{
 "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": "neodymium-block-magnets",
 "name": "Neodymium block magnets: 30 × 10 × 4 mm",
 "kind": "hardware",
 "category": "Hardware",
 "group": "Magnets & seals",
 "year": null,
 "question": "What size is a 30 × 10 × 4 block magnet?",
 "tags": [
  "magnet",
  "neodymium",
  "block magnet",
  "tri-clamp",
  "stirling",
  "long earth society"
 ],
 "aliases": [
  "30x10x4 magnet",
  "block magnet 30 x 10 x 4",
  "neodymium bar magnet dimensions"
 ],
 "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/neodymium-block-magnets/",
 "sheet_txt": "https://xemstudio.com/objects/neodymium-block-magnets/sheet.txt",
 "sheet": {
  "basis": "Nominal size as sold; magnetised through the 4 mm dimension",
  "overall_mm": {
   "length": null,
   "width": null,
   "height": null
  },
  "notes": [
   "A rectangular neodymium block 30 × 10 × 4 mm, magnetised through its 4 mm thickness, a stock size. Drawn at the nominal size with square edges.",
   "On the free-piston mover 48 of them sit on the 12 flats of the core in four rows, alternately N and S outward."
  ],
  "table": {
   "columns": [
    "length_mm",
    "width_mm",
    "thickness_mm",
    "magnetised"
   ],
   "rows": [
    [
     30,
     10,
     4,
     "through 4"
    ]
   ]
  }
 },
 "sheet_text": "Neodymium block magnets: 30 × 10 × 4 mm — dimension sheet\nSource: Xem Studio, https://xemstudio.com/objects/neodymium-block-magnets/  (CC BY 4.0)\nBasis: Nominal size as sold; magnetised through the 4 mm dimension\nCatalog version: 2026-10-20\n\nSizes: see table below\n- A rectangular neodymium block 30 × 10 × 4 mm, magnetised through its 4 mm thickness, a stock size. Drawn at the nominal size with square edges.\n- On the free-piston mover 48 of them sit on the 12 flats of the core in four rows, alternately N and S outward.\n\nlength_mm  width_mm  thickness_mm  magnetised\n30  10  4  through 4\n\nFiles elsewhere (not hosted by Xem Studio; license as stated by the publisher):\n- Xem Studio: tools/gen_ta_power.py: the network model and every dimension on this page — code — CC BY 4.0 — https://xemstudio.com/\n- Long Earth Society: 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/neodymium-block-magnets/index.json\nAPI: https://xemstudio.com/api/geometry?object=neodymium-block-magnets\n",
 "sources": [
  {
   "publisher": "Xem Studio",
   "title": "tools/gen_ta_power.py: the network model and every dimension on this page",
   "url": "https://xemstudio.com/",
   "formats": [
    "code"
   ],
   "license": "CC BY 4.0",
   "license_verified": true,
   "hosted": false
  },
  {
   "publisher": "Long Earth Society",
   "title": "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": [
  "neodymium-disc-magnets",
  "free-piston-mover-2in"
 ],
 "fits": [],
 "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": "inner face",
   "exact": "30 × 10",
   "mates": "mover-core flat (bonded)",
   "fit": "designed",
   "files": "all"
  },
  {
   "feature": "outer face to sleeve",
   "exact": "r 22.66 (corners r 23.2) under the Ø47.00 sleeve bore",
   "mates": "mover sleeve (no contact)",
   "fit": "designed",
   "files": "all"
  }
 ],
 "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": "Which way is it magnetised?",
   "a": "Through the 4 mm thickness, so one 30 × 10 face is N and the other S."
  }
 ],
 "files_license": null,
 "offers": [
  {
   "file": "magnet-block-30x10x4",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "CC BY 4.0 (Xem Studio)",
   "step": "https://xemstudio.com/files/hardware/neodymium-block-magnets/magnet-block-30x10x4.step",
   "stl": "https://xemstudio.com/files/hardware/neodymium-block-magnets/magnet-block-30x10x4.stl",
   "note": "block magnet 30 × 10 × 4, magnetised through the 4 mm thickness"
  }
 ],
 "markdown": "https://xemstudio.com/objects/neodymium-block-magnets/index.md"
}