{
 "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-adapter-5-to-8mm",
 "name": "Shaft adapter Ø5 to Ø8 × 20",
 "kind": "hardware",
 "category": "Stirling engines",
 "group": "Drives & mechanisms",
 "year": null,
 "question": "How does an 8 mm bore flywheel go on a 5 mm crankshaft?",
 "tags": [
  "adapter",
  "sleeve",
  "shaft",
  "flywheel",
  "5 mm to 8 mm",
  "stirling",
  "long earth society"
 ],
 "aliases": [
  "5mm to 8mm shaft adapter",
  "flywheel on 5mm shaft",
  "shaft reducer sleeve",
  "bore adapter 5 8"
 ],
 "overall_mm": {
  "length": null,
  "width": null,
  "height": null
 },
 "official_cad": false,
 "xem_status": "free-files",
 "les": true,
 "free_files": 1,
 "url": "https://xemstudio.com/objects/shaft-adapter-5-to-8mm/",
 "sheet_txt": "https://xemstudio.com/objects/shaft-adapter-5-to-8mm/sheet.txt",
 "sheet": {
  "basis": "Sleeve with a Ø5 bore and Ø8 OD, two M3 radial holes",
  "overall_mm": {
   "length": null,
   "width": null,
   "height": null
  },
  "notes": [
   "A sleeve Ø8 OD × Ø5 bore × 20 long.",
   "Two Ø2.5 radial holes (M3 tap drill) through both walls, 5 mm from each end: one grub bears on the Ø5 shaft's flat, the other lines up under the flywheel's set screw.",
   "It puts any Ø8-bore hub (the Ø80–Ø150 spoked flywheels) on a Ø5 crankshaft."
  ],
  "table": {
   "columns": [
    "feature",
    "value_mm"
   ],
   "rows": [
    [
     "OD",
     8
    ],
    [
     "bore",
     5
    ],
    [
     "length",
     20
    ],
    [
     "grub holes",
     "2 × Ø2.5 at 5 and 15"
    ]
   ]
  }
 },
 "sheet_text": "Shaft adapter Ø5 to Ø8 × 20 — dimension sheet\nSource: Xem Studio, https://xemstudio.com/objects/shaft-adapter-5-to-8mm/  (CC BY 4.0)\nBasis: Sleeve with a Ø5 bore and Ø8 OD, two M3 radial holes\nCatalog version: 2026-10-20\n\nSizes: see table below\n- A sleeve Ø8 OD × Ø5 bore × 20 long.\n- Two Ø2.5 radial holes (M3 tap drill) through both walls, 5 mm from each end: one grub bears on the Ø5 shaft's flat, the other lines up under the flywheel's set screw.\n- It puts any Ø8-bore hub (the Ø80–Ø150 spoked flywheels) on a Ø5 crankshaft.\n\nfeature  value_mm\nOD  8\nbore  5\nlength  20\ngrub holes  2 × Ø2.5 at 5 and 15\n\nFiles elsewhere (not hosted by Xem Studio; license as stated by the publisher):\n- Long Earth Society: Tri-clamp Stirling engine builds — web, video — LES site — https://longearthsociety.com/engineering/\n\nFree files (CC BY 4.0, Xem Studio; STEP + STL, 1 parts): https://xemstudio.com/files/hardware/shaft-adapter-5-to-8mm/index.json\nAPI: https://xemstudio.com/api/geometry?object=shaft-adapter-5-to-8mm\n",
 "sources": [
  {
   "publisher": "Long Earth Society",
   "title": "Tri-clamp Stirling 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": [
  "spoked-flywheels",
  "stirling-crankshafts",
  "shaft-couplers",
  "set-screws-metric"
 ],
 "fits": [
  {
   "role": "Goes in or on",
   "items": [
    {
     "slug": "stirling-crankshafts",
     "why": "Ø5 bore on the D-flat shaft"
    }
   ]
  },
  {
   "role": "Connects to",
   "items": [
    {
     "slug": "spoked-flywheels",
     "why": "Ø8 OD in the flywheel's Ø8 bore"
    }
   ]
  },
  {
   "role": "Also needed",
   "items": [
    {
     "slug": "set-screws-metric",
     "why": "two M3 grubs"
    }
   ]
  }
 ],
 "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": "shaft-adapter bore",
   "exact": "Ø5",
   "mates": "Ø5 crankshaft",
   "fit": "slide",
   "files": "shaft-adapter-"
  },
  {
   "feature": "shaft-adapter OD",
   "exact": "Ø8",
   "mates": "Ø8 flywheel hub",
   "fit": "slide",
   "files": "shaft-adapter-"
  },
  {
   "feature": "shaft-adapter grub holes",
   "exact": "Ø2.5",
   "mates": "M3 tap drill",
   "fit": "designed",
   "files": "shaft-adapter-"
  }
 ],
 "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": "The flywheel has an 8 mm bore and the crankshaft is 5 mm. What goes between?",
   "a": "This adapter: Ø5 bore, Ø8 OD, 20 long, two M3 grub holes."
  },
  {
   "q": "How long is the shaft adapter?",
   "a": "20 mm, with grub holes 5 mm in from each end."
  }
 ],
 "files_license": null,
 "offers": [
  {
   "file": "shaft-adapter-5-to-8",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "CC BY 4.0 (Xem Studio)",
   "step": "https://xemstudio.com/files/hardware/stirling-linkage-fittings/shaft-adapter-5-to-8.step",
   "stl": "https://xemstudio.com/files/hardware/stirling-linkage-fittings/shaft-adapter-5-to-8.stl",
   "note": "Ø5 → Ø8 shaft adapter × 20 with two M3 grubs: puts a Ø8-bore flywheel (Ø80–150) on a Ø5 crankshaft"
  }
 ],
 "markdown": "https://xemstudio.com/objects/shaft-adapter-5-to-8mm/index.md"
}