Square Head Machine Bolts
Square Head Machine Bolts
Square Head Machine bolts are used for fastening BRK hardware and line construction specialty products to crossarm poles and other structures as well as attaching the wooden crossarms to the pole. Square head machine bolts have an added semi-cone point and a thread length unique to BRK fasteners depending on the length of the bolts. Square head machine bolts have a square nut assembled.
| Bolt Diameter | D | F | C | H | |||||
|---|---|---|---|---|---|---|---|---|---|
| Body Diameter | Width Across Flats | Width Across Corners | Height | ||||||
| Max | Basic | Max | Min | Max | Min | Basic | Max | Min | |
| 1⁄2 | 0.515 | 3⁄4 | 0.750 | 0.725 | 1.061 | 0.995 | 21⁄64 | 0.348 | 0.308 |
| 5⁄8 | 0.642 | 15⁄16 | 0.938 | 0.906 | 1.326 | 1.244 | 27⁄64 | 0.444 | 0.400 |
| 3⁄4 | 0.768 | 11⁄8 | 1.125 | 1.088 | 1.591 | 1.494 | 1⁄2 | 0.524 | 0.476 |
| 7⁄8 | 0.895 | 15⁄16 | 1.312 | 1.269 | 1.856 | 1.742 | 19⁄32 | 0.620 | 0.568 |
| 1 | 1.022 | 11⁄2 | 1.500 | 1.450 | 2.121 | 1.991 | 21⁄32 | 0.684 | 0.628 |
| 11⁄8 | 1.149 | 111⁄16 | 1.688 | 1.631 | 2.386 | 2.239 | 3⁄4 | 0.780 | 0.720 |
| 11⁄4 | 1.277 | 17⁄8 | 1.875 | 1.812 | 2.652 | 2.489 | 27⁄32 | 0.876 | 0.812 |
| 13⁄8 | 1.404 | 21⁄16 | 2.062 | 1.994 | 2.917 | 2.738 | 29⁄32 | 0.940 | 0.872 |
| 11⁄2 | 1.531 | 21⁄4 | 2.250 | 2.175 | 3.182 | 2.986 | 1 | 1.036 | 0.964 |
| 13⁄4* | 29⁄16 | 13⁄16 | |||||||
| 2* | 215⁄16 | 15⁄16 | |||||||
Dimensions per ASME B18.2.1 1996 * ASME only defines head dimensions up to 1-1/2″. Dimensions for 1-3/4 and 2″ are approximate and not covered under the ASME dimensional specifications. | |||||||||
Standard Thread Lengths
| *Bolts shorter and/or smaller than those listed in the table shall have minimum thread lengths in accordance with American National Standard for Square and Hex Bolts and Screws, B18.2.1* | ||
| Diameters | Bolt length | Thread length |
|---|---|---|
3/8″, 1/2″, 5/8″, 3/4″, 7/8″, 1″ | 4″ up to less than 8″ | 3″ |
3/8″, 1/2″, 5/8″, 3/4″, 7/8″, 1″, 1-1/4″ | 8″ up to less than 12″ | 4″ |
3/8″, 1/2″, 5/8″, 3/4″, 7/8″, 1″, 1-1/4″ | 12″ and over | 6″ |
