{ "id": "unified-thread-limits", "source": "https://ctrlplanner.com/walkback", "license": "CC-BY-4.0", "attribution": "ctrlPlanner, https://ctrlplanner.com/walkback", "title": "Unified inch screw thread pitch diameter limits", "standard": [ "ASME B1.1", "Federal Screw Thread Specification H28" ], "description": "Pitch diameter limits for the whole of the UNC, UNF and UNEF series in classes 2A, 3A, 2B and 3B, computed from the basic thread geometry and the class tolerance formula rather than transcribed from a table.", "method": "pitch = 1/n. Basic pitch diameter = D - 0.649519 x pitch. Class 2A tolerance = 0.0015 x D^(1/3) + 0.0015 x sqrt(LE) + 0.015 x pitch^(2/3), where LE is the length of engagement: the major diameter for UNC and UNF, nine pitches for UNEF. Allowance on external classes 2A = 0.3 x that tolerance. Class 3A = 0.75x, internal classes = 1.3x their external counterpart. Every derived figure is computed from the unrounded tolerance and rounded once to four places.", "notes": [ "Pitch diameter only. Major and minor diameter limits come from a different set of formulas this engine does not carry.", "Classes 1A and 1B are not published: their tolerance relationship could not be verified against a printed table, and a guessed limit on a thread is scrap.", "An external thread hangs below basic by its allowance; an internal thread starts at basic exactly, because the allowance is applied to the external thread only.", "The length of engagement is not the same for every series, and it is carried on every row here rather than assumed. Computing a UNEF thread at the major diameter, which is right for UNC and UNF, is out by about a ten-thousandth on both limits.", "The constant-pitch UN series -- 8-UN, 12-UN, 16-UN and the rest -- is absent. No published UN row could be corroborated, the length-of-engagement convention demonstrably differs between series, and a generated table on an assumed one would be wrong in a way nothing here would catch.", "UNC and UNF stop at 1-1/2, which is the largest size checked against a printed table. UNEF is listed complete." ], "classes": [ { "threadClass": "2A", "side": "external", "fit": "general purpose" }, { "threadClass": "3A", "side": "external", "fit": "close" }, { "threadClass": "2B", "side": "internal", "fit": "general purpose" }, { "threadClass": "3B", "side": "internal", "fit": "close" } ], "rows": [ { "size": "#1-64 UNC", "series": "UNC", "majorDiameter": 0.073, "threadsPerInch": 64, "threadClass": "2A", "lengthOfEngagement": "diameter", "basicPitchDiameter": 0.0629, "allowance": 0.0006, "tolerance": 0.002, "pitchDiameterMin": 0.0603, "pitchDiameterMax": 0.0623, "unit": "in" }, { "size": "#1-64 UNC", "series": "UNC", "majorDiameter": 0.073, "threadsPerInch": 64, "threadClass": "3A", "lengthOfEngagement": "diameter", "basicPitchDiameter": 0.0629, "allowance": 0, "tolerance": 0.0015, "pitchDiameterMin": 0.0614, "pitchDiameterMax": 0.0629, "unit": "in" }, { "size": "#1-64 UNC", "series": "UNC", "majorDiameter": 