{
 "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": "list-fpse-generator-2in",
 "name": "Build list: Free-piston Stirling generator, 2 in tri-clamp (pressurised, linear alternator)",
 "kind": "list",
 "category": "Stirling engines",
 "group": "Guide",
 "year": null,
 "question": "What parts do I need to build a Free-piston Stirling generator, 2 in tri-clamp (pressurised, linear alternator)?",
 "tags": [
  "list",
  "build",
  "stirling",
  "long earth society",
  "tri-clamp",
  "free piston",
  "generator",
  "pressurised",
  "linear alternator"
 ],
 "aliases": [
  "free piston stirling generator build",
  "fpse tri clamp",
  "linear alternator stirling build list",
  "pressurised free piston stirling",
  "helium stirling generator diy"
 ],
 "overall_mm": {
  "length": null,
  "width": null,
  "height": null
 },
 "official_cad": false,
 "xem_status": "not-scanned",
 "les": true,
 "free_files": 0,
 "url": "https://xemstudio.com/objects/list-fpse-generator-2in/",
 "sheet_txt": "https://xemstudio.com/objects/list-fpse-generator-2in/sheet.txt",
 "sheet": {
  "basis": "Every part is a free STEP/STL on this site or a standard part with its own page; quantities are the full count, every screw, nut, pin, gasket and clamp.",
  "overall_mm": {
   "length": null,
   "width": null,
   "height": null
  },
  "notes": [
   "A real free-piston Stirling generator in standard 2 in sanitary fittings: closed-end hot spool over a torch, annular screen regenerator, flexure leaves clamped in the joints, a magnet-carrying power piston in a bored spool with the alternator outside its wall, helium or air at up to 10 bar.",
   "Numbers: Ø48 piston ±5 mm, Ø39.4 displacer ±4.5 leading 68° · 45 Hz · helium 10 bar: 43 W electrical, 24 % of 180 W into the head · air 10 bar 28 W · 1 bar: 0.1 W helium, 0.1 W air · relief 15 bar g"
  ],
  "table": {
   "columns": [
    "subsystem",
    "object",
    "parts",
    "qty",
    "note"
   ],
   "rows": [
    [
     null,
     "tri-clamp-torch-stand",
     "torch-stand-40",
     1,
     "on the bench under the hot end, post toward +Y; the heat source is a propane or butane torch head in its ring"
    ],
    [
     null,
     "set-screws-metric",
     "set-m4x10",
     3,
     "centre the torch head in the ring"
    ],
    [
     null,
     "tri-clamp-split-burner-shroud",
     "shroud-half-2in-split",
     2,
     "round the hot end, lids clamped on the tube above the fins"
    ],
    [
     null,
     "tri-clamp-hot-end-fin-sleeve",
     "fin-sleeve-half-2in-76",
     2,
     "optional heat exchanger: clamped on the lower 66 mm of S1"
    ],
    [
     null,
     "socket-head-cap-screws-metric",
     "shcs-m4x16",
     4,
     "optional, with the fin sleeve: its ears"
    ],
    [
     null,
     "tri-clamp-closed-end-spool",
     "closed-spool-2in-152.4",
     1,
     "S1, the hot end: closed end down"
    ],
    [
     null,
     "fpse-displacer-cylinder",
     "fpse-liner-40-rim64",
     1,
     "in S1, rim clamped in joint A"
    ],
    [
     null,
     "fpse-fin-inserts",
     "fpse-heater-insert-41.5x47.5",
     1,
     "optional heat exchanger: on the liner's lower end"
    ],
    [
     null,
     "fpse-regenerator-screen-ring",
     "regen-ring-41.5x47.5x0.2",
     389,
     "100 mesh screen rings, stacked on the liner's spokes up to its rim"
    ],
    [
     null,
     "tri-clamp-leaf-half-gasket",
     "leaf-half-gasket-2in-w0.45",
     6,
     "two each at joint A (liner rim), C and D (piston leaves), beads outward"
    ],
    [
     null,
     "tri-clamp-leaf-half-gasket",
