{
 "version": "2026-10-20",
 "license": "Dimension sheets: CC BY 4.0. Standard and published-size files: CC BY 4.0. Xem Studio's own designs (files_license = Xem Studio Design License): free to use and sell things from, not to redistribute as files — https://xemstudio.com/license/. Other publishers' files: their own license, linked beside them.",
 "slug": "face-spiral-disc-m1-r20-8-4turns-d100",
 "name": "Face spiral (scroll) disc, pitch 3.14 (module 1), r 20 → 46.39, Ø100 × 6",
 "kind": "modern",
 "category": "Mechanisms",
 "group": "Screws & feeds",
 "year": null,
 "question": "What is a face spiral disc?",
 "tags": [
  "mechanism part",
  "507 mechanical movements"
 ],
 "aliases": [
  "face spiral",
  "scroll",
  "spiral disc",
  "face worm",
  "scroll plate",
  "disco con espiral frontal (caracol)",
  "Spiralscheibe (Schnecke auf der Stirnseite)"
 ],
 "overall_mm": {
  "length": 100,
  "width": 100,
  "height": 8.25
 },
 "official_cad": false,
 "xem_status": "free-files",
 "les": false,
 "free_files": 1,
 "url": "https://xemstudio.com/objects/face-spiral-disc-m1-r20-8-4turns-d100/",
 "sheet_txt": "https://xemstudio.com/objects/face-spiral-disc-m1-r20-8-4turns-d100/sheet.txt",
 "sheet": {
  "basis": "Xem Studio design following Brown's figure (1868); true size, no printing allowance",
  "overall_mm": {
   "length": 100,
   "width": 100,
   "height": 8.25
  },
  "notes": [
   "A Ø100 × 6 disc with one raised Archimedean spiral rib on its face: radial pitch p = π m = 3.14 mm, from radius 20 to 46.39 (8.4 turns), Ø8 bore. The rib's radial section is the basic rack of module 1 (20° flanks, πm/2 thick at its pitch height 1.25 mm above the face, top at 2.25 mm): seen by a toothed part standing over the face, the rib is a rack that advances p per turn of the disc — a worm unrolled onto a face.",
   "Swept along the spiral with the profile kept upright and normal to the path; the bottom of the rib runs 0.5 mm into the disc so it is one solid.",
   "Xem Studio design following Brown's figure; true size, no printing allowance (apply your own to the mating features)."
  ],
  "table": {
   "columns": [
    "dimension",
    "value"
   ],
   "rows": [
    [
     "pitch p",
     "3.14 mm (module 1)"
    ],
    [
     "spiral",
     "r 20 → 46.39, 8.4 turns"
    ],
    [
     "rib height",
     "2.25 mm above the face"
    ],
    [
     "disc",
     "Ø100 × 6"
    ],
    [
     "bore",
     "Ø8"
    ]
   ]
  }
 },
 "sheet_text": "Face spiral (scroll) disc, pitch 3.14 (module 1), r 20 → 46.39, Ø100 × 6 — dimension sheet\nSource: Xem Studio, https://xemstudio.com/objects/face-spiral-disc-m1-r20-8-4turns-d100/  (sheet CC BY 4.0; files Xem Studio Design License, https://xemstudio.com/license/)\nBasis: Xem Studio design following Brown's figure (1868); true size, no printing allowance\nCatalog version: 2026-10-20\n\nOverall (mm): length 100.0, width 100.0, height 8.25\n- A Ø100 × 6 disc with one raised Archimedean spiral rib on its face: radial pitch p = π m = 3.14 mm, from radius 20 to 46.39 (8.4 turns), Ø8 bore. The rib's radial section is the basic rack of module 1 (20° flanks, πm/2 thick at its pitch height 1.25 mm above the face, top at 2.25 mm): seen by a toothed part standing over the face, the rib is a rack that advances p per turn of the disc — a worm unrolled onto a face.\n- Swept along the spiral with the profile kept upright and normal to the path; the bottom of the rib runs 0.5 mm into the disc so it is one solid.\n- Xem Studio design following Brown's figure; true size, no printing allowance (apply your own to the mating features).