{
 "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": "tri-clamp-crank-web",
 "name": "Tri-clamp crank web: Ø8 bore, Ø3 crank pin at 8, 12 and 18 mm throw",
 "kind": "hardware",
 "category": "Stirling engines",
 "group": "Tri-clamp engine parts",
 "year": null,
 "question": "What crank web gives a 24 mm stroke on an 8 mm shaft?",
 "tags": [
  "crank web",
  "crank disc",
  "crankshaft",
  "tri-clamp",
  "stirling",
  "long earth society"
 ],
 "aliases": [
  "crank web 8mm shaft",
  "crank disc 24mm stroke",
  "stirling crank web stl",
  "tri clamp crank web"
 ],
 "overall_mm": {
  "length": null,
  "width": null,
  "height": null
 },
 "official_cad": false,
 "xem_status": "free-files",
 "les": true,
 "free_files": 3,
 "url": "https://xemstudio.com/objects/tri-clamp-crank-web/",
 "sheet_txt": "https://xemstudio.com/objects/tri-clamp-crank-web/sheet.txt",
 "sheet": {
  "basis": "Stroke 16 / 24 / 36 mm (0.46 × bore) for the 1.5 / 2 / 3 in pistons; web Ø = 2 × (throw + 6)",
  "overall_mm": {
   "length": null,
   "width": null,
   "height": null
  },
  "notes": [
   "A round crank web: Ø8 shaft bore, Ø3 crank-pin hole at half the stroke, and an Ø2.5 radial hole for an M3 grub onto the shaft. Two webs face each other with the pin between them.",
   "1.5 in: Ø28, pin at 8 mm (16 mm stroke). 2 in: Ø36, pin at 12 mm (24 mm stroke). 3 in: Ø48, pin at 18 mm (36 mm stroke). All 5 mm thick.",
   "Shaft order: tower, web, con-rod, web, tower with 1 mm gaps, inside the crank frame's 21 mm tower gap; the crank pin between the webs is Ø3 × 19."
  ],
  "table": {
   "columns": [
    "spool_in",
    "web_od_mm",
    "shaft_bore_mm",
    "pin_hole_mm",
    "throw_mm",
    "stroke_mm",
    "thickness_mm"
   ],
   "rows": [
    [
     "1.5",
     28,
     8,
     3,
     8,
     16,
     5
    ],
    [
     "2",
     36,
     8,
     3,
     12,
     24,
     5
    ],
    [
     "3",
     48,
     8,
     3,
     18,
     36,
     5
    ]
   ]
  }
 },
 "sheet_text": "Tri-clamp crank web: Ø8 bore, Ø3 crank pin at 8, 12 and 18 mm throw — dimension sheet\nSource: Xem Studio, https://xemstudio.com/objects/tri-clamp-crank-web/  (CC BY 4.0)\nBasis: Stroke 16 / 24 / 36 mm (0.46 × bore) for the 1.5 / 2 / 3 in pistons; web Ø = 2 × (throw + 6)\nCatalog version: 2026-10-20\n\nSizes: see table below\n- A round crank web: Ø8 shaft bore, Ø3 crank-pin hole at half the stroke, and an Ø2.5 radial hole for an M3 grub onto the shaft. Two webs face each other with the pin between them.\n- 1.5 in: Ø28, pin at 8 mm (16 mm stroke). 2 in: Ø36, pin at 12 mm (24 mm stroke). 3 in: Ø48, pin at 18 mm (36 mm stroke). All 5 mm thick.\n- Shaft order: tower, web, con-rod, web, tower with 1 mm gaps, inside the crank frame's 21 mm tower gap; the crank pin between the webs is Ø3 × 19.\n\nspool_in  web_od_mm  shaft_bore_mm  pin_hole_mm  throw_mm  stroke_mm  thickness_mm\n1.5  28  8  3  8  16  5\n2  36  8  3  12  24  5\n3  48  8  3  18  36  5\n\nFiles elsewhere (not hosted by Xem Studio; license as stated by the publisher):\n- Long Earth Society: Tri-clamp Stirling engine builds — web, video — LES site — https://longearthsociety.com/engineering/\n- James R. Senft: An Introduction to Stirling Engines (piston fit and leakage) — book — Moriya Press [verify license at link] — https://www.stirlingengine.com/\n- ASME: BPE tube dimensions (16 ga sanitary tube) — standard — ASME [verify license at link] — https://www.asme.org/codes-standards/find-codes-standards/bpe-bioprocessing-equipment\n\nFree files (CC BY 4.0, Xem Studio; STEP + STL, 3 parts): https://xemstudio.com/files/hardware/tri-clamp-crank-web/index.json\nAPI: https://xemstudio.com/api/geometry?object=tri-clamp-crank-web\n",
 "sources": [
  {
   "publisher": "Long Earth Society",
   "title": "Tri-clamp Stirling engine builds",
   "url": "https://longearthsociety.com/engineering/",
   "formats": [
    "web",
    "video"
   ],
