{
 "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-linear-alternator-module-2in-open",
 "name": "Build list: Linear alternator module, 2 in, open frame (exposed flexures)",
 "kind": "list",
 "category": "Electronics",
 "group": "Generators & alternators",
 "year": null,
 "question": "What parts do I need to build a Linear alternator module, 2 in, open frame (exposed flexures)?",
 "tags": [
  "list",
  "build",
  "stirling",
  "long earth society",
  "tri-clamp",
  "linear alternator",
  "free piston",
  "test unit",
  "open frame",
  "unpressurised"
 ],
 "aliases": [
  "open frame linear alternator",
  "linear alternator exposed flexures",
  "clamp on linear alternator desk stirling",
  "unpressurised linear alternator module",
  "tri clamp linear alternator open"
 ],
 "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-linear-alternator-module-2in-open/",
 "sheet_txt": "https://xemstudio.com/objects/list-linear-alternator-module-2in-open/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": [
   "The same linear alternator on an open frame: it clamps on the end of an unpressurised engine with one 2 in ferrule face, and the leaves, the mover's ends and the stator sit in the open where you can see and reach them.",
   "Ø48 piston ±5 mm (±6 max) · moving mass 899 g · leaves 8851 N/m · Bl 28.8 N/A · coil 3.40 Ω, ≈25 mH · f₀ 15.8 Hz on the leaves alone · back open to the room · 167.7 mm from face A",
   "The version I use most. Face A is the same: the 42 mm bored spool with the Ø48 clearance-seal piston cup, clamped on the end of a desk engine, the power end of a tri-clamp Stirling or any 2 in device at 1 bar. Behind the piston there is no bounce space: its back breathes to the room.",
   "The spool's second ferrule carries the open frame, clamped like an end cap: frame base with leaf 1 on its seat, a clamp ring on 10 mm posts, the stator sleeve with the same stator and coil as the closed module, a top plate on 5 mm posts, the seat ring with leaf 2 and its clamp ring. The same mover, leaves, magnets and coil as the closed module: only the tube rod is longer.",
   "Nothing covers the leaves: you can watch them work, change leaf set or mass discs with a screwdriver, and centre the mover by eye. The datasheet compares both versions and says when to use which.",
   "Leaf set A (0.8) is the standard build; set B (0.5, on rim shims) and the mass discs are tuning parts. The same leaves also clamp between half gaskets in any spool-to-spool joint, as in the closed module."
  ],
  "table": {
   "columns": [
    "subsystem",
    "object",
    "parts",
    "qty",
    "note"
   ],
   "rows": [
    [
     "",
     "linear-alternator-module-spools-2in",
     "spool-2in-42mm-bored-48.00",
     1,
     "face A (to the engine) and the piston's cylinder; its second ferrule carries the frame base"
    ],
    [
     "",
     "linear-alternator-module-open-frame-2in",
     "la-frame-base-2in-ferrule",
     1,
     "clamped on the spool's second ferrule; leaf 1's seat on top"
    ],
    [
     "",
     "tri-clamp-gasket",
     "tc-gasket-2in",
     2,
     "Type B at face A (to the engine) and between the spool and the frame base"
    ],
    [
     "",
     "tri-clamp-clamps",
     "clamp-half-2in",
     4,
     "two standard 2 in clamps: face A to the engine, the spool to the frame base"
    ],
    [
     "",
     "socket-head-cap-screws-metric",
     "shcs-m5x30",
     4,
     "two per clamp"
    ],
    [
     "",
     "hex-nuts-metric",
     "nut-m5",
     4,
     "in the clamps' hex traps"
    ],
    [
     "",
     "tri-clamp-flexure-leaf",
     "leaf-2in-piston-t0.8",
     2,
     "choose one leaf set, A (standard 0.8): leaf 1 in the frame base's seat, leaf 2 (turned over, opposite hand) in the seat ring"