0.073, "threadsPerInch": 64, "threadClass": "2B", "lengthOfEngagement": "diameter", "basicPitchDiameter": 0.0629, "allowance": 0, "tolerance": 0.0026, "pitchDiameterMin": 0.0629, "pitchDiameterMax": 0.0655, "unit": "in" }, { "size": "#1-64 UNC", "series": "UNC", "majorDiameter": 0.073, "threadsPerInch": 64, "threadClass": "3B", "lengthOfEngagement": "diameter", "basicPitchDiameter": 0.0629, "allowance": 0, "tolerance": 0.0019, "pitchDiameterMin": 0.0629, "pitchDiameterMax": 0.0648, "unit": "in" }, { "size": "#2-56 UNC", "series": "UNC", "majorDiameter": 0.086, "threadsPerInch": 56, "threadClass": "2A", "lengthOfEngagement": "diameter", "basicPitchDiameter": 0.0744, "allowance": 0.0006, "tolerance": 0.0021, "pitchDiameterMin": 0.0717, "pitchDiameterMax": 0.0738, "unit": "in" }, { "size": "#2-56 UNC", "series": "UNC", "majorDiameter": 0.086, "threadsPerInch": 56, "threadClass": "3A", "lengthOfEngagement": "diameter", "basicPitchDiameter": 0.0744, "allowance": 0, "tolerance": 0.0016, "pitchDiameterMin": 0.0728, "pitchDiameterMax": 0.0744, "unit": "in" }, { "size": "#2-56 UNC", "series": "UNC", "majorDiameter": 0.086, "threadsPerInch": 56, "threadClass": "2B", "lengthOfEngagement": "diameter", "basicPitchDiameter": 0.0744, "allowance": 0, "tolerance": 0.0028, "pitchDiameterMin": 0.0744, "pitchDiameterMax": 0.0772, "unit": "in" }, { "size": "#2-56 UNC", "series": "UNC", "majorDiameter": 0.086, "threadsPerInch": 56, "threadClass": "3B", "lengthOfEngagement": "diameter", "basicPitchDiameter": 0.0744, "allowance": 0, "tolerance": 0.0021, "pitchDiameterMin": 0.0744, "pitchDiameterMax": 0.0765, "unit": "in" }, { "size": "#3-48 UNC", "series": "UNC", "majorDiameter": 0.099, "threadsPerInch": 48, "threadClass": "2A", "lengthOfEngagement": "diameter", "basicPitchDiameter": 0.0855, "allowance": 0.0007, "tolerance": 0.0023, "pitchDiameterMin": 0.0825, "pitchDiameterMax": 0.0848, "unit": "in" }, { "size": "#3-48 UNC", "series": "UNC", "majorDiameter": 0.099, "threadsPerInch": 48, "threadClass": "3A", "lengthOfEngagement": "diameter", "basicPitchDiameter": 0.0855, "allowance": 0, "tolerance": 0.0017, "pitchDiameterMin": 0.0838, "pitchDiameterMax": 0.0855, "unit": "in" }, { "size": "#3-48 UNC", "series": "UNC", "majorDiameter": 0.099, "threadsPerInch": 48, "threadClass": "2B", "lengthOfEngagement": "diameter", "basicPitchDiameter": 0.0855, "allowance": 0, "tolerance": 0.003, "pitchDiameterMin": 0.0855, "pitchDiameterMax": 0.0885, "unit": "in" }, { "size": "#3-48 UNC", "series": "UNC", "majorDiameter": 0.099, "threadsPerInch": 48, "threadClass": "3B", "lengthOfEngagement": "diameter", "basicPitchDiameter": 0.0855, "allowance": 0, "tolerance": 0.0022, "pitchDiameterMin": 0.0855, "pitchDiameterMax": 0.0877, "unit": "in" }, { "size": "#4-40 UNC", "series": "UNC", "majorDiameter": 0.112, "threadsPerInch": 40, "threadClass": "2A", "lengthOfEngagement": "diameter", "basicPitchDiameter": 0.0958, "allowance": 0.0008, "tolerance": 0.0025, "pitchDiameterMin": 0.0925, "pitchDiameterMax": 