{
 "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": "involute-splines-iso-4156-metric-module",
 "name": "Involute splines ISO 4156 (metric module, 30° side fit): pitch, major and minor diameter by module and tooth count + example shaft STEP/STL",
 "kind": "standard",
 "category": "Hardware",
 "group": "Bearings, rails & motion",
 "year": null,
 "question": "What are the pitch, major and minor diameters of an ISO 4156 involute spline for module 2 and 24 teeth?",
 "tags": [
  "involute spline",
  "spline",
  "iso 4156",
  "metric module",
  "30 degree",
  "spline shaft",
  "din 5480",
  "power transmission",
  "standard"
 ],
 "aliases": [
  "iso 4156 spline",
  "involute spline module",
  "spline major diameter module formula",
  "module 2 spline 24 teeth",
  "spline pitch diameter m z",
  "din 5480 spline dimensions",
  "metric involute spline dimensions",
  "spline minor diameter flat root",
  "iso 4156 table",
  "spline shaft step file metric",
  "spline shaft stl",
  "involute spline calculator module",
  "30 degree involute spline metric",
  "m 1.5 spline 24 teeth",
  "spline diameters m (z+1)"
 ],
 "overall_mm": {
  "length": null,
  "width": null,
  "height": null
 },
 "official_cad": false,
 "xem_status": "free-files",
 "les": false,
 "free_files": 10,
 "url": "https://xemstudio.com/objects/involute-splines-iso-4156-metric-module/",
 "sheet_txt": "https://xemstudio.com/objects/involute-splines-iso-4156-metric-module/sheet.txt",
 "sheet": {
  "basis": "ISO 4156:1981 Table 2 formulas (sample pages) and Roymech's transcription of the same table; basic dimensions, esv = 0, no tolerance; true involute shaft sections drawn from them",
  "overall_mm": {
   "length": null,
   "width": null,
   "height": null
  },
  "notes": [
   "ISO 4156 (straight cylindrical involute splines, metric module, side fit) names a spline by module m and tooth count z. Pressure angles 30°, 37.5° and 45°; this page tabulates the 30° forms. Basic formulas (ISO 4156:1981 Table 2 sample pages, confirmed by Roymech's transcription): pitch Ø D = m z; circular pitch π m; basic tooth thickness π m / 2; external major Ø 30° m (z + 1); external minor Ø 30° flat root m (z − 1.5) and fillet root m (z − 1.8); internal major Ø minimum 30° flat root m (z + 1.5) and fillet root m (z + 1.8); 37.5° fillet root: external major m (z + 0.9), external minor m (z − 1.4), internal major m (z + 1.4); 45° fillet root: external major m (z + 0.8), external minor m (z − 1.2), internal major m (z + 1.2); form radius cF = 0.1 m.",
   "The standard's major / minor diameters carry an effective-variation term (esv / tan αD, with esv the effective tooth thickness deviation, and the machining allowance (T + λ) / tan αD for the maximum internal major diameter); the table lists the basic values, esv = 0. The modules are 0.25 to 10 (ISO 4156 scope; Machinery's Handbook lists the preferred series 0.25, 0.5, 0.75, 1, 1.25, 1.5, 1.75, 2, 2.5, 3, 4, 5, 6, 8, 10). Tolerance classes H/h, H/f, H/e, H/d (side fit) apply tooth thickness deviations from ISO 286-type fundamental deviations; those are not in the table.",
   "Compare ANSI B92.1 (inch pitch): the ANSI flat-root external minor is (N − 1.35) / P (or − 1.2 for 16/32 and finer) against ISO's m (z − 1.5); the two systems are not identical even at the same pitch diameter. Files: 10 external spline shaft sections, 25 mm long, one extruded solid with the basic 30° flat-root tooth: pitch, major and minor diameters from the table, true involute flanks, tooth thickness half the circular pitch. The 25 mm length is an example; the root fillet is not modelled (the flank is carried down to the root circle). Fillet-root and 37.5° / 45° shafts and internal splines are not drawn.",
   "The standard (ISO 4156-1 to -3) is sold by ISO and linked, not reproduced; tooth counts are not limited by the sample pages read, so any z follows from the formulas."
