It was the square head machine bolts that were the industry standard before Hex bolts became prominent. However, presently, square bolts are used largely for aesthetic purposes, offering a rustic finish to a new structure. Besides, they are also used to match existing fasteners of older structures. Square leg screws are also sometimes used to serve such purposes. Machine bolts or cross arm bolts are supplied primarily to the utility industry where they include an added cone point.
BBI manufactures superior quality square bolts. With a diameter of 1/2″ – 2″, these bolts fulfill most specifications of the ASTM, SAE and AASHTO. In fact, we can even create special tooling to help produce nonstandard bolt heads / head dimensions with the preferred logo and/or name. We also stock square head blanks that can be used for small orders or expedited deliveries.
baseline Bolt does not stock any square head machine bolts, and in most cases, square head bolts are not readily available through fastener distributors. Typically, square head bolts will need to be custom manufactured.
Standard Thread Lengths
Bolt lengths < 6″: Thread length = (2 X diameter) + 1/4″
Bolt lengths > 6″: Thread length = (2 X diameter) + 1/2″
Square Head Dimensions
|Body Diameter||Width Across Flats||Width Across Corners||Height|
* 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.
Dimensions per ASME B18.2.1 1996