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External Threads - Class 2A

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Nominal Size & Threads/lnch & Series Designation Allowance Major Diameter Pitch Diameter
Max Min Max Min Max Tolerance
0-80 UNF 0.0005 0.0595 0.0563 0.0514 0.0496 0.0018
1-64 UNC 0.0006 0.0724 0.0686 0.0623 0.0603 0.0020
1-72 UNF 0.0006 0.0724 0.0689 0.0634 0.0615 0.0019
2-56 UNG 0.0006 0.0854 0.0813 0.0738 0.0717 0.0021
2-64 UNF 0.0006 0.0854 0.0816 0.0753 0.0733 0.0020
3-48 UNG 0.0007 0.0938 0.0938 0.0848 0.0825 0.0023
3-56 UNF 0.0007 0.0983 0.0942 0.0867 0.0845 0.0022
4-40 UNG 0.0008 0.1112 0.1061 0.0950 0.0925 0.0025
4-48 UNF 0.0007 0.1113 0.1068 0.0978 0.0954 0.0024
5-40 UNC 0.0008 0.1242 0.1191 0.1080 0.1054 0.0026
5-44 UNF 0.0007 0.1243 0.1195 0.1095 0.1070 0.0025
6-32 UNG 0.0008 0.1372 0.1312 0.1169 0.1141 0.0028
6-40 UNF 0.0008 0.1372 0.1321 0.1210 0.1184 0.0026
8-32 UNG 0.0009 0.1631 0.1571 0.1428 0.1399 0.0029
8-36 UNF 0.0008 0.1632 0.1577 0.1452 0.1424 0.0028
10-24 UNG 0.0010 0.1890 0.1818 0.1619 0.1586 0.0033
10-32 UNF 0.0009 0.1891 0.1831 0.1688 0.1658 0.0030
12-24 UNG 0.0010 0.2150 0.2078 0.1879 0.1845 0.0034
12-28 UNF 0.0010 0.2150 0.2085 0.1918 0.1886 0.0032
1/4-20 UNG 0.0011 0.2489 0.2408 0.2164 0.2127 0.0037
1/4-28 UNF 0.0010 0.2490 0.2425 0.2258 0.2225 0.0033
5/16-18 UNG 0.0012 0.3113 0.3026 0.2752 0.2712 0.0040
5/16-24 UNF 0.0011 0.3114 0.3042 0.2843 0.2806 0.0037
3/8-16 UNG 0.0013 0.3737 0.3643 0.3331 0.3287 0.0044
3/8-24 UNF 0.0011 0.3739 0.3667 0.3468 0.3430 0.0038
7/16-14 UNG 0.0014 0.4361 0.4258 0.3897 0.3850 0.0047
7/16-20 UNF 0.0013 0.4362 0.4281 0.4037 0.3995 0.0042
1/2-13 UNG 0.0015 0.4985 0.4876 0.4485 0.4435 0.0050
1/2-20 UNF 0.0013 0.4987 0.4906 0.4662 0.4619 0.0043
9/16-12 UNG 0.0016 0.5609 0.5495 0.5068 0.5016 0.0052
9/16-18 UNF 0.0014 0.5611 0.5524 0.5250 0.5205 0.0045
5/8-11 UNG 0.0016 0.6234 0.6113 0.5644 0.5589 0.0055
5/8-18 UNF 0.0014 0.6236 0.6149 0.5875 0.5828 0.0047
3/4-10 UNG 0.0018 0.7482 0.7353 0.6832 0.6773 0.0059
3/4-16 UNF 0.0015 0.7485 0.7391 0.7079 0.7029 0.0050
7/8-9 UNG 0.0019 0.8731 0.8592 0.8009 0.7946 0.0063
7/8-14 UNF 0.0016 0.0834 0.8631 0.8270 0.8216 0.0054
1-8 UNG 0.0020 0.9980 0.9830 0.9168 0.9100 0.0068
1-12 UNF 0.0018 0.9982 0.9868 0.9441 0.9382 0.0059
1-14 UNS 0.0017 0.9983 0.9880 0.9519 0.9463 0.0056