  ],
  "table": {
   "columns": [
    "module m, mm",
    "teeth z",
    "pitch Ø D = m z, mm",
    "major Ø external (30°) m (z + 1)",
    "minor Ø external, flat root m (z − 1.5)",
    "minor Ø external, fillet root m (z − 1.8)",
    "major Ø internal min, flat root m (z + 1.5)",
    "major Ø internal min, fillet root m (z + 1.8)"
   ],
   "rows": [
    [
     "0.5",
     10,
     "5",
     "5.5",
     "4.25",
     "4.1",
     "5.75",
     "5.9"
    ],
    [
     "0.5",
     12,
     "6",
     "6.5",
     "5.25",
     "5.1",
     "6.75",
     "6.9"
    ],
    [
     "0.5",
     16,
     "8",
     "8.5",
     "7.25",
     "7.1",
     "8.75",
     "8.9"
    ],
    [
     "0.5",
     20,
     "10",
     "10.5",
     "9.25",
     "9.1",
     "10.75",
     "10.9"
    ],
    [
     "0.5",
     24,
     "12",
     "12.5",
     "11.25",
     "11.1",
     "12.75",
     "12.9"
    ],
    [
     "0.5",
     30,
     "15",
     "15.5",
     "14.25",
     "14.1",
     "15.75",
     "15.9"
    ],
    [
     "0.5",
     36,
     "18",
     "18.5",
     "17.25",
     "17.1",
     "18.75",
     "18.9"
    ],
    [
     "0.5",
     48,
     "24",
     "24.5",
     "23.25",
     "23.1",
     "24.75",
     "24.9"
    ],
    [
     "0.75",
     10,
     "7.5",
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     "6.375",
     "6.15",
     "8.625",
     "8.85"
    ],
    [
     "0.75",
     12,
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     "10.35"
    ],
    [
     "0.75",
     16,
     "12",
     "12.75",
     "10.875",
     "10.65",
     "13.125",
     "13.35"
    ],
    [
     "0.75",
     20,
     "15",
     "15.75",
     "13.875",
     "13.65",
     "16.125",
     "16.35"
    ],
    [
     "0.75",
     24,
     "18",
     "18.75",
     "16.875",
     "16.65",
     "19.125",
     "19.35"
    ],
    [
     "0.75",
     30,
     "22.5",
     "23.25",
     "21.375",
     "21.15",
     "23.625",
     "23.85"
    ],
    [
     "0.75",
     36,
     "27",
     "27.75",
     "25.875",
     "25.65",
     "28.125",
     "28.35"
    ],
    [
     "0.75",
     48,
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     "37.125",
     "37.35"
    ],
    [
     "1",
     10,
     "10",
     "11",
     "8.5",
     "8.2",
     "11.5",
     "11.8"
    ],
    [
     "1",
     12,
     "12",
     "13",
     "10.5",
     "10.2",
     "13.5",
     "13.8"
    ],
    [
     "1",
     16,
     "16",
     "17",
     "14.5",
     "14.2",
     "17.5",
     "17.8"
    ],
    [
     "1",
     20,
     "20",
     "21",
     "18.5",
     "18.2",
     "21.5",
     "21.8"
    ],
    [
     "1",
     24,
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     "1",
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    ],
    [
     "1",
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    ],
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     "1",
     48,
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    ],
    [
     "1.25",
     10,
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     "10.25",
     "14.375",
     "14.75"
    ],
    [
     "1.25",
     12,
     "15",
     "16.25",
     "13.125",
     "12.75",
     "16.875",
     "17.25"
    ],
    [
     "1.25",
     16,
     "20",
     "21.25",
     "18.125",
     "17.75",
     "21.875",
     "22.25"
    ],
    [
     "1.25",
     20,
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     "23.125",
     "22.75",
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     "27.25"
    ],
    [
     "1.25",
     24,
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     "28.125",
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     "31.875",
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    ],
    [
     "1.25",
     30,
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     36,
