{
 "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": "power-cylinder-piston-crosshead",
 "name": "Power cylinder liners, piston blanks, crosshead and guide (the non-syringe power piston)",
 "kind": "hardware",
 "category": "Stirling engines",
 "group": "Drives & mechanisms",
 "year": null,
 "question": "How do I make a power piston and cylinder for a Stirling engine without a syringe?",
 "tags": [
  "piston",
  "cylinder",
  "liner",
  "crosshead",
  "wrist pin",
  "seal",
  "stirling",
  "gamma",
  "long earth society"
 ],
 "aliases": [
  "stirling engine piston and cylinder",
  "graphite piston glass cylinder",
  "lapped piston clearance",
  "crosshead design model engine",
  "power piston stirling",
  "wrist pin 3mm"
 ],
 "overall_mm": {
  "length": null,
  "width": null,
  "height": null
 },
 "official_cad": false,
 "xem_status": "free-files",
 "les": true,
 "free_files": 11,
 "url": "https://xemstudio.com/objects/power-cylinder-piston-crosshead/",
 "sheet_txt": "https://xemstudio.com/objects/power-cylinder-piston-crosshead/sheet.txt",
 "sheet": {
  "basis": "Trunk piston and crosshead practice for model engines: clearance-seal piston lapped into a honed liner (10–25 µm radial), or a graphite piston in a glass tube; crosshead takes the con-rod side load so the piston only moves axially",
  "overall_mm": {
   "length": null,
   "width": null,
   "height": null
  },
  "notes": [
   "Two ways to seal: (1) lapped fit: brass or aluminium piston turned 0.05 under, lapped with fine compound into a honed brass/stainless liner until it falls through slowly under its own weight; (2) graphite piston in a borosilicate glass tube (16 or 20 mm test tube / tube): self-lubricating, near-zero friction, the premium option. Printed liners and pistons here are for prototyping the layout; a printed piston will not seal.",
   "Sizes: Ø16 (1.65 mL per 12 mm stroke... see table), Ø20, Ø25, Ø30. For the 2 in tri-clamp gamma with the Ø46 × 90 displacer at 20 mm stroke, a Ø20 × 12 mm stroke piston (3.8 mL) is in the right range; Ø16 at 15 mm for the 1.5 in.",
   "Crosshead: a Ø8 slider on the Ø3 piston rod running in a guide bushing; the con-rod's angle pushes sideways on the crosshead, not the piston, so the lapped seal stays round. Trunk alternative: wrist pin in the piston boss, con-rod directly on it; fine for short rods (L ≥ 4 × stroke).",
   "Flange: 4 × M3 on a Ø(D + 16) circle, matches the power head's socket pattern when drilled; seal with a paper or silicone gasket."
  ],
  "table": {
   "columns": [
    "bore_mm",
    "liner_len_mm",
    "piston_len_mm",
    "ml_per_12mm_stroke"
   ],
   "rows": [
    [
     16,
     40,
     14,
     2.41
    ],
    [
     20,
     45,
     18,
     3.77
    ],
    [
     25,
     50,
     22,
     5.89
    ],
    [
     30,
     55,
     27,
     8.48
    ]
   ]
  }
 },
 "sheet_text": "Power cylinder liners, piston blanks, crosshead and guide (the non-syringe power piston) — dimension sheet\nSource: Xem Studio, https://xemstudio.com/objects/power-cylinder-piston-crosshead/  (CC BY 4.0)\nBasis: Trunk piston and crosshead practice for model engines: clearance-seal piston lapped into a honed liner (10–25 µm radial), or a graphite piston in a glass tube; crosshead takes the con-rod side load so the piston only moves axially\nCatalog version: 2026-10-20\n\nSizes: see table below\n- Two ways to seal: (1) lapped fit: brass or aluminium piston turned 0.05 under, lapped with fine compound into a honed brass/stainless liner until it falls through slowly under its own weight; (2) graphite piston in a borosilicate glass tube (16 or 20 mm test tube / tube): self-lubricating, near-zero friction, the premium option. Printed liners and pistons here are for prototyping the layout; a printed piston will not seal.