{
 "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": "hex-nut-weights",
 "name": "Hex nuts M8, M10, M12, 3/8 in and 1/2 in (flywheel weights)",
 "kind": "hardware",
 "category": "Stirling engines",
 "group": "Drives & mechanisms",
 "year": null,
 "question": "What are the dimensions of the hex nuts that fill the flywheel pockets?",
 "tags": [
  "hex nut",
  "nut",
  "flywheel weight",
  "iso 4032",
  "asme b18.2.2",
  "stirling",
  "long earth society"
 ],
 "aliases": [
  "m10 nut dimensions",
  "1/2 inch nut size",
  "m12 nut across flats",
  "hex nut step file",
  "3/8 nut dimensions"
 ],
 "overall_mm": {
  "length": null,
  "width": null,
  "height": null
 },
 "official_cad": false,
 "xem_status": "free-files",
 "les": true,
 "free_files": 5,
 "url": "https://xemstudio.com/objects/hex-nut-weights/",
 "sheet_txt": "https://xemstudio.com/objects/hex-nut-weights/sheet.txt",
 "sheet": {
  "basis": "ISO 4032 (M8, M10, M12) and ASME B18.2.2 finished hex (3/8, 1/2 in) envelopes; bore at the thread major Ø",
  "overall_mm": {
   "length": null,
   "width": null,
   "height": null
  },
  "notes": [
   "Hex nut envelopes: across flats × thickness, across corners, and a bore at the thread major Ø (thread not drawn).",
   "M8 13 × 6.8 (AC 15.01); M10 16 × 8.4 (18.48); M12 18 × 10.8 (20.78); 3/8 in 14.29 × 8.33 (16.50); 1/2 in 19.05 × 11.11 (22.00).",
   "Each sits in the matching flywheel pocket with one flat facing outward, flush with the rim face."
  ],
  "table": {
   "columns": [
    "file",
    "thread",
    "across flats",
    "across corners",
    "thickness",
    "bore"
   ],
   "rows": [
    [
     "nut-m8",
     "M8",
     13,
     15.01,
     6.8,
     8
    ],
    [
     "nut-m10",
     "M10",
     16,
     18.48,
     8.4,
     10
    ],
    [
     "nut-m12",
     "M12",
     18,
     20.78,
     10.8,
     12
    ],
    [
     "nut-3-8in",
     "3/8 in",
     14.29,
     16.5,
     8.33,
     9.53
    ],
    [
     "nut-1-2in",
     "1/2 in",
     19.05,
     22,
     11.11,
     12.7
    ]
   ]
  }
 },
 "sheet_text": "Hex nuts M8, M10, M12, 3/8 in and 1/2 in (flywheel weights) — dimension sheet\nSource: Xem Studio, https://xemstudio.com/objects/hex-nut-weights/  (CC BY 4.0)\nBasis: ISO 4032 (M8, M10, M12) and ASME B18.2.2 finished hex (3/8, 1/2 in) envelopes; bore at the thread major Ø\nCatalog version: 2026-10-20\n\nSizes: see table below\n- Hex nut envelopes: across flats × thickness, across corners, and a bore at the thread major Ø (thread not drawn).\n- M8 13 × 6.8 (AC 15.01); M10 16 × 8.4 (18.48); M12 18 × 10.8 (20.78); 3/8 in 14.29 × 8.33 (16.50); 1/2 in 19.05 × 11.11 (22.00).\n- Each sits in the matching flywheel pocket with one flat facing outward, flush with the rim face.\n\nfile  thread  across flats  across corners  thickness  bore\nnut-m8  M8  13.0  15.01  6.8  8.0\nnut-m10  M10  16.0  18.48  8.4  10.0\nnut-m12  M12  18.0  20.78  10.8  12.0\nnut-3-8in  3/8 in  14.29  16.5  8.33  9.53\nnut-1-2in  1/2 in  19.05  22.0  11.11  12.7\n\nFiles elsewhere (not hosted by Xem Studio; license as stated by the publisher):\n- ISO: ISO 4032 Hexagon regular nuts (style 1) — standard — ISO [verify license at link] — https://www.iso.org/standard/72624.html\n- ASME: ASME B18.2.2 Nuts for general applications — standard — ASME [verify license at link] — https://www.asme.org/codes-standards/find-codes-standards/b18-2-2-nuts-for-general-applications-machine-screw-nuts-hex-square-hex-flange-coupling-nuts-(inch-series)\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, 5 parts): https://xemstudio.com/files/hardware/hex-nut-weights/index.json\nAPI: https://xemstudio.com/api/geometry?object=hex-nut-weights\n",
