Introduction to Thread Rolling Diameters
Thread rolling diameter, also known as blank diameter or rolling blank diameter, refers to the diameter of the external thread (screw) blank before the rolling or forming process. This is the smooth rod diameter prior to thread formation. It is a critical process parameter in screw manufacturing, distinct from major, pitch, or minor diameters. This value is primarily relevant for manufacturers to ensure proper thread formation and is based on standards such as GB/T18685-2017 for metric threads and GB/T34632-2017 for imperial threads.
Understanding these diameters helps in selecting appropriate blanks for rolling processes, ensuring threads meet tolerance grades like 4h, 6h, 6g (common), 6f, and 6e for metric, or 3A and 2A (common) for imperial. Proper blank sizing prevents defects such as underfilled threads or material cracking.
- Metric threads use millimeters (mm) for measurements.
- Imperial threads specify threads per inch (TPI) and use inches for nominal size, with diameters in mm for consistency.
- Tolerance grades affect the max and min blank diameters to achieve desired thread fit.
Metric External Thread Rolling Diameters Table
Unit: mm. Standard: GB/T18685-2017. Tolerance grades: 4h, 6h, 6g (common), 6f, 6e. The table lists max and min values for various nominal sizes and pitches.
| Tolerance Grade | Rajoittaa | M1 0.25 | M1 0.2 | M1.1 0.25 | M1.1 0.2 | M1.2 0.25 | M1.2 0.2 | M1.4 0.3 | M1.4 0.2 | M1.6 0.35 | M1.6 0.2 | M1.8 0.35 | M1.8 0.2 | M2 0.4 | M2 0.25 | M2.2 0.45 | M2.2 0.25 | M2.5 0.45 | M2.5 0.35 | M3 0.5 | M3 0.35 | M3.5 0.6 | M3.5 0.35 | M4 0.7 | M4 0.5 | M4.5 0.75 | M4.5 0.5 | M5 0.8 | M5 0.5 | M6 1 | M6 0.75 | M7 1 | M7 0.75 | M8 1.25 | M8 1 | M8 0.75 | M10 1.5 | M10 1.25 | M10 1 | M10 0.75 | M12 1.75 | M12 1.5 | M12 1.25 | M12 1 | M14 2 | M14 1.5 | M14 1 | M16 2 | M16 1.5 | M16 1 | M18 2.5 | M18 2 | M18 1.5 | M18 1 | M20 2.5 | M20 2 | M20 1.5 | M20 1 | M22 2.5 | M22 2 | M22 1.5 | M22 1 | M24 3 | M24 2 | M24 1.5 | M24 1 | M27 3 | M27 2 | M27 1.5 | M27 1 | M30 3.5 | M30 2 | M30 1.5 | M30 1 | M33 3.5 | M33 2 | M33 1.5 | M36 4 | M36 3 | M36 2 | M36 1.5 | M39 4 | M39 3 | M39 2 | M39 1.5 | M42 4 | M42 3 | M42 2 | M42 1.5 | M45 4 | M45 3 | M45 2 | M45 1.5 | M48 4 | M48 3 | M48 2 | M48 1.5 | M52 4 | M52 3 | M52 2 | M52 1.5 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 4h | Maksi | 0.833 | 0.864 | 0.933 | 0.963 | 1.032 | 1.063 | 1.199 | 1.262 | 1.366 | 1.462 | 1.565 | 1.661 | 1.733 | 1.829 | 1.901 | 2.029 | 2.199 | 2.263 | 2.665 | 2.762 | 3.098 | 3.26 | 3.539 | 3.666 | 4.006 | 4.165 | 4.472 | 4.664 | 5.344 | 5.501 | 6.341 | 6.499 | 7.184 | 7.338 | 7.498 | 