    ],
    [
     "",
     "linear-alternator-module-tuning-2in",
     "leaf-2in-piston-t0.5",
     2,
     "choose one leaf set, B (soft 0.5, tuning): in place of the 0.8 leaves; leaf 2 turned over"
    ],
    [
     "",
     "linear-alternator-module-tuning-2in",
     "la-rim-shim-64x0.3",
     2,
     "choose one leaf set, B (soft 0.5, tuning): one under each soft leaf's rim in its seat"
    ],
    [
     "",
     "linear-alternator-module-open-frame-2in",
     "la-frame-leaf-clamp-ring-80-posts10",
     1,
     "on leaf 1's rim, posts up"
    ],
    [
     "",
     "linear-alternator-module-open-frame-2in",
     "la-frame-stator-sleeve-48x66",
     1,
     "on the posts; the stator round it"
    ],
    [
     "",
     "linear-alternator-module-open-frame-2in",
     "la-frame-stator-top-plate-80-posts5",
     1,
     "on the sleeve's top flange, posts up"
    ],
    [
     "",
     "linear-alternator-module-open-frame-2in",
     "la-frame-leaf-seat-ring-80",
     1,
     "on the top plate's posts; leaf 2's seat on top"
    ],
    [
     "",
     "linear-alternator-module-open-frame-2in",
     "la-frame-leaf-clamp-ring-80",
     1,
     "on leaf 2's rim"
    ],
    [
     "",
     "socket-head-cap-screws-metric",
     "shcs-m3x25",
     3,
     "down through the sleeve's lower flange, the posts and the lower clamp ring into the frame base"
    ],
    [
     "",
     "socket-head-cap-screws-metric",
     "shcs-m3x12",
     3,
     "down through the top plate into the sleeve's top flange"
    ],
    [
     "",
     "socket-head-cap-screws-metric",
     "shcs-m3x16",
     3,
     "down through the upper clamp ring and the seat ring into the top plate's posts"
    ],
    [
     "",
     "linear-alternator-module-mover-2in",
     "la-piston-cup-48x24",
     1,
     "in the 42 bored spool, crown toward face A"
    ],
    [
     "",
     "linear-alternator-module-mover-2in",
     "la-tube-rod-18x14x151.70",
     1,
     "pressed into the cup's socket; through both leaves"
    ],
    [
     "",
     "linear-alternator-module-mover-2in",
     "la-magnet-carrier-47x56",
     1,
     "pressed on the tube rod, centred in the stator sleeve"
    ],
    [
     "",
     "neodymium-disc-magnets",
     "magnet-12x3",
     40,
     "4 rows of 10 in the carrier, faces out: S, N, N, S from face A"
    ],
    [
     "",
     "fpse-hub-collars",
     "fpse-collar-18x28",
     4,
     "either side of each leaf's hub on the tube rod"
    ],
    [
     "",
     "set-screws-metric",
     "set-m3x4",
     4,
     "one grub per collar"
    ],
    [
     "",
     "fpse-linear-alternator-stator",
     "fpse-stator-pack-43deg",
     8,
     "round the stator sleeve at the magnets' centre"
    ],
    [
     "",
     "fpse-linear-alternator-stator",
     "fpse-bobbin-65",
     1,
     "between the teeth; slid over the sleeve's Ø64 top flange first"
    ],
    [
     "",
     "fpse-linear-alternator-stator",
     "fpse-coil-300t",
     1,
     "300 turns of 0.71 mm enamelled wire on the bobbin; the leads leave through the housing"
    ],
    [
     "",
     "fpse-linear-alternator-stator",
     "fpse-stator-housing-half",
     2,
     "clamp the packs onto the sleeve"
    ],
    [
     "",
     "socket-head-cap-screws-metric",
     "shcs-m4x20",
     4,
     "stator housing ears"
    ],
    [
     "",
     "hex-nuts-metric",
     "nut-m4",
     4,
     "stator housing ears"
    ],
    [
     "",
     "linear-alternator-module-tuning-2in",
     "la-mass-disc-41x26x4",
     4,
     "optional (tuning): add-on mass discs on the crown inside the cup, 0 to 4"
    ],
    [
     "",
     "socket-head-cap-screws-metric",
     "shcs-m3x20",
     3,
     "optional (tuning): hold 4 discs (3 × M3 × 16 for 3, × 12 for 2, × 8 for 1)"