     "leaf-half-gasket-2in-w0.6",
     2,
     "joint B, round the displacer leaf"
    ],
    [
     null,
     "sanitary-high-pressure-clamp",
     "hp-clamp-2in",
     5,
     "rated above the 15 bar gauge relief setting"
    ],
    [
     null,
     "tri-clamp-spool",
     "tc-spool-2in-3in",
     2,
     "S3 (cooler and compression space) and S5 (bounce space between the piston leaves)"
    ],
    [
     null,
     "fpse-fin-inserts",
     "fpse-cooler-insert-40x47.5",
     1,
     "optional heat exchanger: pressed into S3"
    ],
    [
     null,
     "tri-clamp-clamp-on-water-jacket",
     "water-jacket-half-2in-20",
     2,
     "optional heat exchanger: on S3 above its hanger, hoses in series"
    ],
    [
     null,
     "socket-head-cap-screws-metric",
     "shcs-m4x12",
     2,
     "optional, with the jacket: its ears"
    ],
    [
     null,
     "fpse-displacer",
     "fpse-displacer-shell-39.4",
     1,
     "hot end down, in the liner"
    ],
    [
     null,
     "fpse-displacer",
     "fpse-displacer-cap-39.4",
     1,
     "closes the shell; its boss carries leaf B's hub"
    ],
    [
     null,
     "tri-clamp-flexure-leaf",
     "leaf-2in-displacer-t0.5",
     1,
     "joint B: the displacer's leaf"
    ],
    [
     null,
     "fpse-hub-collars",
     "fpse-collar-12x20",
     1,
     "on the rod over leaf B's hub"
    ],
    [
     null,
     "fpse-displacer-rod",
     "fpse-displacer-rod-12x10",
     1,
     "in the cap's socket, up through the piston"
    ],
    [
     null,
     "fpse-displacer-rod",
     "fpse-rod-plug-12",
     1,
     "in the rod's top"
    ],
    [
     null,
     "fpse-displacer-rod",
     "fpse-stinger-3x87.05",
     1,
     "plug to the gas-spring piston, through the gland"
    ],
    [
     null,
     "fpse-displacer-gas-spring",
     "fpse-gas-spring-piston-18",
     1,
     "on the stinger, in the gas-spring cylinder"
    ],
    [
     null,
     "fpse-displacer-gas-spring",
     "fpse-gas-spring-gland-18",
     1,
     "closes the gas-spring cylinder's bottom"
    ],
    [
     null,
     "fpse-displacer-gas-spring",
     "fpse-gas-spring-cylinder-18",
     1,
     "pressed into the top of S6"
    ],
    [
     null,
     "socket-head-cap-screws-metric",
     "shcs-m3x16",
     3,
     "gland to the gas-spring cylinder, heads underneath"
    ],
    [
     null,
     "set-screws-metric",
     "set-m3x4",
     7,
     "collars (5), rod plug (1), gas-spring piston (1)"
    ],
    [
     null,
     "tri-clamp-bored-spool",
     "spool-2in-6in-bored-48.00",
     1,
     "S4: the power cylinder, Ø48.00 bore"
    ],
    [
     null,
     "fpse-power-piston",
     "fpse-piston-48-40mag",
     1,
     "in S4, crown down"
    ],
    [
     null,
     "neodymium-disc-magnets",
     "magnet-12x3",
     40,
     "4 rows of 10, faces out: S, N, N, S from the crown up"
    ],
    [
     null,
     "fpse-power-piston",
     "fpse-piston-top-plate",
     1,
     "in the carrier's bore on the hub"
    ],
    [
     null,
     "fpse-power-piston",
     "fpse-tube-rod-18x14",
     1,
     "piston to above leaf D"
    ],
    [
     null,
     "tri-clamp-flexure-leaf",
     "leaf-2in-piston-t0.8",
     2,
     "joints C and D; D turned over (opposite hand)"
    ],
    [
     null,
     "fpse-hub-collars",
     "fpse-collar-18x28",
     4,
     "two each side of each piston leaf's hub"
    ],
    [
     null,
     "fpse-linear-alternator-stator",
     "fpse-stator-pack-43deg",
     8,
     "round S4 at the magnets' height"
    ],
    [
     null,
     "fpse-linear-alternator-stator",
     "fpse-bobbin-65",
