{
 "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": "displacer-rods",
 "name": "Displacer rods Ø2 × 60, 78, 100 and 180, Ø3 × 100, 150 and 200",
 "kind": "hardware",
 "category": "Stirling engines",
 "group": "Drives & mechanisms",
 "year": null,
 "question": "What size rod connects a Stirling displacer to its crank?",
 "tags": [
  "displacer rod",
  "rod",
  "2 mm",
  "3 mm",
  "stirling",
  "long earth society"
 ],
 "aliases": [
  "stirling displacer rod",
  "3mm displacer rod length",
  "displacer rod diameter",
  "3mm rod step file",
  "2mm displacer rod"
 ],
 "overall_mm": {
  "length": null,
  "width": null,
  "height": null
 },
 "official_cad": false,
 "xem_status": "free-files",
 "les": true,
 "free_files": 7,
 "url": "https://xemstudio.com/objects/displacer-rods/",
 "sheet_txt": "https://xemstudio.com/objects/displacer-rods/sheet.txt",
 "sheet": {
  "basis": "Solid rods at the bore Ø of the parts they pass through: Ø3 for the tri-clamp heads, Ø2 for the can-engine cap and LTD top plate",
  "overall_mm": {
   "length": null,
   "width": null,
   "height": null
  },
  "notes": [
   "Solid rods with 0.3 chamfers at both ends, plain round, no flat: Ø3 × 100, 150 and 200, and Ø2 × 60, 78, 100 and 180.",
   "On the tri-clamp engines the rod runs from the displacer cap's socket (M3 grub) up through the head's Ø3 bore, which is its guide and seal, to the rod clevis.",
   "Rod length = displacer cap to clevis plus the stroke.",
   "On the can engine and the LTD engines the Ø2 rod runs through the Ø2 bore in the can cap or the LTD top plate, from the displacer (flush with its underside) to the rod-clevis-2mm: 180 on the can engine, 76 on the Ø100 LTD.",
   "On the rhombic and free-piston engines the same Ø3 rod runs up the inside of the Ø5 tube piston rod (Ø3.4 bore)."
  ],
  "table": {
   "columns": [
    "file",
    "Ø",
    "length"
   ],
   "rows": [
    [
     "rod-2x60",
     2,
     60
    ],
    [
     "rod-2x76",
     2,
     78
    ],
    [
     "rod-2x100",
     2,
     100
    ],
    [
     "rod-2x180",
     2,
     180
    ],
    [
     "rod-3x100",
     3,
     100
    ],
    [
     "rod-3x150",
     3,
     150
    ],
    [
     "rod-3x200",
     3,
     200
    ]
   ]
  }
 },
 "sheet_text": "Displacer rods Ø2 × 60, 78, 100 and 180, Ø3 × 100, 150 and 200 — dimension sheet\nSource: Xem Studio, https://xemstudio.com/objects/displacer-rods/  (CC BY 4.0)\nBasis: Solid rods at the bore Ø of the parts they pass through: Ø3 for the tri-clamp heads, Ø2 for the can-engine cap and LTD top plate\nCatalog version: 2026-10-20\n\nSizes: see table below\n- Solid rods with 0.3 chamfers at both ends, plain round, no flat: Ø3 × 100, 150 and 200, and Ø2 × 60, 78, 100 and 180.\n- On the tri-clamp engines the rod runs from the displacer cap's socket (M3 grub) up through the head's Ø3 bore, which is its guide and seal, to the rod clevis.\n- Rod length = displacer cap to clevis plus the stroke.\n- On the can engine and the LTD engines the Ø2 rod runs through the Ø2 bore in the can cap or the LTD top plate, from the displacer (flush with its underside) to the rod-clevis-2mm: 180 on the can engine, 76 on the Ø100 LTD.\n- On the rhombic and free-piston engines the same Ø3 rod runs up the inside of the Ø5 tube piston rod (Ø3.4 bore).\n\nfile  Ø  length\nrod-2x60  2  60\nrod-2x76  2  78\nrod-2x100  2  100\nrod-2x180  2  180\nrod-3x100  3  100\nrod-3x150  3  150\nrod-3x200  3  200\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, 7 parts): https://xemstudio.com/files/hardware/displacer-rods/index.json\nAPI: https://xemstudio.com/api/geometry?object=displacer-rods\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": [
  "rod-clevises",
  "tri-clamp-displacer",
  "tube-piston-rods-5mm",
  "stirling-crankshafts",
  "can-engine-cap",
  "ltd-top-plate"
 ],
 "fits": [
  {
   "role": "Goes in or on",
   "items": [
    {
     "slug": "tri-clamp-displacer",
     "why": "Ø3 rod in the displacer cap socket and the head's Ø3 bore"
    },
    {
     "slug": "tube-piston-rods-5mm",
     "why": "runs inside the Ø3.4 bore"
    },
    {
     "slug": "can-engine-cap",
     "why": "Ø2 rod in the cap's Ø2 bore"
    },
    {
     "slug": "ltd-top-plate",
     "why": "Ø2 rod in the top plate's Ø2 bore"
    }
   ]
  },
  {
   "role": "Connects to",
   "items": [
    {
     "slug": "rod-clevises",
     "why": "Ø3 socket with 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": "shafts, rods, pins",
   "exact": "Ø3 / Ø5 / Ø8",
   "mates": "the bores listed on each mating object",
   "fit": "slide",
   "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": "What diameter is the displacer rod?",
   "a": "Ø3 on the tri-clamp engines, where it slides in the head's Ø3 bore and seats in the displacer cap and rod clevis sockets. Ø2 on the can engine and LTD engines, through the Ø2 bore in the cap or top plate."
