ASME B18.2.1 Heavy Hex Cap Screws
| Nominal Size or Basic Product Diameter | Body Diameter, E (See Para. 4.6) | Width Across Flats, F (See Para. 2.1.2) | Width Across Corners, G | Head Height, H | Minimum Wrenching Height, J | Thread Length for Screw Lengths, LT (See Para. 4.7) | Transition Thread Length, Y (See Para. 4.7) | Maximum Total Runout of Bearing Surface FIM (See Para. 4.4) | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Max. | Min. | Basic | Max. | Min. | Max. | Min. | Basic | Max. | Min. | 6 in. and Shorter | Over 6 in. | Reference | ||||
| ASME B18.2.1 - 3⁄8 | 0.375 | 0.375 | 0.36 | 11⁄16 | 0.688 | 0.669 | 0.794 | 0.763 | 15⁄64 | 0.243 | 0.226 | 0.16 | 1 | 1.25 | 0.312 | 0.014 |
| ASME B18.2.1 - 1⁄2 | 0.5 | 0.5 | 0.482 | 7⁄8 | 0.875 | 0.85 | 1.01 | 0.969 | 5⁄16 | 0.323 | 0.302 | 0.215 | 1.25 | 1.5 | 0.385 | 0.016 |
| ASME B18.2.1 - 5⁄8 | 0.625 | 0.625 | 0.605 | 1 1⁄16 | 1.062 | 1.031 | 1.227 | 1.175 | 25⁄64 | 0.403 | 0.378 | 0.269 | 1.5 | 1.75 | 0.455 | 0.019 |
| ASME B18.2.1 - 3⁄4 | 0.75 | 0.75 | 0.729 | 1 1⁄4 | 1.25 | 1.212 | 1.443 | 1.383 | 15⁄32 | 0.483 | 0.455 | 0.324 | 1.75 | 2 | 0.5 | 0.022 |
| ASME B18.2.1 - 7⁄8 | 0.875 | 0.875 | 0.852 | 1 7⁄16 | 1.438 | 1.394 | 1.66 | 1.589 | 35⁄64 | 0.563 | 0.531 | 0.378 | 2 | 2.25 | 0.556 | 0.025 |
| ASME B18.2.1 - 1 | 1 | 1 | 0.976 | 1 5⁄8 | 1.625 | 1.575 | 1.876 | 1.796 | 39⁄64 | 0.627 | 0.591 | 0.416 | 2.25 | 2.5 | 0.625 | 0.028 |
| ASME B18.2.1 - 1 1⁄8 | 1.125 | 1.125 | 1.098 | 1 13⁄16 | 1.812 | 1.756 | 2.093 | 2.002 | 11⁄16 | 0.718 | 0.658 | 0.461 | 2.5 | 2.75 | 0.714 | 0.032 |
| ASME B18.2.1 - 1 1⁄4 | 1.25 | 1.25 | 1.223 | 2 | 2 | 1.938 | 2.309 | 2.209 | 25⁄32 | 0.813 | 0.749 | 0.53 | 2.75 | 3 | 0.714 | 0.035 |
| ASME B18.2.1 - 1 3⁄8 | 1.375 | 1.375 | 1.345 | 2 3⁄16 | 2.188 | 2.119 | 2.526 | 2.416 | 27⁄32 | 0.878 | 0.81 | 0.569 | 3 | 3.25 | 0.833 | 0.038 |
| ASME B18.2.1 - 1 1⁄2 | 1.5 | 1.5 | 1.47 | 2 3⁄8 | 2.375 | 2.3 | 2.742 | 2.622 | 15⁄16 | 0.974 | 0.902 | 0.64 | 3.25 | 3.5 | 0.833 | 0.041 |
| ASME B18.2.1 - 1 5⁄8 | 1.625 | 1.625 | 1.591 | 2 9⁄16 | 2.562 | 2.481 | 2.959 | 2.829 | 1 | 1.038 | 0.962 | 0.694 | 3.5 | 3.75 | 0.909 | 0.044 |
| ASME B18.2.1 - 13⁄4 | 1.75 | 1.75 | 1.716 | 2 3⁄4 | 2.75 | 2.662 | 3.175 | 3.035 | 1 3⁄32 | 1.134 | 1.054 | 0.748 | 3.75 | 4 | 1 | 0.048 |
| ASME B18.2.1 - 1 7⁄8 | 1.875 | 1.875 | 1.839 | 2 15⁄16 | 2.938 | 2.844 | 3.392 | 3.242 | 1 5⁄32 | 1.198 | 1.114 | 0.802 | 4 | 4.25 | 1 | 0.052 |
