{
 "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": "tooth-lock-washers-inch-asme-b18-21-1",
 "name": "Tooth lock washers, inch (ASME B18.21.1): internal and external tooth star washers, #2 to 1 in, ID, OD, thickness + ring envelopes",
 "kind": "standard",
 "category": "Hardware",
 "group": "Fasteners",
 "year": null,
 "question": "What are the ID, OD and thickness of a #8 or 1/4 internal tooth or external tooth lock washer?",
 "tags": [
  "tooth lock washer",
  "star washer",
  "internal tooth lock washer",
  "external tooth lock washer",
  "serrated lock washer",
  "shakeproof washer",
  "asme b18.21.1",
  "fastener",
  "washer",
  "inch"
 ],
 "aliases": [
  "internal tooth lock washer dimensions",
  "external tooth lock washer dimensions",
  "#8 star washer od",
  "1/4 external tooth lock washer od",
  "#10 internal tooth lock washer id",
  "star washer size chart",
  "tooth lock washer thickness 1/4",
  "3/8 internal tooth lock washer",
  "star washer 5/16 od",
  "asme b18.21.1 tooth lock washer",
  "internal vs external tooth washer",
  "tooth lock washer stl"
 ],
 "overall_mm": {
  "length": 31.6,
  "width": 31.6,
  "height": 1.7
 },
 "official_cad": false,
 "xem_status": "free-files",
 "les": false,
 "free_files": 20,
 "url": "https://xemstudio.com/objects/tooth-lock-washers-inch-asme-b18-21-1/",
 "sheet_txt": "https://xemstudio.com/objects/tooth-lock-washers-inch-asme-b18-21-1/sheet.txt",
 "sheet": {
  "basis": "AFT Fasteners and Tanner Bolt (internal tooth, ASME B18.21.1-2009, identical numbers) and Tanner Bolt with Aspen Fasteners (external tooth, B18.21.1-2009 and -1999, identical numbers); 20 ring envelopes as files",
  "overall_mm": {
   "length": 31.6,
   "width": 31.6,
   "height": 1.7
  },
  "notes": [
   "Inches (OD also in mm). Internal tooth: #2 to 1-1/4 in; external tooth: #2 to 1 in. Each row: nominal size, inside diameter max / min, outside diameter max / min, thickness max / min. AFT's and Tanner's internal-tooth tables carry the same numbers for every size. Tanner's external table (2009) and Aspen's (1999) also agree on every size, including the odd 'nominal' of 0.086 / 0.563 for #2 and 9/16 (Aspen rounds 9/16 to .563; Tanner prints .5625).",
   "Column reading: the PDFs print a leading decimal that is the size's nominal diameter, then the inside diameter pair (larger first on the sources that label it 'max'), the outside pair and the thickness pair. The labels in the extracted PDFs are partly garbled, so max / min follow the larger / smaller of each pair; check against the standard if a figure matters. One AFT / Tanner row not tabulated: '1/8 pipe' (a pipe-size washer printed with a different column pattern).",
   "Number of teeth is not printed in any table read here, and is left out. Tooth shape (twist angle, tooth width) is not published as numbers.",
   "Files: rings (annuli) at the ID min and OD max of the washer and the maximum thickness, for #4, #6, #8, #10, 1/4, 5/16, 3/8, 1/2, 5/8 and 3/4 in, internal and external. Teeth, their twist and the washer's spring are not modelled. McMaster-Carr sells tooth lock washers with per-part STEP; linked, not copied. Metric forms: serrated-lock-washers-din-6798. Split washers: split-lock-washers-inch-asme-b18-21-1."