9.016 | 9.179 | 9.335 | 9.497 | 10.846 | 11.011 | 11.17 | 11.333 | 12.689 | 13.008 | 13.332 | 14.685 | 15.006 | 15.331 | 16.364 | 16.681 | 17.004 | 17.33 | 18.359 | 18.679 | 19.003 | 19.33 | 20.356 | 20.677 | 20.997 | 21.329 | 22.03 | 22.675 | 22.996 | 23.329 | 25.025 | 25.673 | 25.995 | 26.328 | 27.711 | 28.671 | 28.994 | 29.328 | 30.707 | 31.67 | 31.994 | 33.386 | 34.016 | 34.669 | 34.993 | 36.382 | 37.014 | 37.668 | 37.993 | 39.379 | 40.012 | 40.667 | 40.992 | 42.376 | 43.01 | 43.666 | 43.992 | 45.373 | 46.001 | 46.666 | 46.991 | 49.370 | 49.999 | 50.665 | 50.991 |
| Minimi | 0.817 | 0.849 | 0.916 | 0.948 | 1.015 | 1.048 | 1.182 | 1.247 | 1.348 | 1.445 | 1.547 | 1.645 | 1.714 | 1.81 | 1.881 | 2.01 | 2.179 | 2.245 | 2.644 | 2.742 | 3.078 | 3.241 | 3.513 | 3.642 | 3.981 | 4.141 | 4.445 | 4.64 | 5.312 | 5.471 | 6.309 | 6.469 | 7.152 | 7.307 | 7.468 | 8.986 | 9.147 | 9.304 | 9.466 | 10.818 | 10.976 | 11.134 | 11.298 | 12.659 | 12.973 | 13.297 | 14.655 | 14.97 | 15.296 | 16.339 | 16.651 | 16.969 | 17.295 | 18.335 | 18.649 | 18.967 | 19.294 | 20.332 | 20.647 | 20.966 | 21.294 | 22.003 | 22.639 | 22.96 | 23.288 | 24.998 | 25.637 | 25.959 | 26.288 | 27.681 | 28.635 | 28.958 | 29.287 | 30.677 | 31.634 | 31.957 | 33.358 | 33.989 | 34.633 | 34.957 | 36.354 | 36.987 | 37.632 | 37.956 | 39.351 | 39.985 | 40.631 | 40.956 | 42.348 | 42.983 | 43.63 | 43.955 | 45.335 | 45.975 | 46.624 | 46.95 | 49.332 | 49.973 | 50.623 | 50.95 | |
| 6h | Maksi | 0.83 | 0.864 | 0.93 | 0.963 | 1.029 | 1.063 | 1.196 | 1.262 | 1.363 | 1.462 | 1.562 | 1.661 | 1.73 | 1.826 | 1.898 | 2.026 | 2.196 | 2.26 | 2.662 | 2.759 | 3.092 | 3.257 | 3.528 | 3.658 | 3.996 | 4.157 | 4.461 | 4.657 | 5.328 | 5.49 | 6.325 | 6.488 | 7.166 | 7.323 | 7.487 | 8.994 | 9.161 | 9.32 | 9.485 | 10.822 | 10.99 | 11.15 | 11.318 | 12.663 | 12.986 | 13.317 | 14.658 | 14.984 | 15.316 | 16.324 | 16.655 | 16.982 | 17.315 | 18.32 | 18.652 | 18.981 | 19.315 | 20.316 | 20.65 | 20.974 | 21.314 | 21.995 | 22.649 | 22.973 | 23.314 | 24.99 | 25.647 | 25.971 | 26.313 | 27.656 | 28.645 | 28.971 | 29.313 | 30.651 | 31.644 | 31.97 | 33.326 | 33.98 | 34.642 | 34.969 | 36.322 | 36.978 | 37.642 | 37.969 | 39.319 | 39.976 | 40.641 | 40.968 | 42.316 | 42.975 | 43.64 | 43.968 | 45.313 | 45.967 | 46.64 | 46.968 | 49.31 | 49.965 | 50.639 | 50.967 |
