{
 "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": "coreless-motor-8520",
 "name": "8520 (820) coreless motor: Ø8.5 × 20 mm, Ø1 shaft",
 "kind": "hardware",
 "category": "Electronics",
 "group": "Motors",
 "year": null,
 "question": "What are the dimensions of an 8520 coreless motor?",
 "tags": [
  "8520",
  "820",
  "coreless",
  "micro motor",
  "brushed motor",
  "motor",
  "motor envelope",
  "stirling"
 ],
 "aliases": [
  "8520 motor dimensions",
  "820 coreless motor",
  "8.5x20 motor",
  "8520 coreless motor size",
  "8520 motor shaft",
  "8520 motor step"
 ],
 "overall_mm": {
  "length": null,
  "width": null,
  "height": null
 },
 "official_cad": false,
 "xem_status": "free-files",
 "les": false,
 "free_files": 1,
 "url": "https://xemstudio.com/objects/coreless-motor-8520/",
 "sheet_txt": "https://xemstudio.com/objects/coreless-motor-8520/sheet.txt",
 "sheet": {
  "basis": "DFRobot FIT0796 and Makeblock 820 listings (they agree). Envelope only: the outside of the motor at its published sizes. The windings, magnets, brushes and bearings inside are not drawn.",
  "overall_mm": {
   "length": null,
   "width": null,
   "height": null
  },
  "notes": [
   "Envelope only: the outside of the motor at its published sizes. The windings, magnets, brushes and bearings inside are not drawn.",
   "The body is a plain Ø8.5 × 20 mm cylinder; the Ø1.0 shaft stands 5 mm out of the front end.",
   "8520 and 820 are the same size: 8.5 mm diameter, 20 mm long.",
   "The leads leave the back end; they and any bearing boss are not drawn (not listed). It is held by its body in a Ø8.5 clip or socket.",
   "Coreless motors have no iron in the rotor, so they turn without cogging; on small, low-power Stirling models they are used as generators or tachometer pickups."
  ],
  "table": {
   "columns": [
    "feature",
    "mm",
    "from"
   ],
   "rows": [
    [
     "body",
     "Ø8.5 × 20",
     "DFRobot FIT0796, Makeblock 820"
    ],
    [
     "shaft",
     "Ø1.0 × 5",
     "DFRobot FIT0796, Makeblock 820"
    ]
   ]
  }
 },
 "sheet_text": "8520 (820) coreless motor: Ø8.5 × 20 mm, Ø1 shaft — dimension sheet\nSource: Xem Studio, https://xemstudio.com/objects/coreless-motor-8520/  (CC BY 4.0)\nBasis: DFRobot FIT0796 and Makeblock 820 listings (they agree). Envelope only: the outside of the motor at its published sizes. The windings, magnets, brushes and bearings inside are not drawn.\nCatalog version: 2026-10-20\n\nSizes: see table below\n- Envelope only: the outside of the motor at its published sizes. The windings, magnets, brushes and bearings inside are not drawn.\n- The body is a plain Ø8.5 × 20 mm cylinder; the Ø1.0 shaft stands 5 mm out of the front end.\n- 8520 and 820 are the same size: 8.5 mm diameter, 20 mm long.\n- The leads leave the back end; they and any bearing boss are not drawn (not listed). It is held by its body in a Ø8.5 clip or socket.\n- Coreless motors have no iron in the rotor, so they turn without cogging; on small, low-power Stirling models they are used as generators or tachometer pickups.\n\nfeature  mm  from\nbody  Ø8.5 × 20  DFRobot FIT0796, Makeblock 820\nshaft  Ø1.0 × 5  DFRobot FIT0796, Makeblock 820\n\nFiles elsewhere (not hosted by Xem Studio; license as stated by the publisher):\n- DFRobot (FIT0796, as listed by Core Electronics): Coreless micro motor 8.5 × 20 mm: Ø8.5 × 20, shaft Ø1 × 5 — web — listing [verify license at link] — https://core-electronics.com.au/4pcs-coreless-micro-motor-8-5-20mm.html.plain.md\n- Makeblock (as listed by Studica): 820 coreless motor: Ø8.5 × 20, output shaft Ø1.0 × 5 — web — listing [verify license at link] — https://www.studica.com/makeblock-820-coreless-motor-pair\n\nFree files (CC BY 4.0, Xem Studio; STEP + STL, 1 parts): https://xemstudio.com/files/hardware/coreless-motor-8520/index.json\nAPI: https://xemstudio.com/api/geometry?object=coreless-motor-8520\n",
 "sources": [
  {
   "publisher": "DFRobot (FIT0796, as listed by Core Electronics)",
   "title": "Coreless micro motor 8.5 × 20 mm: Ø8.5 × 20, shaft Ø1 × 5",
   "url": "https://core-electronics.com.au/4pcs-coreless-micro-motor-8-5-20mm.html.plain.md",
   "formats": [
    "web"
   ],
   "license": "listing",
   "license_verified": false,
   "hosted": false
  },
  {
   "publisher": "Makeblock (as listed by Studica)",
   "title": "820 coreless motor: Ø8.5 × 20, output shaft Ø1.0 × 5",
   "url": "https://www.studica.com/makeblock-820-coreless-motor-pair",
   "formats": [
    "web"
   ],
   "license": "listing",
   "license_verified": false,
   "hosted": false
  }
 ],
 "xem": {
  "status": "free-files",
  "sheet_free": true,
  "mesh_price_usd": null,
  "step_price_usd": null,
  "tolerance_mm": null
 },
 "related": [
  "coreless-motor-716",
  "dc-motor-130-size"
 ],
 "fits": [
  {
   "role": "Alternatives",
   "items": [
    {
     "slug": "coreless-motor-716",
     "why": "smaller Ø7 × 16, Ø0.8 shaft"
    },
    {
     "slug": "dc-motor-130-size",
     "why": "iron-core can, Ø2 shaft"
    }
   ]
  },
  {
   "role": "Also needed",
   "items": [
    {
     "slug": "leds-tht",
     "why": "an LED across the leads shows generator output"
    }
   ]
  }
 ],
 "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",
   "exact": "Ø1.0",
   "mates": "propeller or pinion bore (pressed on)",
   "fit": "press",
   "files": "coreless-8520"
  },
  {
   "feature": "body",
   "exact": "Ø8.5 × 20",
   "mates": "clip or socket",
   "fit": "socket",
   "files": "coreless-8520"
  }
 ],
 "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 size is an 8520 motor?",
   "a": "Ø8.5 mm × 20 mm body with a Ø1.0 mm shaft 5 mm long."
  },
  {
   "q": "Is an 820 motor the same as an 8520?",
   "a": "Yes: both are 8.5 mm × 20 mm with a 1 mm shaft."
  }
 ],
 "files_license": null,
 "offers": [
  {
   "file": "coreless-8520",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "CC BY 4.0 (Xem Studio)",
   "step": "https://xemstudio.com/files/hardware/coreless-motor-8520/coreless-8520.step",
   "stl": "https://xemstudio.com/files/hardware/coreless-motor-8520/coreless-8520.stl",
   "note": "8520 coreless envelope: Ø8.5 × 20 body, Ø1.0 shaft 5 long"
  }
 ],
 "markdown": "https://xemstudio.com/objects/coreless-motor-8520/index.md"
}