{
 "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": "lazy-tongs-mechanism",
 "name": "Lazy tongs (three-cell scissor linkage)",
 "kind": "hardware",
 "category": "Mechanisms",
 "group": "Linkages",
 "year": null,
 "question": "How much do lazy tongs multiply motion?",
 "tags": [
  "mechanism",
  "linkages",
  "kinematics",
  "507 mechanical movements"
 ],
 "aliases": [
  "lazy tongs",
  "scissor linkage",
  "scissor mechanism",
  "extending tongs",
  "tenazas extensibles (mecanismo de tijera)",
  "Nürnberger Schere"
 ],
 "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/lazy-tongs-mechanism/",
 "sheet_txt": "https://xemstudio.com/objects/lazy-tongs-mechanism/sheet.txt",
 "sheet": {
  "basis": "Xem Studio design following Brown No. 144 (1868)",
  "overall_mm": {
   "length": null,
   "width": null,
   "height": null
  },
  "notes": [
   "Crossed bars pinned at their middles and ends: closing the handles a little extends the far end a lot. With n cells the end moves n times as far as the first cell's joint (3 here), and every joint stays on the centre line.",
   "Each bar is the 80 mm centre-hole link; length along the axis = 2·n·40·cos α (207.8 mm at α = 30° here).",
   "Brown's No. 144 (lazy tongs); the scissor lift and the extending mirror arm are the same linkage.",
   "Parts (each has its own page): centre-hole-link-80, dowel-pins-metric.",
   "Brown's movement No. 144 (1868) shows it; this model is a Xem Studio design following his figure, every part at true size."
  ],
  "table": {
   "columns": [
    "parameter",
    "value"
   ],
   "rows": [
    [
     "cells",
     "3"
    ],
    [
     "bars",
     "6 × 80 mm centre-hole links"
    ],
    [
     "angle drawn",
     "30° to the axis"
    ],
    [
     "reach at 30°",
     "207.8 mm"
    ]
   ]
  }
 },
 "sheet_text": "Lazy tongs (three-cell scissor linkage) — dimension sheet\nSource: Xem Studio, https://xemstudio.com/objects/lazy-tongs-mechanism/  (CC BY 4.0)\nBasis: Xem Studio design following Brown No. 144 (1868)\nCatalog version: 2026-10-20\n\nSizes: see table below\n- Crossed bars pinned at their middles and ends: closing the handles a little extends the far end a lot. With n cells the end moves n times as far as the first cell's joint (3 here), and every joint stays on the centre line.\n- Each bar is the 80 mm centre-hole link; length along the axis = 2·n·40·cos α (207.8 mm at α = 30° here).\n- Brown's No. 144 (lazy tongs); the scissor lift and the extending mirror arm are the same linkage.\n- Parts (each has its own page): centre-hole-link-80, dowel-pins-metric.\n- Brown's movement No. 144 (1868) shows it; this model is a Xem Studio design following his figure, every part at true size.\n\nparameter  value\ncells  3\nbars  6 × 80 mm centre-hole links\nangle drawn  30° to the axis\nreach at 30°  207.8 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. 144: figure, his text and an animation — web — Publisher's page; dimensions are facts — https://507movements.com/mm_144.html\n\nFree files (CC BY 4.0, Xem Studio; STEP + STL, 1 parts): https://xemstudio.com/files/hardware/lazy-tongs-mechanism/index.json\nAPI: https://xemstudio.com/api/geometry?object=lazy-tongs-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. 144: figure, his text and an animation",
   "url": "https://507movements.com/mm_144.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": [
  "centre-hole-link-80",
  "dowel-pins-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 much do lazy tongs multiply motion?",
   "a": "Crossed bars pinned at their middles and ends: closing the handles a little extends the far end a lot. With n cells the end moves n times as far as the first cell's joint (3 here), and every joint stays on the centre line."
  }
 ],
 "files_license": null,
 "offers": [
  {
   "file": "lazy-tongs-mechanism-assembly",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "CC BY 4.0 (Xem Studio)",
   "step": "https://xemstudio.com/files/hardware/lazy-tongs-mechanism/lazy-tongs-mechanism-assembly.step",
   "stl": "https://xemstudio.com/files/hardware/lazy-tongs-mechanism/lazy-tongs-mechanism-assembly.stl",
   "note": "Assembled mechanism, all parts placed at one pose (STEP keeps each part separate)"
  }
 ],
 "markdown": "https://xemstudio.com/objects/lazy-tongs-mechanism/index.md"
}