UNEF = Unified National Extra Fine. This is one of three graded series: UNC (Unified National Corase); UNF (Unified National Fine); and UNEF (Unified National Extra Fine). The Nominal Major Diameter and Threads-per-inch (Pitch) are defined by ANSI/ASME B1.1 and are the choices for the customary Unified screws and
nuts.
Nominal
Diameter
Major
Diameter
Inch
Major
Diameter
mm
Tapping Drill
Size
mm
TPI
Pitch
mm
#12 - 32 UNEF
0.2160
5.486
4.80
32
0.794
1/4" - 32 UNEF
0.2500
6.350
5.70
32
0.794
5/16" - 32 UNEF
0.3125
7.938
7.25
32
0.794
3/8" - 32 UNEF
0.3750
9.525
8.85
32
0.794
7/16" - 28 UNEF
0.4375
11.112
10.35
28
0.907
1/2" - 28 UNEF
0.5000
12.700
11.80
28
0.907
9/16" - 24 UNEF
0.5625
14.288
13.40
24
1.058
5/8" - 24 UNEF
0.6250
15.875
15.00
24
1.058
11/16" - 24 UNEF
0.6875
17.462
16.60
24
1.058
3/4" - 20 UNEF
0.7500
19.050
18.00
20
1.270
13/16" - 20 UNEF
0.8125
20.638
19.60
20
1.270
7/8" - 20 UNEF
0.8750
22.225
21.15
20
1.270
15/16" - 20 UNEF
0.9375
23.812
22.70
20
1.270
1" - 20 UNEF
1.0000
25.400
24.30
20
1.270
1-1/16" - 18 UNEF
1.0625
26.988
25.80
18
1.411
1-1/8" - 18 UNEF
1.1250
28.575
27.35
18
1.411
1-1/4" - 18 UNEF
1.2500
31.750
30.55
18
1.411
1-5/16" - 18 UNEF
1.3125
33.338
32.10
18
1.411
1-3/8" - 18 UNEF
1.3750
34.925
33.70
18
1.411
1-7/16" - 18 UNEF
1.4375
36.512
35.30
18
1.411
1-1/2" - 18 UNEF
1.5000
38.100
36.90
18
1.411
1-9/16" - 18 UNEF
1.5625
39.688
38.55
18
1.411
1-5/8" - 18 UNEF
1.6250
41.275
40.10
18
1.411
1-11/16" - 18 UNEF
1.6875
42.862
41.60
18
1.411
UNEF Screw Thread
Disclaimer:
This data is provided for general information only. The intention
is to provide accurate information; regardless; errors may exist
in the supplied information. If accuracy is critical, base your
final decisions on the data provided in the root document: ANSI/ASME
B1.1:2003; which is a copyrighted document. To purchase a copy visit
an Authorized Reseller.
Comments:
Original Posting: 7/14/2009
Last Revision: 5/16/2016
Error corrections in, or comments about, the above data can be sent
to: office@gagecrib.com
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6701 Old 28th St SE, Suite B
Grand Rapids, MI 49546-6937
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