     1,
     "between the teeth; slid over S4's flange first"
    ],
    [
     null,
     "fpse-linear-alternator-stator",
     "fpse-coil-300t",
     1,
     "300 turns of 0.71 mm enamelled wire on the bobbin"
    ],
    [
     null,
     "fpse-linear-alternator-stator",
     "fpse-stator-housing-half",
     2,
     "clamp the packs onto S4"
    ],
    [
     null,
     "socket-head-cap-screws-metric",
     "shcs-m4x20",
     10,
     "stator housing (4), shroud lids (2), hanger ears (4)"
    ],
    [
     null,
     "hex-nuts-metric",
     "nut-m4",
     16,
     "stator housing (4), shroud (2), hanger ears (4), fin sleeve (4, optional), jacket (2, optional)"
    ],
    [
     null,
     "tri-clamp-spool",
     "tc-spool-2in-6in",
     1,
     "S6: holds the displacer's gas spring"
    ],
    [
     null,
     "tri-clamp-gasket",
     "tc-gasket-2in",
     1,
     "joint E under the port cap"
    ],
    [
     null,
     "tri-clamp-port-cap",
     "port-cap-2in-4x-npt18",
     1,
     "on S6: fill valve, pressure gauge, relief valve, and a plug or pressure transducer"
    ],
    [
     null,
     "npt-thread-envelopes",
     "npt-1-8-male",
     4,
     "the 1/8 NPT stems of the fill valve, gauge, relief valve and plug (bodies are the builder's choice)"
    ],
    [
     null,
     "2020-aluminum-extrusion",
     "2020-300",
     2,
     "uprights; they end below the stator"
    ],
    [
     null,
     "2020-aluminum-extrusion",
     "2020-200",
     2,
     "rails on the bench behind the uprights, clamped or screwed to the bench"
    ],
    [
     null,
     "t-slot-corner-brackets",
     "corner-bracket-20",
     4,
     "two per upright"
    ],
    [
     null,
     "button-head-screws-metric",
     "button-m5x10",
     8,
     "bracket screws"
    ],
    [
     null,
     "flat-washers-metric",
     "washer-m5",
     8,
     ""
    ],
    [
     null,
     "drop-in-t-nuts",
     "tnut-dropin-20-m5",
     12,
     "8 brackets, 2 per hanger"
    ],
    [
     null,
     "spool-hanger-collars",
     "hanger-2in-tab",
     2,
     "two stacked on S3, below the jacket"
    ],
    [
     null,
     "spool-hanger-collars",
     "hanger-2in-plain",
     2,
     ""
    ],
    [
     null,
     "socket-head-cap-screws-metric",
     "shcs-m5x16",
     4,
     "hanger bars into the uprights' T-nuts"
    ]
   ]
  }
 },
 "sheet_text": "Build list: Free-piston Stirling generator, 2 in tri-clamp (pressurised, linear alternator) — dimension sheet\nSource: Xem Studio, https://xemstudio.com/objects/list-fpse-generator-2in/  (CC BY 4.0)\nBasis: Every part is a free STEP/STL on this site or a standard part with its own page; quantities are the full count, every screw, nut, pin, gasket and clamp.\nCatalog version: 2026-10-20\n\nSizes: see table below\n- A real free-piston Stirling generator in standard 2 in sanitary fittings: closed-end hot spool over a torch, annular screen regenerator, flexure leaves clamped in the joints, a magnet-carrying power piston in a bored spool with the alternator outside its wall, helium or air at up to 10 bar.