Round head bolts (button head) are commonly used in wood connections. Round head bolts are similar to carriage bolts, but without the square neck under the head. Because they are used with wood, round head bolts are rarely high strength and virtually always supplied in a standard ASTM A307 specification.
Manufacturing
Portland Bolt manufactures button head bolts from 1⁄2” through 11⁄4 ” diameter in most ASTM, AASHTO, and SAE specifications. Special tooling can be created to produce nonstandard head dimensions, button head bolts larger than 11⁄4” in diameter, or bolt heads with your company’s name and/or logo.
Standard Thread Length
Bolt lengths ≤ 6″: Thread length = (2 X diameter) + 1⁄4”
Bolt lengths > 6″: Thread length = (2 X diameter) + 1⁄2”
Round Head Bolt Dimensions
| Bolt Diameter | C | H | ||
|---|---|---|---|---|
| Head Diameter | Head Height | |||
| Max | Min | Max | Min | |
| 1⁄2 | 1.094 | 1.032 | 0.270 | 0.250 |
| 5⁄8 | 1.344 | 1.219 | 0.344 | 0.313 |
| 3⁄4 | 1.594 | 1.469 | 0.406 | 0.375 |
| 7⁄8 | 1.844 | 1.719 | 0.469 | 0.438 |
| 1 | 2.094 | 1.969 | 0.531 | 0.500 |
| 11⁄4 | 2.850 | 0.531 | 0.500 | |
|
*Dimensions per ASME B18.5 1990 (R 1998) cover diameters up to 1". Bolts over 1" use custom head dimensions. |
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