{
 "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": "ltd-crank-stand",
 "name": "LTD crank stand for a 623 bearing, axis 112 above the foot",
 "kind": "hardware",
 "category": "Stirling engines",
 "group": "Can & LTD engines",
 "year": null,
 "question": "What are the dimensions of the crank stand on a coffee-cup Stirling engine?",
 "tags": [
  "ltd",
  "crank stand",
  "623",
  "stirling",
  "long earth society"
 ],
 "aliases": [
  "ltd stirling crank stand",
  "coffee cup stirling bearing stand",
  "623 stand 45 mm"
 ],
 "overall_mm": {
  "length": null,
  "width": null,
  "height": null
 },
 "official_cad": false,
 "xem_status": "free-files",
 "les": true,
 "free_files": 1,
 "url": "https://xemstudio.com/objects/ltd-crank-stand/",
 "sheet_txt": "https://xemstudio.com/objects/ltd-crank-stand/sheet.txt",
 "sheet": {
  "basis": "623 bearing (3 × 10 × 4) pocket at the bearing OD; M3 clearance Ø3.4 (ISO 273)",
  "overall_mm": {
   "length": null,
   "width": null,
   "height": null
  },
  "notes": [
   "The bearing stand that holds the LTD engine's Ø3 crankshaft above the top plate: a 40 × 6 upright, 119 tall, with a 28 × 14 arch under it that straddles the plate's bosses, on two 20 × 10 × 3 feet (one 68 mm foot with the arch cut out).",
   "A Ø10 pocket through the 6 mm upright, 112 mm above the foot's underside, holds a 623 bearing (fit: press). That height is what the con-rod needs to reach a piston inside the 90 mm syringe barrel standing in the top plate.",
   "Two Ø3.4 holes 54 mm apart in the feet take M3 × 8 screws into the top plate's tapped pads. Two stands carry one crankshaft, with the flywheel between them."
  ],
  "table": {
   "columns": [
    "part",
    "height",
    "shaft axis",
    "pocket",
    "feet",
    "holes"
   ],
   "rows": [
    [
     "ltd-crank-stand-a112",
     119,
     112,
     "Ø10 × 6",
     "68 × 10 × 3 less the 28 arch",
     "2 × Ø3.4 at 54"
    ]
   ]
  }
 },
 "sheet_text": "LTD crank stand for a 623 bearing, axis 112 above the foot — dimension sheet\nSource: Xem Studio, https://xemstudio.com/objects/ltd-crank-stand/  (CC BY 4.0)\nBasis: 623 bearing (3 × 10 × 4) pocket at the bearing OD; M3 clearance Ø3.4 (ISO 273)\nCatalog version: 2026-10-20\n\nSizes: see table below\n- The bearing stand that holds the LTD engine's Ø3 crankshaft above the top plate: a 40 × 6 upright, 119 tall, with a 28 × 14 arch under it that straddles the plate's bosses, on two 20 × 10 × 3 feet (one 68 mm foot with the arch cut out).\n- A Ø10 pocket through the 6 mm upright, 112 mm above the foot's underside, holds a 623 bearing (fit: press). That height is what the con-rod needs to reach a piston inside the 90 mm syringe barrel standing in the top plate.\n- Two Ø3.4 holes 54 mm apart in the feet take M3 × 8 screws into the top plate's tapped pads. Two stands carry one crankshaft, with the flywheel between them.\n\npart  height  shaft axis  pocket  feet  holes\nltd-crank-stand-a112  119  112  Ø10 × 6  68 × 10 × 3 less the 28 arch  2 × Ø3.4 at 54\n\nFiles elsewhere (not hosted by Xem Studio; license as stated by the publisher):\n- Wikipedia: Stirling engine — web — CC BY-SA 4.0 (text) — https://en.wikipedia.org/wiki/Stirling_engine\n- James R. Senft: An Introduction to Low Temperature Differential Stirling Engines — book — Moriya Press [verify license at link] — https://www.stirlingengine.com/\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, 1 parts): https://xemstudio.com/files/hardware/ltd-crank-stand/index.json\nAPI: https://xemstudio.com/api/geometry?object=ltd-crank-stand\n",
 "sources": [
  {
   "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": "James R. Senft",
   "title": "An Introduction to Low Temperature Differential Stirling Engines",
   "url": "https://www.stirlingengine.com/",
   "formats": [
    "book"
   ],
   "license": "Moriya Press",
   "license_verified": false,
   "hosted": false
  },
  {
   "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": [
  "ltd-top-plate",
  "can-engine-crank-stand",
  "ball-bearings-metric",
  "stirling-crankshafts",
  "list-ltd-coffee-cup"
 ],
 "fits": [
  {
   "role": "Goes in or on",
   "items": [
    {
     "slug": "ltd-top-plate",
     "why": "2 × M3 down onto the top plate"
    },
    {
     "slug": "ball-bearings-metric",
     "why": "623 in the Ø10 pocket"
    }
   ]
  },
  {
   "role": "Connects to",
   "items": [
    {
     "slug": "stirling-crankshafts",
     "why": "Ø3 crankshaft through the 623s"
    }
   ]
  },
  {
   "role": "Alternatives",
   "items": [
    {
     "slug": "can-engine-crank-stand",
     "why": "40 / 60 / 80 mm stands"
    }
   ]
  }
 ],
 "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": "stand bearing pockets",
   "exact": "Ø10",
   "mates": "623 bearing",
   "fit": "press",
   "files": "ltd-crank-stand-"
  },
  {
   "feature": "stand foot holes",
   "exact": "Ø3.4",
   "mates": "M3 screw clearance (ISO 273)",
   "fit": "designed",
   "files": "ltd-crank-stand-"
  },
  {
   "feature": "stand arch",
   "exact": "28 × 14",
   "mates": "top-plate bosses (no contact)",
   "fit": "designed",
   "files": "ltd-crank-stand-"
  }
 ],
 "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 bearing goes in the LTD crank stand?",
   "a": "A 623 (3 × 10 × 4) in the Ø10 pocket, 112 mm up."
  },
  {
   "q": "How many stands does the LTD engine use?",
   "a": "Two, 20 mm apart along the Ø3 × 40 crankshaft, with the flywheel between them and a crank disc outside each."
  }
 ],
 "files_license": null,
 "offers": [
  {
   "file": "ltd-crank-stand-a112",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "CC BY 4.0 (Xem Studio)",
   "step": "https://xemstudio.com/files/hardware/ltd-coffee-cup-engine-kit/ltd-crank-stand-a112.step",
   "stl": "https://xemstudio.com/files/hardware/ltd-coffee-cup-engine-kit/ltd-crank-stand-a112.stl",
   "note": "crank stand: upright 40 × 6 × 119, Ø10 pocket through it for a 623 with its axis 112 above the foot, 28 × 14 arch under it, 68 × 10 × 3 foot with 2 × Ø3.4 at 54 mm (two per engine)"
  }
 ],
 "markdown": "https://xemstudio.com/objects/ltd-crank-stand/index.md"
}