Vintage Knowledge - Threads

 

BA (British Association)

SIZE PITCH APROX OUTSIDE DIA CORE DIA DEPTH OF THREAD DRILLS SPANNER
[Series]   TPI             TAPPING CLEARANCE A/F
  Metric   Imperial Metric Imperial Metric Imperial Metric Imperial Metric Imperial Metric  
0 1.00 25.400 0.2360 5.99 0.1890 4.80 0.0240 0.61 No. 9 4.98 1/4 6.35 0.413
1 0.90 28.222 0.2090 5.31 0.1660 4.22 0.0210 0.53 11/64 4.37 No. 2 5.61 0.365
2 0.81 31.358 0.1850 4.70 0.1470 3.73 0.0190 0.48 No. 24 3.86 No. 10 4.91 0.324
3 0.73 34.795 0.1610 4.09 0.1270 3.23 0.0170 0.43 No. 29 3.45 11/64 4.37 0.282
4 0.66 38.485 0.1420 3.61 0.1110 2.82 0.0160 0.41 No. 31 3.05 No. 27 3.66 0.248
5 0.59 43.051 0.1260 3.20 0.0980 2.49 0.0140 0.36 No. 38 2.58 No. 30 3.26 0.22
6 0.53 47.925 0.1100 2.79 0.0850 2.16 0.0120 0.30 No. 43 2.26 No. 33 2.87 0.193
7 0.48 52.917 0.0980 2.49 0.0750 1.91 0.0110 0.28 No. 46 2.06 No. 37 2.64
8 0.43 59.070 0.0870 2.21 0.0660 1.68 0.0100 0.25 No. 50 1.78 No. 43 2.26
9 0.39 65.128 0.0750 1.91 0.0560 1.42 0.0090 0.23 No. 53 1.51 No. 48 1.93
10 0.35 72.571 0.0660 1.68 0.0500 1.27 0.0070 0.18 No. 55 1.32 No. 50 1.78

BSF ( British Standard Fine )

SIZE TPI OUTSIDE DIA CORE DIA DEPTH OF THREAD DRILLS
[inches]               CLEARANCE TAPPING
    Imperial Metric Imperial Metric Imperial Metric Imperial Metric Imperial Metric
3/16 32 0.1875 4.76 0.1475 3.75 0.0200 0.51   4.90 No 22 4.00
7/32 28 0.2188 5.56 0.1730 4.39 0.0229 0.58   5.70 No 15 4.60
1/4 26 0.2500 6.35 0.2000 5.08 0.0250 0.63 17/64 6.75 No. 3 5.50
9/32 26 0.2800 7.14 0.2300 5.89 0.0255 0.64       6.10
5/16 22 0.3125 7.94 0.2540 6.45 0.0290 0.74 21/64 8.33 17/64 6.75
3/8 20 0.3750 9.53 0.3110 7.90 0.0320 0.81 25/64 9.92 21/64 8.33
7/16 18 0.4375 11.11 0.3660 9.30 0.0360 0.91 29/64 11.51 3/8 9.53
1/2 16 0.5000 12.70 0.4200 10.67 0.0400 1.02 17/32 13.49 7/16 11.11
9/16 16 0.5625 14.29 0.4820 12.24 0.0400 1.02 19/32 15.08 1/2 12.70
5/8 14 0.6250 15.88 0.5330 13.54 0.0460 1.17 21/32 16.67 9/16 14.29
11/16 14 0.6875 17.46 0.5960 15.14 0.0457 1.16   17.75   15.50
3/4 12 0.7500 19.05 0.6430 16.33 0.0530 1.35 25/32 19.84 43/64 17.07
13/16 12 0.8100 20.64 0.7100 17.92 0.0550 1.36       18.25
7/8 11 0.8750 22.23 0.7590 19.28 0.0580 1.47 29/32 23.02 25/32 19.84
1 10 1.0000 25.40 0.8720 22.15 0.0640 1.63 1 1/16 26.99 29/32 23.02
1 1/8 9 1.1250 28.58 0.9830 24.97 0.0710 1.80 1 3/16 30.16 1 1/64 25.80
1 1/4 9 1.2500 31.75 1.1080 28.14 0.0710 1.80 1 5/16 33.34 1 9/64 28.97
1 3/8 8 1.3750 34.93 1.2150 30.86 0.0800 2.03 1 7/16 36.51 1 1/4 31.75
1 1/2 8 1.5000 38.10 1.3400 34.04 0.0800 2.03 1 9/16 39.69 1 3/8 34.93
1 5/8 8 1.6300 41.30 1.4600 37.21 0.0800 2.03       37.50
1 3/4 7 1.7500 44.45 1.5670 39.80 0.0915 2.32   45.00   41.00
2 7 2.0000 50.8 1.8170 46.15 0.0915 2.32   52.00   47.00
2 1/4 6 2.2500 57.15 2.0366 51.73 0.1067 2.71   58.00   53.00
2 1/2 6 2.5000 63.5 2.2866 58.08 0.1067 2.71   64.00   58.00

