Archive for March, 2012

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Tap Drill Sizes

TapDrillSizesChart.pdf

TAP DRILL SIZES FOR CUT AND FORMED THREADS
TAP     SIZE TAP DRILL SIZE
Cut Thread Formed Thread
0-80 3/64 .0469 54 .0545
1-64 53 .0595 1.65 mm .065
1-72 53 ,0595 1.7 mm .0669
2-56 50 .0700 5/64 .0781
2-64 50 .0700 2 mm .0787
3-48 46 .0810 43 .089
3-56 45 .0820 2.3 mm .0906
4-40 43 .0890 39 .0995
4-48 3/32 .0938 2.6 mm .1024
5-40 38 .1015 33 .113
5-44 37 .1040 2.9 mm .1142
6-32 34 .1110 1/8 .125
6-40 32 .1160 3.2 mm .1260
8-32 29 .1360 25 .1495
8-36 29 .1360 24 .1520
10-24 23 .1540 11/64 .1719
10-32 20 .1610 16 .1770
12-24 15 .1800 5 mm .1968
12-28 13 .1850 8 .1990
1/4-20 13/64 .2031 1 .2280
1/4-28 7/32 .2187 A .2340
5/16-18 G .2610 7.3 mm .2874
5/16-24 J .2770 M .2950
3/8-16 O .3160 S .3480
3/8-24 R .3390 T .358
7/16-14 U .3680 13/32 .406
7/16-20 25/64 .3906 10.5 mm .4134
1/2-13 27/64 .4219 * .466
1/2-20 29/64 .4531 * .478
9/16-12 31/64 .4844 * .525
9/16-18 33/64 .5156 * ,538
5/8-11 35/64 .5469 * .584
5/8-18 37/64 .5781 * .600
11/16-11 39/64 .6094 * .646
11/16-16 5/8 .6250 * .660
3/4-10 21/32 .6562 45/64 .7031
3/4-16 11/16 .6875 * .722
7/8-9 49/64
7/8-14 13/16
1-8 7/8
1-4 15/16
1-1/8-7 63/64
1-1/8-12 1-3/64

CUT TAP NOTE: At times, you can drill a slightly larger hole to make the tapping process a bit easier. This can be done without sacrificing much of the thread’s strength. This is because most of a thread’s strength is found at its base. By making the hole larger, you are essentially cutting off the tip of a thread, not its base. You are also lowering the amount of resistance encountered while cutting the thread. This is a trick that some machinists use when they are concerned about breaking a tap tool in a hole, lowering the horsepower (HP) requirement for a self-reversing tap head or automatic tapping machine such as a Control Feed Tapper or Lead Screw tap machine.