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.
