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