BSW (British Standard Whitworth)

SIZE TPI OUTSIDE DIA CORE DIA DEPTH OF THREAD DRILLS

 

              CLEARANCE TAPPING
[inches]   Imperial Metric Imperial Metric Imperial Metric Imperial Metric Imperial Metric
1/16 60 0.062 1.59 0.041 1.05 0.011 0.27       1.15
3/32 48 0.094 2.38 0.067 1.70 0.013 0.34       1.90
1/8 40 0.125 3.18 0.093 2.36 0.016 0.41 9/64 3.57 No. 38 2.60
5/32 32 0.156 3.97 0.116 2.95 0.020 0.51 11/64 4.37 1/8 3.20
3/16 24 0.187 4.75 0.134 3.40 0.027 0.69 13/64 5.16 No. 27 3.70
7/32 24 0.219 5.56 0.166 4.22 0.027 0.69 15/64 5.95 No. 19 4.30
1/4 20 0.250 6.35 0.186 4.72 0.032 0.81 17/64 6.75 No. 9 5.00
5/16 18 0.312 7.92 0.241 6.12 0.036 0.91 21/64 8.33 1/4 6.40
3/8 16 0.375 9.53 0.295 7.49 0.040 1.02 25/64 9.92 5/16 8.00
7/16 14 0.437 11.10 0.346 8.79 0.046 1.17 29/64 11.51 Letter U 9.40
1/2 12 0.500 12.70 0.393 9.98 0.053 1.35 17/32 13.49 27/64 10.80
9/16 12 0.563 14.29 0.456 11.58 0.053 1.35 19/32 15.08 15/32 12.00
5/8 11 0.625 15.88 0.509 12.93 0.058 1.47 21/32 16.67 17/32 13.50
11/16 11 0.688 17.48 0.571 14.50 0.058 1.47   17.75   15.00
3/4 10 0.750 19.05 0.622 15.80 0.064 1.63 25/32 19.84 21/32 17.00
13/16 10 0.813 20.65 0.684 17.37 0.064 1.63   21.00   18.00
7/8 9 0.875 22.23 0.733 18.62 0.071 1.80 29/32 23.02 49/64 19.50
15/16 9 0.938 23.83 0.795 20.19 0.071 1.80   24.00   20.75
1 8 1.000 25.40 0.840 21.34 0.080 2.03 1 1/16 26.99 7/8 22.50
1 1/8 7 1.125 28.58 0.942 23.93 0.092 2.34 1 3/16 30.16 1 25.50
1 1/4 7 1.250 31.75 1.067 27.10 0.092 2.34 1 5/16 33.34 1 7/64 28.50
1 3/8 6 1.375 34.93 1.162 29.51 0.107 2.72 1 7/16 36.51 1 7/32 31.00
1 1/2 6 1.500 38.10 1.287 32.69 0.107 2.72 1 9/16 39.69 1 11/32 34.50
1 5/8 5 1.625 41.28 1.369 34.77 0.128 3.25   41.5   35.50
1 3/4 5 1.750 44.45 1.494 37.95 0.128 3.25   45   38.50
1 7/8 4.5 1.875 47.63 1.591 40.40 0.142 3.61   48   41.25
2 4.5 2.000 50.80 1.715 43.57 0.142 3.61   51   44.5


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