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     48,
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     16,
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     "21.75",
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     "26.25",
     "26.7"
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    [
     "1.5",
     20,
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     "31.5",
     "27.75",
     "27.3",
     "32.25",
     "32.7"
    ],
    [
     "1.5",
     24,
     "36",
     "37.5",
     "33.75",
     "33.3",
     "38.25",
     "38.7"
    ],
    [
     "1.5",
     30,
     "45",
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     "42.75",
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    ],
    [
     "1.5",
     36,
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     "51.75",
     "51.3",
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     "56.7"
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    [
     "1.5",
     48,
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    ],
    [
     "1.75",
     12,
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     "18.375",
     "17.85",
     "23.625",
     "24.15"
    ],
    [
     "1.75",
     16,
     "28",
     "29.75",
     "25.375",
     "24.85",
     "30.625",
     "31.15"
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     20,
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     "32.375",
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     "1.75",
     24,
     "42",
     "43.75",
     "39.375",
     "38.85",
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    ],
    [
     "1.75",
     30,
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     "1.75",
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     "64.75",
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     "27",
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     "63",
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     "99",
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     24,
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     "63.75",
     "64.5"
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     "2.5",
     30,
     "75",
     "77.5",
     "71.25",
     "70.5",
     "78.75",
     "79.5"
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    [
     "2.5",
     36,
     "90",
     "92.5",
     "86.25",
     "85.5",
     "93.75",
     "94.5"
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     "2.5",
     48,
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     "116.25",
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     "123.75",
     "124.5"
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     "3",
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     "33",
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     "3",
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     "54.6",
     "64.5",
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 "sheet_text": "Involute splines ISO 4156 (metric module, 30° side fit): pitch, major and minor diameter by module and tooth count + example shaft STEP/STL — dimension sheet\nSource: Xem Studio, https://xemstudio.com/objects/involute-splines-iso-4156-metric-module/  (sheet CC BY 4.0)\nBasis: ISO 4156:1981 Table 2 formulas (sample pages) and Roymech's transcription of the same table; basic dimensions, esv = 0, no tolerance; true involute shaft sections drawn from them\nCatalog version: 2026-10-20\n\nSizes: see table below\n- ISO 4156 (straight cylindrical involute splines, metric module, side fit) names a spline by module m and tooth count z. Pressure angles 30°, 37.5° and 45°; this page tabulates the 30° forms. Basic formulas (ISO 4156:1981 Table 2 sample pages, confirmed by Roymech's transcription): pitch Ø D = m z; circular pitch π m; basic tooth thickness π m / 2; external major Ø 30° m (z + 1); external minor Ø 30° flat root m (z − 1.5) and fillet root m (z − 1.8); internal major Ø minimum 30° flat root m (z + 1.5) and fillet root m (z + 1.8); 37.5° fillet root: external major m (z + 0.9), external minor m (z − 1.4), internal major m (z + 1.4); 45° fillet root: external major m (z + 0.8), external minor m (z − 1.2), internal major m (z + 1.2); form radius cF = 0.1 m.