   "license": "LES site",
   "license_verified": true,
   "hosted": false
  },
  {
   "publisher": "James R. Senft",
   "title": "An Introduction to Stirling Engines (piston fit and leakage)",
   "url": "https://www.stirlingengine.com/",
   "formats": [
    "book"
   ],
   "license": "Moriya Press",
   "license_verified": false,
   "hosted": false
  },
  {
   "publisher": "ASME",
   "title": "BPE tube dimensions (16 ga sanitary tube)",
   "url": "https://www.asme.org/codes-standards/find-codes-standards/bpe-bioprocessing-equipment",
   "formats": [
    "standard"
   ],
   "license": "ASME",
   "license_verified": false,
   "hosted": false
  }
 ],
 "xem": {
  "status": "free-files",
  "sheet_free": true,
  "mesh_price_usd": null,
  "step_price_usd": null,
  "tolerance_mm": null
 },
 "related": [
  "tri-clamp-crank-frame",
  "tri-clamp-con-rod",
  "counterweighted-crank-discs",
  "stirling-crankshafts",
  "set-screws-metric"
 ],
 "fits": [
  {
   "role": "Goes in or on",
   "items": [
    {
     "slug": "tri-clamp-crank-frame",
     "why": "two webs between the towers on the Ø8 shaft"
    }
   ]
  },
  {
   "role": "Connects to",
   "items": [
    {
     "slug": "tri-clamp-con-rod",
     "why": "Ø3 crank pin through the rod's 623"
    }
   ]
  },
  {
   "role": "Alternatives",
   "items": [
    {
     "slug": "counterweighted-crank-discs",
     "why": "balanced webs"
    }
   ]
  },
  {
   "role": "Also needed",
   "items": [
    {
     "slug": "stirling-crankshafts",
     "why": "Ø8 shaft, Ø3 × 19 crank pin"
    },
    {
     "slug": "set-screws-metric",
     "why": "M3 grub"
    }
   ]
  }
 ],
 "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-web shaft bore",
   "exact": "Ø8",
   "mates": "Ø8 D-flat crankshaft",
   "fit": "slide",
   "files": "crank-web-"
  },
  {
   "feature": "crank-web pin hole",
   "exact": "Ø3",
   "mates": "Ø3 crank pin",
   "fit": "press",
   "files": "crank-web-"
  },
  {
   "feature": "crank-web grub hole",
   "exact": "Ø2.5",
   "mates": "M3 tap drill",
   "fit": "designed",
   "files": "crank-web-"
  }
 ],
 "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": "What stroke do the tri-clamp crank webs give?",
   "a": "16 mm (1.5 in), 24 mm (2 in) and 36 mm (3 in): the Ø3 pin is 8, 12 or 18 mm off the Ø8 bore."
  },
  {
   "q": "How is the web fixed to the shaft?",
   "a": "An M3 grub in the Ø2.5 radial hole, onto the Ø8 shaft (on its flat if it has one)."
  }
 ],
 "files_license": null,
 "offers": [
  {
   "file": "crank-web-1.5in-s16",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "CC BY 4.0 (Xem Studio)",
   "step": "https://xemstudio.com/files/hardware/tri-clamp-power-pistons/crank-web-1.5in-s16.step",
   "stl": "https://xemstudio.com/files/hardware/tri-clamp-power-pistons/crank-web-1.5in-s16.stl",
   "note": "1.5 in crank web: Ø8 bore on the D-flat shaft with an M3 tapped grub hole, Ø3 pin at 8 mm (16 mm stroke); two per crank"
  },
  {
   "file": "crank-web-2in-s24",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "CC BY 4.0 (Xem Studio)",
   "step": "https://xemstudio.com/files/hardware/tri-clamp-power-pistons/crank-web-2in-s24.step",
   "stl": "https://xemstudio.com/files/hardware/tri-clamp-power-pistons/crank-web-2in-s24.stl",
   "note": "2 in crank web: Ø8 bore on the D-flat shaft with an M3 tapped grub hole, Ø3 pin at 12 mm (24 mm stroke); two per crank"
  },
  {
   "file": "crank-web-3in-s36",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "CC BY 4.0 (Xem Studio)",
   "step": "https://xemstudio.com/files/hardware/tri-clamp-power-pistons/crank-web-3in-s36.step",
   "stl": "https://xemstudio.com/files/hardware/tri-clamp-power-pistons/crank-web-3in-s36.stl",
   "note": "3 in crank web: Ø8 bore on the D-flat shaft with an M3 tapped grub hole, Ø3 pin at 18 mm (36 mm stroke); two per crank"
  }
 ],
 "markdown": "https://xemstudio.com/objects/tri-clamp-crank-web/index.md"
}