{
 "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": "tube-piston-rods-5mm",
 "name": "Tube piston rods Ø5 × Ø3.4",
 "kind": "hardware",
 "category": "Stirling engines",
 "group": "Drives & mechanisms",
 "year": null,
 "question": "What tube piston rod lets the displacer rod pass through the piston?",
 "tags": [
  "piston rod",
  "tube",
  "5 mm",
  "beta",
  "stirling",
  "long earth society"
 ],
 "aliases": [
  "hollow piston rod stirling",
  "5mm tube piston rod",
  "beta stirling piston rod",
  "tube rod step"
 ],
 "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/tube-piston-rods-5mm/",
 "sheet_txt": "https://xemstudio.com/objects/tube-piston-rods-5mm/sheet.txt",
 "sheet": {
  "basis": "Ø5 OD tube with a Ø3.4 bore, so the Ø3 displacer rod passes inside without touching",
  "overall_mm": {
   "length": null,
   "width": null,
   "height": null
  },
  "notes": [
   "Ø5 OD × Ø3.4 ID tubes, 80, 120 and 160 long, 0.3 chamfers on both ends.",
   "The OD seats in the piston plug's Ø5 socket and in the rhombic lower yoke or the flexure hub collars; the Ø3 displacer rod runs inside with 0.2 mm radial gap by design.",
   "Wall thickness 0.8."
  ],
  "table": {
   "columns": [
    "file",
    "OD",
    "ID",
    "length"
   ],
   "rows": [
    [
     "tube-rod-5x3.4x80",
     5,
     3.4,
     80
    ],
    [
     "tube-rod-5x3.4x120",
     5,
     3.4,
     120
    ],
    [
     "tube-rod-5x3.4x160",
     5,
     3.4,
     160
    ]
   ]
  }
 },
 "sheet_text": "Tube piston rods Ø5 × Ø3.4 — dimension sheet\nSource: Xem Studio, https://xemstudio.com/objects/tube-piston-rods-5mm/  (CC BY 4.0)\nBasis: Ø5 OD tube with a Ø3.4 bore, so the Ø3 displacer rod passes inside without touching\nCatalog version: 2026-10-20\n\nSizes: see table below\n- Ø5 OD × Ø3.4 ID tubes, 80, 120 and 160 long, 0.3 chamfers on both ends.\n- The OD seats in the piston plug's Ø5 socket and in the rhombic lower yoke or the flexure hub collars; the Ø3 displacer rod runs inside with 0.2 mm radial gap by design.\n- Wall thickness 0.8.\n\nfile  OD  ID  length\ntube-rod-5x3.4x80  5  3.4  80\ntube-rod-5x3.4x120  5  3.4  120\ntube-rod-5x3.4x160  5  3.4  160\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, 3 parts): https://xemstudio.com/files/hardware/tube-piston-rods-5mm/index.json\nAPI: https://xemstudio.com/api/geometry?object=tube-piston-rods-5mm\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": [
  "displacer-rods",
  "rod-clevises",
  "rhombic-crank-gear",
  "tri-clamp-flexure-head",
  "tri-clamp-power-piston"
 ],
 "fits": [
  {
   "role": "Goes in or on",
   "items": [
    {
     "slug": "tri-clamp-flexure-head",
     "why": "Ø5 OD in the piston plug socket"
    }
   ]
  },
  {
   "role": "Connects to",
   "items": [
    {
     "slug": "rhombic-crank-gear",
     "why": "Ø5 tube on the lower yoke"
    },
    {
     "slug": "rod-clevises",
     "why": "rod-clevis-5mm-tube socket"
    }
   ]
  },
  {
   "role": "Also needed",
   "items": [
    {
     "slug": "displacer-rods",
     "why": "Ø3 rod runs inside"
    }
   ]
  }
 ],
 "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"
  },
  {
   "feature": "tube rod bore",
   "exact": "Ø3.4",
   "mates": "Ø3 rod (no contact)",
   "fit": "designed",
   "files": "tube-rod-"
  },
  {
   "feature": "tube rod OD",
   "exact": "Ø5",
   "mates": "piston plug socket / yoke / collars",
   "fit": "slide",
   "files": "tube-rod-"
  }
 ],
 "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": "Why is the piston rod a tube?",
   "a": "In a beta or free-piston engine the displacer rod passes through the piston: the Ø3 rod runs inside the Ø3.4 bore of the Ø5 tube."
  },
  {
   "q": "What does the tube rod connect to?",
   "a": "The piston plug socket (Ø5) at one end; the rhombic lower yoke, the flexure hub collars or the 5 mm tube rod clevis at the other."
  }
 ],
 "files_license": null,
 "offers": [
  {
   "file": "tube-rod-5x3.4x80",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "CC BY 4.0 (Xem Studio)",
   "step": "https://xemstudio.com/files/hardware/stirling-shafts-and-rods/tube-rod-5x3.4x80.step",
   "stl": "https://xemstudio.com/files/hardware/stirling-shafts-and-rods/tube-rod-5x3.4x80.stl",
   "note": "Ø5 × Ø3.4 × 80 tube piston rod: into the piston plug socket, onto the rhombic lower yoke or the flexure collars; the Ø3 displacer rod runs inside"
  },
  {
   "file": "tube-rod-5x3.4x120",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "CC BY 4.0 (Xem Studio)",
   "step": "https://xemstudio.com/files/hardware/stirling-shafts-and-rods/tube-rod-5x3.4x120.step",
   "stl": "https://xemstudio.com/files/hardware/stirling-shafts-and-rods/tube-rod-5x3.4x120.stl",
   "note": "Ø5 × Ø3.4 × 120 tube piston rod: into the piston plug socket, onto the rhombic lower yoke or the flexure collars; the Ø3 displacer rod runs inside"
  },
  {
   "file": "tube-rod-5x3.4x160",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "CC BY 4.0 (Xem Studio)",
   "step": "https://xemstudio.com/files/hardware/stirling-shafts-and-rods/tube-rod-5x3.4x160.step",
   "stl": "https://xemstudio.com/files/hardware/stirling-shafts-and-rods/tube-rod-5x3.4x160.stl",
   "note": "Ø5 × Ø3.4 × 160 tube piston rod: into the piston plug socket, onto the rhombic lower yoke or the flexure collars; the Ø3 displacer rod runs inside"
  }
 ],
 "markdown": "https://xemstudio.com/objects/tube-piston-rods-5mm/index.md"
}