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 0.8750 0.8750 0.8750 0.8750 0.8750 0.8750 0.9375 0.9375 0.9375 0.9375 0.9375 0.9375 0.9375 0.9375 0.9375 0.9375 1.0000 1.0000 1.0000 1.0000 1.0000 1.0000 1.0000 1.0000 1.0000 1.0000 1.0000 1.0000 1.0000
Class
2A 0.0012 0.8738 0.8666 2A 0.0012 0.8738 0.8671 2A 0.0012 0.8738 0.8673 3A 0.0000 0.8750 0.8685 2A 0.0011 0.8739 0.8679 3A 0.0000 0.8750 0.8690 2A 0.0017 0.9358 0.9244 3A 0.0000 0.9375 0.9261 2A 0.0015 0.9360 0.9266 3A 0.0000 0.9375 0.9281 2A 0.0014 0.9361 0.9280 3A 0.0000 0.9375 0.9294 2A 0.0012 0.9363 0.9298 3A 0.0000 0.9375 0.9310 2A 0.0011 0.9364 0.9304 3A 0.0000 0.9375 0.9315 1A 0.0020 0.9980 0.9755 3A 0.0000 1.0000 0.9850 2A 0.0018 0.9982 0.9853 1A 0.0018 0.9982 0.9810 2A 0.0018 0.9982 0.9868 3A 0.0000 1.0000 0.9886 1A 0.0017 0.9983 0.9828 2A 0.0016 0.9894 0.9881 3A 0.0000 1.0000 0.9897 2A 0.0015 0.9985 0.9891 3A 0.0000 1.0000 0.9906 2A 0.0014 0.9986 0.9899
— 0.8467 0.8425 — 0.8497 0.8457 — 0.8506 0.8467 — 0.8518 0.8489 — 0.8536 0.8499 — 0.8547 0.8519 — 0.8817 0.8761 — 0.8834 0.8792 — 0.8954 0.8904 — 0.8969 0.8932 — 0.9036 0.8991 — 0.9050 0.9016 — 0.9131 0.9092 — 0.9143 0.9113 — 0.9161 0.9123 — 0.9172 0.9144 — 0.9168 0.9067 — 0.9188 0.9137 — 0.9332 0.9270 — 0.9441 0.9353 — 0.9441 0.9382 — 0.9459 0.9415 — 0.9519 0.9435 — 0.9520 0.9467 — 0.9536 0.9496 — 0.9579 0.9529 — 0.9594 0.9557 — 0.9625 0.9578
0.8242 0.8297 0.8313 0.8325 0.8367 0.8378 0.8366 0.8383 0.8616 0.8631 0.8766 0.8780 0.8938 0.8950 0.8992 0.9003 0.8492 0.8492 0.8512 0.8791 0.8990 0.8990 0.9008 0.9132 0.9133 0.9149 0.9241 0.9256 0.9324
2B 0.830 2B 0.835 2B 0.836
0.840 0.844 0.845
0.8479 0.8533 0.8509 0.8561 0.8518 0.8569 0.8518 0.8556 0.8547 0.8595 0.8547 0.8583 0.8834 0.8907 0.8834 0.8889 0.8969 0.9033 0.8969 0.9017 0.9050 0.9109 0.9050 0.9094 0.9143 0.9194 0.9143 0.9181 0.9172 0.9221 0.9172 0.9209 0.9188 0.9320 0.9188 0.9276 0.9188 0.9254 0.9350 0.9430 0.9459 0.9573 0.9459 0.9535 0.9459 0.9516 0.9536 0.9645 0.9536 0.9605 0.9536 0.9588 0.9594 0.9659 0.9594 0.9643 0.9639 0.9701
7 ∕ 8 -24 UNS 7 ∕ 8 -27 UNS 7 ∕ 8 -28 UN
3B 0.8360 0.8426
2B 0.841
0.849
7 ∕ 8 -32 UN
3B 0.8410 0.8469
2B 0.847
0.865
15 ∕ 16 -12 UN
3B 0.8470 0.8575
2B 0.870
0.884
15 ∕ 16 -16 UN
3B 0.8700 0.8784
2B 0.883
0.895
15 ∕ 16 -20 UNEF
3B 0.8830 0.8911
2B 0.899
0.907
15 ∕ 16 -28 UN
3B 0.8990 0.9051
2B 0.904
0.911
15 ∕ 16 -32 UN
3B 0.9040 0.9094
1-8 UNC
1B 0.865 2B 0.865 2B 0.892 1B 0.910 2B 0.910 1B 0.923 2B 0.923
0.890 0.890 0.913 0.928 0.928 0.938 0.938
2A 0.0020 0.9980 0.9830 0.9755 0.9168 0.9101
3B 0.8650 0.8797
1-10 UNS 1-12 UNF
3B 0.9100 0.9198
1-14 UNS f
3B 0.9230 0.9315
1-16 UN
2B 0.932
0.946
3B 0.9320 0.9409
1-18 UNS
2B 0.940
0.953
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