{
 "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-rack-feed-mechanism",
 "name": "Face spiral on a disc as a drill feed: scroll driving a rack",
 "kind": "hardware",
 "category": "Mechanisms",
 "group": "Screws & feeds",
 "year": null,
 "question": "How does a spiral on a disc give a drill its feed?",
 "tags": [
  "mechanism",
  "screws & feeds",
  "kinematics",
  "507 mechanical movements"
 ],
 "aliases": [
  "drill feed scroll",
  "spiral feed",
  "scroll and rack",
  "face spiral rack",
  "avance de taladro por espiral frontal",
  "Bohrvorschub mit Spiralscheibe und Zahnstange"
 ],
 "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/face-spiral-rack-feed-mechanism/",
 "sheet_txt": "https://xemstudio.com/objects/face-spiral-rack-feed-mechanism/sheet.txt",
 "sheet": {
  "basis": "Xem Studio design following Brown No. 99 (1868)",
  "overall_mm": {
   "length": null,
   "width": null,
   "height": null
  },
  "notes": [
   "Resize: multiply every length by one factor k and the motion stays identical: angles, ratios, timing and the formulas below do not change, because a mechanism's motion depends only on the ratios of its lengths. Here, scales with k: feed per turn, rack height over the face; stays the same: disc, rack.",
   "Resize: fit clearances stay in mm (a slide fit is the same gap at any size); keep every printed wall and pin at least two nozzle widths; mass grows with k³ but part strength only with k², so at k = 2 parts are about 8× heavier and 4× stronger: check pins and thin links when scaling up.",
   "A spiral rib on the face of a disc engages a rack that slides radially over it: every turn of the disc moves the rack one pitch (3.14 mm) outward or inward — a slow, smooth feed from a continuously turning disc, the scroll-chuck principle used for the feed motion of drilling machines (the rack is on the drill's spindle sleeve).",
   "The rib's radial section is the module 1 basic rack; the feed rack's teeth were generated by the rib across the rack's 8 mm width, so they curve to follow the spiral and mesh without binding. With this 8.4-turn scroll (r 20 → 46.39) the 6-tooth rack stays fully on the rib over about ±3 mm of travel about the drawn position; a longer scroll gives a longer stroke. Checked at six positions over two turns: no overlap beyond contact.",
   "Brown's No. 99 (spiral guide on the face of a disc, drilling-machine feed). Drawn with the disc turned 90°, the rack's centre 31.78 mm from the disc's axis; the rack's guide is not drawn.",
   "Parts (each has its own page): face-spiral-disc-m1-r20-8-4turns-d100, face-spiral-feed-rack-m1-6t-w8, linear-shafts-h6.",
   "Brown's movement No. 99 (1868) shows it; this model is a Xem Studio design following his figure, every part at true size."
  ],
  "table": {
   "columns": [
    "parameter",
    "value"
   ],
   "rows": [
    [
     "disc",
     "Ø100 × 6, spiral r 20 → 46.39 (8.4 turns)"
    ],
    [
     "feed per turn",
     "3.14 mm"
    ],
    [
     "rack",
     "6 T, module 1, 19.05 long"
    ],
    [
     "rack height over the face",
     "pitch line 1.25 mm"
    ]
   ]
  }
 },
 "sheet_text": "Face spiral on a disc as a drill feed: scroll driving a rack — dimension sheet\nSource: Xem Studio, https://xemstudio.com/objects/face-spiral-rack-feed-mechanism/  (sheet CC BY 4.0; files Xem Studio Design License, https://xemstudio.com/license/)\nBasis: Xem Studio design following Brown No. 99 (1868)\nCatalog version: 2026-10-20\n\nSizes: see table below\n- Resize: multiply every length by one factor k and the motion stays identical: angles, ratios, timing and the formulas below do not change, because a mechanism's motion depends only on the ratios of its lengths. Here, scales with k: feed per turn, rack height over the face; stays the same: disc, rack.\n- Resize: fit clearances stay in mm (a slide fit is the same gap at any size); keep every printed wall and pin at least two nozzle widths; mass grows with k³ but part strength only with k², so at k = 2 parts are about 8× heavier and 4× stronger: check pins and thin links when scaling up.\n- A spiral rib on the face of a disc engages a rack that slides radially over it: every turn of the disc moves the rack one pitch (3.14 mm) outward or inward — a slow, smooth feed from a continuously turning disc, the scroll-chuck principle used for the feed motion of drilling machines (the rack is on the drill's spindle sleeve).\n- The rib's radial section is the module 1 basic rack; the feed rack's teeth were generated by the rib across the rack's 8 mm width, so they curve to follow the spiral and mesh without binding. With this 8.4-turn scroll (r 20 → 46.39) the 6-tooth rack stays fully on the rib over about ±3 mm of travel about the drawn position; a longer scroll gives a longer stroke. Checked at six positions over two turns: no overlap beyond contact.\n- Brown's No. 99 (spiral guide on the face of a disc, drilling-machine feed). Drawn with the disc turned 90°, the rack's centre 31.78 mm from the disc's axis; the rack's guide is not drawn.\n- Parts (each has its own page): face-spiral-disc-m1-r20-8-4turns-d100, face-spiral-feed-rack-m1-6t-w8, linear-shafts-h6.\n- Brown's movement No. 99 (1868) shows it; this model is a Xem Studio design following his figure, every part at true size.\n\nparameter  value\ndisc  Ø100 × 6, spiral r 20 → 46.39 (8.4 turns)\nfeed per turn  3.14 mm\nrack  6 T, module 1, 19.05 long\nrack height over the face  pitch line 1.25 mm\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\nFree files (Xem Studio Design License, Xem Studio; STEP + STL, 1 parts): https://xemstudio.com/files/hardware/face-spiral-rack-feed-mechanism/index.json\nAPI: https://xemstudio.com/api/geometry?object=face-spiral-rack-feed-mechanism\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
  }
 ],
 "xem": {
  "status": "free-files",
  "sheet_free": true,
  "mesh_price_usd": null,
  "step_price_usd": null,
  "tolerance_mm": null
 },
 "related": [
  "face-spiral-disc-m1-r20-8-4turns-d100",
  "face-spiral-feed-rack-m1-6t-w8",
  "linear-shafts-h6"
 ],
 "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": "How does a spiral on a disc give a drill its feed?",
   "a": "A spiral rib on the face of a disc engages a rack that slides radially over it: every turn of the disc moves the rack one pitch (3.14 mm) outward or inward — a slow, smooth feed from a continuously turning disc, the scroll-chuck principle used for the feed motion of drilling machines (the rack is on the drill's spindle sleeve)."
  }
 ],
 "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-rack-feed-mechanism-assembly",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "Xem Studio Design License",
   "step": "https://xemstudio.com/files/hardware/face-spiral-rack-feed-mechanism/face-spiral-rack-feed-mechanism-assembly.step",
   "stl": "https://xemstudio.com/files/hardware/face-spiral-rack-feed-mechanism/face-spiral-rack-feed-mechanism-assembly.stl",
   "note": "Assembled mechanism, all parts placed at one pose (STEP keeps each part separate)"
  }
 ],
 "markdown": "https://xemstudio.com/objects/face-spiral-rack-feed-mechanism/index.md"
}