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A lag screw is usually a heavy self-tapping screw with a square or hexagonal head that is driven in with a wrench. ASME B18.2.1 has specified both square lag screw and hex lag screw in full-diameter body or reduced-diameter body. As illustrated in Figure-a & Figure-c, the lag screw shall be furnished with an approximate 60°-angle gimlet end point or cone point.
Size | E | F | ||
Max. | Min. | Max. | Min. | |
No. 10 | 0.199 | 0.178 | 0.281 | 0.271 |
1/4" | 0.260 | 0.237 | 0.375 | 0.362 |
5/16" | 0.324 | 0.298 | 0.500 | 0.484 |
3/8" | 0.388 | 0.360 | 0.562 | 0.544 |
7/16" | 0.452 | 0.421 | 0.625 | 0.603 |
1/2" | 0.515 | 0.482 | 0.750 | 0.725 |
5/8" | 0.642 | 0.605 | 0.938 | 0.906 |
3/4" | 0.768 | 0.729 | 1.125 | 1.088 |
7/8" | 0.895 | 0.852 | 1.312 | 1.269 |
1" | 1.022 | 0.976 | 1.500 | 1.450 |
1-1/8" | 1.149 | 1.098 | 1.688 | 1.631 |
1-1/4" | 1.277 | 1.223 | 1.875 | 1.812 |
Size | G | S | |
Max. | Min. | ||
No. 10 | 0.398 | 0.372 | 0.094 |
1/4" | 0.530 | 0.498 | 0.094 |
5/16" | 0.707 | 0.665 | 0.125 |
3/8" | 0.795 | 0.747 | 0.125 |
7/16" | 0.884 | 0.828 | 0.156 |
1/2" | 1.061 | 0.995 | 0.156 |
5/8" | 1.326 | 1.244 | 0.312 |
3/4" | 1.591 | 1.494 | 0.375 |
7/8" | 1.856 | 1.742 | 0.375 |
1" | 2.121 | 1.991 | 0.625 |
1-1/8" | 2.386 | 2.239 | 0.625 |
1-1/4" | 2.652 | 2.489 | 0.625 |
Size | H | R | |||
Basic | Max. | Min. | Max. | Min. | |
No.10 | 1/8 | 0.140 | 0.110 | 0.03 | 0.01 |
1/4" | 11/64 | 0.188 | 0.156 | 0.03 | 0.01 |
5/16" | 13/64 | 0.220 | 0.186 | 0.03 | 0.01 |
3/8" | 1/4 | 0.268 | 0.232 | 0.03 | 0.01 |
7/16" | 19/64 | 0.316 | 0.278 | 0.03 | 0.01 |
1/2" | 21/64 | 0.348 | 0.308 | 0.03 | 0.01 |
5/8" | 27/64 | 0.444 | 0.400 | 0.06 | 0.02 |
3/4" | 1/2 | 0.524 | 0.476 | 0.06 | 0.02 |
7/8" | 19/32 | 0.620 | 0.568 | 0.06 | 0.02 |
1" | 21/32 | 0.684 | 0.628 | 0.09 | 0.03 |
1-1/8" | 3/4 | 0.780 | 0.720 | 0.09 | 0.03 |
1-1/4" | 27/32 | 0.876 | 0.812 | 0.09 | 0.03 |
Size | E | F | ||
Max. | Min. | Max. | Min. | |
No. 10 | 0.199 | 0.178 | 0.281 | 0.271 |
1/4" | 0.260 | 0.237 | 0.438 | 0.425 |
5/16" | 0.324 | 0.298 | 0.500 | 0.484 |
3/8" | 0.388 | 0.360 | 0.562 | 0.544 |
7/16" | 0.452 | 0.421 | 0.625 | 0.603 |
1/2" | 0.515 | 0.482 | 0.750 | 0.725 |
5/8" | 0.642 | 0.605 | 0.938 | 0.906 |
3/4" | 0.768 | 0.729 | 1.125 | 1.088 |
7/8" | 0.895 | 0.852 | 1.312 | 1.269 |
1" | 1.022 | 0.976 | 1.500 | 1.450 |
1-1/8" | 1.149 | 1.098 | 1.688 | 1.631 |
1-1/4" | 1.277 | 1.223 | 1.875 | 1.812 |
Size | G | S | |
Max. | Min. | ||
No. 10 | 0.323 | 0.309 | 0.094 |
1/4" | 0.505 | 0.484 | 0.094 |
5/16" | 0.577 | 0.552 | 0.125 |
3/8" | 0.650 | 0.620 | 0.125 |
7/16" | 0.722 | 0.687 | 0.156 |
1/2" | 0.866 | 0.826 | 0.156 |
5/8" | 1.083 | 1.033 | 0.312 |
3/4" | 1.299 | 1.240 | 0.375 |
7/8" | 1.516 | 1.447 | 0.375 |
1" | 1.732 | 1.653 | 0.625 |
1-1/8" | 1.949 | 1.859 | 0.625 |
1-1/4" | 2.165 | 2.066 | 0.625 |
Size | H | R | |||
Basic | Max. | Min. | Max. | Min. | |
No.10 | 1/8 | 0.140 | 0.110 | 0.03 | 0.01 |
1/4" | 11/64 | 0.188 | 0.150 | 0.03 | 0.01 |
5/16" | 7/32 | 0.235 | 0.195 | 0.03 | 0.01 |
3/8" | 1/4" | 0.268 | 0.226 | 0.03 | 0.01 |
7/16" | 19/64 | 0.316 | 0.272 | 0.03 | 0.01 |
1/2" | 11/32 | 0.364 | 0.302 | 0.03 | 0.01 |
5/8" | 27/64 | 0.444 | 0.378 | 0.06 | 0.02 |
3/4" | 1/2 | 0.524 | 0.455 | 0.06 | 0.02 |
7/8" | 37/64 | 0.604 | 0.531 | 0.06 | 0.02 |
1" | 43/64 | 0.700 | 0.591 | 0.09 | 0.03 |
1-1/8" | 3/4 | 0.780 | 0.658 | 0.09 | 0.03 |
1-1/4" | 27/32 | 0.876 | 0.749 | 0.09 | 0.03 |
ASME B18.2.1 Nine Types of Bolts & Screws | ||
---|---|---|
Square Head Bolt | Hex Bolt | Heavy Hex Bolt |
Askew Head Bolt | Hex Cap Screw | Heavy Hex Screw |
Hex Flange Screw | Lobed Head Screw | Lag Screw |