{
 "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": "set-screws-metric",
 "name": "Set screws (grub screws), M3–M8 (ISO 4026)",
 "kind": "hardware",
 "category": "Hardware",
 "group": "Fasteners",
 "year": null,
 "question": "What size set screw holds a 5 mm shaft coupler or pulley?",
 "tags": [
  "screw",
  "set screw",
  "grub screw",
  "fastener",
  "stirling",
  "long earth society"
 ],
 "aliases": [
  "grub screw",
  "m3 set screw",
  "iso 4026",
  "din 913"
 ],
 "overall_mm": {
  "length": null,
  "width": null,
  "height": null
 },
 "official_cad": false,
 "xem_status": "free-files",
 "les": true,
 "free_files": 27,
 "url": "https://xemstudio.com/objects/set-screws-metric/",
 "sheet_txt": "https://xemstudio.com/objects/set-screws-metric/sheet.txt",
 "sheet": {
  "basis": "ISO 4026 flat point, hex socket",
  "overall_mm": {
   "length": null,
   "width": null,
   "height": null
  },
  "notes": [
   "Headless; the whole length is thread. Used to lock pulleys, couplers and collars onto shafts: use two at 90° and seat one on the shaft's D-flat.",
   "Hex keys: M3 1.5, M4 2, M5 2.5, M6 3, M8 4 mm. Cup and dog points exist; flat point is the common one in printer kits."
  ],
  "table": {
   "columns": [
    "thread",
    "hex_key_mm",
    "common_lengths_mm"
   ],
   "rows": [
    [
     "M3",
     1.5,
     "3, 4, 5, 6, 8, 10"
    ],
    [
     "M4",
     2,
     "4, 5, 6, 8, 10, 12"
    ],
    [
     "M5",
     2.5,
     "5, 6, 8, 10, 12"
    ],
    [
     "M6",
     3,
     "6, 8, 10, 12, 16"
    ],
    [
     "M8",
     4,
     "8, 10, 12, 16, 20"
    ]
   ]
  }
 },
 "sheet_text": "Set screws (grub screws), M3–M8 (ISO 4026) — dimension sheet\nSource: Xem Studio, https://xemstudio.com/objects/set-screws-metric/  (CC BY 4.0)\nBasis: ISO 4026 flat point, hex socket\nCatalog version: 2026-10-20\n\nSizes: see table below\n- Headless; the whole length is thread. Used to lock pulleys, couplers and collars onto shafts: use two at 90° and seat one on the shaft's D-flat.\n- Hex keys: M3 1.5, M4 2, M5 2.5, M6 3, M8 4 mm. Cup and dog points exist; flat point is the common one in printer kits.\n\nthread  hex_key_mm  common_lengths_mm\nM3  1.5  3, 4, 5, 6, 8, 10\nM4  2.0  4, 5, 6, 8, 10, 12\nM5  2.5  5, 6, 8, 10, 12\nM6  3.0  6, 8, 10, 12, 16\nM8  4.0  8, 10, 12, 16, 20\n\nFiles elsewhere (not hosted by Xem Studio; license as stated by the publisher):\n- McMaster-Carr: Socket 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/socket-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, 27 parts): https://xemstudio.com/files/hardware/set-screws-metric/index.json\nAPI: https://xemstudio.com/api/geometry?object=set-screws-metric\n",
 "sources": [
  {
   "publisher": "McMaster-Carr",
   "title": "Socket head screws (free STEP/IGES/STL per part, for your own design use; no redistribution)",
   "url": "https://www.mcmaster.com/products/socket-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": [
  "gt2-pulleys",
  "shaft-couplers",
  "nema-17-stepper",
  "socket-head-cap-screws-metric"
 ],
 "faq": [
  {
   "q": "What set screw do GT2 pulleys use?",
   "a": "M3 × 3 or M3 × 4, two per pulley at 90°, 1.5 mm hex key."
  },
  {
   "q": "What size set screw for a 5 mm to 8 mm coupler?",
   "a": "M4 × 5 or M4 × 6, 2 mm hex key; most aluminium couplers come with them."
  }
 ],
 "files_license": null,
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 "markdown": "https://xemstudio.com/objects/set-screws-metric/index.md"
}