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28UN - 60 Degree Unified Threads

The 28 thread series (28-UN) have been used more or less widely in industry for various applications where the Standard Coarse, Fine or Extra-fine Series were not as applicable. They are now recognized as Standard Unified Thread Series in a specified selection of diameters for each pitch.

5/16" - 1" 1 1/16" - 1 1/2"

28UN Threads
5/16" - 28UN 2A 0.001 7.912 7.747 - 7.323 7.236 6.83 2B 6.96 7.163 7.348 7.46 7.938
5/16" - 28UN 3A 0 7.938 7.772 - 7.348 7.282 6.855 3B 6.96 7.13 7.348 7.432 7.938
3/8" - 28UN 2A 0.0011 9.497 9.332 - 8.908 8.816 8.415 2B 8.534 8.763 8.936 9.053 9.525
3/8" - 28UN 3A 0 9.525 9.36 - 8.936 8.867 8.443 3B 8.534 8.702 8.936 9.025 9.525
9/16" - 28UN 2A 0.0011 14.26 14.094 - 13.67 13.576 13.178 2B 13.31 13.513 13.698 13.82 14.288
9/16" - 28UN 3A 0 14.288 14.122 - 13.698 13.627 13.205 3B 13.31 13.465 13.698 13.79 14.288
5/8" - 28UN 2A 0.0011 15.847 15.682 - 15.258 15.161 14.765 2B 14.884 15.113 15.286 15.41 15.875
5/8" - 28UN 3A 0 15.875 15.71 - 15.286 15.215 14.793 3B 14.884 15.052 15.286 15.38 15.875
11/16" - 28UN 2A 0.0011 17.435 17.269 - 16.845 16.749 16.353 2B 16.485 16.688 16.873 16.998 17.463
11/16" - 28UN 3A 0 17.463 17.297 - 16.873 16.802 16.38 3B 16.485 16.64 16.873 16.967 17.463
3/4" - 28UN 2A 0.0012 19.02 18.854 - 18.43 18.334 17.937 2B 18.059 18.288 18.461 18.588 19.05
3/4" - 28UN 3A 0 19.05 18.885 - 18.461 18.387 17.968 3B 18.059 18.227 18.461 18.555 19.05
13/16" - 28UN 2A 0.0012 20.607 20.442 - 20.018 19.921 19.525 2B 19.66 19.863 20.048 20.175 20.638
13/16" - 28UN 3A 0 20.638 20.472 - 20.048 19.975 19.555 3B 19.66 19.815 20.048 20.142 20.638
7/8" - 28UN 2A 0.0012 22.195 22.029 - 21.605 21.509 21.112 2B 21.234 21.463 21.636 21.763 22.225
7/8" - 28UN 3A 0 22.225 22.06 - 21.636 21.562 21.143 3B 21.234 21.402 21.636 21.73 22.225
15/16" - 28UN 2A 0.0012 23.782 23.617 - 23.193 23.091 22.7 2B 22.835 23.038 23.223 23.355 23.813
15/16" - 28UN 3A 0 23.813 23.647 - 23.223 23.147 22.73 3B 22.835 22.99 23.223 23.322 23.813
1 3/8" - 28UN 3A 0 34.925 34.544 - 32.863 32.725 31.145 3B 31.496 31.869 32.863 33.04 34.925
1" - 28UN 2A 0.0012 25.37 25.204 - 24.78 24.679 24.287 2B 24.409 24.638 24.811 24.943 25.4
1" - 28UN 3A 0 25.4 25.235 - 24.811 24.735 24.318 3B 24.409 24.577 24.811 24.91 25.4
1 1/16" - 28UN 2A 0.0012 26.957 26.792 - 26.368 26.266 25.875 2B 26.01 26.213 26.398 26.53 26.988
1 1/16" - 28UN 3A 0 26.988 26.822 - 26.398 26.322 25.905 3B 26.01 26.165 26.398 26.497 26.988
1 1/8" - 28UN 2A 0.0012 28.545 28.379 - 27.955 27.854 27.462 2B 27.584 27.813 27.986 28.118 28.575
1 1/8" - 28UN 3A 0 28.575 28.41 - 27.986 27.91 27.493 3B 27.584 27.752 27.986 28.085 28.575
1 3/8" - 28UN 2A 0.0012 30.132 29.967 - 29.543 29.439 29.05 2B 29.185 29.388 29.573 29.708 30.163
1 3/8" - 28UN 3A 0 30.163 29.997 - 29.573 29.494 29.08 3B 29.185 29.34 29.573 29.675 30.163
1 1/4" - 28UN 2A 0.0012 31.72 31.554 - 31.13 31.026 30.637 2B 30.759 30.988 31.161 31.295 31.75
1 1/4" - 28UN 3A 0 31.75 31.585 - 31.161 31.082 30.668 3B 30.759 30.927 31.161 31.262 31.75
1 5/16" - 28UN 2A 0.0012 33.307 33.142 - 32.718 32.614 32.225 2B 32.36 32.563 32.748 32.883 33.338
1 5/16" - 28UN 3A 0 33.338 33.172 - 32.748 32.669 32.255 3B 32.36 32.515 32.748 32.85 33.338
1 3/8" - 28UN 2A 0.0012 34.895 34.729 - 34.305 34.201 33.812 2B 33.934 34.163 34.336 34.47 34.925
1 3/8" - 28UN 3A 0 34.925 34.76 - 34.336 34.257 33.843 3B 33.934 34.102 34.336 34.437 34.925
1 7/16" - 28UN 2A 0.0013 36.479 36.314 - 35.89 35.784 35.397 2B 35.535 35.738 35.923 36.063 36.513
1 7/16" - 28UN 3A 0 36.513 36.347 - 35.923 35.844 35.43 3B 35.535 35.69 35.923 36.027 36.513
1 1/2" - 28UN 2A 0.0013 38.067 37.902 - 37.478 37.371 36.985 2B 37.109 37.338 37.511 37.65 38.1
1 1/2" - 28UN 3A 0 38.1 37.935 - 37.511 37.432 37.018 3B 37.109 37.277 37.511 37.615 38.1