  ],
  "table": {
   "columns": [
    "type",
    "size",
    "nominal (in)",
    "ID max / min (in)",
    "OD max / min (in)",
    "thickness max / min (in)",
    "OD max (mm)"
   ],
   "rows": [
    [
     "internal tooth",
     "#2",
     "0.086",
     "0.095 / 0.089",
     "0.200 / 0.175",
     "0.016 / 0.010",
     "5.08"
    ],
    [
     "internal tooth",
     "#3",
     "0.099",
     "0.109 / 0.102",
     "0.232 / 0.215",
     "0.016 / 0.010",
     "5.89"
    ],
    [
     "internal tooth",
     "#4",
     "0.112",
     "0.123 / 0.115",
     "0.270 / 0.245",
     "0.018 / 0.012",
     "6.86"
    ],
    [
     "internal tooth",
     "#5",
     "0.125",
     "0.136 / 0.129",
     "0.280 / 0.255",
     "0.020 / 0.014",
     "7.11"
    ],
    [
     "internal tooth",
     "#6",
     "0.138",
     "0.150 / 0.141",
     "0.295 / 0.275",
     "0.022 / 0.016",
     "7.49"
    ],
    [
     "internal tooth",
     "#8",
     "0.164",
     "0.176 / 0.168",
     "0.340 / 0.325",
     "0.023 / 0.018",
     "8.64"
    ],
    [
     "internal tooth",
     "#10",
     "0.19",
     "0.204 / 0.195",
     "0.381 / 0.365",
     "0.024 / 0.018",
     "9.68"
    ],
    [
     "internal tooth",
     "#12",
     "0.216",
     "0.231 / 0.221",
     "0.410 / 0.394",
     "0.027 / 0.020",
     "10.41"
    ],
    [
     "internal tooth",
     "1/4",
     "0.25",
     "0.267 / 0.256",
     "0.478 / 0.460",
     "0.028 / 0.023",
     "12.14"
    ],
    [
     "internal tooth",
     "5/16",
     "0.312",
     "0.332 / 0.320",
     "0.610 / 0.594",
     "0.034 / 0.028",
     "15.49"
    ],
    [
     "internal tooth",
     "3/8",
     "0.375",
     "0.398 / 0.384",
     "0.692 / 0.670",
     "0.040 / 0.032",
     "17.58"
    ],
    [
     "internal tooth",
     "7/16",
     "0.438",
     "0.464 / 0.448",
     "0.789 / 0.740",
     "0.040 / 0.032",
     "20.04"
    ],
    [
     "internal tooth",
     "1/2",
     "0.5",
     "0.530 / 0.512",
     "0.900 / 0.867",
     "0.045 / 0.037",
     "22.86"
    ],
    [
     "internal tooth",
     "9/16",
     "0.5625",
     "0.596 / 0.576",
     "0.985 / 0.957",
     "0.045 / 0.037",
     "25.02"
    ],
    [
     "internal tooth",
     "5/8",
     "0.625",
     "0.663 / 0.640",
     "1.071 / 1.045",
     "0.050 / 0.042",
     "27.20"
    ],
    [
     "internal tooth",
     "3/4",
     "0.75",
     "0.795 / 0.769",
     "1.245 / 1.220",
     "0.055 / 0.047",
     "31.62"
    ],
    [
     "internal tooth",
     "7/8",
     "0.875",
     "0.927 / 0.894",
     "1.410 / 1.364",
     "0.060 / 0.052",
     "35.81"
    ],
    [
     "internal tooth",
     "1",
     "1.",
     "1.060 / 1.019",
     "1.637 / 1.590",
     "0.067 / 0.059",
     "41.58"
    ],
    [
     "internal tooth",
     "1-1/8",
     "1.125",
     "1.192 / 1.144",
     "1.830 / 1.799",
     "0.067 / 0.059",
     "46.48"
    ],
    [
     "internal tooth",
     "1-1/4",
     "1.25",
     "1.325 / 1.275",
     "1.975 / 1.921",
     "0.067 / 0.059",
     "50.16"
    ],
    [
     "external tooth",
     "#2",
     "0.086",
     "0.095 / 0.086",
     "0.189 / 0.177",
     "0.013 / 0.010",
     "4.80"
    ],
    [
     "external tooth",
     "#3",
     "0.099",
     "0.109 / 0.102",
     "0.235 / 0.220",
     "0.016 / 0.010",
     "5.97"
    ],
    [
     "external tooth",
     "#4",
     "0.112",
     "0.123 / 0.115",
