{
 "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": "axial-flux-generator-kit",
 "name": "Axial-flux alternator kit: magnet rotor plates, 3-phase stator, coil bobbins, hall RPM pickup",
 "kind": "hardware",
 "category": "Stirling engines",
 "group": "Generators & instruments",
 "year": null,
 "question": "How do I build a small axial flux generator with 3D printed parts and neodymium magnets?",
 "tags": [
  "generator",
  "alternator",
  "axial flux",
  "magnet",
  "coil",
  "stator",
  "rotor",
  "stirling",
  "long earth society"
 ],
 "aliases": [
  "axial flux generator 3d print",
  "diy alternator neodymium magnets",
  "12 pole 9 coil generator",
  "stirling engine generator",
  "coil bobbin stl",
  "hall sensor rpm mount",
  "axial flux rotor"
 ],
 "overall_mm": {
  "length": null,
  "width": null,
  "height": null
 },
 "official_cad": false,
 "xem_status": "free-files",
 "les": true,
 "free_files": 6,
 "url": "https://xemstudio.com/objects/axial-flux-generator-kit/",
 "sheet_txt": "https://xemstudio.com/objects/axial-flux-generator-kit/sheet.txt",
 "sheet": {
  "basis": "Classic coreless axial-flux layout: 12 magnets / 9 coils (3-phase) on Ø90, or 8 / 6 on Ø70; magnets Ø10 × 3 N42 from the library; sized to the Ø8 flywheel shaft and 608 bearings",
  "overall_mm": {
   "length": null,
   "width": null,
   "height": null
  },
  "notes": [
   "Rotor: Ø90 plate with 12 Ø10 × 3 magnets on a 72 mm circle, poles alternating N-S around the ring; a second rotor opposite (N facing S across the gap) doubles the flux. Gap rotor-to-rotor 8 mm with a 4 mm stator between. Steel backing plates (1 mm) behind the magnets add ~40% flux.",
   "Stator: 9 coils on the same 72 mm circle, wired 3-phase (coils 1-4-7, 2-5-8, 3-6-9 in series), rectified with a 3-phase bridge. ~150 turns of 0.3 mm enamelled wire per bobbin ≈ 1.5 Ω; at 600 rpm on the 12-pole rotor expect roughly 4–6 V open circuit per phase and a watt or two into a load: enough for the fan and LEDs, the demonstrator's purpose.",
   "Frequency = rpm × poles / 120 = 600 × 12 / 120 = 60 Hz. Volts scale with rpm and turns; current with wire gauge; power with magnet count and area. Hall sensor (A3144 or SS49E in the printed mount) facing a rotor magnet gives one pulse per magnet: rpm = pulses × 60 / 12.",
   "LES: the flywheel alternator on the generator builds; the chain/belt to a NEMA 17 used as a generator is the lazy alternative (the NEMA 17 entry covers it)."
  ],
  "table": {
   "columns": [
    "part",
    "size",
    "magnets_or_coils",
    "shaft"
   ],
   "rows": [
    [
     "rotor 90",
     "Ø90 × 5 + hub",
     "12 × Ø10×3",
     "Ø8"
    ],
    [
     "rotor 70",
     "Ø70 × 5 + hub",
     "8 × Ø10×3",
     "Ø5"
    ],
    [
     "stator 90",
     "Ø90 × 4",
     "9 coils",
     "clears Ø14"
    ],
    [
     "stator 70",
     "Ø70 × 4",
     "6 coils",
     "clears Ø11"
    ],
    [
     "bobbin",
     "Ø10 × 8, Ø13 flanges",
     "150 t × 0.3 mm",
     "—"
    ],
    [
     "hall mount",
     "14 × 10 × 20",
     "TO-92",
     "M3"
    ]
   ]
  }
 },
