{
 "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": "geneva-drive",
 "name": "Geneva drive: 4 and 6 station wheels, R30, with drive discs",
 "kind": "hardware",
 "category": "Stirling engines",
 "group": "Drives & mechanisms",
 "year": null,
 "question": "How do I make a Geneva drive with 3D printed parts?",
 "tags": [
  "geneva",
  "geneva drive",
  "maltese cross",
  "intermittent",
  "indexing",
  "mechanism",
  "motion",
  "stirling",
  "long earth society"
 ],
 "aliases": [
  "geneva mechanism stl",
  "geneva drive 3d print",
  "maltese cross mechanism",
  "indexing mechanism"
 ],
 "overall_mm": {
  "length": null,
  "width": null,
  "height": null
 },
 "official_cad": false,
 "xem_status": "free-files",
 "les": true,
 "free_files": 4,
 "url": "https://xemstudio.com/objects/geneva-drive/",
 "sheet_txt": "https://xemstudio.com/objects/geneva-drive/sheet.txt",
 "sheet": {
  "basis": "Geneva geometry: centre distance c = R / cos(π/n), drive pin radius R·tan(π/n); Ø5 pin, Ø5 shafts",
  "overall_mm": {
   "length": null,
   "width": null,
   "height": null
  },
  "notes": [
   "Turns continuous rotation into steps: the wheel indexes 360/n degrees once per turn of the drive, then is held by the drive's locking disc until the next index.",
   "Wheels are R30 × 6 with 5 mm slots for the Ø5 drive pin. The drive is a 3 mm base plate carrying the locking disc and the pin; the wheel runs in the plane of the disc and pin, 3 mm above the base.",
   "The locking arcs on the wheel are 0.3 mm larger than the locking disc: a designed gap, keep it.",
   "Checked over a full turn of the drive for both wheels: pin, disc and wheel never overlap."
  ],
  "table": {
   "columns": [
    "stations",
    "index angle",
    "centre distance",
    "drive pin radius",
    "locking disc radius"
   ],
   "rows": [
    [
     "4",
     "90°",
     "42.4 mm",
     "30.0 mm",
     "26.0 mm"
    ],
    [
     "6",
     "60°",
     "34.6 mm",
     "17.3 mm",
     "13.3 mm"
    ]
   ]
  }
 },
 "sheet_text": "Geneva drive: 4 and 6 station wheels, R30, with drive discs — dimension sheet\nSource: Xem Studio, https://xemstudio.com/objects/geneva-drive/  (CC BY 4.0)\nBasis: Geneva geometry: centre distance c = R / cos(π/n), drive pin radius R·tan(π/n); Ø5 pin, Ø5 shafts\nCatalog version: 2026-10-20\n\nSizes: see table below\n- Turns continuous rotation into steps: the wheel indexes 360/n degrees once per turn of the drive, then is held by the drive's locking disc until the next index.\n- Wheels are R30 × 6 with 5 mm slots for the Ø5 drive pin. The drive is a 3 mm base plate carrying the locking disc and the pin; the wheel runs in the plane of the disc and pin, 3 mm above the base.\n- The locking arcs on the wheel are 0.3 mm larger than the locking disc: a designed gap, keep it.\n- Checked over a full turn of the drive for both wheels: pin, disc and wheel never overlap.\n\nstations  index angle  centre distance  drive pin radius  locking disc radius\n4  90°  42.4 mm  30.0 mm  26.0 mm\n6  60°  34.6 mm  17.3 mm  13.3 mm\n\nFiles elsewhere (not hosted by Xem Studio; license as stated by the publisher):\n- Wikipedia: Geneva drive — web — CC BY-SA 4.0 (text) — https://en.wikipedia.org/wiki/Geneva_drive\n- Long Earth Society: Engine and rig builds on extrusion frames — web, video — LES site — https://longearthsociety.com/engineering/\n\nFree files (CC BY 4.0, Xem Studio; STEP + STL, 4 parts): https://xemstudio.com/files/hardware/geneva-drive/index.json\nAPI: https://xemstudio.com/api/geometry?object=geneva-drive\n",
 "sources": [
  {