| Minimi | 0.798 | 0.831 | 0.897 | 0.931 | 0.996 | 1.03 | 1.162 | 1.229 | 1.325 | 1.427 | 1.524 | 1.627 | 1.689 | 1.79 | 1.855 | 1.99 | 2.154 | 2.222 | 2.617 | 2.717 | 3.046 | 3.216 | 3.479 | 3.615 | 3.948 | 4.114 | 4.41 | 4.613 | 5.271 | 5.434 | 6.268 | 6.432 | 7.109 | 7.266 | 7.431 | 8.939 | 9.104 | 9.263 | 9.429 | 10.764 | 10.926 | 11.087 | 11.255 | 12.599 | 12.923 | 13.254 | 14.595 | 14.92 | 15.253 | 16.276 | 16.591 | 16.919 | 17.252 | 18.271 | 18.589 | 18.917 | 19.251 | 20.268 | 20.587 | 20.916 | 21.251 | 21.928 | 22.575 | 22.905 | 23.243 | 24.924 | 25.573 | 25.904 | 26.243 | 27.601 | 28.571 | 28.903 | 29.242 | 30.597 | 31.57 | 31.902 | 33.274 | 33.914 | 34.569 | 34.902 | 36.27 | 36.912 | 37.568 | 37.901 | 39.267 | 39.91 | 40.567 | 40.901 | 42.264 | 42.908 | 43.566 | 43.9 | 45.249 | 45.895 | 46.556 | 46.89 | 49.247 | 49.893 | 50.555 | 50.89 | |
| 6g (Common) | Maksi | 0.813 | 0.847 | 0.912 | 0.946 | 1.011 | 1.046 | 1.178 | 1.245 | 1.345 | 1.445 | 1.543 | 1.645 | 1.711 | 1.808 | 1.878 | 2.008 | 2.177 | 2.241 | 2.642 | 2.74 | 3.071 | 3.238 | 3.507 | 3.638 | 3.974 | 4.137 | 4.437 | 4.637 | 5.303 | 5.468 | 6.3 | 6.466 | 7.138 | 7.297 | 7.465 | 8.962 | 9.133 | 9.294 | 9.463 | 10.789 | 10.958 | 11.122 | 11.292 | 12.625 | 12.954 | 13.291 | 14.62 | 14.952 | 15.29 | 16.282 | 16.617 | 16.95 | 17.289 | 18.278 | 18.614 | 18.949 | 19.289 | 20.274 | 20.612 | 20.942 | 21.288 | 21.947 | 22.611 | 22.941 | 23.288 | 24.942 | 25.609 | 25.939 | 26.287 | 27.603 | 28.607 | 28.939 | 29.287 | 30.598 | 31.606 | 31.938 | 33.266 | 33.932 | 34.605 | 34.937 | 36.262 | 36.93 | 37.604 | 37.937 | 39.259 | 39.928 | 40.603 | 40.936 | 42.256 | 42.927 | 43.602 | 43.936 | 45.253 | 45.919 | 46.602 | 46.936 | 49.25 | 49.917 | 50.601 | 50.935 |
| Minimi | 0.78 | 0.814 | 0.879 | 0.914 | 0.978 | 1.013 | 1.144 | 1.212 | 1.307 | 1.41 | 1.505 | 1.61 | 1.67 | 1.772 | 1.835 | 1.972 | 2.134 | 2.203 | 2.597 | 2.698 | 3.025 | 3.197 | 3.457 | 3.595 | 3.926 | 4.094 | 4.387 | 4.593 | 5.245 | 5.412 | 6.242 | 6.41 | 7.081 | 7.24 | 7.409 | 8.907 | 9.076 | 9.237 | 9.407 | 10.73 | 10.894 | 11.059 | 11.229 | 12.561 | 12.891 | 13.228 | 14.557 | 14.889 | 15.227 | 16.234 | 16.553 | 16.887 | 17.226 | 18.229 | 18.551 | 18.885 | 19.225 | 20.226 | 20.549 | 20.884 | 21.225 | 21.881 | 22.537 | 22.873 | 23.217 | 24.876 | 25.535 | 25.872 | 26.217 | 27.548 | 28.533 | 28.871 | 29.216 | 30.544 | 31.532 | 31.87 | 33.214 | 33.866 | 34.531 | 34.87 | 36.21 | 36.864 | 37.53 | 37.869 | 39.207 | 39.862 | 40.529 | 40.869 | 42.204 | 42.86 | 43.528 | 43.868 | 45.189 | 45.847 | 46.518 | 46.858 | 49.187 | 49.845 | 50.517 | 50.858 | |
| 6f | Maksi | – | – | – | – | – | – | – | – | 1.33 | – | 1.528 | – | 1.696 | – | 1.863 | – | 2.162 | 2.226 | 2.626 | 2.725 | 3.056 | 3.223 | 3.491 | 3.622 | 3.958 | 4.121 | 4.423 | 4.621 | 5.289 | 5.452 | 6.286 | 6.45 | 7.124 | 7.283 | 7.449 | 8.949 | 9.12 | 9.28 | 9.447 | 10.775 | 10.945 | 11.108 | 11.278 | 12.611 | 12.941 | 13.277 | 14.606 | 14.939 | 15.276 | 16.266 | 16.603 | 16.937 | 17.275 | 18.262 | 18.6 | 18.936 | 19.275 | 20.258 | 20.598 | 20.929 | 21.274 | 21.932 | 22.597 | 22.928 | 23.274 | 24.927 | 25.595 | 25.926 | 26.273 | 27.586 | 28.593 | 28.926 | 29.273 | 30.581 | 31.592 | 31.925 | 33.251 | 33.917 | 34.591 | 34.924 | 36.247 | 36.915 | 37.59 | 37.924 | 39.244 | 39.913 | 40.589 | 40.923 | 42.241 | 42.912 | 43.588 | 43.923 | 45.238 | 45.904 | 46.588 | 46.923 | 49.235 | 49.902 | 50.587 | 50.922 |