 "sources": [
  {
   "publisher": "ISO",
   "title": "ISO 4032 Hexagon regular nuts (style 1)",
   "url": "https://www.iso.org/standard/72624.html",
   "formats": [
    "standard"
   ],
   "license": "ISO",
   "license_verified": false,
   "hosted": false
  },
  {
   "publisher": "ASME",
   "title": "ASME B18.2.2 Nuts for general applications",
   "url": "https://www.asme.org/codes-standards/find-codes-standards/b18-2-2-nuts-for-general-applications-machine-screw-nuts-hex-square-hex-flange-coupling-nuts-(inch-series)",
   "formats": [
    "standard"
   ],
   "license": "ASME",
   "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": [
  "nut-pocket-flywheels",
  "hex-nuts-metric",
  "nyloc-nuts-metric"
 ],
 "fits": [
  {
   "role": "Goes in or on",
   "items": [
    {
     "slug": "nut-pocket-flywheels",
     "why": "hex pocket at the across-flats"
    }
   ]
  },
  {
   "role": "Alternatives",
   "items": [
    {
     "slug": "hex-nuts-metric",
     "why": "M2–M8 nut range"
    }
   ]
  }
 ],
 "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": "What are M10 hex nut dimensions?",
   "a": "16 across flats, 18.48 across corners, 8.4 thick (ISO 4032)."
  },
  {
   "q": "What are 1/2 in hex nut dimensions?",
   "a": "3/4 in (19.05) across flats, 7/16 in (11.11) thick (ASME B18.2.2 finished hex)."
  }
 ],
 "files_license": null,
 "offers": [
  {
   "file": "nut-m8",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "CC BY 4.0 (Xem Studio)",
   "step": "https://xemstudio.com/files/hardware/nut-weighted-flywheels/nut-m8.step",
   "stl": "https://xemstudio.com/files/hardware/nut-weighted-flywheels/nut-m8.stl",
   "note": "M8 hex nut, 13 across flats × 6.8: the flywheel weight"
  },
  {
   "file": "nut-m10",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "CC BY 4.0 (Xem Studio)",
   "step": "https://xemstudio.com/files/hardware/nut-weighted-flywheels/nut-m10.step",
   "stl": "https://xemstudio.com/files/hardware/nut-weighted-flywheels/nut-m10.stl",
   "note": "M10 hex nut, 16 across flats × 8.4: the flywheel weight"
  },
  {
   "file": "nut-m12",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "CC BY 4.0 (Xem Studio)",
   "step": "https://xemstudio.com/files/hardware/nut-weighted-flywheels/nut-m12.step",
   "stl": "https://xemstudio.com/files/hardware/nut-weighted-flywheels/nut-m12.stl",
   "note": "M12 hex nut, 18 across flats × 10.8: the flywheel weight"
  },
  {
   "file": "nut-3-8in",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "CC BY 4.0 (Xem Studio)",
   "step": "https://xemstudio.com/files/hardware/nut-weighted-flywheels/nut-3-8in.step",
   "stl": "https://xemstudio.com/files/hardware/nut-weighted-flywheels/nut-3-8in.stl",
   "note": "3/8 in hex nut, 14.29 across flats × 8.33: the flywheel weight"
  },
  {
   "file": "nut-1-2in",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "CC BY 4.0 (Xem Studio)",
   "step": "https://xemstudio.com/files/hardware/nut-weighted-flywheels/nut-1-2in.step",
   "stl": "https://xemstudio.com/files/hardware/nut-weighted-flywheels/nut-1-2in.stl",
   "note": "1/2 in hex nut, 19.05 across flats × 11.11: the flywheel weight"
  }
 ],
 "markdown": "https://xemstudio.com/objects/hex-nut-weights/index.md"
}