ANSI B18.5.2.1M Round Bolt

This Standard covers the general and dimensional data for metric series round head short square neck bolts recognized as an American National Standard and intended primarily for applications in thin metals.

The inclusion of dimensional data in this Standard is not intended to imply that all sizes described are production stock items.Consumers should consult with suppliers concerning lists of stock production items.

Leader-Fastener® ANSI B18.5.2.1M Round Bolts produced to this Standard are functionally interchangeable with bolts which conform to ISO 8678:1988. Differences between this Standard and ISO 8678 are: size M14, materials other than steel, and minor variations in tolerances,such as, permissible swell, fin, or die seam on the body of bolts with nominal engths longer than 150 mm. Dimensional requirements in addition to, or different from ISO 8678, are shown in bold type in this Standard.

Round head bolts are frequently used in rail, heavy equipment, and agricultural applications.  The bolts have a low profile head that does not interfere with many applications where a dramatic protrusion from a hex head or other style would.  There are a variety of styles that include under head features to hold the bolt in place while a nut is being tightened.

Leader-Fastener® NSI/ASME B 18.5.2.1M - 2011 Metric round head short square neck bolts