Stud Bolts Key Terms

Understand the basics of stud bolt products for smarter selection of studs

By Howard Robertson

Stud bolts (generally called studs) are screw-style bolts that are threaded at either end, one end or all the way through. Studs are essential components of industrial equipment and construction projects. They come in various types, such as single-end studs, double-end studs, tap end studs and full thread studs. Historically, wooden studs were used in construction projects. However, metal or steel studs are currently used for almost all applications, as metal and steel studs do not warp, shrink or rot.

If you want to use studs for your applications, you will need to be conversant with certain terms that you will hear from professionals in the fasteners industry. This guide will introduce you to some key terms, such as thread angle, thread pitch, major diameter, minor diameter, metric threads and acme threads.

Thread angle

As the name indicates, thread angle is the angle formed by the two sides of the thread with each other. For acme threads, the thread angle is 29°, whereas, for square threads, this angle is 0°.
Try: Republic Drill Corporation, a reputable manufacturer of industrial cutting tools, provides a glossary of technical terms, including thread angle and thread pitch. You can also read through the engineering terms glossary at International Technical Services.

Thread pitch

Thread pitch (or pitch) is the distance from a point on a screw thread to the corresponding point on the next thread measured parallel to the axis of the stud.
Try: For definition of thread pitch, read through the glossary of technical terms at Roton Products, a supplier of industrial screws.

Major diameter

Major diameter is another important specification of an industrial stud bolt. Major diameter can be defined as the diameter of an imaginary cylinder parallel with the crests of the threads.
Try: Bolt Depot, an online retailer of fastener products, provides definitions for various fastener terms, including major diameter.

Minor diameter

Minor diameter is the diameter of an imaginary cylinder that just touches the roots of the stud threads.
Try: Allmetal Screw Products, a manufacturer of stainless steel fastener products, offers a glossary of important fastener terms. You can also read through the thread glossary at eMachineShop.

Acme threads

Acme threads are threads that are trapezoidal and have thread angles of 29° or 30°. Cutting acme threads is easier, so studs with acme threads are generally cheaper than those with metric threads. However, acme threads have lower efficiency. Acme threads come in three classes: general purpose, centralizing and stub acme.
Try: DiracDelta.co.uk, an engineering information resource, provides technical data about acme threads. In addition, you can read through the glossary of technical terms at Nook Industries (PDF).

Metric threads

Metric threads are square shaped threads and are difficult to manufacture. For studs, metric threads come in two types: coarse threads and fine threads.
Try: Metrication.com provides different thread dimensions for standard metric threads. Newman Tools, an industrial tool supplier, provides technical data about metric coarse threads and metric fine threads.

Self loosening

Due to vibration of stud bolts or equipment that contains these bolts, a stud might become loose. This action is not desirable, as it can lead to failure of fastened equipment.
Try: For more description on self loosening, read through the fastener glossary at Bolt Science.

Left or right hand threads

This specification indicates the direction of winding of an industrial stud. A left hand thread, when viewed axially, winds in a counterclockwise direction and inversely, a right hand thread, when viewed axially, winds in a clockwise direction. The thread direction is generally right hand, unless indicated specifically.
Try: For definitions of left hand threads and right hand threads, read through the glossary of thread terms at All American Security Fasteners.