\n- The standard's major / minor diameters carry an effective-variation term (esv / tan αD, with esv the effective tooth thickness deviation, and the machining allowance (T + λ) / tan αD for the maximum internal major diameter); the table lists the basic values, esv = 0. The modules are 0.25 to 10 (ISO 4156 scope; Machinery's Handbook lists the preferred series 0.25, 0.5, 0.75, 1, 1.25, 1.5, 1.75, 2, 2.5, 3, 4, 5, 6, 8, 10). Tolerance classes H/h, H/f, H/e, H/d (side fit) apply tooth thickness deviations from ISO 286-type fundamental deviations; those are not in the table.\n- Compare ANSI B92.1 (inch pitch): the ANSI flat-root external minor is (N − 1.35) / P (or − 1.2 for 16/32 and finer) against ISO's m (z − 1.5); the two systems are not identical even at the same pitch diameter. Files: 10 external spline shaft sections, 25 mm long, one extruded solid with the basic 30° flat-root tooth: pitch, major and minor diameters from the table, true involute flanks, tooth thickness half the circular pitch. The 25 mm length is an example; the root fillet is not modelled (the flank is carried down to the root circle). Fillet-root and 37.5° / 45° shafts and internal splines are not drawn.\n- The standard (ISO 4156-1 to -3) is sold by ISO and linked, not reproduced; tooth counts are not limited by the sample pages read, so any z follows from the formulas.\n\nmodule m, mm  teeth z  pitch Ø D = m z, mm  major Ø external (30°) m (z + 1)  minor Ø external, flat root m (z − 1.5)  minor Ø external, fillet root m (z − 1.8)  major Ø internal min, flat root m (z + 1.5)  major Ø internal min, fillet root m (z + 1.8)\n0.5  10  5  5.5  4.25  4.1  5.75  5.9\n0.5  12  6  6.5  5.25  5.1  6.75  6.9\n0.5  16  8  8.5  7.25  7.1  8.75  8.9\n0.5  20  10  10.5  9.25  9.1  10.75  10.9\n0.5  24  12  12.5  11.25  11.1  12.75  12.9\n0.5  30  15  15.5  14.25  14.1  15.75  15.9\n0.5  36  18  18.5  17.25  17.1  18.75  18.9\n0.5  48  24  24.5  23.25  23.1  24.75  24.9\n0.75  10  7.5  8.25  6.375  6.15  8.625  8.85\n0.75  12  9  9.75  7.875  7.65  10.125  10.35\n0.75  16  12  12.75  10.875  10.65  13.125  13.35\n0.75  20  15  15.75  13.875  13.65  16.125  16.35\n0.75  24  18  18.75  16.875  16.65  19.125  19.35\n0.75  30  22.5  23.25  21.375  21.15  23.625  23.85\n0.75  36  27  27.75  25.875  25.65  28.125  28.35\n0.75  48  36  36.75  34.875  34.65  37.125  37.35\n1  10  10  11  8.5  8.2  11.5  11.8\n1  12  12  13  10.5  10.2  13.5  13.8\n1  16  16  17  14.5  14.2  17.5  17.8\n1  20  20  21  18.5  18.2  21.5  21.8\n1  24  24  25  22.5  22.2  25.5  25.8\n1  30  30  31  28.5  28.2  31.5  31.8\n1  36  36  37  34.5  34.2  37.5  37.8\n1  48  48  49  46.5  46.2  49.5  49.8\n1.25  10  12.5  13.75  10.625  10.25  14.375  14.75\n1.25  12  15  16.25  13.125  12.75  16.875  17.25\n1.25  16  20  21.25  18.125  17.75  21.875  22.25\n1.25  20  25  26.25  23.125  22.75  26.875  27.25\n1.25  24  30  31.25  28.125  27.75  31.875  32.25\n1.25  30  37.5  38.75  35.625  35.25  39.375  39.75\n1.25  36  45  46.25  43.125  42.75  46.875  47.25\n1.25  48  60  61.25  58.125  57.75  61.875  62.25\n1.5  10  15  16.5  12.75  12.3  17.25  17.7\n1.5  12  18  19.5  15.75  15.3  20.25  20.7\n1.5  16  24  25.5  21.75  21.3  26.25  26.7\n1.5  20  30  31.5  27.75  27.3  32.25  32.7\n1.5  24  36  37.5  33.75  33.3  38.25  38.7\n1.5  30  