|
UNC / UNF Sizes
|
major
diameter
[inches] |
threads per inch |
major
diameter
[mm] |
tap drill size |
coarse
UNC |
fine
UNF |
extra fine
UNEF |
Coarse
UNC |
fine
UNF |
extra fine
UNEF |
#0 = 0.0600 |
– |
80 |
|
1.5240 |
|
3/64 in |
|
#1 = 0.0730 |
64 |
72 |
|
1.8542 |
#53 |
#53 |
|
#2 = 0.0860 |
56 |
64 |
|
2.1844 |
#50 |
#50 |
|
#3 = 0.0990 |
48 |
56 |
|
2.5146 |
#47 |
#45 |
|
|
#4 = 0.1120 |
40 |
48 |
|
2.8448 |
#43 |
#42 |
|
#5 = 0.1250 |
40 |
44 |
|
3.1750 |
#38 |
#37 |
|
#6 = 0.1380 |
32 |
40 |
|
3.5052 |
#36 |
#33 |
|
#8 = 0.1640 |
32 |
36 |
|
4.1656 |
#29 |
#29 |
|
#10 = 0.1900 |
24 |
32 |
|
4.8260 |
#25 |
#21 |
|
#12 = 0.2160 |
24 |
28 |
32 |
5.4864 |
#16 |
#14 |
|
1/4 |
20 |
28 |
32 |
6.3500 |
#7 |
#3 |
|
5/16 |
18 |
24 |
32 |
7.9375 |
F |
I |
|
3/8 |
16 |
24 |
32 |
9.5250 |
5/16 in |
Q |
|
7/16 |
14 |
20 |
28 |
11.1125 |
U |
25/64 in |
|
1/2 |
13 |
20 |
28 |
12.7000 |
27/64 in |
29/64 in |
|
9/16 |
12 |
18 |
24 |
14.2875 |
31/64 in |
33/64 in |
|
5/8 |
11 |
18 |
24 |
15.8750 |
17/32 in |
37/64 in |
|
3/4 |
10 |
16 |
20 |
19.0500 |
21/32 in |
11/16 in |
|
7/8 |
9 |
14 |
20 |
22.2250 |
49/64 in |
13/16 in |
|
1 |
8 |
12 |
20 |
25.4000 |
7/8 in |
59/64 in |
|
Formula for number screw sizes:
Diameter = Screw size # × 0.013" + 0.060"
Example: #10 × 0.013" + 0.060" = 0.190" diameter
NOTE: Sometimes "special" thread profiles (UNS) are used, for example a 0.619 in (15.7 mm) major diameter with 20 teeth per inch. UNS threads are rarely used for bolts, but rather on nuts, tapped holes, and threaded OD's. Because of this UNS taps and threads are readily available. Most UNS threads have more
threads per inch than the correlating UNF or UNEF standard, therefore they are often the strongest thread available. Because of this they are often used in applications where high stresses are encountered, such as machine tool spindles or automotive spindles.
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|