     "0.260 / 0.245",
     "0.018 / 0.012",
     "6.60"
    ],
    [
     "external tooth",
     "#5",
     "0.125",
     "0.136 / 0.129",
     "0.285 / 0.270",
     "0.020 / 0.014",
     "7.24"
    ],
    [
     "external tooth",
     "#6",
     "0.138",
     "0.150 / 0.141",
     "0.320 / 0.305",
     "0.022 / 0.016",
     "8.13"
    ],
    [
     "external tooth",
     "#8",
     "0.164",
     "0.176 / 0.168",
     "0.381 / 0.365",
     "0.023 / 0.018",
     "9.68"
    ],
    [
     "external tooth",
     "#10",
     "0.19",
     "0.204 / 0.195",
     "0.410 / 0.395",
     "0.024 / 0.018",
     "10.41"
    ],
    [
     "external tooth",
     "#12",
     "0.216",
     "0.231 / 0.221",
     "0.475 / 0.460",
     "0.027 / 0.020",
     "12.06"
    ],
    [
     "external tooth",
     "1/4",
     "0.25",
     "0.267 / 0.256",
     "0.510 / 0.494",
     "0.028 / 0.023",
     "12.95"
    ],
    [
     "external tooth",
     "5/16",
     "0.312",
     "0.332 / 0.320",
     "0.610 / 0.588",
     "0.034 / 0.028",
     "15.49"
    ],
    [
     "external tooth",
     "3/8",
     "0.375",
     "0.398 / 0.384",
     "0.694 / 0.670",
     "0.040 / 0.032",
     "17.63"
    ],
    [
     "external tooth",
     "7/16",
     "0.438",
     "0.464 / 0.448",
     "0.760 / 0.740",
     "0.040 / 0.032",
     "19.30"
    ],
    [
     "external tooth",
     "1/2",
     "0.5",
     "0.530 / 0.513",
     "0.900 / 0.880",
     "0.045 / 0.037",
     "22.86"
    ],
    [
     "external tooth",
     "9/16",
     "0.563",
     "0.596 / 0.576",
     "0.985 / 0.960",
     "0.045 / 0.037",
     "25.02"
    ],
    [
     "external tooth",
     "5/8",
     "0.625",
     "0.663 / 0.641",
     "1.070 / 1.045",
     "0.050 / 0.042",
     "27.18"
    ],
    [
     "external tooth",
     "3/4",
     "0.75",
     "0.795 / 0.768",
     "1.260 / 1.220",
     "0.055 / 0.047",
     "32.00"
    ],
    [
     "external tooth",
     "7/8",
     "0.875",
     "0.927 / 0.897",
     "1.410 / 1.380",
     "0.060 / 0.052",
     "35.81"
    ],
    [
     "external tooth",
     "1",
     "1.",
     "1.060 / 1.025",
     "1.620 / 1.590",
     "0.067 / 0.059",
     "41.15"
    ]
   ]
  }
 },
 "sheet_text": "Tooth lock washers, inch (ASME B18.21.1): internal and external tooth star washers, #2 to 1 in, ID, OD, thickness + ring envelopes — dimension sheet\nSource: Xem Studio, https://xemstudio.com/objects/tooth-lock-washers-inch-asme-b18-21-1/  (sheet CC BY 4.0)\nBasis: AFT Fasteners and Tanner Bolt (internal tooth, ASME B18.21.1-2009, identical numbers) and Tanner Bolt with Aspen Fasteners (external tooth, B18.21.1-2009 and -1999, identical numbers); 20 ring envelopes as files\nCatalog version: 2026-10-20\n\nOverall (mm): length 31.6, width 31.6, height 1.7\n- Inches (OD also in mm). Internal tooth: #2 to 1-1/4 in; external tooth: #2 to 1 in. Each row: nominal size, inside diameter max / min, outside diameter max / min, thickness max / min. AFT's and Tanner's internal-tooth tables carry the same numbers for every size. Tanner's external table (2009) and Aspen's (1999) also agree on every size, including the odd 'nominal' of 0.086 / 0.563 for #2 and 9/16 (Aspen rounds 9/16 to .563; Tanner prints .5625).