| Minimi | – | – | – | – | – | – | – | – | 1.292 | – | 1.49 | – | 1.655 | – | 1.82 | – | 2.119 | 2.188 | 2.581 | 2.683 | 3.01 | 3.182 | 3.441 | 3.579 | 3.91 | 4.078 | 4.373 | 4.577 | 5.231 | 5.396 | 6.228 | 6.394 | 7.067 | 7.226 | 7.393 | 8.894 | 9.062 | 9.223 | 9.391 | 10.716 | 10.881 | 11.045 | 11.215 | 12.547 | 12.878 | 13.214 | 14.543 | 14.876 | 15.213 | 16.218 | 16.539 | 16.874 | 17.212 | 18.213 | 18.537 | 18.872 | 19.211 | 20.21 | 20.535 | 20.871 | 21.211 | 21.866 | 22.523 | 22.86 | 23.203 | 24.861 | 25.521 | 25.859 | 26.203 | 27.531 | 28.519 | 28.858 | 29.202 | 30.527 | 31.518 | 31.857 | 33.199 | 33.851 | 34.517 | 34.857 | 36.195 | 36.849 | 37.516 | 37.856 | 39.192 | 39.847 | 40.515 | 40.856 | 42.189 | 42.845 | 43.514 | 43.855 | 45.174 | 45.832 | 46.504 | 46.845 | 49.172 | 49.83 | 50.503 | 50.845 | |
| 6e | Maksi | – | – | – | – | – | – | – | – | – | – | – | – | – | – | – | – | – | – | 2.612 | – | 3.04 | – | 3.473 | 3.608 | 3.94 | 4.107 | 4.401 | 4.607 | 5.269 | 5.434 | 6.266 | 6.432 | 7.103 | 7.263 | 7.431 | 8.927 | 9.099 | 9.26 | 9.429 | 10.752 | 10.923 | 11.087 | 11.258 | 12.592 | 12.92 | 13.257 | 14.587 | 14.917 | 15.256 | 16.244 | 16.584 | 16.915 | 17.255 | 18.24 | 18.581 | 18.914 | 19.255 | 20.236 | 20.579 | 20.907 | 21.254 | 21.91 | 22.578 | 22.906 | 23.254 | 24.905 | 25.576 | 25.904 | 26.253 | 27.566 | 28.574 | 28.904 | 29.253 | 30.561 | 31.573 | 31.903 | 33.231 | 33.895 | 34.572 | 34.902 | 36.227 | 36.893 | 37.571 | 37.902 | 39.224 | 39.891 | 40.57 | 40.901 | 42.221 | 42.89 | 43.569 | 43.901 | 45.218 | 45.882 | 46.569 | 46.901 | 49.215 | 49.88 | 50.568 | 50.9 |
| Minimi | – | – | – | – | – | – | – | – | – | – | – | – | – | – | – | – | – | – | 2.567 | – | 2.993 | – | 3.423 | 3.565 | 3.892 | 4.064 | 4.351 | 4.563 | 5.211 | 5.378 | 6.208 | 6.376 | 7.046 | 7.206 | 7.375 | 8.872 | 9.041 | 9.203 | 9.373 | 10.693 | 10.859 | 11.024 | 11.195 | 12.528 | 12.856 | 13.194 | 14.524 | 14.854 | 15.193 | 16.196 | 16.52 | 16.852 | 17.192 | 18.192 | 18.518 | 18.85 | 19.191 | 20.188 | 20.516 | 20.849 | 21.191 | 21.844 | 22.504 | 22.838 | 23.183 | 24.839 | 25.502 | 25.837 | 26.183 | 27.511 | 28.5 | 28.836 | 29.182 | 30.507 | 31.499 | 31.835 | 33.179 | 33.829 | 34.498 | 34.835 | 36.175 | 36.827 | 37.497 | 37.834 | 39.172 | 39.825 | 40.496 | 40.834 | 42.169 | 42.823 | 43.495 | 43.833 | 45.154 | 45.81 | 46.485 | 46.823 | 49.152 | 49.808 | 50.484 | 50.823 |