45  46.5  42.75  42.3  47.25  47.7\n1.5  36  54  55.5  51.75  51.3  56.25  56.7\n1.5  48  72  73.5  69.75  69.3  74.25  74.7\n1.75  10  17.5  19.25  14.875  14.35  20.125  20.65\n1.75  12  21  22.75  18.375  17.85  23.625  24.15\n1.75  16  28  29.75  25.375  24.85  30.625  31.15\n1.75  20  35  36.75  32.375  31.85  37.625  38.15\n1.75  24  42  43.75  39.375  38.85  44.625  45.15\n1.75  30  52.5  54.25  49.875  49.35  55.125  55.65\n1.75  36  63  64.75  60.375  59.85  65.625  66.15\n1.75  48  84  85.75  81.375  80.85  86.625  87.15\n2  10  20  22  17  16.4  23  23.6\n2  12  24  26  21  20.4  27  27.6\n2  16  32  34  29  28.4  35  35.6\n2  20  40  42  37  36.4  43  43.6\n2  24  48  50  45  44.4  51  51.6\n2  30  60  62  57  56.4  63  63.6\n2  36  72  74  69  68.4  75  75.6\n2  48  96  98  93  92.4  99  99.6\n2.5  10  25  27.5  21.25  20.5  28.75  29.5\n2.5  12  30  32.5  26.25  25.5  33.75  34.5\n2.5  16  40  42.5  36.25  35.5  43.75  44.5\n2.5  20  50  52.5  46.25  45.5  53.75  54.5\n2.5  24  60  62.5  56.25  55.5  63.75  64.5\n2.5  30  75  77.5  71.25  70.5  78.75  79.5\n2.5  36  90  92.5  86.25  85.5  93.75  94.5\n2.5  48  120  122.5  116.25  115.5  123.75  124.5\n3  10  30  33  25.5  24.6  34.5  35.4\n3  12  36  39  31.5  30.6  40.5  41.4\n3  16  48  51  43.5  42.6  52.5  53.4\n3  20  60  63  55.5  54.6  64.5  65.4\n3  24  72  75  67.5  66.6  76.5  77.4\n3  30  90  93  85.5  84.6  94.5  95.4\n3  36  108  111  103.5  102.6  112.5  113.4\n3  48  144  147  139.5  138.6  148.5  149.4\n4  10  40  44  34  32.8  46  47.2\n4  12  48  52  42  40.8  54  55.2\n4  16  64  68  58  56.8  70  71.2\n4  20  80  84  74  72.8  86  87.2\n4  24  96  100  90  88.8  102  103.2\n4  30  120  124  114  112.8  126  127.2\n4  36  144  148  138  136.8  150  151.2\n4  48  192  196  186  184.8  198  199.2\n5  10  50  55  42.5  41  57.5  59\n5  12  60  65  52.5  51  67.5  69\n5  16  80  85  72.5  71  87.5  89\n5  20  100  105  92.5  91  107.5  109\n5  24  120  125  112.5  111  127.5  129\n5  30  150  155  142.5  141  157.5  159\n5  36  180  185  172.5  171  187.5  189\n5  48  240  245  232.5  231  247.5  249\n6  10  60  66  51  49.2  69  70.8\n6  12  72  78  63  61.2  81  82.8\n6  16  96  102  87  85.2  105  106.8\n6  20  120  126  111  109.2  129  130.8\n6  24  144  150  135  133.2  153  154.8\n6  30  180  186  171  169.2  189  190.8\n6  36  216  222  207  205.2  225  226.8\n6  48  288  294  279  277.2  297  298.8\n8  10  80  88  68  65.6  92  94.4\n8  12  96  104  84  81.6  108  110.4\n8  16  128  136  116  113.6  140  142.4\n8  20  160  168  148  145.6  172  174.4\n8  24  192  200  180  177.6  204  206.4\n8  30  240  248  228  225.6  252  254.4\n8  36  288  296  276  273.6  300  302.4\n8  48  384  392  372  369.6  396  398.4\n10  10  100  110  85  82  115  118\n10  12  120  130  105  102  135  138\n10  16  160  170  145  142  175  178\n10  20  200  210  185  182  215  218\n10  24  240  250  225  222  255  258\n10  30  300  310  285  282  315  318\n10  36  360  370  345  342  375  378\n10  48  480  490  465  462  495  498\n\nFiles elsewhere (not hosted by Xem Studio; license as stated by the publisher):\n- iTeh Standards: ISO 4156:1981 sample pages: Table 2 basic formulas (m z, m (z + 1), m (z - 1.5), m (z + 1.5)), modules 0.25 to 10 — web — Publisher's page; dimensions are facts — https://cdn.standards.iteh.ai/samples/9921/e5c84452a1134654b8dede51d1d84e10/ISO-4156-1981.pdf\n- Roymech: Involute splines (ISO 4156): module formulas for 30 degree flat and fillet root, 37.5 and 45 degrees — web — Publisher's page; dimensions are facts — https://roymech.org/Useful_Tables/Keyways/Splines_Inv.html\n- ISO: ISO 4156-1:2005 Straight cylindrical involute splines, metric module, side fit (standard; sold, not reproduced) — standard — ISO; dimensions are facts [verify license