0.095, "unit": "in" }, { "size": "#4-40 UNC", "series": "UNC", "majorDiameter": 0.112, "threadsPerInch": 40, "threadClass": "3A", "lengthOfEngagement": "diameter", "basicPitchDiameter": 0.0958, "allowance": 0, "tolerance": 0.0019, "pitchDiameterMin": 0.0939, "pitchDiameterMax": 0.0958, "unit": "in" }, { "size": "#4-40 UNC", "series": "UNC", "majorDiameter": 0.112, "threadsPerInch": 40, "threadClass": "2B", "lengthOfEngagement": "diameter", "basicPitchDiameter": 0.0958, "allowance": 0, "tolerance": 0.0033, "pitchDiameterMin": 0.0958, "pitchDiameterMax": 0.0991, "unit": "in" }, { "size": "#4-40 UNC", "series": "UNC", "majorDiameter": 0.112, "threadsPerInch": 40, "threadClass": "3B", "lengthOfEngagement": "diameter", "basicPitchDiameter": 0.0958, "allowance": 0, "tolerance": 0.0024, "pitchDiameterMin": 0.0958, "pitchDiameterMax": 0.0982, "unit": "in" }, { "size": "#5-40 UNC", "series": "UNC", "majorDiameter": 0.125, "threadsPerInch": 40, "threadClass": "2A", "lengthOfEngagement": "diameter", "basicPitchDiameter": 0.1088, "allowance": 0.0008, "tolerance": 0.0026, "pitchDiameterMin": 0.1054, "pitchDiameterMax": 0.108, "unit": "in" }, { "size": "#5-40 UNC", "series": "UNC", "majorDiameter": 0.125, "threadsPerInch": 40, "threadClass": "3A", "lengthOfEngagement": "diameter", "basicPitchDiameter": 0.1088, "allowance": 0, "tolerance": 0.0019, "pitchDiameterMin": 0.1069, "pitchDiameterMax": 0.1088, "unit": "in" }, { "size": "#5-40 UNC", "series": "UNC", "majorDiameter": 0.125, "threadsPerInch": 40, "threadClass": "2B", "lengthOfEngagement": "diameter", "basicPitchDiameter": 0.1088, "allowance": 0, "tolerance": 0.0033, "pitchDiameterMin": 0.1088, "pitchDiameterMax": 0.1121, "unit": "in" }, { "size": "#5-40 UNC", "series": "UNC", "majorDiameter": 0.125, "threadsPerInch": 40, "threadClass": "3B", "lengthOfEngagement": "diameter", "basicPitchDiameter": 0.1088, "allowance": 0, "tolerance": 0.0025, "pitchDiameterMin": 0.1088, "pitchDiameterMax": 0.1113, "unit": "in" }, { "size": "#6-32 UNC", "series": "UNC", "majorDiameter": 0.138, "threadsPerInch": 32, "threadClass": "2A", "lengthOfEngagement": "diameter", "basicPitchDiameter": 0.1177, "allowance": 0.0008, "tolerance": 0.0028, "pitchDiameterMin": 0.1141, "pitchDiameterMax": 0.1169, "unit": "in" }, { "size": "#6-32 UNC", "series": "UNC", "majorDiameter": 0.138, "threadsPerInch": 32, "threadClass": "3A", "lengthOfEngagement": "diameter", "basicPitchDiameter": 0.1177, "allowance": 0, "tolerance": 0.0021, "pitchDiameterMin": 0.1156, "pitchDiameterMax": 0.1177, "unit": "in" }, { "size": "#6-32 UNC", "series": "UNC", "majorDiameter": 0.138, "threadsPerInch": 32, "threadClass": "2B", "lengthOfEngagement": "diameter", "basicPitchDiameter": 0.1177, "allowance": 0, "tolerance": 0.0037, "pitchDiameterMin": 0.1177, "pitchDiameterMax": 0.1214, "unit": "in" }, { "size": "#6-32 UNC", "series": "UNC", "majorDiameter": 0.138, "threadsPerInch": 32, "threadClass": "3B", "lengthOfEngagement": "diameter", "basicPitchDiameter": 