Table 3. Standard Series and Selected Combinations—Unified Screw Threads Table 3. (Continued) Standard Series and Selected Combinations—Unified Screw Threads
External b
Internal b
Nominal Size, Threads per Inch, and Series Designation a
Major Diameter
UNR Minor Dia., c Max (Ref.)
Major Diameter
Pitch Diameter
Minor Diameter
Pitch Diameter
Allow ance
Max d
Min e
Max d
Class
Min
Min
Min
Max
Min
Max
Min 0.6250 0.6250 0.6875 0.6875 0.6875 0.6875 0.6875 0.6875 0.6875 0.6875 0.6875 0.6875 0.6875 0.6875 0.7500 0.7500 0.7500 0.7500 0.7500 0.7500 0.7500 0.7500 0.7500 0.7500 0.7500 0.7500 0.7500 0.7500
Class
2A 0.0011 0.6239 0.6179 3A 0.0000 0.6250 0.6190 2A 0.0016 0.6859 0.6745 3A 0.0000 0.6875 0.6761 2A 0.0014 0.6861 0.6767 3A 0.0000 0.6875 0.6781 2A 0.0013 0.6862 0.6781 3A 0.0000 0.6875 0.6794 2A 0.0012 0.6863 0.6791 3A 0.0000 0.6875 0.6803 2A 0.0011 0.6864 0.6799 3A 0.0000 0.6875 0.6810 2A 0.0011 0.6864 0.6804 3A 0.0000 0.6875 0.6815 1A 0.0018 0.7482 0.7288 3A 0.0000 0.7500 0.7371 2A 0.0017 0.7483 0.7369 3A 0.0000 0.7500 0.7386 2A 0.0015 0.7485 0.7382 1A 0.0015 0.7485 0.7343 2A 0.0015 0.7485 0.7391 3A 0.0000 0.7500 0.7406 2A 0.0014 0.7486 0.7399 2A 0.0013 0.7487 0.7406 3A 0.0000 0.7500 0.7419 2A 0.0012 0.7488 0.7416 2A 0.0012 0.7488 0.7421
— 0.6036 0.6000 — 0.6047 0.6020 — 0.6318 0.6263 — 0.6334 0.6293 — 0.6455 0.6407 — 0.6469 0.6433 — 0.6537 0.6493 — 0.6550 0.6517 — 0.6592 0.6552 — 0.6604 0.6574 — 0.6632 0.6594 — 0.6643 0.6614 — 0.6661 0.6625 — 0.6672 0.6645 — 0.6832 0.6744 — 0.6850 0.6806 — 0.6942 0.6887 — 0.6959 0.6918 — 0.7021 0.6970 — 0.7079 0.7004 — 0.7079 0.7029 — 0.7094 0.7056 — 0.7125 0.7079 — 0.7162 0.7118 — 0.7175 0.7142 — 0.7217 0.7176 — 0.7247 0.7208
0.5867 0.5878 0.5867 0.5883 0.6117 0.6131 0.6267 0.6280 0.6367 0.6379 0.6439 0.6450 0.6492 0.6503 0.6291 0.6291 0.6309 0.6491 0.6508 0.6634 0.6741 0.6741 0.6756 0.6824 0.6892 0.6905 0.6992 0.7047
2B 0.591
0.599
0.6047 0.6093 0.6047 0.6082 0.6334 0.6405 0.6334 0.6387 0.6469 0.6532 0.6469 0.6516 0.6550 0.6607 0.6550 0.6593 0.6604 0.6657 0.6604 0.6643 0.6643 0.6692 0.6643 0.6680 0.6672 0.6719 0.6672 0.6707 0.6850 0.6965 0.6850 0.6927 0.6850 0.6907 0.6959 0.7031 0.6959 0.7013 0.7036 0.7103 0.7094 0.7192 0.7094 0.7159 0.7094 0.7143 0.7139 0.7199 0.7175 0.7232 0.7175 0.7218 0.7229 0.7282 0.7259 0.7310
5 ∕ 8 -32 UN
3B 0.5910 0.5969
2B 0.597
0.615
11 ∕ 16 -12 UN
3B 0.5970 0.6085
2B 0.620
0.634
11 ∕ 16 -16 UN
3B 0.6200 0.6284
2B 0.633
0.645
11 ∕ 16 -20 UN
3B 0.6330 0.6411
2B 0.642
0.652
11 ∕ 16 -24 UNEF
3B 0.6420 0.6494
2B 0.649
0.657
11 ∕ 16 -28 UN
3B 0.6490 0.6551
2B 0.654
0.661
11 ∕ 16 -32 UN
3B 0.6540 0.6594
1B 0.642 2B 0.642
0.663 0.663
3 ∕ 4 -10 UNC
2A 0.0018 0.7482 0.7353 0.7288 0.6832 0.6773
3B 0.6420 0.6545
2B 0.660
0.678
3 ∕ 4 -12 UN
3B 0.6600 0.6707
2B 0.673 1B 0.682 2B 0.682 2B 0.690 2B 0.696 2B 0.705 2B 0.710
0.688 0.696 0.696 0.703 0.707 0.715 0.719
3 ∕ 4 -14 UNS 3 ∕ 4 -16 UNF
3B 0.6820 0.6909
3 ∕ 4 -18 UNS 3 ∕ 4 -20 UNEF 3 ∕ 4 -24 UNS 3 ∕ 4 -27 UNS
3B 0.6960 0.7036
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