Besly Cutting Tools, Inc 16200 Woodmint Lane South Beloit IL 61080 815-389-2231    Close

Besly Drill Selector for Cutting Taps
Fractional Sizes
Tap Size Drill
to Use		 Drill Decimal
Equivalent		  Theoretical
% of
Thread		 Probable
Oversize		 Probable
Hole Size		  % of
Thread
1/4-20 9  .1960  83 .0038 .1998  77
  8  .1990  79 .0038 .2028  73
  7  .2010  75 .0038 .2048  70
  13/64  .2031  72 .0038 .2069  66
  6  .2040  71 .0038 .2078  65
  5  .2055  69 .0038 .2093  63
  4  .2090  63 .0038 .2128  57
1/4-28 3  .2130  80 .0038 .2168  72
5/16-18 F  .2570  77 .0038 .2608  72
  G  .2610  71 .0041 .2651  66
5/16-24 H  .2660  86 .0041 .2701  78
  I  .2720  75 .0041 .2761  67
3/8-16 5/16  .3125  77 .0044 .3169  72
  O  .3160  73 .0044 .3204  68
3/8-24 21/64  .3281  87 .0044 .3325  79
  Q  .3320  79 .0044 .3364  71
7/16-14 T  .3580  86 .0046 .3626  81
  23/64  .3594  84 .0046 .3640  79
  U  .3680  75 .0046 .3726  70
  3/8  .3750  67 .0046 .3796  62
  V  .3770  65 .0046 .3816  60
7/16-20 W  .3860  79 .0046 .3906  72
  25/64  .3906  72 .0046 .3952  65
1/2-13 27/64  .4219  78 .0047 .4266  73
1/2-20 29/64  .4531  72 .0047 .4578  65
9/16-12 15/32  .4688  87 .0048 .4736  82
  31/64  .4844  72 .0048 .4892  68
9/16-18 1/2  .5000  87 .0048 .5048  80
5/8-11 17/32  .5313  79 .0049 .5362  75
  35/64  .5469  66 .0049 .5518  62
5/8-18 9/16  .5625  87 .0049 .5674  80
3/4-10 41/64  .6406  84 .0050 .6456  80
  21/32  .6563  72 .0050 .6613  68
3/4-16 11/16  .6875  77 .0050 .6925  71
7/8-9 49/64  .7656  76 .0052 .7708  72
  25/32  .7812  65 .0052 .7864  61
7/8-14 51/64  .7969  84 .0052 .8021  79
  13/16  .8125  67 .0052 .8177  62
1"-8 55/64  .8594  87 .0059 .8653  83
  7/8  .8750  77 .0059 .8809  73
  55/64  .8906  67 .0059 .8965  64
1"-12 23/32  .9063  87 .0060 .9122  81
  59/64  .9219  72 .0060 .9279  67
1"-14 59/64  .9219  84 .0060 .9279  78
  15/16  .9375  67 .0060 .9435  61
1-1/8-7 31/32  .9688  84 .0062 .9750  81
  63/64  .9844  76 .0067 .9911  72
  1"  1.0000  67 .0070 1.0070  64
1-1/8-12 1-1/32 1.0313  87 .0071 1.0384  80
  1-3/64 1.0469  72 .0072 1.0541  66
1-1/4-7 1-3/32 1.0938  84      
  1-7/64 1.1094  76      
  1-1/8 1.1250  67      
1-1/4-12 1-5/32 1.1563  87      
  1-11/64 1.1719  72      
1-3/8-6 1-3/16 1.1875  87      
  1-13/64 1.2031  79      
  1-7/32 1.2188  72      
  1-15/64 1.2344  65      
1-3/8-12 1-9/32 1.2813  87      
  1-19/64  1.2969  72      
1-1/2-6 1-5/16 1.3125  87      
  1-21/64 1.3281  79      
  1-11/32  1.3438  72      
  1-23/64 1.3594  65      
1-1/2-12 1-13/32 1.4063  87      
  1-27/64 1.4219  72      

Copyright 2008 by Besly Cutting Tools, Inc. All Rights Reserved.                            Close