{
 "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-rd-link-webs",
 "name": "Link webs: a second crank throw on the first crank pin",
 "kind": "hardware",
 "category": "Hardware",
 "group": "Stirling & thermoacoustic",
 "year": null,
 "question": "How do I put two crank pins at different angles on one overhung crank?",
 "tags": [
  "crank web",
  "crank",
  "two throw",
  "tri-clamp",
  "stirling",
  "long earth society"
 ],
 "aliases": [
  "two pin crank",
  "crank web 90 degree",
  "overhung double crank"
 ],
 "overall_mm": {
  "length": null,
  "width": null,
  "height": null
 },
 "official_cad": false,
 "xem_status": "free-files",
 "les": true,
 "free_files": 2,
 "url": "https://xemstudio.com/objects/tri-clamp-rd-link-webs/",
 "sheet_txt": "https://xemstudio.com/objects/tri-clamp-rd-link-webs/sheet.txt",
 "sheet": {
  "basis": "Design values (pin radii and angles set by the engines' kinematics); Ø3 dowel pins (ISO 8734)",
  "overall_mm": {
   "length": null,
   "width": null,
   "height": null
  },
  "notes": [
   "The web is pressed on crank pin 1 (which is pressed in the crank disc) and carries crank pin 2. The power con-rod runs on pin 1 between the disc and the web; the displacer drive runs on pin 2 outside the web. The shaft ends at the disc, so nothing crosses the con-rods' path.",
   "Beta web: pin 2 at the same 10 mm radius, 90° from pin 1. Gamma web: pin 2 at 7 mm, 45° from pin 1; with the bell crank's own lag the displacer leads the power piston's volume by close to a quarter turn.",
   "Turn the web over to swap which way pin 2 leads: the web is the same both ways."
  ],
  "table": {
   "columns": [
    "part",
    "pin1_radius_mm",
    "pin2_radius_mm",
    "angle_deg",
    "thickness_mm"
   ],
   "rows": [
    [
     "rd-link-web-r10-90",
     10,
     10,
     90,
     14
    ],
    [
     "rd-link-web-r7-45",
     10,
     7,
     45,
     14
    ]
   ]
  }
 },
 "sheet_text": "Link webs: a second crank throw on the first crank pin — dimension sheet\nSource: Xem Studio, https://xemstudio.com/objects/tri-clamp-rd-link-webs/  (CC BY 4.0)\nBasis: Design values (pin radii and angles set by the engines' kinematics); Ø3 dowel pins (ISO 8734)\nCatalog version: 2026-10-20\n\nSizes: see table below\n- The web is pressed on crank pin 1 (which is pressed in the crank disc) and carries crank pin 2. The power con-rod runs on pin 1 between the disc and the web; the displacer drive runs on pin 2 outside the web. The shaft ends at the disc, so nothing crosses the con-rods' path.\n- Beta web: pin 2 at the same 10 mm radius, 90° from pin 1. Gamma web: pin 2 at 7 mm, 45° from pin 1; with the bell crank's own lag the displacer leads the power piston's volume by close to a quarter turn.\n- Turn the web over to swap which way pin 2 leads: the web is the same both ways.\n\npart  pin1_radius_mm  pin2_radius_mm  angle_deg  thickness_mm\nrd-link-web-r10-90  10.0  10.0  90.0  14.0\nrd-link-web-r7-45  10.0  7.0  45.0  14.0\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, 2 parts): https://xemstudio.com/files/hardware/tri-clamp-rd-link-webs/index.json\nAPI: https://xemstudio.com/api/geometry?object=tri-clamp-rd-link-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": [
  "counterweighted-crank-discs",
  "tri-clamp-rd-power-head",
  "list-tri-clamp-rd-beta",
  "list-tri-clamp-rd-gamma"
 ],
 "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": "pin holes",
   "exact": "Ø3 (two)",
   "mates": "Ø3 crank pins (dowels)",
   "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 the engine turn?",
   "a": "The way that makes the displacer lead the power piston; turning the web over reverses it."
  }
 ],
 "files_license": null,
 "offers": [
  {
   "file": "rd-link-web-r10-90",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "CC BY 4.0 (Xem Studio)",
   "step": "https://xemstudio.com/files/hardware/tri-clamp-rd-link-webs/rd-link-web-r10-90.step",
   "stl": "https://xemstudio.com/files/hardware/tri-clamp-rd-link-webs/rd-link-web-r10-90.stl",
   "note": "link web 14 thick: Ø3 press holes for crank pin 1 (radius 10) and pin 2 (radius 10) 90° apart about the shaft axis, Ø12 ends"
  },
  {
   "file": "rd-link-web-r7-45",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "CC BY 4.0 (Xem Studio)",
   "step": "https://xemstudio.com/files/hardware/tri-clamp-rd-link-webs/rd-link-web-r7-45.step",
   "stl": "https://xemstudio.com/files/hardware/tri-clamp-rd-link-webs/rd-link-web-r7-45.stl",
   "note": "link web 14 thick: Ø3 press holes for crank pin 1 (radius 10) and pin 2 (radius 7) 45° apart about the shaft axis, Ø12 ends"
  }
 ],
 "markdown": "https://xemstudio.com/objects/tri-clamp-rd-link-webs/index.md"
}