Types of Sockets

Socket wrenches offer a fast, efficient way to tighten or loosen many types of fasteners, primarily nuts and bolts. These straightforward tools are helpful to everyone from the hobbyist to the expert. In addition to being easy to use and effective, the socket wrench can present a lot of different options due to the variety of sockets available, including differences in measurement, shape, and even mechanical properties.

Metric and Imperial Sockets

The two most common measurement systems for sockets, like with most mechnical tools, are metric and imperial, or standard (i.e. inches), units. While sockets can be very similar, they are only suited for like nuts and bolts—a metric socket for a metric bolt, and a standard socket for a standard bolt. Incompatibilities run the risk of stripping the bolt head, which can lead to other problems. There are many drive sizes to match the different types of bolts and screws, and for standard applications these bolts and screws follow standard sizes for ease of use. For more complicated applications or applications involving patented brands, sometimes the sockets and bolts or screws will be specific to the application.

You can view a list of all the different socket head sizes at this page.

“Point” Shapes

Socket point shapes refer to the shape of the socket —usually a dodecagon (also called a double hexagon) or a hexagon. These are the standard shapes currently in use, although octagons were previously common due to the ubiquity of square-shaped bolt and screw heads, which has declined in recent years. The hexagon shape will match up exactly to a bolt or screw head, while the double-hexagon will match up with multiple “starting” points.

Socket Length Concerns

When deciding on socket length, it is best to consider the application requirements. There are essentially two basic socket lengths: standard, or shallow, and deep. Shallow sockets can fit into tight locations, as well as close angles and open areas. Deeper sockets can also reach out-of-the-way bolts and screws, but are commonly used for “inverted” ratcheting when a bolt is screwed upwards.

Special Impact Socket Types

More and more fasteners are being made of special materials. While traditional fasteners can be made out of a number of materials, standard sockets can generally be fitted to them for tightening needs. However, if materials clash—that is, if a fastener is of particularly dense and cannot easily be turned—one needs an impact socket. This is a socket that is made of a soft but strong type of steel, usually chrome-molybdenum, that will be able to turn the dense nut without breaking.