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Pre Tap Drill Size

Inch Cutting Tap

Tap
Drill Size
Decimal Equivalent
5/16-24
I
0.2720
5/16-18
F
0.2570
1/4-28
3
0.2130
1/4-20
7
0.2010
12-28
15
0.1800
12-24
16
0.1770
10-32
21
0.1590
10-24
26
0.1470
8-36
29
0.1360
8-32
29
0.1360
6-40
33
0.1130
6-32
36
0.1065
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