at link] — https://standards.iteh.ai/catalog/standards/iso/91545c02-7de1-4792-ba81-e79b17716af6/iso-4156-1-2005\n- Machinery's Handbook, 31st ed. (online edition): Table 3: basic dimensions for involute splines ANSI B92.1-1996: pitch series 2.5/5 to 128/256, 6 to 60 teeth at 30 degrees — web — Publisher's page; dimensions are facts — https://online.flippingbook.com/view/954046886/1000\n\nFree files (CC BY 4.0, Xem Studio; STEP + STL, 10 parts): https://xemstudio.com/files/hardware/involute-splines-iso-4156-metric-module/index.json\nAPI: https://xemstudio.com/api/geometry?object=involute-splines-iso-4156-metric-module\n",
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   "publisher": "iTeh Standards",
   "title": "ISO 4156:1981 sample pages: Table 2 basic formulas (m z, m (z + 1), m (z - 1.5), m (z + 1.5)), modules 0.25 to 10",
   "url": "https://cdn.standards.iteh.ai/samples/9921/e5c84452a1134654b8dede51d1d84e10/ISO-4156-1981.pdf",
   "formats": [
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   "license": "Publisher's page; dimensions are facts",
   "license_verified": true,
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  {
   "publisher": "Roymech",
   "title": "Involute splines (ISO 4156): module formulas for 30 degree flat and fillet root, 37.5 and 45 degrees",
   "url": "https://roymech.org/Useful_Tables/Keyways/Splines_Inv.html",
   "formats": [
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   "license": "Publisher's page; dimensions are facts",
   "license_verified": true,
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  {
   "publisher": "ISO",
   "title": "ISO 4156-1:2005 Straight cylindrical involute splines, metric module, side fit (standard; sold, not reproduced)",
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   "publisher": "Machinery's Handbook, 31st ed. (online edition)",
   "title": "Table 3: basic dimensions for involute splines ANSI B92.1-1996: pitch series 2.5/5 to 128/256, 6 to 60 teeth at 30 degrees",
   "url": "https://online.flippingbook.com/view/954046886/1000",
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 "xem": {
  "status": "free-files",
  "sheet_free": true,
  "mesh_price_usd": null,
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  "tolerance_mm": null
 },
 "related": [
  "involute-splines-ansi-b92-1-30deg-flat-root",
  "sae-straight-side-splines-4-6-10-16",
  "spur-gears-module-1",
  "spur-gears-module-2",
  "gear-racks-iso-53-module-1-to-3",
  "parallel-keys-din-6885"
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 "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": "external spline",
   "exact": "D = m z, major m (z + 1), flat-root minor m (z − 1.5), fillet-root minor m (z − 1.8) (basic)",
   "mates": "internal spline of the same module and z (internal major m (z + 1.5) flat root, m (z + 1.8) fillet root, minimum)",
   "fit": "designed",
   "files": "spline-shaft"
  },
  {
   "feature": "tooth form",
   "exact": "30°, basic tooth thickness π m / 2 on the pitch circle",
   "mates": "internal spline of the same module, z and 30° pressure angle",
   "fit": "designed",
   "files": "spline-shaft"
  }
 ],
 "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 major diameter of a module 2, 24-tooth ISO 4156 spline?",
   "a": "External major m (z + 1) = 50 mm; pitch Ø 48 mm; external minor Ø (flat root) m (z − 1.5) = 45 mm, fillet root m (z − 1.8) = 44.4 mm (basic values)."
  },
  {
   "q": "How is an ISO 4156 spline sized?",
   "a": "By module and number of teeth: pitch diameter = module × teeth, with the pressure angle 30°, 37.5° or 45° and a flat or fillet root."
  },
  {
   "q": "Is ISO 4156 the same as DIN 5480?",
   "a": "Related but not identical: DIN 5480 is the German module system with its own fit tables; this page is ISO 4156 only."