\n- Numbers: Ø48 piston ±5 mm, Ø39.4 displacer ±4.5 leading 68° · 45 Hz · helium 10 bar: 43 W electrical, 24 % of 180 W into the head · air 10 bar 28 W · 1 bar: 0.1 W helium, 0.1 W air · relief 15 bar g\n\nsubsystem  object  parts  qty  note\nNone  tri-clamp-torch-stand  torch-stand-40  1  on the bench under the hot end, post toward +Y; the heat source is a propane or butane torch head in its ring\nNone  set-screws-metric  set-m4x10  3  centre the torch head in the ring\nNone  tri-clamp-split-burner-shroud  shroud-half-2in-split  2  round the hot end, lids clamped on the tube above the fins\nNone  tri-clamp-hot-end-fin-sleeve  fin-sleeve-half-2in-76  2  optional heat exchanger: clamped on the lower 66 mm of S1\nNone  socket-head-cap-screws-metric  shcs-m4x16  4  optional, with the fin sleeve: its ears\nNone  tri-clamp-closed-end-spool  closed-spool-2in-152.4  1  S1, the hot end: closed end down\nNone  fpse-displacer-cylinder  fpse-liner-40-rim64  1  in S1, rim clamped in joint A\nNone  fpse-fin-inserts  fpse-heater-insert-41.5x47.5  1  optional heat exchanger: on the liner's lower end\nNone  fpse-regenerator-screen-ring  regen-ring-41.5x47.5x0.2  389  100 mesh screen rings, stacked on the liner's spokes up to its rim\nNone  tri-clamp-leaf-half-gasket  leaf-half-gasket-2in-w0.45  6  two each at joint A (liner rim), C and D (piston leaves), beads outward\nNone  tri-clamp-leaf-half-gasket  leaf-half-gasket-2in-w0.6  2  joint B, round the displacer leaf\nNone  sanitary-high-pressure-clamp  hp-clamp-2in  5  rated above the 15 bar gauge relief setting\nNone  tri-clamp-spool  tc-spool-2in-3in  2  S3 (cooler and compression space) and S5 (bounce space between the piston leaves)\nNone  fpse-fin-inserts  fpse-cooler-insert-40x47.5  1  optional heat exchanger: pressed into S3\nNone  tri-clamp-clamp-on-water-jacket  water-jacket-half-2in-20  2  optional heat exchanger: on S3 above its hanger, hoses in series\nNone  socket-head-cap-screws-metric  shcs-m4x12  2  optional, with the jacket: its ears\nNone  fpse-displacer  fpse-displacer-shell-39.4  1  hot end down, in the liner\nNone  fpse-displacer  fpse-displacer-cap-39.4  1  closes the shell; its boss carries leaf B's hub\nNone  tri-clamp-flexure-leaf  leaf-2in-displacer-t0.5  1  joint B: the displacer's leaf\nNone  fpse-hub-collars  fpse-collar-12x20  1  on the rod over leaf B's hub\nNone  fpse-displacer-rod  fpse-displacer-rod-12x10  1  in the cap's socket, up through the piston\nNone  fpse-displacer-rod  fpse-rod-plug-12  1  in the rod's top\nNone  fpse-displacer-rod  fpse-stinger-3x87.05  1  plug to the gas-spring piston, through the gland\nNone  fpse-displacer-gas-spring  fpse-gas-spring-piston-18  1  on the stinger, in the gas-spring cylinder\nNone  fpse-displacer-gas-spring  fpse-gas-spring-gland-18  1  closes the gas-spring cylinder's bottom\nNone  fpse-displacer-gas-spring  fpse-gas-spring-cylinder-18  1  pressed into the top of S6\nNone  socket-head-cap-screws-metric  shcs-m3x16  3  gland to the gas-spring cylinder, heads underneath\nNone  set-screws-metric  set-m3x4  7  collars (5), rod plug (1), gas-spring piston (1)\nNone  tri-clamp-bored-spool  spool-2in-6in-bored-48.00  1  S4: the power cylinder, Ø48.00 bore\nNone  fpse-power-piston  fpse-piston-48-40mag  1  in S4, crown down\nNone  neodymium-disc-magnets  magnet-12x3  40  4 rows of 10, faces out: S, N, N, S from the crown up\nNone  fpse-power-piston  fpse-piston-top-plate  1  in the carrier's bore on the hub\nNone  fpse-power-piston  fpse-tube-rod-18x14  1  piston to above leaf D\nNone  tri-clamp-flexure-leaf  leaf-2in-piston-t0.8  2  joints C and D; D turned over (opposite hand)\nNone  fpse-hub-collars  fpse-collar-18x28  4  two each side of each piston leaf's hub\nNone  fpse-linear-alternator-stator  fpse-stator-pack-43deg  8  round S4 at the magnets' height\nNone  fpse-linear-alternator-stator  fpse-bobbin-65  1  between the teeth; slid over S4's flange first\nNone  fpse-linear-alternator-stator  fpse-coil-300t  1  300 turns of 0.71 mm enamelled wire on the bobbin\nNone  fpse-linear-alternator-stator  