{
 "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": "shaft-couplers",
 "name": "Flexible shaft couplers, 5–10 mm bores",
 "kind": "hardware",
 "category": "Hardware",
 "group": "Motion",
 "year": null,
 "question": "What size is a 5 mm to 8 mm flexible coupler?",
 "tags": [
  "coupler",
  "coupling",
  "motion",
  "shaft"
 ],
 "aliases": [
  "5 to 8 coupler",
  "flexible coupling",
  "helical coupler",
  "motor coupler"
 ],
 "overall_mm": {
  "length": null,
  "width": null,
  "height": null
 },
 "official_cad": false,
 "xem_status": "free-files",
 "les": false,
 "free_files": 6,
 "url": "https://xemstudio.com/objects/shaft-couplers/",
 "sheet_txt": "https://xemstudio.com/objects/shaft-couplers/sheet.txt",
 "sheet": {
  "basis": "Common aluminium helical (beam) couplers as sold for 3D printers and CNC kits",
  "overall_mm": {
   "length": null,
   "width": null,
   "height": null
  },
  "notes": [
   "Ø19 × 25 mm for 5 → 5 and 5 → 8; Ø25 × 30 mm for 6.35/8/10 mm bores. Two set screws per end at 90°.",
   "Helical couplers take 0.2 mm misalignment; for a lead screw also add a bearing block at the far end or let the end float.",
   "Spiral cut is shown as three slots in these files; the envelope is what matters for the print."
  ],
  "table": {
   "columns": [
    "bore_1_mm",
    "bore_2_mm",
    "od_mm",
    "length_mm",
    "set_screws"
   ],
   "rows": [
    [
     5,
     5,
     19,
     25,
     "M4 × 2 per end"
    ],
    [
     5,
     8,
     19,
     25,
     "M4 × 2 per end"
    ],
    [
     5,
     8,
     25,
     30,
     "M4 × 2 per end"
    ],
    [
     6.35,
     8,
     25,
     30,
     "M4 × 2 per end"
    ],
    [
     8,
     8,
     25,
     30,
     "M4 × 2 per end"
    ],
    [
     8,
     10,
     25,
     30,
     "M4 × 2 per end"
    ]
   ]
  }
 },
 "sheet_text": "Flexible shaft couplers, 5–10 mm bores — dimension sheet\nSource: Xem Studio, https://xemstudio.com/objects/shaft-couplers/  (CC BY 4.0)\nBasis: Common aluminium helical (beam) couplers as sold for 3D printers and CNC kits\nCatalog version: 2026-10-20\n\nSizes: see table below\n- Ø19 × 25 mm for 5 → 5 and 5 → 8; Ø25 × 30 mm for 6.35/8/10 mm bores. Two set screws per end at 90°.\n- Helical couplers take 0.2 mm misalignment; for a lead screw also add a bearing block at the far end or let the end float.\n- Spiral cut is shown as three slots in these files; the envelope is what matters for the print.\n\nbore_1_mm  bore_2_mm  od_mm  length_mm  set_screws\n5  5  19  25  M4 × 2 per end\n5  8  19  25  M4 × 2 per end\n5  8  25  30  M4 × 2 per end\n6.35  8  25  30  M4 × 2 per end\n8  8  25  30  M4 × 2 per end\n8  10  25  30  M4 × 2 per end\n\nFiles elsewhere (not hosted by Xem Studio; license as stated by the publisher):\n- McMaster-Carr: Shaft couplings (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/shaft-couplings/\n- Wikipedia: Coupling — web — CC BY-SA 4.0 (text) — https://en.wikipedia.org/wiki/Coupling\n\nFree files (CC BY 4.0, Xem Studio; STEP + STL, 6 parts): https://xemstudio.com/files/hardware/shaft-couplers/index.json\nAPI: https://xemstudio.com/api/geometry?object=shaft-couplers\n",
 "sources": [
  {
   "publisher": "McMaster-Carr",
   "title": "Shaft couplings (free STEP/IGES/STL per part, for your own design use; no redistribution)",
   "url": "https://www.mcmaster.com/products/shaft-couplings/",
   "formats": [
    "STEP",
    "IGES",
    "STL",
    "PDF"
   ],
   "license": "McMaster-Carr site terms: personal design use, no redistribution",
   "license_verified": false,
   "hosted": false
  },
  {
   "publisher": "Wikipedia",
   "title": "Coupling",
   "url": "https://en.wikipedia.org/wiki/Coupling",
   "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": [
  "lead-screw-t8",
  "nema-17-stepper",
  "set-screws-metric",
  "nema-steppers-8-to-34"
 ],
 "faq": [
  {
   "q": "What coupler connects a NEMA 17 to a T8 lead screw?",
   "a": "A 5 mm → 8 mm flexible coupler, Ø19 × 25 mm (or Ø25 × 30 for more torque)."
  },
  {
   "q": "What is the OD of a 5x8 flexible coupler?",
   "a": "19 mm on the small (25 mm long) version, 25 mm on the 30 mm long version."
  }
 ],
 "files_license": null,
 "offers": [
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   "file": "coupler-5x5-d19",
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    "step",
    "stl"
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   "license": "CC BY 4.0 (Xem Studio)",
   "step": "https://xemstudio.com/files/hardware/shaft-couplers/coupler-5x5-d19.step",
   "stl": "https://xemstudio.com/files/hardware/shaft-couplers/coupler-5x5-d19.stl",
   "note": "flexible coupler 5 → 5 mm, Ø19 × 25; spiral shown as slots"
  },
  {
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   "price_usd": 0,
   "license": "CC BY 4.0 (Xem Studio)",
   "step": "https://xemstudio.com/files/hardware/shaft-couplers/coupler-5x8-d19.step",
   "stl": "https://xemstudio.com/files/hardware/shaft-couplers/coupler-5x8-d19.stl",
   "note": "flexible coupler 5 → 8 mm, Ø19 × 25; spiral shown as slots"
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   "step": "https://xemstudio.com/files/hardware/shaft-couplers/coupler-5x8-d25.step",
   "stl": "https://xemstudio.com/files/hardware/shaft-couplers/coupler-5x8-d25.stl",
   "note": "flexible coupler 5 → 8 mm, Ø25 × 30; spiral shown as slots"
  },
  {
   "file": "coupler-6.35x8-d25",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "CC BY 4.0 (Xem Studio)",
   "step": "https://xemstudio.com/files/hardware/shaft-couplers/coupler-6.35x8-d25.step",
   "stl": "https://xemstudio.com/files/hardware/shaft-couplers/coupler-6.35x8-d25.stl",
   "note": "flexible coupler 6.35 → 8 mm, Ø25 × 30; spiral shown as slots"
  },
  {
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   "formats": [
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    "stl"
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   "step": "https://xemstudio.com/files/hardware/shaft-couplers/coupler-8x8-d25.step",
   "stl": "https://xemstudio.com/files/hardware/shaft-couplers/coupler-8x8-d25.stl",
   "note": "flexible coupler 8 → 8 mm, Ø25 × 30; spiral shown as slots"
  },
  {
   "file": "coupler-8x10-d25",
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   "step": "https://xemstudio.com/files/hardware/shaft-couplers/coupler-8x10-d25.step",
   "stl": "https://xemstudio.com/files/hardware/shaft-couplers/coupler-8x10-d25.stl",
   "note": "flexible coupler 8 → 10 mm, Ø25 × 30; spiral shown as slots"
  }
 ],
 "markdown": "https://xemstudio.com/objects/shaft-couplers/index.md"
}