\n- Column reading: the PDFs print a leading decimal that is the size's nominal diameter, then the inside diameter pair (larger first on the sources that label it 'max'), the outside pair and the thickness pair. The labels in the extracted PDFs are partly garbled, so max / min follow the larger / smaller of each pair; check against the standard if a figure matters. One AFT / Tanner row not tabulated: '1/8 pipe' (a pipe-size washer printed with a different column pattern).\n- Number of teeth is not printed in any table read here, and is left out. Tooth shape (twist angle, tooth width) is not published as numbers.\n- Files: rings (annuli) at the ID min and OD max of the washer and the maximum thickness, for #4, #6, #8, #10, 1/4, 5/16, 3/8, 1/2, 5/8 and 3/4 in, internal and external. Teeth, their twist and the washer's spring are not modelled. McMaster-Carr sells tooth lock washers with per-part STEP; linked, not copied. Metric forms: serrated-lock-washers-din-6798. Split washers: split-lock-washers-inch-asme-b18-21-1.\n\ntype  size  nominal (in)  ID max / min (in)  OD max / min (in)  thickness max / min (in)  OD max (mm)\ninternal tooth  #2  0.086  0.095 / 0.089  0.200 / 0.175  0.016 / 0.010  5.08\ninternal tooth  #3  0.099  0.109 / 0.102  0.232 / 0.215  0.016 / 0.010  5.89\ninternal tooth  #4  0.112  0.123 / 0.115  0.270 / 0.245  0.018 / 0.012  6.86\ninternal tooth  #5  0.125  0.136 / 0.129  0.280 / 0.255  0.020 / 0.014  7.11\ninternal tooth  #6  0.138  0.150 / 0.141  0.295 / 0.275  0.022 / 0.016  7.49\ninternal tooth  #8  0.164  0.176 / 0.168  0.340 / 0.325  0.023 / 0.018  8.64\ninternal tooth  #10  0.19  0.204 / 0.195  0.381 / 0.365  0.024 / 0.018  9.68\ninternal tooth  #12  0.216  0.231 / 0.221  0.410 / 0.394  0.027 / 0.020  10.41\ninternal tooth  1/4  0.25  0.267 / 0.256  0.478 / 0.460  0.028 / 0.023  12.14\ninternal tooth  5/16  0.312  0.332 / 0.320  0.610 / 0.594  0.034 / 0.028  15.49\ninternal tooth  3/8  0.375  0.398 / 0.384  0.692 / 0.670  0.040 / 0.032  17.58\ninternal tooth  7/16  0.438  0.464 / 0.448  0.789 / 0.740  0.040 / 0.032  20.04\ninternal tooth  1/2  0.5  0.530 / 0.512  0.900 / 0.867  0.045 / 0.037  22.86\ninternal tooth  9/16  0.5625  0.596 / 0.576  0.985 / 0.957  0.045 / 0.037  25.02\ninternal tooth  5/8  0.625  0.663 / 0.640  1.071 / 1.045  0.050 / 0.042  27.20\ninternal tooth  3/4  0.75  0.795 / 0.769  1.245 / 1.220  0.055 / 0.047  31.62\ninternal tooth  7/8  0.875  0.927 / 0.894  1.410 / 1.364  0.060 / 0.052  35.81\ninternal tooth  1  1.  1.060 / 1.019  1.637 / 1.590  0.067 / 0.059  41.58\ninternal tooth  1-1/8  1.125  1.192 / 1.144  1.830 / 1.799  0.067 / 0.059  46.48\ninternal tooth  1-1/4  1.25  1.325 / 1.275  1.975 / 1.921  0.067 / 0.059  50.16\nexternal tooth  #2  0.086  0.095 / 0.086  0.189 / 0.177  0.013 / 0.010  4.80\nexternal tooth  #3  0.099  0.109 / 0.102  0.235 / 0.220  0.016 / 0.010  5.97\nexternal tooth  #4  0.112  0.123 / 0.115  0.260 / 0.245  0.018 / 0.012  6.60\nexternal tooth  #5  0.125  0.136 / 0.129  0.285 / 0.270  0.020 / 0.014  7.24\nexternal tooth  #6  0.138  0.150 / 0.141  0.320 / 0.305  0.022 / 0.016  8.13\nexternal tooth  #8  0.164  0.176 / 0.168  0.381 / 0.365  0.023 / 0.018  9.68\nexternal tooth  #10  0.19  0.204 / 0.195  0.410 / 0.395  0.024 / 0.018  10.41\nexternal tooth  #12  0.216  0.231 / 0.221  0.475 / 0.460  0.027 / 0.020  12.06\nexternal tooth  1/4  0.25  0.267 / 0.256  0.510 / 0.494  0.028 / 0.023  12.95\nexternal tooth  5/16  0.312  0.332 / 0.320  0.610 / 0.588  0.034 / 0.028  