| ASME B18.2.1 - 2 | 2 | 2 | 1.964 | 3 1⁄8 | 3.125 | 3.025 | 3.608 | 3.449 | 1 7⁄32 | 1.263 | 1.175 | 0.825 | 4.25 | 4.5 | 1.111 | 0.055 |
| ASME B18.2.1 - 2 1⁄4 | 2.25 | 2.25 | 2.214 | 3 1⁄2 | 3.5 | 3.388 | 4.041 | 3.862 | 1 3⁄8 | 1.423 | 1.327 | 0.933 | ... | 5 | 1.111 | 0.061 |
| ASME B18.2.1 - 2 1⁄2 | 2.5 | 2.5 | 2.461 | 3 7⁄8 | 3.875 | 3.75 | 4.474 | 4.275 | 1 7⁄32 | 1.583 | 1.479 | 1.042 | ... | 5.5 | 1.25 | 0.068 |
| ASME B18.2.1 - 2 3⁄4 | 2.75 | 2.75 | 2.711 | 4 1⁄4 | 4.25 | 4.112 | 4.907 | 4.688 | 1 1⁄16 | 1.744 | 1.632 | 1.151 | ... | 6 | 1.25 | 0.074 |
| ASME B18.2.1 - 3 | 3 | 3 | 2.961 | 4 5⁄8 | 4.625 | 4.475 | 5.34 | 5.102 | 1 7⁄8 | 1.935 | 1.815 | 1.29 | ... | 6.5 | 1.25 | 0.081 |
| ASME B18.2.1 - 3 1⁄4 | 3.25 | 3.25 | 3.21 | 5 | 5 | 4.838 | 5.774 | 5.515 | 2 | 2.126 | 1.998 | 1.399 | ... | 7 | 1.25 | 0.091 |
| ASME B18.2.1 - 31⁄2 | 3.5 | 3.5 | 3.461 | 5 3⁄8 | 5.375 | 5.2 | 6.207 | 5.928 | 2 1⁄4 | 2.256 | 2.12 | 1.484 | ... | 7.5 | 1.25 | 0.098 |
| ASME B18.2.1 - 3 3⁄4 | 3.75 | 3.75 | 3.7109 | 5 3⁄4 | 5.75 | 5.562 | 6.64 | 6.341 | 2 3⁄8 | 2.447 | 2.303 | 1.612 | ... | 8 | 1.25 | 0.105 |
| ASME B18.2.1 - 4 | 4 | 4 | 3.9609 | 6 1⁄8 | 6.125 | 5.925 | 7.073 | 6.755 | 2 1⁄2 | 2.576 | 2.424 | 1.697 | ... | 8.5 | 1.25 | 0.112 |
| ASME B18.2.1 - 4 1⁄4 | 4.25 | 4.25 | 4.2228 | 6 1⁄2 | 6.5 | 6.288 | 7.506 | 7.168 | 2 3⁄4 | 2.768 | 2.608 | 1.826 | ... | 9 | 1.25 | 0.119 |
| ASME B18.2.1 - 4 1⁄2 | 4.5 | 4.5 | 4.4727 | 6 7⁄8 | 6.875 | 6.65 | 7.939 | 7.581 | 2 7⁄8 | 2.896 | 2.728 | 1.91 | ... | 9.5 | 1.25 | 0.126 |
| ASME B18.2.1 - 4 3⁄4 | 4.75 | 4.75 | 4.7227 | 7 1⁄4 | 7.25 | 7.012 | 8.372 | 7.994 | 3 | 3.088 | 2.912 | 2.038 | ... | 10 | 1.25 | 0.133 |
| ASME B18.2.1 - 5 | 5 | 5 | 4.9726 | 7 5⁄8 | 7.625 | 7.375 | 8.805 | 8.408 | 3 1⁄8 | 3.217 | 3.033 | 2.123 | ... | 10.5 | 1.25 | 0.14 |
| ASME B18.2.1 - 51⁄4 | 5.25 | 5.25 | 5.2226 | 8 | 8 | 7.738 | 9.238 | 8.821 | 3 3⁄8 | 3.408 | 3.216 | 2.251 | ... | 11 | 1.25 | 0.147 |
| ASME B18.2.1 - 51⁄2 | 5.5 | 5.5 | 5.4726 | 8 3⁄8 | 8.375 | 8.1 | 9.671 | 9.234 | 3 1⁄2 | 3.538 | 3.338 | 2.337 | ... | 11.5 | 1.25 | 0.154 |
| ASME B18.2.1 - 53⁄4 | 5.75 | 5.75 | 5.7225 | 8 3⁄4 | 8.75 | 8.462 | 10.104 | 9.647 | 3 5⁄8 | 3.729 | 3.521 | 2.465 | ... | 12 | 1.25 | 0.161 |
| ASME B18.2.1 - 6 | 6 | 6 | 5.9725 | 9 1⁄8 | 9.125 | 8.825 | 10.537 | 10.06 | 3 3⁄4 | 3.858 | 3.642 | 2.549 | ... | 12.5 | 1.25 | 0.168 |
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