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3/8 hex lag screw envelope
3/8 hex lag screw envelope: hex head 9/16 in across flats (basic) × 1/4 in high (basic) on a plain Ø9.52 mm (3/8 in nominal) shank, example length 3 in (76.2 mm) under the head (Xem's choice); no thread, chamfer, washer face or point
Exact dimensions. True size, no tolerance added. Threads are plain cylinders at the major diameter.
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Dimensions
| size (in) | 3/8 |
|---|---|
| TPI | 7 |
| shank E max / min (in) | .388 / .360 |
| across flats F, basic (AFT) | 9/16 |
| F max / min (AFT, in) | .562 / .544 |
| across flats F (Engineers Edge) | 9/16 |
| across corners G max / min (in) | .650 / .620 |
| head height H, basic (AFT) | 1/4 |
| H max / min (AFT, in) | .268 / .226 |
| shank hole (in) | 3/8 |
| pilot, softwood III & IV (in) | 11/64 |
| pilot, medium wood II (in) | 15/64 |
| pilot, hardwood I (in) | 1/4 |
| pilot (Portland Bolt / Haydon, in) | 15/64 |
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Hex lag screws, 1/4 to 1/2 in (ASME B18.2.1): shank, head width and height, pilot holes + envelope models: every size, notes, mating features and sources. What are the head size and pilot hole for a 3/8 lag screw?