    ],
    [
     "",
     "linear-alternator-module-2in-datasheet",
     "",
     1,
     "load resistor: non-inductive, power rated above the expected output; value on the datasheet: bought, not drawn"
    ],
    [
     "",
     "linear-alternator-module-2in-datasheet",
     "",
     1,
     "series capacitor: non-polar, C = 1/(ω² L) for the running frequency (datasheet), rated above the voltage across it: bought, not drawn"
    ]
   ]
  }
 },
 "sheet_text": "Build list: Linear alternator module, 2 in, open frame (exposed flexures) — dimension sheet\nSource: Xem Studio, https://xemstudio.com/objects/list-linear-alternator-module-2in-open/  (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- The same linear alternator on an open frame: it clamps on the end of an unpressurised engine with one 2 in ferrule face, and the leaves, the mover's ends and the stator sit in the open where you can see and reach them.\n- Ø48 piston ±5 mm (±6 max) · moving mass 899 g · leaves 8851 N/m · Bl 28.8 N/A · coil 3.40 Ω, ≈25 mH · f₀ 15.8 Hz on the leaves alone · back open to the room · 167.7 mm from face A\n- The version I use most. Face A is the same: the 42 mm bored spool with the Ø48 clearance-seal piston cup, clamped on the end of a desk engine, the power end of a tri-clamp Stirling or any 2 in device at 1 bar. Behind the piston there is no bounce space: its back breathes to the room.\n- The spool's second ferrule carries the open frame, clamped like an end cap: frame base with leaf 1 on its seat, a clamp ring on 10 mm posts, the stator sleeve with the same stator and coil as the closed module, a top plate on 5 mm posts, the seat ring with leaf 2 and its clamp ring. The same mover, leaves, magnets and coil as the closed module: only the tube rod is longer.\n- Nothing covers the leaves: you can watch them work, change leaf set or mass discs with a screwdriver, and centre the mover by eye. The datasheet compares both versions and says when to use which.\n- Leaf set A (0.8) is the standard build; set B (0.5, on rim shims) and the mass discs are tuning parts. The same leaves also clamp between half gaskets in any spool-to-spool joint, as in the closed module.\n\nsubsystem  object  parts  qty  note\n  linear-alternator-module-spools-2in  spool-2in-42mm-bored-48.00  1  face A (to the engine) and the piston's cylinder; its second ferrule carries the frame base\n  linear-alternator-module-open-frame-2in  la-frame-base-2in-ferrule  1  clamped on the spool's second ferrule; leaf 1's seat on top\n  tri-clamp-gasket  tc-gasket-2in  2  Type B at face A (to the engine) and between the spool and the frame base\n  tri-clamp-clamps  clamp-half-2in  4  two standard 2 in clamps: face A to the engine, the spool to the frame base\n  socket-head-cap-screws-metric  shcs-m5x30  4  two per clamp\n  hex-nuts-metric  nut-m5  4  in the clamps' hex traps\n  tri-clamp-flexure-leaf  leaf-2in-piston-t0.8  2  choose one leaf set, A (standard 0.8): leaf 1 in the frame base's seat, leaf 2 (turned over, opposite hand) in the seat ring\n  linear-alternator-module-tuning-2in  leaf-2in-piston-t0.5  2  choose one leaf set, B (soft 0.5, tuning): in place of the 0.8 leaves; leaf 2 turned over\n  linear-alternator-module-tuning-2in  la-rim-shim-64x0.3  2  choose one leaf set, B (soft 0.5, tuning): one under each soft leaf's rim in its seat\n  linear-alternator-module-open-frame-2in  la-frame-leaf-clamp-ring-80-posts10  1  on leaf 1's rim, posts up\n  linear-alternator-module-open-frame-2in  la-frame-stator-sleeve-48x66  1  on the posts; the stator round it\n  linear-alternator-module-open-frame-2in  la-frame-stator-top-plate-80-posts5  1  on the sleeve's top flange, posts up\n  linear-alternator-module-open-frame-2in  