15.49\nexternal tooth  3/8  0.375  0.398 / 0.384  0.694 / 0.670  0.040 / 0.032  17.63\nexternal tooth  7/16  0.438  0.464 / 0.448  0.760 / 0.740  0.040 / 0.032  19.30\nexternal tooth  1/2  0.5  0.530 / 0.513  0.900 / 0.880  0.045 / 0.037  22.86\nexternal tooth  9/16  0.563  0.596 / 0.576  0.985 / 0.960  0.045 / 0.037  25.02\nexternal tooth  5/8  0.625  0.663 / 0.641  1.070 / 1.045  0.050 / 0.042  27.18\nexternal tooth  3/4  0.75  0.795 / 0.768  1.260 / 1.220  0.055 / 0.047  32.00\nexternal tooth  7/8  0.875  0.927 / 0.897  1.410 / 1.380  0.060 / 0.052  35.81\nexternal tooth  1  1.  1.060 / 1.025  1.620 / 1.590  0.067 / 0.059  41.15\n\nFiles elsewhere (not hosted by Xem Studio; license as stated by the publisher):\n- AFT Fasteners: Internal tooth lock washer (ASME B18.21.1-2009): nominal, ID max / min, OD max / min, thickness max / min — web — Publisher's page; dimensions are facts — https://www.aftfasteners.com/internal-tooth-lock-washer/\n- Tanner Bolt: Internal tooth lock washers, ASME B18.21.1-2009 (PDF) — web — Maker datasheet; numbers only — https://www.tannerbolt.com/media/akeneo_connector/Washersinternal.pdf\n- Tanner Bolt: External tooth lock washers, ASME B18.21.1-2009 (PDF) — web — Maker datasheet; numbers only — https://www.tannerbolt.com/media/akeneo_connector/Washersexternal.pdf\n- Aspen Fasteners: External tooth lockwasher specification (ASME B18.21.1-1999) — web — Distributor datasheet; numbers only — https://www.aspenfasteners.com/content/pdf/external_tooth_lockwasher_specification.pdf\n- McMaster-Carr: Internal tooth lock washers (free STEP/IGES per part, for your own design use; no redistribution) — STEP, IGES, PDF — McMaster-Carr site terms: personal design use, no redistribution [verify license at link] — https://www.mcmaster.com/products/internal-tooth-lock-washers/\n- McMaster-Carr: Internal-external tooth lock washers (free STEP/IGES per part, for your own design use; no redistribution) — STEP, IGES, PDF — McMaster-Carr site terms: personal design use, no redistribution [verify license at link] — https://www.mcmaster.com/shims/internal-external-tooth-lock-washers\n\nFree files (CC BY 4.0, Xem Studio; STEP + STL, 20 parts): https://xemstudio.com/files/hardware/tooth-lock-washers-inch-asme-b18-21-1/index.json\nAPI: https://xemstudio.com/api/geometry?object=tooth-lock-washers-inch-asme-b18-21-1\n",
 "sources": [
  {
   "publisher": "AFT Fasteners",
   "title": "Internal tooth lock washer (ASME B18.21.1-2009): nominal, ID max / min, OD max / min, thickness max / min",
   "url": "https://www.aftfasteners.com/internal-tooth-lock-washer/",
   "formats": [
    "web"
   ],
   "license": "Publisher's page; dimensions are facts",
   "license_verified": true,
   "hosted": false
  },
  {
   "publisher": "Tanner Bolt",
   "title": "Internal tooth lock washers, ASME B18.21.1-2009 (PDF)",
   "url": "https://www.tannerbolt.com/media/akeneo_connector/Washersinternal.pdf",
   "formats": [
    "web"
   ],
   "license": "Maker datasheet; numbers only",
   "license_verified": true,
   "hosted": false
  },
  {
   "publisher": "Tanner Bolt",
   "title": "External tooth lock washers, ASME B18.21.1-2009 (PDF)",
   "url": "https://www.tannerbolt.com/media/akeneo_connector/Washersexternal.pdf",
   "formats": [
    "web"
   ],
   "license": "Maker datasheet; numbers only",
   "license_verified": true,