 "sheet_text": "Axial-flux alternator kit: magnet rotor plates, 3-phase stator, coil bobbins, hall RPM pickup — dimension sheet\nSource: Xem Studio, https://xemstudio.com/objects/axial-flux-generator-kit/  (CC BY 4.0)\nBasis: Classic coreless axial-flux layout: 12 magnets / 9 coils (3-phase) on Ø90, or 8 / 6 on Ø70; magnets Ø10 × 3 N42 from the library; sized to the Ø8 flywheel shaft and 608 bearings\nCatalog version: 2026-10-20\n\nSizes: see table below\n- Rotor: Ø90 plate with 12 Ø10 × 3 magnets on a 72 mm circle, poles alternating N-S around the ring; a second rotor opposite (N facing S across the gap) doubles the flux. Gap rotor-to-rotor 8 mm with a 4 mm stator between. Steel backing plates (1 mm) behind the magnets add ~40% flux.\n- Stator: 9 coils on the same 72 mm circle, wired 3-phase (coils 1-4-7, 2-5-8, 3-6-9 in series), rectified with a 3-phase bridge. ~150 turns of 0.3 mm enamelled wire per bobbin ≈ 1.5 Ω; at 600 rpm on the 12-pole rotor expect roughly 4–6 V open circuit per phase and a watt or two into a load: enough for the fan and LEDs, the demonstrator's purpose.\n- Frequency = rpm × poles / 120 = 600 × 12 / 120 = 60 Hz. Volts scale with rpm and turns; current with wire gauge; power with magnet count and area. Hall sensor (A3144 or SS49E in the printed mount) facing a rotor magnet gives one pulse per magnet: rpm = pulses × 60 / 12.\n- LES: the flywheel alternator on the generator builds; the chain/belt to a NEMA 17 used as a generator is the lazy alternative (the NEMA 17 entry covers it).\n\npart  size  magnets_or_coils  shaft\nrotor 90  Ø90 × 5 + hub  12 × Ø10×3  Ø8\nrotor 70  Ø70 × 5 + hub  8 × Ø10×3  Ø5\nstator 90  Ø90 × 4  9 coils  clears Ø14\nstator 70  Ø70 × 4  6 coils  clears Ø11\nbobbin  Ø10 × 8, Ø13 flanges  150 t × 0.3 mm  —\nhall mount  14 × 10 × 20  TO-92  M3\n\nFiles elsewhere (not hosted by Xem Studio; license as stated by the publisher):\n- Wikipedia: Axial flux motor — web — CC BY-SA 4.0 (text) — https://en.wikipedia.org/wiki/Axial_flux_motor\n- Wikipedia: Alternator — web — CC BY-SA 4.0 (text) — https://en.wikipedia.org/wiki/Alternator\n- Hugh Piggott: A Wind Turbine Recipe Book (axial-flux alternator design) — web, PDF — Author's site [verify license at link] — http://scoraigwind.co.uk/\n- Long Earth Society: Engine and rig builds — web, video — LES site — https://longearthsociety.com/engineering/\n\nFree files (CC BY 4.0, Xem Studio; STEP + STL, 6 parts): https://xemstudio.com/files/hardware/axial-flux-generator-kit/index.json\nAPI: https://xemstudio.com/api/geometry?object=axial-flux-generator-kit\n",
 "sources": [
  {
   "publisher": "Wikipedia",
   "title": "Axial flux motor",
   "url": "https://en.wikipedia.org/wiki/Axial_flux_motor",
   "formats": [
    "web"
   ],
   "license": "CC BY-SA 4.0 (text)",
   "license_verified": true,
   "hosted": false
  },
  {
   "publisher": "Wikipedia",
   "title": "Alternator",
   "url": "https://en.wikipedia.org/wiki/Alternator",
   "formats": [
    "web"
   ],
   "license": "CC BY-SA 4.0 (text)",
   "license_verified": true,
   "hosted": false
  },
  {
   "publisher": "Hugh Piggott",
   "title": "A Wind Turbine Recipe Book (axial-flux alternator design)",
   "url": "http://scoraigwind.co.uk/",
   "formats": [
    "web",
    "PDF"
   ],
   "license": "Author's site",
   "license_verified": false,
   "hosted": false
  },
  {
   "publisher": "Long Earth Society",
   "title": "Engine and rig 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": [
  "neodymium-disc-magnets",
  "608-bearing",
  "crank-conrod-flywheel-kit",
  "roller-chain-sprockets",
  "nema-17-stepper",
  "shaft-collars-clips-and-shafts",
  "instrument-mounts"
 ],
 "faq": [
  {
   "q": "How many magnets and coils for a small axial flux generator?",
   "a": "12 magnets and 9 coils (3-phase) is the standard small layout; 8 and 6 for a 70 mm rotor. Poles must alternate N-S around the rotor; coils = 3/4 of poles for 3-phase."