la-frame-leaf-seat-ring-80  1  on the top plate's posts; leaf 2's seat on top\n  linear-alternator-module-open-frame-2in  la-frame-leaf-clamp-ring-80  1  on leaf 2's rim\n  socket-head-cap-screws-metric  shcs-m3x25  3  down through the sleeve's lower flange, the posts and the lower clamp ring into the frame base\n  socket-head-cap-screws-metric  shcs-m3x12  3  down through the top plate into the sleeve's top flange\n  socket-head-cap-screws-metric  shcs-m3x16  3  down through the upper clamp ring and the seat ring into the top plate's posts\n  linear-alternator-module-mover-2in  la-piston-cup-48x24  1  in the 42 bored spool, crown toward face A\n  linear-alternator-module-mover-2in  la-tube-rod-18x14x151.70  1  pressed into the cup's socket; through both leaves\n  linear-alternator-module-mover-2in  la-magnet-carrier-47x56  1  pressed on the tube rod, centred in the stator sleeve\n  neodymium-disc-magnets  magnet-12x3  40  4 rows of 10 in the carrier, faces out: S, N, N, S from face A\n  fpse-hub-collars  fpse-collar-18x28  4  either side of each leaf's hub on the tube rod\n  set-screws-metric  set-m3x4  4  one grub per collar\n  fpse-linear-alternator-stator  fpse-stator-pack-43deg  8  round the stator sleeve at the magnets' centre\n  fpse-linear-alternator-stator  fpse-bobbin-65  1  between the teeth; slid over the sleeve's Ø64 top flange first\n  fpse-linear-alternator-stator  fpse-coil-300t  1  300 turns of 0.71 mm enamelled wire on the bobbin; the leads leave through the housing\n  fpse-linear-alternator-stator  fpse-stator-housing-half  2  clamp the packs onto the sleeve\n  socket-head-cap-screws-metric  shcs-m4x20  4  stator housing ears\n  hex-nuts-metric  nut-m4  4  stator housing ears\n  linear-alternator-module-tuning-2in  la-mass-disc-41x26x4  4  optional (tuning): add-on mass discs on the crown inside the cup, 0 to 4\n  socket-head-cap-screws-metric  shcs-m3x20  3  optional (tuning): hold 4 discs (3 × M3 × 16 for 3, × 12 for 2, × 8 for 1)\n  linear-alternator-module-2in-datasheet    1  load resistor: non-inductive, power rated above the expected output; value on the datasheet: bought, not drawn\n  linear-alternator-module-2in-datasheet    1  series capacitor: non-polar, C = 1/(ω² L) for the running frequency (datasheet), rated above the voltage across it: bought, not drawn\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-linear-alternator-module-2in-open\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": [
  "linear-alternator-module-2in-datasheet",
  "list-linear-alternator-module-2in-closed",
  "linear-alternator-module-open-frame-2in",
  "linear-alternator-module-mover-2in",
  "linear-alternator-module-spools-2in",
  "linear-alternator-module-tuning-2in",
  "fpse-linear-alternator-stator",
  "tri-clamp-flexure-leaf",
  "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": "When do I use the open frame?",
   "a": "On engines at 1 bar: desk and demo engines, the cold or power end of a tri-clamp Stirling, quick swaps, and whenever you want to see and retune the leaves. For a charged engine, a loop or a ring, use the closed module."
  },
  {
   "q": "Why is its frequency lower?",
   "a": "Nothing pushes back on the piston but the leaves and the engine's own gas: 15.8 Hz on the leaves alone, higher on an engine (the datasheet lists it for engine volumes from 50 to 400 cm³). The closed module's bounce space is the stiff spring that the open frame leaves out."
  },
  {
   "q": "Where is the electricity?",
   "a": "Two leads from the coil on the stator housing. Always connect the load before the engine runs."
  }
 ],
 "files_license": null,
 "offers": [],
 "markdown": "https://xemstudio.com/objects/list-linear-alternator-module-2in-open/index.md"
}