{
 "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-head-screws-metric",
 "name": "Hex head screws, M3–M8 (ISO 4017)",
 "kind": "hardware",
 "category": "Hardware",
 "group": "Fasteners",
 "year": null,
 "question": "What size hex pocket holds an M5 hex head bolt so it can't turn?",
 "tags": [
  "screw",
  "bolt",
  "hex head",
  "fastener",
  "iso 4017"
 ],
 "aliases": [
  "hex bolt",
  "hex head bolt",
  "m5 hex bolt",
  "iso 4017",
  "din 933",
  "captive bolt head pocket"
 ],
 "overall_mm": {
  "length": null,
  "width": null,
  "height": null
 },
 "official_cad": false,
 "xem_status": "free-files",
 "les": false,
 "free_files": 21,
 "url": "https://xemstudio.com/objects/hex-head-screws-metric/",
 "sheet_txt": "https://xemstudio.com/objects/hex-head-screws-metric/sheet.txt",
 "sheet": {
  "basis": "ISO 4017 (fully threaded hex head screws): width across flats s and head height k",
  "overall_mm": {
   "length": null,
   "width": null,
   "height": null
  },
  "notes": [
   "Hex head: s across flats, k high, corners s × 1.155. A pocket that keeps the head from turning is drawn at s × k exactly (see Mating features), so a nut can be run down from the other side with one tool.",
   "Used in the two-bolt tri-clamp clamps: M5 × 30 in the 1½–4 in clamp halves, M8 in the 10 and 12 in clamps; each clamp half has the head pocket on one lug and a plain hole on the other."
  ],
  "table": {
   "columns": [
    "thread",
    "width_af_mm",
    "corner_mm",
    "head_height_mm",
    "lengths_mm"
   ],
   "rows": [
    [
     "M3",
     5.5,
     6.4,
     2,
     "10, 16, 20"
    ],
    [
     "M4",
     7,
     8.1,
     2.8,
     "12, 16, 20, 25"
    ],
    [
     "M5",
     8,
     9.2,
     3.5,
     "16, 20, 25, 30, 40"
    ],
    [
     "M6",
     10,
     11.5,
     4,
     "20, 25, 30, 40"
    ],
    [
     "M8",
     13,
     15,
     5.3,
     "20, 25, 30, 40, 50"
    ]
   ]
  }
 },
 "sheet_text": "Hex head screws, M3–M8 (ISO 4017) — dimension sheet\nSource: Xem Studio, https://xemstudio.com/objects/hex-head-screws-metric/  (CC BY 4.0)\nBasis: ISO 4017 (fully threaded hex head screws): width across flats s and head height k\nCatalog version: 2026-10-20\n\nSizes: see table below\n- Hex head: s across flats, k high, corners s × 1.155. A pocket that keeps the head from turning is drawn at s × k exactly (see Mating features), so a nut can be run down from the other side with one tool.\n- Used in the two-bolt tri-clamp clamps: M5 × 30 in the 1½–4 in clamp halves, M8 in the 10 and 12 in clamps; each clamp half has the head pocket on one lug and a plain hole on the other.\n\nthread  width_af_mm  corner_mm  head_height_mm  lengths_mm\nM3  5.5  6.4  2.0  10, 16, 20\nM4  7.0  8.1  2.8  12, 16, 20, 25\nM5  8.0  9.2  3.5  16, 20, 25, 30, 40\nM6  10.0  11.5  4.0  20, 25, 30, 40\nM8  13.0  15.0  5.3  20, 25, 30, 40, 50\n\nFiles elsewhere (not hosted by Xem Studio; license as stated by the publisher):\n- McMaster-Carr: Hex head screws (free STEP/IGES/STL per part, for your own design use; no redistribution) — STEP, IGES, STL, PDF — McMaster-Carr site terms: personal design use, no redistribution [verify license at link] — https://www.mcmaster.com/products/hex-head-screws/\n- Wikipedia: Screw — web — CC BY-SA 4.0 (text) — https://en.wikipedia.org/wiki/Screw\n\nFree files (CC BY 4.0, Xem Studio; STEP + STL, 21 parts): https://xemstudio.com/files/hardware/hex-head-screws-metric/index.json\nAPI: https://xemstudio.com/api/geometry?object=hex-head-screws-metric\n",
 "sources": [
  {
   "publisher": "McMaster-Carr",
   "title": "Hex head screws (free STEP/IGES/STL per part, for your own design use; no redistribution)",
   "url": "https://www.mcmaster.com/products/hex-head-screws/",
   "formats": [
    "STEP",
    "IGES",
    "STL",
    "PDF"
   ],
   "license": "McMaster-Carr site terms: personal design use, no redistribution",
   "license_verified": false,
   "hosted": false
  },
  {
   "publisher": "Wikipedia",
   "title": "Screw",
   "url": "https://en.wikipedia.org/wiki/Screw",
   "formats": [
    "web"
   ],
   "license": "CC BY-SA 4.0 (text)",
   "license_verified": true,
   "hosted": false
  }
 ],
 "xem": {