  }
 ],
 "files_license": null,
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   "note": "ISO 4156 30° flat-root external spline shaft section, module 0.5, 30 teeth: pitch Ø15 mm, major Ø15.5 mm, minor (root) Ø14.25 mm; basic tooth (thickness half the circular pitch, no tolerance, effective-variation shift esv = 0), true involute flank carried down to the root circle (root fillet not modelled); the 25 mm length is an example, no chamfer, no bore"
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   "note": "ISO 4156 30° flat-root external spline shaft section, module 1, 20 teeth: pitch Ø20 mm, major Ø21 mm, minor (root) Ø18.5 mm; basic tooth (thickness half the circular pitch, no tolerance, effective-variation shift esv = 0), true involute flank carried down to the root circle (root fillet not modelled); the 25 mm length is an example, no chamfer, no bore"
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   "note": "ISO 4156 30° flat-root external spline shaft section, module 1.5, 16 teeth: pitch Ø24 mm, major Ø25.5 mm, minor (root) Ø21.75 mm; basic tooth (thickness half the circular pitch, no tolerance, effective-variation shift esv = 0), true involute flank carried down to the root circle (root fillet not modelled); the 25 mm length is an example, no chamfer, no bore"
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   "note": "ISO 4156 30° flat-root external spline shaft section, module 1.5, 24 teeth: pitch Ø36 mm, major Ø37.5 mm, minor (root) Ø33.75 mm; basic tooth (thickness half the circular pitch, no tolerance, effective-variation shift esv = 0), true involute flank carried down to the root circle (root fillet not modelled); the 25 mm length is an example, no chamfer, no bore"
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   "note": "ISO 4156 30° flat-root external spline shaft section, module 2, 16 teeth: pitch Ø32 mm, major Ø34 mm, minor (root) Ø29 mm; basic tooth (thickness half the circular pitch, no tolerance, effective-variation shift esv = 0), true involute flank carried down to the root circle (root fillet not modelled); the 25 mm length is an example, no chamfer, no bore"
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   "step": "https://xemstudio.com/files/hardware/involute-splines-iso-4156-metric-module/spline-shaft-iso-4156-m2-z24.step",
   "stl": "https://xemstudio.com/files/hardware/involute-splines-iso-4156-metric-module/spline-shaft-iso-4156-m2-z24.stl",
   "note": "ISO 4156 30° flat-root external spline shaft section, module 2, 24 teeth: pitch Ø48 mm, major Ø50 mm, minor (root) Ø45 mm; basic tooth (thickness half the circular pitch, no tolerance, effective-variation shift esv = 0), true involute flank carried down to the root circle (root fillet not modelled); the 25 mm length is an example, no chamfer, no bore"
  },
  {
   "file": "spline-shaft-iso-4156-m2-5-z18",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "CC BY 4.0 (Xem Studio)",
   "step": "https://xemstudio.com/files/hardware/involute-splines-iso-4156-metric-module/spline-shaft-iso-4156-m2-5-z18.step",
   "stl": "https://xemstudio.com/files/hardware/involute-splines-iso-4156-metric-module/spline-shaft-iso-4156-m2-5-z18.stl",
   "note": "ISO 4156 30° flat-root external spline shaft section, module 2.5, 18 teeth: pitch Ø45 mm, major Ø47.5 mm, minor (root) Ø41.25 mm; basic tooth (thickness half the circular pitch, no tolerance, effective-variation shift esv = 0), true involute flank carried down to the root circle (root fillet not modelled); the 25 mm length is an example, no chamfer, no bore"
  },
  {
   "file": "spline-shaft-iso-4156-m3-z14",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "CC BY 4.0 (Xem Studio)",
   "step": "https://xemstudio.com/files/hardware/involute-splines-iso-4156-metric-module/spline-shaft-iso-4156-m3-z14.step",
   "stl": "https://xemstudio.com/files/hardware/involute-splines-iso-4156-metric-module/spline-shaft-iso-4156-m3-z14.stl",
   "note": "ISO 4156 30° flat-root external spline shaft section, module 3, 14 teeth: pitch Ø42 mm, major Ø45 mm, minor (root) Ø37.5 mm; basic tooth (thickness half the circular pitch, no tolerance, effective-variation shift esv = 0), true involute flank carried down to the root circle (root fillet not modelled); the 25 mm length is an example, no chamfer, no bore"
  },
  {
   "file": "spline-shaft-iso-4156-m3-z20",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "CC BY 4.0 (Xem Studio)",
   "step": "https://xemstudio.com/files/hardware/involute-splines-iso-4156-metric-module/spline-shaft-iso-4156-m3-z20.step",
   "stl": "https://xemstudio.com/files/hardware/involute-splines-iso-4156-metric-module/spline-shaft-iso-4156-m3-z20.stl",
   "note": "ISO 4156 30° flat-root external spline shaft section, module 3, 20 teeth: pitch Ø60 mm, major Ø63 mm, minor (root) Ø55.5 mm; basic tooth (thickness half the circular pitch, no tolerance, effective-variation shift esv = 0), true involute flank carried down to the root circle (root fillet not modelled); the 25 mm length is an example, no chamfer, no bore"
  }
 ],
 "markdown": "https://xemstudio.com/objects/involute-splines-iso-4156-metric-module/index.md"
}