{
 "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": "differential-screw-mechanism",
 "name": "Differential screw (fine adjustment)",
 "kind": "hardware",
 "category": "Mechanisms",
 "group": "Screws",
 "year": null,
 "question": "How does a differential screw give fine adjustment?",
 "tags": [
  "mechanism",
  "screws",
  "kinematics"
 ],
 "aliases": [
  "differential screw",
  "differential thread",
  "fine adjustment screw"
 ],
 "overall_mm": {
  "length": null,
  "width": null,
  "height": null
 },
 "official_cad": false,
 "xem_status": "not-scanned",
 "les": false,
 "free_files": 0,
 "url": "https://xemstudio.com/objects/differential-screw-mechanism/",
 "sheet_txt": "https://xemstudio.com/objects/differential-screw-mechanism/sheet.txt",
 "sheet": {
  "basis": "Xem Studio drawing; classic mechanism (Brown No. 266)",
  "overall_mm": {
   "length": null,
   "width": null,
   "height": null
  },
  "notes": [
   "Two threads of pitch p₁ and p₂ on one screw, each in its own nut, one nut fixed: a turn moves the free nut by p₁ − p₂ (0.25 mm for 1.25 and 1.0 mm), with the strength of coarse threads.",
   "Same hand on both threads gives the difference; opposite hands give the sum (a turnbuckle).",
   "Used in micrometer stages and precision adjusters. Brown's movement 266 shows a shaft with two pitches moving a bearing by their difference.",
   "Parts (each has its own page): differential-screw-m8, threaded-rods-metric, hex-nuts-metric. Brown's movement No. 266 shows it (1868)."
  ],
  "table": {
   "columns": [
    "parameter",
    "value"
   ],
   "rows": [
    [
     "pitch p₁",
     "1.25 mm"
    ],
    [
     "pitch p₂",
     "1.0 mm"
    ],
    [
     "advance / turn",
     "0.25 mm"
    ]
   ]
  }
 },
 "sheet_text": "Differential screw (fine adjustment) — dimension sheet\nSource: Xem Studio, https://xemstudio.com/objects/differential-screw-mechanism/  (CC BY 4.0)\nBasis: Xem Studio drawing; classic mechanism (Brown No. 266)\nCatalog version: 2026-10-20\n\nSizes: see table below\n- Two threads of pitch p₁ and p₂ on one screw, each in its own nut, one nut fixed: a turn moves the free nut by p₁ − p₂ (0.25 mm for 1.25 and 1.0 mm), with the strength of coarse threads.\n- Same hand on both threads gives the difference; opposite hands give the sum (a turnbuckle).\n- Used in micrometer stages and precision adjusters. Brown's movement 266 shows a shaft with two pitches moving a bearing by their difference.\n- Parts (each has its own page): differential-screw-m8, threaded-rods-metric, hex-nuts-metric. Brown's movement No. 266 shows it (1868).\n\nparameter  value\npitch p₁  1.25 mm\npitch p₂  1.0 mm\nadvance / turn  0.25 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\nXem Studio scan: not needed; this is a published standard. The sheet is the geometry.\nAPI: https://xemstudio.com/api/geometry?object=differential-screw-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
  }
 ],
 "xem": {
  "status": "not-scanned",
  "sheet_free": true,
  "mesh_price_usd": null,
  "step_price_usd": null,
  "tolerance_mm": null
 },
 "related": [
  "differential-screw-m8",
  "threaded-rods-metric",
  "hex-nuts-metric"
 ],
 "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 differential screw give fine adjustment?",
   "a": "Two threads of pitch p₁ and p₂ on one screw, each in its own nut, one nut fixed: a turn moves the free nut by p₁ − p₂ (0.25 mm for 1.25 and 1.0 mm), with the strength of coarse threads."
  }
 ],
 "files_license": null,
 "offers": [],
 "markdown": "https://xemstudio.com/objects/differential-screw-mechanism/index.md"
}