\n- Sizes: Ø16 (1.65 mL per 12 mm stroke... see table), Ø20, Ø25, Ø30. For the 2 in tri-clamp gamma with the Ø46 × 90 displacer at 20 mm stroke, a Ø20 × 12 mm stroke piston (3.8 mL) is in the right range; Ø16 at 15 mm for the 1.5 in.\n- Crosshead: a Ø8 slider on the Ø3 piston rod running in a guide bushing; the con-rod's angle pushes sideways on the crosshead, not the piston, so the lapped seal stays round. Trunk alternative: wrist pin in the piston boss, con-rod directly on it; fine for short rods (L ≥ 4 × stroke).\n- Flange: 4 × M3 on a Ø(D + 16) circle, matches the power head's socket pattern when drilled; seal with a paper or silicone gasket.\n\nbore_mm  liner_len_mm  piston_len_mm  ml_per_12mm_stroke\n16  40  14  2.41\n20  45  18  3.77\n25  50  22  5.89\n30  55  27  8.48\n\nFiles elsewhere (not hosted by Xem Studio; license as stated by the publisher):\n- Wikipedia: Crosshead — web — CC BY-SA 4.0 (text) — https://en.wikipedia.org/wiki/Crosshead\n- Wikipedia: Piston — web — CC BY-SA 4.0 (text) — https://en.wikipedia.org/wiki/Piston\n- James R. Senft: Miniature Stirling engine piston fits (LTD book) — book — reference [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, 11 parts): https://xemstudio.com/files/hardware/power-cylinder-piston-crosshead/index.json\nAPI: https://xemstudio.com/api/geometry?object=power-cylinder-piston-crosshead\n",
 "sources": [
  {
   "publisher": "Wikipedia",
   "title": "Crosshead",
   "url": "https://en.wikipedia.org/wiki/Crosshead",
   "formats": [
    "web"
   ],
   "license": "CC BY-SA 4.0 (text)",
   "license_verified": true,
   "hosted": false
  },
  {
   "publisher": "Wikipedia",
   "title": "Piston",
   "url": "https://en.wikipedia.org/wiki/Piston",
   "formats": [
    "web"
   ],
   "license": "CC BY-SA 4.0 (text)",
   "license_verified": true,
   "hosted": false
  },
  {
   "publisher": "James R. Senft",
   "title": "Miniature Stirling engine piston fits (LTD book)",
   "url": "https://www.stirlingengine.com/",
   "formats": [
    "book"
   ],
   "license": "reference",
   "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": [
  "plastic-syringes",
  "borosilicate-test-tubes",
  "free-piston-core",
  "crank-conrod-flywheel-kit",
  "bearing-housings-and-rod-supports",
  "tri-clamp-displacers-and-heads"
 ],
 "fits": [
  {
   "role": "Goes in or on",
   "items": [
    {
     "slug": "gamma-base-plate-and-beam",
     "why": "liner on the base plate"
    }
   ]
  },
  {
   "role": "Connects to",
   "items": [
    {
     "slug": "crank-conrod-flywheel-kit",
     "why": "con-rod to the crosshead clevis"
    }
   ]
  },
  {
   "role": "Alternatives",
   "items": [
    {
     "slug": "tri-clamp-power-pistons",
     "why": "full-bore piston in the spool itself"
    },
    {
     "slug": "syringe-pistons",
     "why": "syringe barrel as the cylinder"
    },
    {
     "slug": "free-piston-core",
     "why": "Ø30 / Ø40 piston blanks"
    }
   ]
  },
  {
   "role": "Also needed",
   "items": [
    {
     "slug": "dowel-pins-metric",
     "why": "Ø3 wrist pin"
    },
    {
     "slug": "brass-tube-ks",
     "why": "or a glass / brass tube as a real liner"
    }
   ]
  }
 ],
 "faq": [
  {
   "q": "What is the best power piston for a hobby Stirling engine?",
   "a": "A graphite piston in a borosilicate glass tube: no lubrication, near-zero friction, good seal. Next best: a lapped brass piston in a brass liner. A syringe is the quick version."
  },
  {
   "q": "How tight should a Stirling piston fit?",
   "a": "Clearance seal: 10–25 µm radial. Test: the piston should slide slowly through the liner under its own weight with the far end closed by a finger, and stop when it is uncovered."
  },
  {
   "q": "Why use a crosshead?",
   "a": "It takes the con-rod's sideways push so the piston sees only axial motion: the lapped fit stays round and friction stays low. Use one whenever the con-rod is short or the piston is lapped."
