EN
17
DRILL DIAMETER FOR INTERNAL THREADS
UNC
UNF
Diameter
Pitch
Drill diameter
Diameter
Pitch
Drill diameter
1/4’’
20
5.1
1/4’’
28
5.5
5/16’’
18
6.5
5/16’’
24
6.9
3/8’’
16
7.9
3/8’’
24
8.5
7/16’’
14
9.3
7/16’’
20
9.8
1/2’’
13
10.7
1/2’’
20
11.4
9/16’’
12
12.2
9/16’’
18
12.9
5/8’’
11
13.6
5/8’’
18
14.5
3/4’’
10
16.5
3/4’’
16
17.4
7/8’’
9
19.4
7/8’’
14
20.4
1’’
8
22.3
1’’
14
23.5
M (coarse)
M (fine)
Diameter
Pitch
Drill diameter
Diameter
Pitch
Drill diameter
M3
0.5
2.4
M3
0.35
2.6
M4
0.7
3.2
M4
0.5
3.5
M5
0.8
4.1
M5
0.5
4.5
M6
1.0
4.9
M6
0.75
5.2
M7
1.0
6.0
M7
0.75
6.2
M8
1.25
6.6
M8
1.0
6.9
M9
1.25
7.8
M9
0.75
8.2
M10
1.5
8.4
M10
1.25
8.6
M11
1.5
9.5
M11
0.75
10.2
M12
1.75
10.1
M12
1.5
10.4
M14
2.0
11.8
M12
1.25
10.6
M16
2.0
13.8
M16
1.5
14.4
M18
2.5
15.5
M18
1.0
17.0
M20
2.5
17.3
M18
1.5
16.4