   "hosted": false
  },
  {
   "publisher": "Aspen Fasteners",
   "title": "External tooth lockwasher specification (ASME B18.21.1-1999)",
   "url": "https://www.aspenfasteners.com/content/pdf/external_tooth_lockwasher_specification.pdf",
   "formats": [
    "web"
   ],
   "license": "Distributor datasheet; numbers only",
   "license_verified": true,
   "hosted": false
  },
  {
   "publisher": "McMaster-Carr",
   "title": "Internal tooth lock washers (free STEP/IGES per part, for your own design use; no redistribution)",
   "url": "https://www.mcmaster.com/products/internal-tooth-lock-washers/",
   "formats": [
    "STEP",
    "IGES",
    "PDF"
   ],
   "license": "McMaster-Carr site terms: personal design use, no redistribution",
   "license_verified": false,
   "hosted": false
  },
  {
   "publisher": "McMaster-Carr",
   "title": "Internal-external tooth lock washers (free STEP/IGES per part, for your own design use; no redistribution)",
   "url": "https://www.mcmaster.com/shims/internal-external-tooth-lock-washers",
   "formats": [
    "STEP",
    "IGES",
    "PDF"
   ],
   "license": "McMaster-Carr site terms: personal design use, no redistribution",
   "license_verified": false,
   "hosted": false
  }
 ],
 "xem": {
  "status": "free-files",
  "sheet_free": true,
  "mesh_price_usd": null,
  "step_price_usd": null,
  "tolerance_mm": null
 },
 "related": [
  "serrated-lock-washers-din-6798",
  "split-lock-washers-inch-asme-b18-21-1",
  "spring-lock-washers-din-127-b",
  "flat-washers-inch",
  "plain-washers-inch-type-b",
  "imperial-machine-screws",
  "socket-head-cap-screws-inch"
 ],
 "fits": [],
 "dimensions": "exact (nominal, no tolerance added)",
 "dimension_rule": "All geometry on Xem Studio is exact (nominal, true size) with no tolerance added. 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. Typical accuracy by process and ISO 286 fits: https://xemstudio.com/tolerances/",
 "mating": [
  {
   "feature": "bore (ring envelope)",
   "exact": "ID min (in): #4 .115 internal / .115 external, #6 .141 / .141, #8 .168 / .168, #10 .195 / .195, 1/4 .256 / .256, 5/16 .320 / .320, 3/8 .384 / .384, 1/2 .512 / .513, 5/8 .640 / .641, 3/4 .769 / .768",
   "mates": "screw of the same nominal size (the bore is the smaller of the ID limits)",
   "fit": "slide",
   "files": "tooth-lock-washer-"
  },
  {
   "feature": "outside",
   "exact": "OD max: see the table (e.g. #8 .340 internal / .381 external; 1/4 .478 / .510 in)",
   "mates": "counterbore or recess at least the washer OD; bearing face under the screw head or nut",
   "fit": "designed",
   "files": "tooth-lock-washer-"
  }
 ],
 "fit_classes": {
  "press": "stays put: pin, tube, bearing or magnet held by interference. ISO 286 equivalent: H7/p6 (locational interference) or tighter.",
  "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. ISO 286 equivalent: H7/g6 or H7/h6.",
  "run": "turns or slides in use: pin in a link, rod through a guide. ISO 286 equivalent: H8/f7 (close running).",
  "socket": "large sliding fit: syringe barrel, sleeve, bobbin in a bore. ISO 286 equivalent: H9/d9 (free running) or looser.",
  "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": "What is the OD of a 1/4 external tooth lock washer?",
   "a": "0.510 in max (0.494 min), ID 0.267 / 0.256 in, thickness 0.028 / 0.023 in (Tanner and Aspen, ASME B18.21.1)."