0.1177, "allowance": 0, "tolerance": 0.0028, "pitchDiameterMin": 0.1177, "pitchDiameterMax": 0.1205, "unit": "in" }, { "size": "#8-32 UNC", "series": "UNC", "majorDiameter": 0.164, "threadsPerInch": 32, "threadClass": "2A", "lengthOfEngagement": "diameter", "basicPitchDiameter": 0.1437, "allowance": 0.0009, "tolerance": 0.0029, "pitchDiameterMin": 0.1399, "pitchDiameterMax": 0.1428, "unit": "in" }, { "size": "#8-32 UNC", "series": "UNC", "majorDiameter": 0.164, "threadsPerInch": 32, "threadClass": "3A", "lengthOfEngagement": "diameter", "basicPitchDiameter": 0.1437, "allowance": 0, "tolerance": 0.0022, "pitchDiameterMin": 0.1415, "pitchDiameterMax": 0.1437, "unit": "in" }, { "size": "#8-32 UNC", "series": "UNC", "majorDiameter": 0.164, "threadsPerInch": 32, "threadClass": "2B", "lengthOfEngagement": "diameter", "basicPitchDiameter": 0.1437, "allowance": 0, "tolerance": 0.0038, "pitchDiameterMin": 0.1437, "pitchDiameterMax": 0.1475, "unit": "in" }, { "size": "#8-32 UNC", "series": "UNC", "majorDiameter": 0.164, "threadsPerInch": 32, "threadClass": "3B", "lengthOfEngagement": "diameter", "basicPitchDiameter": 0.1437, "allowance": 0, "tolerance": 0.0028, "pitchDiameterMin": 0.1437, "pitchDiameterMax": 0.1465, "unit": "in" }, { "size": "#10-24 UNC", "series": "UNC", "majorDiameter": 0.19, "threadsPerInch": 24, "threadClass": "2A", "lengthOfEngagement": "diameter", "basicPitchDiameter": 0.1629, "allowance": 0.001, "tolerance": 0.0033, "pitchDiameterMin": 0.1586, "pitchDiameterMax": 0.1619, "unit": "in" }, { "size": "#10-24 UNC", "series": "UNC", "majorDiameter": 0.19, "threadsPerInch": 24, "threadClass": "3A", "lengthOfEngagement": "diameter", "basicPitchDiameter": 0.1629, "allowance": 0, "tolerance": 0.0025, "pitchDiameterMin": 0.1604, "pitchDiameterMax": 0.1629, "unit": "in" }, { "size": "#10-24 UNC", "series": "UNC", "majorDiameter": 0.19, "threadsPerInch": 24, "threadClass": "2B", "lengthOfEngagement": "diameter", "basicPitchDiameter": 0.1629, "allowance": 0, "tolerance": 0.0043, "pitchDiameterMin": 0.1629, "pitchDiameterMax": 0.1672, "unit": "in" }, { "size": "#10-24 UNC", "series": "UNC", "majorDiameter": 0.19, "threadsPerInch": 24, "threadClass": "3B", "lengthOfEngagement": "diameter", "basicPitchDiameter": 0.1629, "allowance": 0, "tolerance": 0.0032, "pitchDiameterMin": 0.1629, "pitchDiameterMax": 0.1661, "unit": "in" }, { "size": "#12-24 UNC", "series": "UNC", "majorDiameter": 0.216, "threadsPerInch": 24, "threadClass": "2A", "lengthOfEngagement": "diameter", "basicPitchDiameter": 0.1889, "allowance": 0.001, "tolerance": 0.0034, "pitchDiameterMin": 0.1845, "pitchDiameterMax": 0.1879, "unit": "in" }, { "size": "#12-24 UNC", "series": "UNC", "majorDiameter": 0.216, "threadsPerInch": 24, "threadClass": "3A", "lengthOfEngagement": "diameter", "basicPitchDiameter": 0.1889, "allowance": 0, "tolerance": 0.0025, "pitchDiameterMin": 0.1864, "pitchDiameterMax": 0.1889, "unit": "in" }, { "size": "#12-24 UNC", "series": "UNC", "majorDiameter": 0.216, "threadsPerInch": 