Sheet1Tapping Drill Sizes for tappingTapping Drill Sizes to use for BSW BSF UNC UNF NS MetricBSP BSPT NPT BSB BA Cycle 26 threadsME 32 threads 40 tpiby The Tapand Die Company, London, UKBRITISH STANDARD WHITWORTH FORM THREADS (55o degree angle)Dia BSW BSF BSBBSP & BSPT BS Conduit Model Engineer WhitformtpiDrill mmtpi Drill mmtpiDrill mmtpiDrill mmtpiDrill mmtpiDrill mmtpiDrill mm1/16"601.23/32481.91/8"402.55288.8402.555/32323.232, 403.2, 3.33/16243.7324.032, 404.0, 4.07/32244.5284.632, 404.8, 4.81/4"205.1265.3265.31911.832, 405.5, 5.524, 285.3, 5.49/32205.8266.0266.132, 406.1, 6.55/16186.5226.8265.832, 406.75, 7.3245.753/8"167.9208.3268.41915.2532, 408.6, 8.9248.47/16149.3189.72610.032, 4010.3, 10.520, 249.8,101/2"1210.51611.12611.51419.01811.532, 4011.9, 12.020, 2411.5, 11.99/161212.11612.72613.12013.15/8"1113.51414.02614.71421.01814.22014.511/161115.11415.52616.52016.23/4"1016.251216.752617.81424.51617.514, 2017.1, 17.87/8919.251119.752621.01428.251620.816, 2020.6, 2115/16920.61121.5 1"822.01022.752624.21130.751823.812, 2023, 241.1/8724.75925.52627.51.1/4728.0928.52630.51139.51830.11.3/8630.1831.52633.71438.11.1/2633.5834.52636.91145.01.3/4539.0741.02643.51151.0 2"4.1/244.5747.02649.61157.01448.8 AMERICAN (60o angle) AMERICAN(60o angle)BSC (60o angle) BA (47.1/2o angle)Dia NC NF NPTDia NC NFDiaBS CycleDia British AssociationtpiDrill mmtpiDrill mmtpiDrill mmtpiDrill mmtpiDrill mmtpiDrill mm diatpiDrill mm1/8"278.7 0801.251/4"265.6 0.2362"25.45.11/4"205.128 5.51811.1 1641.55721.559/32266.35 10.208728.24.55/1618 6.6246.9 2561.85641.95/16267.2 20.161434.84.01/2"1310.82011.51418.0 3482.1562.153/8"268.7 30.161434.83.49/161212.21812.9 4402.35482.47/162610.3 40.141738.53.05/81113.51814.5 5402.65442.71/2"2611.9 50.126432.653/41016.51617.51423.25 6322.85402.959/162013.1 60.110247.92.37/8919.51420.4 8323.5363.59/162613.5 70.098452.92.05 1"822.251226.510243.9324.15/82014.5 80.086659.11.81.1/8725.01226.512244.5284.75/8"2615.0 90.074865.11.551.1/4728.01229.511.538.03/42017.8100.066972.61.41.3/8630.751232.753/4"2618.2110.059181.91.21.1/2634.01236.011.544.0120.051290.91.051.3/4539.5130.04721020.98 2"11.556.0140.0394109.90.80150.0354120.50.70160.0311133.30.60METRIC THREAD SIZES (60o angle) mmDrill mm mmDrill mm mmDrill mm mmDrill mmmDrill mmmmDrill mm0.8 x .19 0.64 x .73.39 x 1 8.014 x 1.512.524 x 123.036 x 333.00.9 x .21 0.74 x .75 3.259 x 1.257.7514x 212.024 x 222.036 x 432.01 x .250.754.5 x .54.010 x .75 9.2515 x 114.024 x 321.039 x 1.537.51.2 x .25 0.954.5 x .75 3.7510 x 1 9.015 x 213.025 x 1.523.539 x 435.01.4 x .3 1.15 x .5 4.510 x 1.258.7516 x 115.027 x 1.525.540 x 1.538.51.6 x .35 1.255 x .75 4.2510 x 1.5 8.516 x 214.027 x 225.042 x 4.537.51.8 x .35 1.455 x .84.211 x.7510.2518 x 117.027 x 324.045 x 4.540.52 x .4 1.65 x .9 4.111 x 110.018 x 1.516.530 x 129.048 x 543.02 x .45 1.555 x 1 4.011x 1.25 9.7518 x 216.030 x 1.528.52.2 x .45 1.755.5 x .9 4.611 x 1.5 9.518 x 2.515.530 x 228.02.3 x .41.96 x .5 5.512 x 111.020 x 119.030 x 327.02.5 x .45 2.16 x .75 5.2512 x 1.2510.7520 x 1.518.532 x 1.530.52.6 x .452.156x 1 5.012 x 1.510.520 x 218.032 x 230.03 x 3.52.657x .756.2512 x 1.7510.2520 x 2.517.533 x 1.531.53 x .5 2.57 x 16.013 x 1.2511.7522 x121.033 x 231.03 x .6 2.48 x .75 7.2513 x 1.7511.2522 x 1.520.533 x 3.529.53.5 x .6 2.98 x 17.04 x 113.022 x 220.036 x 1.534.54 x .5 3.58 x 1.25 6.7514 x 1.2512.7522x 2.519.536 x 333.0