  },
  {
   "q": "What is the difference between an internal and external tooth washer?",
   "a": "Teeth on the bore (internal) or on the outside (external); the internal form has a smaller OD, e.g. 0.478 vs 0.510 in for 1/4 (same ID and thickness)."
  },
  {
   "q": "How many teeth does a #10 star washer have?",
   "a": "Not printed in the sources read here."
  }
 ],
 "files_license": null,
 "offers": [
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   "stl": "https://xemstudio.com/files/hardware/tooth-lock-washers-inch-asme-b18-21-1/tooth-lock-washer-int-no4-envelope.stl",
   "note": "internal tooth lock washer #4 envelope: ring from ID min 0.115 in (Ø2.92 mm) to OD max 0.270 in (Ø6.86 mm), thickness max 0.018 in (0.46 mm); teeth and their twist are not modelled"
  },
  {
   "file": "tooth-lock-washer-int-no6-envelope",
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   "note": "internal tooth lock washer #6 envelope: ring from ID min 0.141 in (Ø3.58 mm) to OD max 0.295 in (Ø7.49 mm), thickness max 0.022 in (0.56 mm); teeth and their twist are not modelled"
  },
  {
   "file": "tooth-lock-washer-int-no8-envelope",
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   "note": "internal tooth lock washer #8 envelope: ring from ID min 0.168 in (Ø4.27 mm) to OD max 0.340 in (Ø8.64 mm), thickness max 0.023 in (0.58 mm); teeth and their twist are not modelled"
  },
  {
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   "note": "internal tooth lock washer #10 envelope: ring from ID min 0.195 in (Ø4.95 mm) to OD max 0.381 in (Ø9.68 mm), thickness max 0.024 in (0.61 mm); teeth and their twist are not modelled"
  },
  {
   "file": "tooth-lock-washer-int-1-4-envelope",
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   "note": "internal tooth lock washer 1/4 envelope: ring from ID min 0.256 in (Ø6.50 mm) to OD max 0.478 in (Ø12.14 mm), thickness max 0.028 in (0.71 mm); teeth and their twist are not modelled"
  },
  {
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   "note": "internal tooth lock washer 5/16 envelope: ring from ID min 0.320 in (Ø8.13 mm) to OD max 0.610 in (Ø15.49 mm), thickness max 0.034 in (0.86 mm); teeth and their twist are not modelled"
  },
  {
   "file": "tooth-lock-washer-int-3-8-envelope",
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   "note": "internal tooth lock washer 3/8 envelope: ring from ID min 0.384 in (Ø9.75 mm) to OD max 0.692 in (Ø17.58 mm), thickness max 0.040 in (1.02 mm); teeth and their twist are not modelled"
  },
  {
   "file": "tooth-lock-washer-int-1-2-envelope",
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   "note": "internal tooth lock washer 1/2 envelope: ring from ID min 0.512 in (Ø13.00 mm) to OD max 0.900 in (Ø22.86 mm), thickness max 0.045 in (1.14 mm); teeth and their twist are not modelled"
  },
  {
   "file": "tooth-lock-washer-int-5-8-envelope",
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   "note": "internal tooth lock washer 5/8 envelope: ring from ID min 0.640 in (Ø16.26 mm) to OD max 1.071 in (Ø27.20 mm), thickness max 0.050 in (1.27 mm); teeth and their twist are not modelled"
  },
  {
   "file": "tooth-lock-washer-int-3-4-envelope",
   "formats": [
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   ],
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   "note": "internal tooth lock washer 3/4 envelope: ring from ID min 0.769 in (Ø19.53 mm) to OD max 1.245 in (Ø31.62 mm), thickness max 0.055 in (1.40 mm); teeth and their twist are not modelled"
  },
  {
   "file": "tooth-lock-washer-ext-no4-envelope",
   "formats": [