11/8-7 UNG 0.0022 1.1228 1.1064 1.0300 1.0228 0.0072
11/8-8 UN 0.0021 1.1229 1.1079 1.0417 1.0348 0.0069
11/8-12 UNF 0.0018 1.1232 1.1118 1.0691 1.0631 0.0060
11/4-7 UNG 0.022 1.2478 1.2314 1.1550 1.1476 0.0074
1114-8 UN 0.0021 1.2479 1.2329 1.1667 1.1597 0.0070
11/4-12 UNF 0.0018 1.2482 1.2368 1.1941 1.1879 0.0062
13/8-6 UNC 0.0024 1.3726 1.3544 1.2643 1.2563 0.0080
13/8-8 UN 0.0022 1.3728 1.3578 1.2916 1.2844 0.0072
13/8-12 UNF 0.0019 1.3731 1.3617 1.3190 1.3127 0.0063
11/2-6 UNC 0.0024 1.4976 1.4794 1.3893 1.3812 0.0081
11/2-8 UN 0.0022 1.4978 1.4828 1.4166 1.4093 0.0073
11/2-12 UNC 0.0019 1.4981 1.4867 1.4440 1.4376 0.0064
15/8-8 UN 0.0022 1.6228 1.6087 1.5416 1.5342 0.0074
13/4-5 UNC 0.0027 1.7473 1.7268 1.6174 1.6085 0.0089
13/4-8 UN 0.0023 1.7477 1.7327 1.6665 1.6590 0.0075
17/8-8 UN 0.0023 1.8727 1.8577 1.7915 1.7838 0.0077
2-41/2 UNC 0.0029 1.9971 1.9751 1.8528 1.8433 0.0095
2-8 UN 0.0023 1.9977 1.9827 1.9165 1.9087 0.0078
21/4-4.5 UNC 0.0029 2.2471 2.2251 2.1028 2.0931 0.0097
21/4-8 UN 0.0024 2.2476 2.2326 2.1664 2.1584 0.0080
2 1/2-4 UNC 0.0031 2.4969 2.4731 2.3345 2.3241 0.0104
2 1/2-8 UN 0.0024 2.4976 2.4826 2.4164 2.4082 0.0082
2 3/4-4 UNC 0.0032 2.7468 2.7230 2.5844 2.5739 0.0105
2 3/4-8 UN 0.0025 2.7475 2.7325 2.6663 2.6580 0.0083
3-4 UNC 0.0032 2.9968 2.9730 2.8344 2.8237 0.0107
3-8 UN 0.0026 2.9974 2.9824 2.9162 2.9077 0.0085
3 1/4-4 UNC 0.0033 3.2467 3.2229 3.0843 3.0734 0.0109
3 1/4-8 UN 0.0026 3.2474 3.2324 3.1662 3.1575 0.0087
3 1/2-4 UNC 0.0033 3.4967 3.4729 3.3343 3.3233 0.0110
3 1/2-8 UN 0.0026 3.4974 3.4824 3.4162 3.4074 0.0088
3 3/4-4 UNC 0.0034 3.7466 3.7228 3.5842 3.5730 0.0112
3 3/4-8 UN 0.0027 3.7473 3.7323 3.6661 3.6571 0.0090
4-4 UNC 0.0034 3.9966 3.9728 3.8342 3.8229 0.0113
4-8 UN 0.0027 3.9973 3.9823 3.9161 3.9070 0.0091
External Threads - Class 2A for Sale External Threads - Class 2A for Sale External Threads - Class 2A for Sale

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Nominal Screw Size O thru l2 1/4 thru 3/4
Nominal Screw Length Tolerance on Length
Up to 1/2 in., Incl. -0.02 -0.03
Over 1/2 to 1 in., Incl. -0.03 -0.03
Over 1 to 2 in., Incl. -0.06 -0.06
Over 2 in. -0.09 -0.09

Disclaimer: The dimensions listed are for reference only. Sizes not listed may be available off the shelf or can be manufactured to customer requirements.

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