{
 "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-con-rod",
 "name": "Tri-clamp con-rod: 58, 70 and 95 mm centres with 623 pockets",
 "kind": "hardware",
 "category": "Stirling engines",
 "group": "Tri-clamp engine parts",
 "year": null,
 "question": "How long is the con-rod for a 2 inch tri-clamp piston?",
 "tags": [
  "con-rod",
  "connecting rod",
  "623",
  "tri-clamp",
  "stirling",
  "long earth society"
 ],
 "aliases": [
  "stirling con rod 623",
  "connecting rod 70mm centres",
  "tri clamp con rod",
  "con-rod stl"
 ],
 "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-con-rod/",
 "sheet_txt": "https://xemstudio.com/objects/tri-clamp-con-rod/sheet.txt",
 "sheet": {
  "basis": "Rod centres = wrist-pin height + crank height + stroke/2 (1.5 in 58, 2 in 70, 3 in 95 mm), keeping the rod angle under 11°",
  "overall_mm": {
   "length": null,
   "width": null,
   "height": null
  },
  "notes": [
   "An I-section connecting rod with a Ø10 pocket for a 623 bearing at each end: the small end on the piston's Ø3 wrist pin, the big end on the Ø3 crank pin.",
   "Centres 58 / 70 / 95 mm for the 1.5 / 2 / 3 in piston and crank frame. 5 mm thick, Ø14 ends, 10 mm wide web recessed 1.2 mm each side (2.6 mm web).",
   "Overall 72 / 84 / 109 mm long. At bottom dead centre the piston skirt is flush with the ferrule face."
  ],
  "table": {
   "columns": [
    "spool_in",
    "centres_mm",
    "overall_len_mm",
    "thickness_mm",
    "end_od_mm",
    "pockets"
   ],
   "rows": [
    [
     "1.5",
     58,
     72,
     5,
     14,
     "623 (Ø10) both ends"
    ],
    [
     "2",
     70,
     84,
     5,
     14,
     "623 (Ø10) both ends"
    ],
    [
     "3",
     95,
     109,
     5,
     14,
     "623 (Ø10) both ends"
    ]
   ]
  }
 },
 "sheet_text": "Tri-clamp con-rod: 58, 70 and 95 mm centres with 623 pockets — dimension sheet\nSource: Xem Studio, https://xemstudio.com/objects/tri-clamp-con-rod/  (CC BY 4.0)\nBasis: Rod centres = wrist-pin height + crank height + stroke/2 (1.5 in 58, 2 in 70, 3 in 95 mm), keeping the rod angle under 11°\nCatalog version: 2026-10-20\n\nSizes: see table below\n- An I-section connecting rod with a Ø10 pocket for a 623 bearing at each end: the small end on the piston's Ø3 wrist pin, the big end on the Ø3 crank pin.\n- Centres 58 / 70 / 95 mm for the 1.5 / 2 / 3 in piston and crank frame. 5 mm thick, Ø14 ends, 10 mm wide web recessed 1.2 mm each side (2.6 mm web).\n- Overall 72 / 84 / 109 mm long. At bottom dead centre the piston skirt is flush with the ferrule face.\n\nspool_in  centres_mm  overall_len_mm  thickness_mm  end_od_mm  pockets\n1.5  58  72  5  14  623 (Ø10) both ends\n2  70  84  5  14  623 (Ø10) both ends\n3  95  109  5  14  623 (Ø10) both ends\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-con-rod/index.json\nAPI: https://xemstudio.com/api/geometry?object=tri-clamp-con-rod\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-power-piston",
  "tri-clamp-crank-web",
  "tri-clamp-crank-frame",
  "ball-bearings-metric",
  "crank-discs-5mm-bore"
 ],
 "fits": [
  {
   "role": "Connects to",
   "items": [
    {
     "slug": "tri-clamp-power-piston",
     "why": "small-end 623 on the Ø3 wrist pin"
    },
    {
     "slug": "tri-clamp-crank-web",
     "why": "big-end 623 on the Ø3 crank pin"
    }
   ]
  },
  {
   "role": "Alternatives",
   "items": [
    {
     "slug": "crank-discs-5mm-bore",
     "why": "other rod lengths"
    }
   ]
  },
  {
   "role": "Also needed",
   "items": [
    {
     "slug": "ball-bearings-metric",
     "why": "two 623 (3 × 10 × 4)"
    }
   ]
  }
 ],
 "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": "con-rod bearing pockets",
   "exact": "Ø10",
   "mates": "623 bearing",
   "fit": "press",
   "files": "conrod-"
  }
 ],
 "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 long is the 2 inch tri-clamp con-rod?",
   "a": "70 mm between centres, 84 mm overall, 5 mm thick, with a 623 pocket (Ø10) at each end."
  },
  {
   "q": "How are the con-rod lengths worked out?",
   "a": "Wrist-pin height + crank height + half the stroke: 23.5 + 34 + 12 ≈ 70 mm for 2 in."
  }
 ],
 "files_license": null,
 "offers": [
  {
   "file": "conrod-1.5in-58",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "CC BY 4.0 (Xem Studio)",
   "step": "https://xemstudio.com/files/hardware/tri-clamp-power-pistons/conrod-1.5in-58.step",
   "stl": "https://xemstudio.com/files/hardware/tri-clamp-power-pistons/conrod-1.5in-58.stl",
   "note": "1.5 in con-rod, 58 mm centres, 5 mm thick, Ø10 623 pockets both ends (wrist pin and crank pin Ø3)"
  },
  {
   "file": "conrod-2in-70",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "CC BY 4.0 (Xem Studio)",
   "step": "https://xemstudio.com/files/hardware/tri-clamp-power-pistons/conrod-2in-70.step",
   "stl": "https://xemstudio.com/files/hardware/tri-clamp-power-pistons/conrod-2in-70.stl",
   "note": "2 in con-rod, 70 mm centres, 5 mm thick, Ø10 623 pockets both ends (wrist pin and crank pin Ø3)"
  },
  {
   "file": "conrod-3in-95",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "CC BY 4.0 (Xem Studio)",
   "step": "https://xemstudio.com/files/hardware/tri-clamp-power-pistons/conrod-3in-95.step",
   "stl": "https://xemstudio.com/files/hardware/tri-clamp-power-pistons/conrod-3in-95.stl",
   "note": "3 in con-rod, 95 mm centres, 5 mm thick, Ø10 623 pockets both ends (wrist pin and crank pin Ø3)"
  }
 ],
 "markdown": "https://xemstudio.com/objects/tri-clamp-con-rod/index.md"
}