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   ],
   "price_usd": 0,
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   "stl": "https://xemstudio.com/files/hardware/tooth-lock-washers-inch-asme-b18-21-1/tooth-lock-washer-ext-no4-envelope.stl",
   "note": "external tooth lock washer #4 envelope: ring from ID min 0.115 in (Ø2.92 mm) to OD max 0.260 in (Ø6.60 mm), thickness max 0.018 in (0.46 mm); teeth and their twist are not modelled"
  },
  {
   "file": "tooth-lock-washer-ext-no6-envelope",
   "formats": [
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   "price_usd": 0,
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   "stl": "https://xemstudio.com/files/hardware/tooth-lock-washers-inch-asme-b18-21-1/tooth-lock-washer-ext-no6-envelope.stl",
   "note": "external tooth lock washer #6 envelope: ring from ID min 0.141 in (Ø3.58 mm) to OD max 0.320 in (Ø8.13 mm), thickness max 0.022 in (0.56 mm); teeth and their twist are not modelled"
  },
  {
   "file": "tooth-lock-washer-ext-no8-envelope",
   "formats": [
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   "note": "external tooth lock washer #8 envelope: ring from ID min 0.168 in (Ø4.27 mm) to OD max 0.381 in (Ø9.68 mm), thickness max 0.023 in (0.58 mm); teeth and their twist are not modelled"
  },
  {
   "file": "tooth-lock-washer-ext-no10-envelope",
   "formats": [
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   "note": "external tooth lock washer #10 envelope: ring from ID min 0.195 in (Ø4.95 mm) to OD max 0.410 in (Ø10.41 mm), thickness max 0.024 in (0.61 mm); teeth and their twist are not modelled"
  },
  {
   "file": "tooth-lock-washer-ext-1-4-envelope",
   "formats": [
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   ],
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   "note": "external tooth lock washer 1/4 envelope: ring from ID min 0.256 in (Ø6.50 mm) to OD max 0.510 in (Ø12.95 mm), thickness max 0.028 in (0.71 mm); teeth and their twist are not modelled"
  },
  {
   "file": "tooth-lock-washer-ext-5-16-envelope",
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   "note": "external tooth lock washer 5/16 envelope: ring from ID min 0.320 in (Ø8.13 mm) to OD max 0.610 in (Ø15.49 mm), thickness max 0.034 in (0.86 mm); teeth and their twist are not modelled"
  },
  {
   "file": "tooth-lock-washer-ext-3-8-envelope",
   "formats": [
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   "note": "external tooth lock washer 3/8 envelope: ring from ID min 0.384 in (Ø9.75 mm) to OD max 0.694 in (Ø17.63 mm), thickness max 0.040 in (1.02 mm); teeth and their twist are not modelled"
  },
  {
   "file": "tooth-lock-washer-ext-1-2-envelope",
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   "note": "external tooth lock washer 1/2 envelope: ring from ID min 0.513 in (Ø13.03 mm) to OD max 0.900 in (Ø22.86 mm), thickness max 0.045 in (1.14 mm); teeth and their twist are not modelled"
  },
  {
   "file": "tooth-lock-washer-ext-5-8-envelope",
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   "note": "external tooth lock washer 5/8 envelope: ring from ID min 0.641 in (Ø16.28 mm) to OD max 1.070 in (Ø27.18 mm), thickness max 0.050 in (1.27 mm); teeth and their twist are not modelled"
  },
  {
   "file": "tooth-lock-washer-ext-3-4-envelope",
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   "note": "external tooth lock washer 3/4 envelope: ring from ID min 0.768 in (Ø19.51 mm) to OD max 1.260 in (Ø32.00 mm), thickness max 0.055 in (1.40 mm); teeth and their twist are not modelled"
  }
 ],
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