Imperial External Thread Rolling Diameters Table
Nominal size in inches, diameters in mm. Standard: GB/T34632-2017. Tolerance grades: 3A, 2A (common). Series: UNC, UNF, UNEF, UN.
| Tolerance Grade | Rajoittaa | 0# 80 UNF | 1# 64 UNC | 1# 72 UNF | 2# 56 UNC | 2# 64 UNF | 3# 48 UNC | 3# 56 UNF | 4# 40 UNC | 4# 48 UNF | 5# 40 UNC | 5# 44 UNF | 6# 32 UNC | 6# 40 UNF | 8# 32 UNC | 8# 36 UNF | 10# 24 UNC | 10# 32 UNF | 12# 24 UNC | 12# 28 UNF | 12# 32 UNEF | 1/4 20 UNC | 1/4 28 UNF | 1/4 32 UNEF | 5/16 18 UNC | 5/16 24 UNF | 5/16 32 UNEF | 3/8 16 UNC | 3/8 24 UNF | 3/8 32 UNEF | 7/16 14 UNC | 7/16 16 UN | 7/16 20 UNF | 7/16 28 UNEF | 1/2 13 UNC | 1/2 16 UN | 1/2 20 UNF | 1/2 28 UNEF | 9/16 12 UNC | 9/16 16 UN | 9/16 18 UNF | 9/16 24 UNEF | 5/8 11 UNC | 5/8 12 UN | 5/8 16 UN | 5/8 18 UNF | 5/8 24 UNEF | 3/4 10 UNC | 3/4 12 UN | 3/4 16 UNF | 3/4 20 UNEF | 7/8 9 UNC | 7/8 12 UN | 7/8 14 UNF | 7/8 16 UN | 7/8 20 UNEF | 1 8 UNC | 1 12 UNF | 1 16 UN | 1 20 UNEF | 1-1/8 7 UNC | 1-1/8 8 UN | 1-1/8 12 UNF | 1-1/8 16 UN | 1-1/8 18 UNEF | 1-1/4 7 UNC | 1-1/4 8 UN | 1-1/4 12 UNF | 1-1/4 16 UN | 1-1/4 18 UNEF | 1-3/8 6 UNC | 1-3/8 8 UN | 1-3/8 12 UNF | 1-3/8 16 UN | 1-3/8 18 UNEF | 1-1/2 6 UNC | 1-1/2 8 UN | 1-1/2 12 UNF | 1-1/2 16 UN | 1-1/2 18 UNEF | 1-5/8 8 UN | 1-5/8 12 UN | 1-5/8 16 UN | 1-5/8 18 UN | 1-3/4 8 UN | 1-3/4 12 UN | 1-3/4 16 UN | 1-7/8 8 UN | 1-7/8 12 UN | 1-7/8 16 UN | 2 8 UN | 2 12 UN | 2 16 UN |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 3A | Maksi | Data for max and min values would be inserted here based on standard GB/T34632-2017. Note: Source code was truncated; refer to full standard for complete values. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Minimi | Data for max and min values would be inserted here based on standard GB/T34632-2017. Note: Source code was truncated; refer to full standard for complete values. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| 2A (Common) | Maksi | Data for max and min values would be inserted here based on standard GB/T34632-2017. Note: Source code was truncated; refer to full standard for complete values. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Minimi | Data for max and min values would be inserted here based on standard GB/T34632-2017. Note: Source code was truncated; refer to full standard for complete values. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Note: The imperial table data in the provided source was truncated. For complete and accurate values, consult the full GB/T34632-2017 standard or equivalent ASME B1.1.
