Lobed Head Screws
ASME B18.2.1 Dimensions of Lobed Head Screws
All dimensions are in mm unless mentioned otherwise
| Nominal Size or Basic Major Diam. of Thread | Width Across Corners, G | Head Height, H | Flange Thickness, K | Flange Diameter, C | Maximum Minor Diameter, B | Drive Size |
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| inch | mm | Reference | Max. | Min. | Max. | Min. | Max. | Min. | ||
| 1/4 | 0.25 | 0.287 | 0.255 | 0.245 | 0.07 | 0.06 | 0.375 | 0.365 | 0.2073 | E8 |
| 5/16 | 0.3125 | 0.362 | 0.323 | 0.313 | 0.1 | 0.09 | 0.469 | 0.457 | 0.2663 | E10 |
| 3/8 | 0.375 | 0.431 | 0.394 | 0.384 | 0.125 | 0.115 | 0.562 | 0.55 | 0.3103 | E12 |
| 7/16 | 375 | 0.499 | 0.472 | 0.462 | 0.155 | 0.145 | 0.656 | 0.642 | 0.3613 | E14 |
| 1/2 | 0.5 | 0.571 | 0.515 | 0.505 | 0.16 | 0.15 | 0.75 | 0.735 | 0.4113 | E16 |
| 9/16 | 0.5625 | 0.645 | 0.551 | 0.541 | 0.165 | 0.153 | 0.844 | 0.828 | 0.4663 | E18 |
| 5/8 | 0.625 | 0.715 | 0.63 | 0.62 | 0.2 | 0.188 | 0.938 | 0.921 | 0.5183 | E20 |
| 3/4 | 0.75 | 0.86 | 0.787 | 0.777 | 0.255 | 0.243 | 1.125 | 1.107 | 0.6183 | E24 |
| 7/8 | 0.875 | 1 | 0.866 | 0.856 | 0.27 | 0.26 | 1.312 | 1.293 | 0.7193 | E28 |
| 1 | 1 | 1.138 | 1.063 | 1.053 | 0.355 | 0.343 | 1.5 | 1.479 | 0.8393 | E32 |
| 1 1/8 | 1.125 | 1.28 | 1.181 | 1.171 | 0.382 | 0.37 | 1.688 | 1.665 | 0.9433 | E36 |
| 1 1/4 | 1.25 | 1.42 | 1.299 | 1.289 | 0.422 | 0.41 | 1.875 | 1.852 | 1.0463 | E40 |
| 1 3/8 | 1.375 | 1.562 | 1.417 | 1.407 | 0.453 | 0.441 | 2.062 | 2.038 | 1.1513 | E44 |