24, "threadClass": "2B", "lengthOfEngagement": "diameter", "basicPitchDiameter": 0.1889, "allowance": 0, "tolerance": 0.0044, "pitchDiameterMin": 0.1889, "pitchDiameterMax": 0.1933, "unit": "in" }, { "size": "#12-24 UNC", "series": "UNC", "majorDiameter": 0.216, "threadsPerInch": 24, "threadClass": "3B", "lengthOfEngagement": "diameter", "basicPitchDiameter": 0.1889, "allowance": 0, "tolerance": 0.0033, "pitchDiameterMin": 0.1889, "pitchDiameterMax": 0.1922, "unit": "in" }, { "size": "1/4-20 UNC", "series": "UNC", "majorDiameter": 0.25, "threadsPerInch": 20, "threadClass": "2A", "lengthOfEngagement": "diameter", "basicPitchDiameter": 0.2175, "allowance": 0.0011, "tolerance": 0.0037, "pitchDiameterMin": 0.2127, "pitchDiameterMax": 0.2164, "unit": "in" }, { "size": "1/4-20 UNC", "series": "UNC", "majorDiameter": 0.25, "threadsPerInch": 20, "threadClass": "3A", "lengthOfEngagement": "diameter", "basicPitchDiameter": 0.2175, "allowance": 0, "tolerance": 0.0028, "pitchDiameterMin": 0.2147, "pitchDiameterMax": 0.2175, "unit": "in" }, { "size": "1/4-20 UNC", "series": "UNC", "majorDiameter": 0.25, "threadsPerInch": 20, "threadClass": "2B", "lengthOfEngagement": "diameter", "basicPitchDiameter": 0.2175, "allowance": 0, "tolerance": 0.0048, "pitchDiameterMin": 0.2175, "pitchDiameterMax": 0.2223, "unit": "in" }, { "size": "1/4-20 UNC", "series": "UNC", "majorDiameter": 0.25, "threadsPerInch": 20, "threadClass": "3B", "lengthOfEngagement": "diameter", "basicPitchDiameter": 0.2175, "allowance": 0, "tolerance": 0.0036, "pitchDiameterMin": 0.2175, "pitchDiameterMax": 0.2211, "unit": "in" }, { "size": "5/16-18 UNC", "series": "UNC", "majorDiameter": 0.3125, "threadsPerInch": 18, "threadClass": "2A", "lengthOfEngagement": "diameter", "basicPitchDiameter": 0.2764, "allowance": 0.0012, "tolerance": 0.004, "pitchDiameterMin": 0.2712, "pitchDiameterMax": 0.2752, "unit": "in" }, { "size": "5/16-18 UNC", "series": "UNC", "majorDiameter": 0.3125, "threadsPerInch": 18, "threadClass": "3A", "lengthOfEngagement": "diameter", "basicPitchDiameter": 0.2764, "allowance": 0, "tolerance": 0.003, "pitchDiameterMin": 0.2734, "pitchDiameterMax": 0.2764, "unit": "in" }, { "size": "5/16-18 UNC", "series": "UNC", "majorDiameter": 0.3125, "threadsPerInch": 18, "threadClass": "2B", "lengthOfEngagement": "diameter", "basicPitchDiameter": 0.2764, "allowance": 0, "tolerance": 0.0053, "pitchDiameterMin": 0.2764, "pitchDiameterMax": 0.2817, "unit": "in" }, { "size": "5/16-18 UNC", "series": "UNC", "majorDiameter": 0.3125, "threadsPerInch": 18, "threadClass": "3B", "lengthOfEngagement": "diameter", "basicPitchDiameter": 0.2764, "allowance": 0, "tolerance": 0.0039, "pitchDiameterMin": 0.2764, "pitchDiameterMax": 0.2803, "unit": "in" }, { "size": "3/8-16 UNC", "series": "UNC", "majorDiameter": 0.375, "threadsPerInch": 16, "threadClass": "2A", "lengthOfEngagement": "diameter", "basicPitchDiameter": 0.3344, "allowance": 0.0013, "tolerance": 0.0044, "pitchDiameterMin": 0.3287, "pitchDiameterMax": 