  "status": "free-files",
  "sheet_free": true,
  "mesh_price_usd": null,
  "step_price_usd": null,
  "tolerance_mm": null
 },
 "related": [
  "hex-nuts-metric",
  "flat-washers-metric",
  "socket-head-cap-screws-metric",
  "tri-clamp-clamps"
 ],
 "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": [
  {
   "feature": "hex head",
   "exact": "s × k (M5 8 × 3.5, M8 13 × 5.3; ISO 4017)",
   "mates": "hex pocket in a clamp lug",
   "fit": "socket",
   "files": "hexbolt-"
  },
  {
   "feature": "shank",
   "exact": "thread major (M5 Ø5)",
   "mates": "clearance hole (ISO 273) and nut",
   "fit": "designed",
   "files": "hexbolt-"
  }
 ],
 "fit_classes": {
  "press": "stays put: pin, tube, bearing or magnet held by interference. Typical FDM: hole +0.0 to +0.1 mm on diameter.",
  "slide": "assembles by hand and is held by a grub, pinch or clamp: shaft in a hub, rod in a socket, spigot in a bore. Typical FDM: +0.2 mm.",
  "run": "turns or slides in use: pin in a link, rod through a guide. Typical FDM: +0.3 mm.",
  "socket": "large sliding fit: syringe barrel, sleeve, bobbin in a bore. Typical FDM: +0.3 mm.",
  "clamp": "split part that closes on the mating part with screws: make it at size.",
  "designed": "a gap that is part of the design (piston fit option, displacer gap, air gap): do not change."
 },
 "faq": [
  {
   "q": "How big is an M5 hex head?",
   "a": "8 mm across flats, 3.5 mm high, 9.2 mm across corners (ISO 4017). A pocket that holds it is 8 AF × 3.5 deep."
  },
  {
   "q": "How big is an M8 hex head?",
   "a": "13 mm across flats, 5.3 mm high, 15.0 mm across corners (ISO 4017)."
  },
  {
   "q": "Why put the bolt head in a hex pocket?",
   "a": "The pocket stops the bolt turning, so the nut on the other side can be tightened with one wrench."
  }
 ],
 "files_license": null,
 "offers": [
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   "file": "hexbolt-m3x10",
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    "step",
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   "license": "CC BY 4.0 (Xem Studio)",
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   "stl": "https://xemstudio.com/files/hardware/hex-head-screws-metric/hexbolt-m3x10.stl",
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   "note": "ISO 4017 M4 × 20 hex head, 7 AF × 2.8 head, thread as plain cylinder"
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  {
   "file": "hexbolt-m4x25",
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   "note": "ISO 4017 M6 × 25 hex head, 10 AF × 4 head, thread as plain cylinder"
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   "note": "ISO 4017 M6 × 30 hex head, 10 AF × 4 head, thread as plain cylinder"
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   "note": "ISO 4017 M6 × 40 hex head, 10 AF × 4 head, thread as plain cylinder"
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   "note": "ISO 4017 M8 × 20 hex head, 13 AF × 5.3 head, thread as plain cylinder"
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   "note": "ISO 4017 M8 × 25 hex head, 13 AF × 5.3 head, thread as plain cylinder"
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  {
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   "stl": "https://xemstudio.com/files/hardware/hex-head-screws-metric/hexbolt-m8x30.stl",
   "note": "ISO 4017 M8 × 30 hex head, 13 AF × 5.3 head, thread as plain cylinder"
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  {
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   "license": "CC BY 4.0 (Xem Studio)",
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   "stl": "https://xemstudio.com/files/hardware/hex-head-screws-metric/hexbolt-m8x40.stl",
   "note": "ISO 4017 M8 × 40 hex head, 13 AF × 5.3 head, thread as plain cylinder"
  },
  {
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   "license": "CC BY 4.0 (Xem Studio)",
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   "stl": "https://xemstudio.com/files/hardware/hex-head-screws-metric/hexbolt-m8x50.stl",
   "note": "ISO 4017 M8 × 50 hex head, 13 AF × 5.3 head, thread as plain cylinder"
  }
 ],
 "markdown": "https://xemstudio.com/objects/hex-head-screws-metric/index.md"
}