  },
  {
   "q": "How long should the displacer rod be?",
   "a": "Displacer cap to rod clevis plus the stroke; the files are 100, 150 and 200 long."
  }
 ],
 "files_license": null,
 "offers": [
  {
   "file": "rod-3x100",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "CC BY 4.0 (Xem Studio)",
   "step": "https://xemstudio.com/files/hardware/stirling-shafts-and-rods/rod-3x100.step",
   "stl": "https://xemstudio.com/files/hardware/stirling-shafts-and-rods/rod-3x100.stl",
   "note": "Ø3 × 100 solid rod: displacer rod (into the displacer cap's grub, through the head's Ø3 bore and the piston crown, into the rod clevis)"
  },
  {
   "file": "rod-3x150",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "CC BY 4.0 (Xem Studio)",
   "step": "https://xemstudio.com/files/hardware/stirling-shafts-and-rods/rod-3x150.step",
   "stl": "https://xemstudio.com/files/hardware/stirling-shafts-and-rods/rod-3x150.stl",
   "note": "Ø3 × 150 solid rod: displacer rod (into the displacer cap's grub, through the head's Ø3 bore and the piston crown, into the rod clevis)"
  },
  {
   "file": "rod-3x200",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "CC BY 4.0 (Xem Studio)",
   "step": "https://xemstudio.com/files/hardware/stirling-shafts-and-rods/rod-3x200.step",
   "stl": "https://xemstudio.com/files/hardware/stirling-shafts-and-rods/rod-3x200.stl",
   "note": "Ø3 × 200 solid rod: displacer rod (into the displacer cap's grub, through the head's Ø3 bore and the piston crown, into the rod clevis)"
  },
  {
   "file": "rod-2x60",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "CC BY 4.0 (Xem Studio)",
   "step": "https://xemstudio.com/files/hardware/stirling-shafts-and-rods/rod-2x60.step",
   "stl": "https://xemstudio.com/files/hardware/stirling-shafts-and-rods/rod-2x60.stl",
   "note": "Ø2 × 60 solid rod: displacer rod for the can and LTD engines (through the Ø2 bore in the can cap or LTD top plate; 76 is the LTD's, 180 the can engine's, displacer to rod clevis)"
  },
  {
   "file": "rod-2x76",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "CC BY 4.0 (Xem Studio)",
   "step": "https://xemstudio.com/files/hardware/stirling-shafts-and-rods/rod-2x76.step",
   "stl": "https://xemstudio.com/files/hardware/stirling-shafts-and-rods/rod-2x76.stl",
   "note": "Ø2 × 76 solid rod: displacer rod for the can and LTD engines (through the Ø2 bore in the can cap or LTD top plate; 76 is the LTD's, 180 the can engine's, displacer to rod clevis)"
  },
  {
   "file": "rod-2x100",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "CC BY 4.0 (Xem Studio)",
   "step": "https://xemstudio.com/files/hardware/stirling-shafts-and-rods/rod-2x100.step",
   "stl": "https://xemstudio.com/files/hardware/stirling-shafts-and-rods/rod-2x100.stl",
   "note": "Ø2 × 100 solid rod: displacer rod for the can and LTD engines (through the Ø2 bore in the can cap or LTD top plate; 76 is the LTD's, 180 the can engine's, displacer to rod clevis)"
  },
  {
   "file": "rod-2x180",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "CC BY 4.0 (Xem Studio)",
   "step": "https://xemstudio.com/files/hardware/stirling-shafts-and-rods/rod-2x180.step",
   "stl": "https://xemstudio.com/files/hardware/stirling-shafts-and-rods/rod-2x180.stl",
   "note": "Ø2 × 180 solid rod: displacer rod for the can and LTD engines (through the Ø2 bore in the can cap or LTD top plate; 76 is the LTD's, 180 the can engine's, displacer to rod clevis)"
  }
 ],
 "markdown": "https://xemstudio.com/objects/displacer-rods/index.md"
}