fpse-stator-housing-half  2  clamp the packs onto S4\nNone  socket-head-cap-screws-metric  shcs-m4x20  10  stator housing (4), shroud lids (2), hanger ears (4)\nNone  hex-nuts-metric  nut-m4  16  stator housing (4), shroud (2), hanger ears (4), fin sleeve (4, optional), jacket (2, optional)\nNone  tri-clamp-spool  tc-spool-2in-6in  1  S6: holds the displacer's gas spring\nNone  tri-clamp-gasket  tc-gasket-2in  1  joint E under the port cap\nNone  tri-clamp-port-cap  port-cap-2in-4x-npt18  1  on S6: fill valve, pressure gauge, relief valve, and a plug or pressure transducer\nNone  npt-thread-envelopes  npt-1-8-male  4  the 1/8 NPT stems of the fill valve, gauge, relief valve and plug (bodies are the builder's choice)\nNone  2020-aluminum-extrusion  2020-300  2  uprights; they end below the stator\nNone  2020-aluminum-extrusion  2020-200  2  rails on the bench behind the uprights, clamped or screwed to the bench\nNone  t-slot-corner-brackets  corner-bracket-20  4  two per upright\nNone  button-head-screws-metric  button-m5x10  8  bracket screws\nNone  flat-washers-metric  washer-m5  8  \nNone  drop-in-t-nuts  tnut-dropin-20-m5  12  8 brackets, 2 per hanger\nNone  spool-hanger-collars  hanger-2in-tab  2  two stacked on S3, below the jacket\nNone  spool-hanger-collars  hanger-2in-plain  2  \nNone  socket-head-cap-screws-metric  shcs-m5x16  4  hanger bars into the uprights' T-nuts\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\nXem Studio scan: not planned; the official CAD above covers it.\nAPI: https://xemstudio.com/api/geometry?object=list-fpse-generator-2in\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": "not-scanned",
  "sheet_free": true,
  "mesh_price_usd": null,
  "step_price_usd": null,
  "tolerance_mm": null
 },
 "related": [
  "fpse-generator-2in-performance",
  "tri-clamp-closed-end-spool",
  "tri-clamp-bored-spool",
  "fpse-power-piston",
  "fpse-linear-alternator-stator",
  "tri-clamp-flexure-leaf",
  "fpse-displacer-gas-spring",
  "sanitary-high-pressure-clamp",
  "list-free-piston-2in"
 ],
 "fits": [],
 "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": [],
 "faq": [
  {
   "q": "Does a free-piston Stirling work at this small size?",
   "a": "Yes when pressurised: power goes with mean pressure, swept volume and frequency. My analysis gives 43 W at 10 bar helium and 0.1 W at 1 bar air from this 48 mm piston at ±5 mm. NASA's Sunpower ASC makes about 80 W from a 1.3 kg convertor on helium; Sunpower's EG-1000 1.1 kW at 50 Hz on 3.0 MPa helium."
  },
  {
   "q": "What charge pressure, and what ratings?",
   "a": "10 bar running for tens of watts; relief at 15 bar gauge; the clamps (high-pressure bolted, published 1000 psi at 70–75 °F, 800 psi at 250 °F) and the gaskets must be rated above the relief setting at their temperature."
  },
  {
   "q": "Where is the electricity?",
   "a": "Two leads from the coil outside the vessel: 41 V peak open circuit at the design point, 43 W into 12 Ω with a 500 µF series capacitor. Rectify and regulate it; never leave the coil open while the engine runs (the load sets the stroke)."
  },
  {
   "q": "What are the risks?",
   "a": "Over-stroke if the load drops (keep a dump resistor switched in), the displacer's tuning (its mass and the gas-spring column set its phase), alignment of the rod through the piston across the joints, the leaves' fatigue, vibration (about 436 N peak), and the clamps and gaskets at temperature."
  }
 ],
 "files_license": null,
 "offers": [],
 "markdown": "https://xemstudio.com/objects/list-fpse-generator-2in/index.md"
}