\n\ndimension  value\npitch p  3.14 mm (module 1)\nspiral  r 20 → 46.39, 8.4 turns\nrib height  2.25 mm above the face\ndisc  Ø100 × 6\nbore  Ø8\n\nFiles elsewhere (not hosted by Xem Studio; license as stated by the publisher):\n- Henry T. Brown (1868, public domain): Five Hundred and Seven Mechanical Movements — scan on archive.org — web — Publisher's page; dimensions are facts — https://archive.org/details/fivehundredseven00browiala\n- 507movements.com: Brown's movement No. 99: figure, his text and an animation — web — Publisher's page; dimensions are facts — https://507movements.com/mm_099.html\n- Xem Studio: drawing — web — Publisher's page; dimensions are facts — https://xemstudio.com/objects/face-spiral-rack-feed-mechanism/\n\nFree files (Xem Studio Design License, Xem Studio; STEP + STL, 1 parts): https://xemstudio.com/files/hardware/face-spiral-disc-m1-r20-8-4turns-d100/index.json\nAPI: https://xemstudio.com/api/geometry?object=face-spiral-disc-m1-r20-8-4turns-d100\n",
 "sources": [
  {
   "publisher": "Henry T. Brown (1868, public domain)",
   "title": "Five Hundred and Seven Mechanical Movements — scan on archive.org",
   "url": "https://archive.org/details/fivehundredseven00browiala",
   "formats": [
    "web"
   ],
   "license": "Publisher's page; dimensions are facts",
   "license_verified": true,
   "hosted": false
  },
  {
   "publisher": "507movements.com",
   "title": "Brown's movement No. 99: figure, his text and an animation",
   "url": "https://507movements.com/mm_099.html",
   "formats": [
    "web"
   ],
   "license": "Publisher's page; dimensions are facts",
   "license_verified": true,
   "hosted": false
  },
  {
   "publisher": "Xem Studio",
   "title": "drawing",
   "url": "https://xemstudio.com/objects/face-spiral-rack-feed-mechanism/",
   "formats": [
    "web"
   ],
   "license": "Publisher's page; dimensions are facts",
   "license_verified": true,
   "hosted": false
  }
 ],
 "xem": {
  "status": "free-files",
  "sheet_free": true,
  "mesh_price_usd": null,
  "step_price_usd": null,
  "tolerance_mm": null
 },
 "related": [
  "face-spiral-rack-feed-mechanism"
 ],
 "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": [],
 "faq": [
  {
   "q": "What is a face spiral disc?",
   "a": "A Ø100 × 6 disc with one raised Archimedean spiral rib on its face: radial pitch p = π m = 3.14 mm, from radius 20 to 46.39 (8.4 turns), Ø8 bore. The rib's radial section is the basic rack of module 1 (20° flanks, πm/2 thick at its pitch height 1.25 mm above the face, top at 2.25 mm): seen by a toothed part standing over the face, the rib is a rack that advances p per turn of the disc — a worm unrolled onto a face."
  }
 ],
 "files_license": {
  "name": "Xem Studio Design License",
  "holder": "Xem Studio",
  "url": "https://xemstudio.com/license/",
  "note": "Xem Studio's own design: free to use, print, modify and sell things made from it; not to be republished or redistributed as files."
 },
 "offers": [
  {
   "file": "face-spiral-disc-m1-r20-8-4turns-d100",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "Xem Studio Design License",
   "step": "https://xemstudio.com/files/hardware/face-spiral-disc-m1-r20-8-4turns-d100/face-spiral-disc-m1-r20-8-4turns-d100.step",
   "stl": "https://xemstudio.com/files/hardware/face-spiral-disc-m1-r20-8-4turns-d100/face-spiral-disc-m1-r20-8-4turns-d100.stl",
   "note": "disc, axis Z, face at z = 0, rib up to z = 2.25"
  }
 ],
 "markdown": "https://xemstudio.com/objects/face-spiral-disc-m1-r20-8-4turns-d100/index.md"
}