0.3331, "unit": "in" }, { "size": "3/8-16 UNC", "series": "UNC", "majorDiameter": 0.375, "threadsPerInch": 16, "threadClass": "3A", "lengthOfEngagement": "diameter", "basicPitchDiameter": 0.3344, "allowance": 0, "tolerance": 0.0033, "pitchDiameterMin": 0.3311, "pitchDiameterMax": 0.3344, "unit": "in" }, { "size": "3/8-16 UNC", "series": "UNC", "majorDiameter": 0.375, "threadsPerInch": 16, "threadClass": "2B", "lengthOfEngagement": "diameter", "basicPitchDiameter": 0.3344, "allowance": 0, "tolerance": 0.0057, "pitchDiameterMin": 0.3344, "pitchDiameterMax": 0.3401, "unit": "in" }, { "size": "3/8-16 UNC", "series": "UNC", "majorDiameter": 0.375, "threadsPerInch": 16, "threadClass": "3B", "lengthOfEngagement": "diameter", "basicPitchDiameter": 0.3344, "allowance": 0, "tolerance": 0.0043, "pitchDiameterMin": 0.3344, "pitchDiameterMax": 0.3387, "unit": "in" }, { "size": "7/16-14 UNC", "series": "UNC", "majorDiameter": 0.4375, "threadsPerInch": 14, "threadClass": "2A", "lengthOfEngagement": "diameter", "basicPitchDiameter": 0.3911, "allowance": 0.0014, "tolerance": 0.0047, "pitchDiameterMin": 0.385, "pitchDiameterMax": 0.3897, "unit": "in" }, { "size": "7/16-14 UNC", "series": "UNC", "majorDiameter": 0.4375, "threadsPerInch": 14, "threadClass": "3A", "lengthOfEngagement": "diameter", "basicPitchDiameter": 0.3911, "allowance": 0, "tolerance": 0.0035, "pitchDiameterMin": 0.3876, "pitchDiameterMax": 0.3911, "unit": "in" }, { "size": "7/16-14 UNC", "series": "UNC", "majorDiameter": 0.4375, "threadsPerInch": 14, "threadClass": "2B", "lengthOfEngagement": "diameter", "basicPitchDiameter": 0.3911, "allowance": 0, "tolerance": 0.0061, "pitchDiameterMin": 0.3911, "pitchDiameterMax": 0.3972, "unit": "in" }, { "size": "7/16-14 UNC", "series": "UNC", "majorDiameter": 0.4375, "threadsPerInch": 14, "threadClass": "3B", "lengthOfEngagement": "diameter", "basicPitchDiameter": 0.3911, "allowance": 0, "tolerance": 0.0046, "pitchDiameterMin": 0.3911, "pitchDiameterMax": 0.3957, "unit": "in" }, { "size": "1/2-13 UNC", "series": "UNC", "majorDiameter": 0.5, "threadsPerInch": 13, "threadClass": "2A", "lengthOfEngagement": "diameter", "basicPitchDiameter": 0.45, "allowance": 0.0015, "tolerance": 0.005, "pitchDiameterMin": 0.4435, "pitchDiameterMax": 0.4485, "unit": "in" }, { "size": "1/2-13 UNC", "series": "UNC", "majorDiameter": 0.5, "threadsPerInch": 13, "threadClass": "3A", "lengthOfEngagement": "diameter", "basicPitchDiameter": 0.45, "allowance": 0, "tolerance": 0.0037, "pitchDiameterMin": 0.4463, "pitchDiameterMax": 0.45, "unit": "in" }, { "size": "1/2-13 UNC", "series": "UNC", "majorDiameter": 0.5, "threadsPerInch": 13, "threadClass": "2B", "lengthOfEngagement": "diameter", "basicPitchDiameter": 0.45, "allowance": 0, "tolerance": 0.0065, "pitchDiameterMin": 0.45, "pitchDiameterMax": 0.4565, "unit": "in" }, { "size": "1/2-13 UNC", "series": "UNC", "majorDiameter": 0.5, "threadsPerInch": 13, "threadClass": "3B", "lengthOfEngagement": "diameter", "basicPitchDiameter": 0.45, "allowance": 