  },
  {
   "q": "How much power from a 90 mm axial flux generator?",
   "a": "With 12 Ø10×3 N42 magnets, dual rotors and 150-turn coils at 600 rpm, roughly 1–3 W; it scales with rpm², magnet area and turns. Enough to light LEDs and run a 40 mm fan from a Stirling engine."
  },
  {
   "q": "What gap between rotor and stator?",
   "a": "As small as the stator thickness and wobble allow: 4 mm stator with 1.5–2 mm air gaps each side (8 mm rotor to rotor). Every mm of gap costs flux."
  }
 ],
 "files_license": null,
 "offers": [
  {
   "file": "rotor-90-12x-10x3-b8",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "CC BY 4.0 (Xem Studio)",
   "step": "https://xemstudio.com/files/hardware/axial-flux-generator-kit/rotor-90-12x-10x3-b8.step",
   "stl": "https://xemstudio.com/files/hardware/axial-flux-generator-kit/rotor-90-12x-10x3-b8.stl",
   "note": "rotor plate Ø90 × 5: 12 pockets for Ø10 × 3 magnets (alternating poles), Ø8 bore hub with set screw (print two for a dual-rotor)"
  },
  {
   "file": "rotor-70-8x-10x3-b5",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "CC BY 4.0 (Xem Studio)",
   "step": "https://xemstudio.com/files/hardware/axial-flux-generator-kit/rotor-70-8x-10x3-b5.step",
   "stl": "https://xemstudio.com/files/hardware/axial-flux-generator-kit/rotor-70-8x-10x3-b5.stl",
   "note": "rotor plate Ø70: 8 magnets Ø10 × 3, Ø5 bore"
  },
  {
   "file": "stator-90-9coil",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "CC BY 4.0 (Xem Studio)",
   "step": "https://xemstudio.com/files/hardware/axial-flux-generator-kit/stator-90-9coil.step",
   "stl": "https://xemstudio.com/files/hardware/axial-flux-generator-kit/stator-90-9coil.stl",
   "note": "stator plate Ø90 × 4: 9 coil pockets (3-phase, 12 pole / 9 slot), 3 mounting ears"
  },
  {
   "file": "stator-70-6coil",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "CC BY 4.0 (Xem Studio)",
   "step": "https://xemstudio.com/files/hardware/axial-flux-generator-kit/stator-70-6coil.step",
   "stl": "https://xemstudio.com/files/hardware/axial-flux-generator-kit/stator-70-6coil.stl",
   "note": "stator plate Ø70: 6 coils (8 pole / 6 slot)"
  },
  {
   "file": "coil-bobbin-10x8",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "CC BY 4.0 (Xem Studio)",
   "step": "https://xemstudio.com/files/hardware/axial-flux-generator-kit/coil-bobbin-10x8.step",
   "stl": "https://xemstudio.com/files/hardware/axial-flux-generator-kit/coil-bobbin-10x8.stl",
   "note": "coil bobbin Ø10 core × 8 long, Ø13 flanges, wire slot; ~150 turns of 0.3 mm wire"
  },
  {
   "file": "hall-sensor-mount-to92",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "CC BY 4.0 (Xem Studio)",
   "step": "https://xemstudio.com/files/hardware/axial-flux-generator-kit/hall-sensor-mount-to92.step",
   "stl": "https://xemstudio.com/files/hardware/axial-flux-generator-kit/hall-sensor-mount-to92.stl",
   "note": "TO-92 hall sensor (A3144 / SS49E) mount: 4.2 × 1.6 slot, M3 foot; faces a rotor magnet for RPM"
  }
 ],
 "markdown": "https://xemstudio.com/objects/axial-flux-generator-kit/index.md"
}