 lightening holes beside the pin (counterweight)"
  },
  {
   "file": "crank-web-56x8-r15",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "CC BY 4.0 (Xem Studio)",
   "step": "https://xemstudio.com/files/hardware/stirling-built-up-crank-webs/crank-web-56x8-r15.step",
   "stl": "https://xemstudio.com/files/hardware/stirling-built-up-crank-webs/crank-web-56x8-r15.stl",
   "note": "crank web Ø56 × 8: Ø8 shaft hole, Ø6 pin hole at r 15 (both press), two Ø11 lightening holes beside the pin (counterweight)"
  },
  {
   "file": "crank-web-56x12-r15",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "CC BY 4.0 (Xem Studio)",
   "step": "https://xemstudio.com/files/hardware/stirling-built-up-crank-webs/crank-web-56x12-r15.step",
   "stl": "https://xemstudio.com/files/hardware/stirling-built-up-crank-webs/crank-web-56x12-r15.stl",
   "note": "crank web Ø56 × 12: Ø8 shaft hole, Ø6 pin hole at r 15 (both press), two Ø11 lightening holes beside the pin (counterweight)"
  },
  {
   "file": "link-web-14-r18-r15-90",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "CC BY 4.0 (Xem Studio)",
   "step": "https://xemstudio.com/files/hardware/stirling-built-up-crank-webs/link-web-14-r18-r15-90.step",
   "stl": "https://xemstudio.com/files/hardware/stirling-built-up-crank-webs/link-web-14-r18-r15-90.stl",
   "note": "link web 14 thick: Ø6 press holes for the piston pin (r 18) and the displacer pin (r 15, 90° on)"
  }
 ],
 "markdown": "https://xemstudio.com/objects/stirling-built-up-crank-webs/index.md"
}