ASME B18.2.1 Square Lag Screws
| Nominal Size or Basic Product Diameter | Body or Shoulder Diameter, E (See Paras. 5.4 and 5.5) | Width Across Flats, F (See Para. 2.1.2) | Width Across Corners, G | Head Height, H | Minimum Shoulder Length, S (See Para. 5.5) | Radius of Fillet, R | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Max. | Min. | Basic | Max. | Min. | Max. | Min. | Basic | Max. | Min. | Max. | Min. | |||
| ASME B18.2.1 - No. 10 | 0.19 | 0.199 | 0.178 | 9⁄32 | 0.281 | 0.271 | 0.398 | 0.372 | 1⁄8 | 0.14 | 0.11 | 0.094 | 0.03 | 0.01 |
| ASME B18.2.1 - 1⁄4 | 0.25 | 0.26 | 0.237 | 3⁄8 | 0.375 | 0.362 | 0.53 | 0.498 | 11⁄64 | 0.188 | 0.156 | 0.094 | 0.03 | 0.01 |
| ASME B18.2.1 - 5⁄16 | 0.3125 | 0.324 | 0.298 | 1⁄2 | 0.5 | 0.484 | 0.707 | 0.665 | 13⁄64 | 0.22 | 0.186 | 0.125 | 0.03 | 0.01 |
| ASME B18.2.1 - 3⁄8 | 0.375 | 0.388 | 0.36 | 9⁄16 | 0.562 | 0.544 | 0.795 | 0.747 | 1⁄4 | 0.268 | 0.232 | 0.125 | 0.03 | 0.01 |
| ASME B18.2.1 - 7⁄16 | 0.4375 | 0.452 | 0.421 | 5⁄8 | 0.625 | 0.603 | 0.884 | 0.828 | 19⁄64 | 0.316 | 0.278 | 0.156 | 0.03 | 0.01 |
| ASME B18.2.1 - 1⁄2 | 0.5 | 0.515 | 0.482 | 3⁄4 | 0.75 | 0.725 | 1.061 | 0.995 | 21⁄64 | 0.348 | 0.308 | 0.156 | 0.03 | 0.01 |
| ASME B18.2.1 - 5⁄8 | 0.625 | 0.642 | 0.605 | 15⁄16 | 0.938 | 0.906 | 1.326 | 1.244 | 27⁄64 | 0.444 | 0.4 | 0.312 | 0.06 | 0.02 |
| ASME B18.2.1 - 3⁄4 | 0.75 | 0.768 | 0.729 | 11⁄8 | 1.125 | 1.088 | 1.591 | 1.494 | 1⁄2 | 0.524 | 0.476 | 0.375 | 0.06 | 0.02 |
| ASME B18.2.1 - 7⁄8 | 0.875 | 0.895 | 0.852 | 15⁄16 | 1.312 | 1.269 | 1.856 | 1.742 | 19⁄32 | 0.62 | 0.568 | 0.375 | 0.06 | 0.02 |
| ASME B18.2.1 - 1 | 1 | 1.022 | 0.976 | 1 1⁄2 | 1.5 | 1.45 | 2.121 | 1.991 | 21⁄32 | 0.684 | 0.628 | 0.625 | 0.09 | 0.03 |
| ASME B18.2.1 - 11⁄8 | 1.125 | 1.149 | 1.098 | 111⁄16 | 1.688 | 1.631 | 2.386 | 2.239 | 3⁄4 | 0.78 | 0.72 | 0.625 | 0.09 | 0.03 |
| ASME B18.2.1 - 11⁄4 | 1.25 | 1.277 | 1.223 | 17⁄8 | 1.875 | 1.812 | 2.652 | 2.489 | 27⁄32 | 0.876 | 0.812 | 0.625 | 0.09 | 0.03 |
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