   "publisher": "Wikipedia",
   "title": "Geneva drive",
   "url": "https://en.wikipedia.org/wiki/Geneva_drive",
   "formats": [
    "web"
   ],
   "license": "CC BY-SA 4.0 (text)",
   "license_verified": true,
   "hosted": false
  },
  {
   "publisher": "Long Earth Society",
   "title": "Engine and rig builds on extrusion frames",
   "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": [
  "stirling-shafts-and-rods",
  "ball-bearings-metric",
  "spur-gears-involute",
  "ratchet-and-pawl"
 ],
 "fits": [
  {
   "role": "Goes in or on",
   "items": [
    {
     "slug": "stirling-shafts-and-rods",
     "why": "Ø5 shafts for wheel and drive"
    }
   ]
  },
  {
   "role": "Alternatives",
   "items": [
    {
     "slug": "ratchet-and-pawl",
     "why": "step motion driven by a rocker"
    }
   ]
  },
  {
   "role": "Also needed",
   "items": [
    {
     "slug": "ball-bearings-metric",
     "why": "625 bearings for the Ø5 shafts"
    }
   ]
  }
 ],
 "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": "wheel and drive bores",
   "exact": "Ø5",
   "mates": "Ø5 shafts",
   "fit": "press",
   "files": "all"
  },
  {
   "feature": "wheel slots",
   "exact": "5",
   "mates": "Ø5 drive pin (slides in them)",
   "fit": "slide",
   "files": "geneva-"
  },
  {
   "feature": "locking arc gap",
   "exact": "0.3",
   "mates": "drive disc",
   "fit": "designed",
   "files": "geneva-"
  }
 ],
 "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": "What centre distance does a Geneva mechanism need?",
   "a": "C = R / cos(π/n): for a 6-station wheel of R30, 34.6 mm; the drive pin sits at R·tan(π/n) = 17.3 mm from the drive centre."
  },
  {
   "q": "How long does the wheel stay still?",
   "a": "For n stations it moves during (180 − 360/n)° of each drive turn: 90° of 360 for 4 stations, 120° for 6."
  }
 ],
 "files_license": null,
 "offers": [
  {
   "file": "geneva-4-wheel-r30",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "CC BY 4.0 (Xem Studio)",
   "step": "https://xemstudio.com/files/hardware/geneva-drive/geneva-4-wheel-r30.step",
   "stl": "https://xemstudio.com/files/hardware/geneva-drive/geneva-4-wheel-r30.stl",
   "note": "Geneva wheel, 4 stations, R30, 5 mm slots, Ø5 bore"
  },
  {
   "file": "geneva-4-drive-r30",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "CC BY 4.0 (Xem Studio)",
   "step": "https://xemstudio.com/files/hardware/geneva-drive/geneva-4-drive-r30.step",
   "stl": "https://xemstudio.com/files/hardware/geneva-drive/geneva-4-drive-r30.stl",
   "note": "Geneva drive for the 4-station wheel: 3 mm base with arm, R26.0 locking disc and Ø5 pin at R30.0 in the wheel's plane, Ø5 bore (centre distance 42.4 mm)"
  },
  {
   "file": "geneva-6-wheel-r30",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "CC BY 4.0 (Xem Studio)",
   "step": "https://xemstudio.com/files/hardware/geneva-drive/geneva-6-wheel-r30.step",
   "stl": "https://xemstudio.com/files/hardware/geneva-drive/geneva-6-wheel-r30.stl",
   "note": "Geneva wheel, 6 stations, R30, 5 mm slots, Ø5 bore"
  },
  {
   "file": "geneva-6-drive-r30",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "CC BY 4.0 (Xem Studio)",
   "step": "https://xemstudio.com/files/hardware/geneva-drive/geneva-6-drive-r30.step",
   "stl": "https://xemstudio.com/files/hardware/geneva-drive/geneva-6-drive-r30.stl",
   "note": "Geneva drive for the 6-station wheel: 3 mm base with arm, R13.3 locking disc and Ø5 pin at R17.3 in the wheel's plane, Ø5 bore (centre distance 34.6 mm)"
  }
 ],
 "markdown": "https://xemstudio.com/objects/geneva-drive/index.md"
}