  }
 ],
 "files_license": null,
 "offers": [
  {
   "file": "liner-16x40-flanged",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "CC BY 4.0 (Xem Studio)",
   "step": "https://xemstudio.com/files/hardware/power-cylinder-piston-crosshead/liner-16x40-flanged.step",
   "stl": "https://xemstudio.com/files/hardware/power-cylinder-piston-crosshead/liner-16x40-flanged.stl",
   "note": "power cylinder liner Ø16 bore × 40, 3 wall, 4 × M3 flange (print to prototype; real liner = honed brass/stainless tube or a glass tube)"
  },
  {
   "file": "piston-16x14-blank",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "CC BY 4.0 (Xem Studio)",
   "step": "https://xemstudio.com/files/hardware/power-cylinder-piston-crosshead/piston-16x14-blank.step",
   "stl": "https://xemstudio.com/files/hardware/power-cylinder-piston-crosshead/piston-16x14-blank.stl",
   "note": "piston blank Ø15.9 × 14: lap to fit; Ø3 rod boss and a Ø3 wrist-pin boss"
  },
  {
   "file": "liner-20x45-flanged",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "CC BY 4.0 (Xem Studio)",
   "step": "https://xemstudio.com/files/hardware/power-cylinder-piston-crosshead/liner-20x45-flanged.step",
   "stl": "https://xemstudio.com/files/hardware/power-cylinder-piston-crosshead/liner-20x45-flanged.stl",
   "note": "power cylinder liner Ø20 bore × 45, 3 wall, 4 × M3 flange (print to prototype; real liner = honed brass/stainless tube or a glass tube)"
  },
  {
   "file": "piston-20x18-blank",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "CC BY 4.0 (Xem Studio)",
   "step": "https://xemstudio.com/files/hardware/power-cylinder-piston-crosshead/piston-20x18-blank.step",
   "stl": "https://xemstudio.com/files/hardware/power-cylinder-piston-crosshead/piston-20x18-blank.stl",
   "note": "piston blank Ø19.9 × 18: lap to fit; Ø3 rod boss and a Ø3 wrist-pin boss"
  },
  {
   "file": "liner-25x50-flanged",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "CC BY 4.0 (Xem Studio)",
   "step": "https://xemstudio.com/files/hardware/power-cylinder-piston-crosshead/liner-25x50-flanged.step",
   "stl": "https://xemstudio.com/files/hardware/power-cylinder-piston-crosshead/liner-25x50-flanged.stl",
   "note": "power cylinder liner Ø25 bore × 50, 3 wall, 4 × M3 flange (print to prototype; real liner = honed brass/stainless tube or a glass tube)"
  },
  {
   "file": "piston-25x22-blank",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "CC BY 4.0 (Xem Studio)",
   "step": "https://xemstudio.com/files/hardware/power-cylinder-piston-crosshead/piston-25x22-blank.step",
   "stl": "https://xemstudio.com/files/hardware/power-cylinder-piston-crosshead/piston-25x22-blank.stl",
   "note": "piston blank Ø24.9 × 22: lap to fit; Ø3 rod boss and a Ø3 wrist-pin boss"
  },
  {
   "file": "liner-30x55-flanged",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "CC BY 4.0 (Xem Studio)",
   "step": "https://xemstudio.com/files/hardware/power-cylinder-piston-crosshead/liner-30x55-flanged.step",
   "stl": "https://xemstudio.com/files/hardware/power-cylinder-piston-crosshead/liner-30x55-flanged.stl",
   "note": "power cylinder liner Ø30 bore × 55, 3 wall, 4 × M3 flange (print to prototype; real liner = honed brass/stainless tube or a glass tube)"
  },
  {
   "file": "piston-30x27-blank",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "CC BY 4.0 (Xem Studio)",
   "step": "https://xemstudio.com/files/hardware/power-cylinder-piston-crosshead/piston-30x27-blank.step",
   "stl": "https://xemstudio.com/files/hardware/power-cylinder-piston-crosshead/piston-30x27-blank.stl",
   "note": "piston blank Ø29.9 × 27: lap to fit; Ø3 rod boss and a Ø3 wrist-pin boss"
  },
  {
   "file": "crosshead-8mm-rod3",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "CC BY 4.0 (Xem Studio)",
   "step": "https://xemstudio.com/files/hardware/power-cylinder-piston-crosshead/crosshead-8mm-rod3.step",
   "stl": "https://xemstudio.com/files/hardware/power-cylinder-piston-crosshead/crosshead-8mm-rod3.stl",
   "note": "crosshead: Ø8 slider on a Ø3 piston rod with a clevis for the con-rod (keeps side load off the piston)"
  },
  {
   "file": "crosshead-guide-8mm",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "CC BY 4.0 (Xem Studio)",
   "step": "https://xemstudio.com/files/hardware/power-cylinder-piston-crosshead/crosshead-guide-8mm.step",
   "stl": "https://xemstudio.com/files/hardware/power-cylinder-piston-crosshead/crosshead-guide-8mm.stl",
   "note": "crosshead guide: Ø8.15 bore × 30, flange with 2 × M3 (or press a 8 × 12 bushing in)"
  },
  {
   "file": "wrist-pin-3x16",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "CC BY 4.0 (Xem Studio)",
   "step": "https://xemstudio.com/files/hardware/power-cylinder-piston-crosshead/wrist-pin-3x16.step",
   "stl": "https://xemstudio.com/files/hardware/power-cylinder-piston-crosshead/wrist-pin-3x16.stl",
   "note": "Ø3 × 16 wrist pin (dowel) for the piston boss"
  }
 ],
 "markdown": "https://xemstudio.com/objects/power-cylinder-piston-crosshead/index.md"
}