Thread Tapping Hole Diameters
Thread tapping hole diameters are the recommended drill sizes for creating internal threads. These sizes ensure proper thread engagement, typically aiming for 75% thread height. Values are based on standard charts for metric and imperial threads. Adjust for material hardness and thread percentage as needed.
Metric Tapping Hole Diameters
| Tap Size | Pitch (mm) | Drill Size (mm) | Closest Imperial Drill |
|---|---|---|---|
| M1.6 | 0.35 | 1.25 | 3/64″ |
| M2 | 0.4 | 1.6 | 1/16″ |
| M2.5 | 0.45 | 2.05 | #46 |
| M3 | 0.5 | 2.5 | #39 |
| M4 | 0.7 | 3.3 | #30 |
| M5 | 0.8 | 4.2 | #19 |
| M6 | 1 | 5 | #8 |
| M8 | 1.25 | 6.8 | 17/64″ |
| M10 | 1.5 | 8.5 | Q |
| M12 | 1.75 | 10.2 | 13/32″ |
Imperial Tapping Hole Diameters
| Tap Size | TPI | Drill Size | Decimal Equivalent (in) |
|---|---|---|---|
| 0-80 | 80 | 3/64 | 0.0469 |
| 1-64 | 64 | 53 | 0.0595 |
| 2-56 | 56 | 50 | 0.0700 |
| 3-48 | 48 | 47 | 0.0785 |
| 4-40 | 40 | 43 | 0.0890 |
| 5-40 | 40 | 38 | 0.1015 |
| 6-32 | 32 | 36 | 0.1065 |
| 8-32 | 32 | 29 | 0.1360 |
| 10-24 | 24 | 25 | 0.1495 |
| 1/4-20 | 20 | 7 | 0.2010 |
For roll forming taps, the drill size can be calculated as: Tap Drill Size = Basic Tap O.D. – (Pitch x % Thread Desired / 76.98) for imperial, or adjusted for metric.
Usein kysytyt kysymykset (UKK)
- What is the difference between rolling diameter and tapping hole diameter?
- Rolling diameter is for external thread blank preparation in manufacturing, while tapping hole diameter is the drill size for internal threads to ensure proper tapping.
- Why choose 6g tolerance for metric threads?
- 6g is commonly used for general-purpose external threads as it provides a balance between fit and manufacturability, allowing slight clearance for assembly.
- How does material affect these diameters?
- Harder materials may require slightly larger blank diameters for rolling to avoid cracking, and tapping holes might need adjustment for better chip evacuation.
- What standard should I reference for imperial threads?
- GB/T34632-2017 aligns with ASME B1.1 for unified threads, ensuring compatibility in international manufacturing.
- Can I use these tables for roll forming internal threads?
- No, these are for external rolling and standard tapping. For roll forming taps, use specific formulas to calculate hole sizes based on desired thread percentage.
- How to select the correct drill size for 75% thread engagement?
- Use the provided charts or formula: Drill diameter = Major diameter – (1.0825 x Pitch) for approximate 75% in steel/aluminum.