0, "tolerance": 0.0048, "pitchDiameterMin": 0.45, "pitchDiameterMax": 0.4548, "unit": "in" }, { "size": "9/16-12 UNC", "series": "UNC", "majorDiameter": 0.5625, "threadsPerInch": 12, "threadClass": "2A", "lengthOfEngagement": "diameter", "basicPitchDiameter": 0.5084, "allowance": 0.0016, "tolerance": 0.0052, "pitchDiameterMin": 0.5016, "pitchDiameterMax": 0.5068, "unit": "in" }, { "size": "9/16-12 UNC", "series": "UNC", "majorDiameter": 0.5625, "threadsPerInch": 12, "threadClass": "3A", "lengthOfEngagement": "diameter", "basicPitchDiameter": 0.5084, "allowance": 0, "tolerance": 0.0039, "pitchDiameterMin": 0.5045, "pitchDiameterMax": 0.5084, "unit": "in" }, { "size": "9/16-12 UNC", "series": "UNC", "majorDiameter": 0.5625, "threadsPerInch": 12, "threadClass": "2B", "lengthOfEngagement": "diameter", "basicPitchDiameter": 0.5084, "allowance": 0, "tolerance": 0.0068, "pitchDiameterMin": 0.5084, "pitchDiameterMax": 0.5152, "unit": "in" }, { "size": "9/16-12 UNC", "series": "UNC", "majorDiameter": 0.5625, "threadsPerInch": 12, "threadClass": "3B", "lengthOfEngagement": "diameter", "basicPitchDiameter": 0.5084, "allowance": 0, "tolerance": 0.0051, "pitchDiameterMin": 0.5084, "pitchDiameterMax": 0.5135, "unit": "in" }, { "size": "5/8-11 UNC", "series": "UNC", "majorDiameter": 0.625, "threadsPerInch": 11, "threadClass": "2A", "lengthOfEngagement": "diameter", "basicPitchDiameter": 0.566, "allowance": 0.0017, "tolerance": 0.0055, "pitchDiameterMin": 0.5588, "pitchDiameterMax": 0.5643, "unit": "in" }, { "size": "5/8-11 UNC", "series": "UNC", "majorDiameter": 0.625, "threadsPerInch": 11, "threadClass": "3A", "lengthOfEngagement": "diameter", "basicPitchDiameter": 0.566, "allowance": 0, "tolerance": 0.0041, "pitchDiameterMin": 0.5619, "pitchDiameterMax": 0.566, "unit": "in" }, { "size": "5/8-11 UNC", "series": "UNC", "majorDiameter": 0.625, "threadsPerInch": 11, "threadClass": "2B", "lengthOfEngagement": "diameter", "basicPitchDiameter": 0.566, "allowance": 0, "tolerance": 0.0072, "pitchDiameterMin": 0.566, "pitchDiameterMax": 0.5732, "unit": "in" }, { "size": "5/8-11 UNC", "series": "UNC", "majorDiameter": 0.625, "threadsPerInch": 11, "threadClass": "3B", "lengthOfEngagement": "diameter", "basicPitchDiameter": 0.566, "allowance": 0, "tolerance": 0.0054, "pitchDiameterMin": 0.566, "pitchDiameterMax": 0.5714, "unit": "in" }, { "size": "3/4-10 UNC", "series": "UNC", "majorDiameter": 0.75, "threadsPerInch": 10, "threadClass": "2A", "lengthOfEngagement": "diameter", "basicPitchDiameter": 0.685, "allowance": 0.0018, "tolerance": 0.0059, "pitchDiameterMin": 0.6773, "pitchDiameterMax": 0.6832, "unit": "in" }, { "size": "3/4-10 UNC", "series": "UNC", "majorDiameter": 0.75, "threadsPerInch": 10, "threadClass": "3A", "lengthOfEngagement": "diameter", "basicPitchDiameter": 0.685, "allowance": 0, "tolerance": 0.0044, "pitchDiameterMin": 0.6806, "pitchDiameterMax": 0.685, "unit": "in" }, { "size": "3/4-10 UNC", "series": "UNC", 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