Employee
Major diameter is a measurement used to identify the size of a stud or bolt. The major diameter of these fasteners represents the distance around the outside of the threads, which is the widest part of the shank. This measurement must be taken around the male threads, and cannot be taken from the female portion of the threads or the fastener head. Major diameter plays a key role in most common bolt identification systems, including metric and non-metric.
By using different measurements on any given screw, users can identify the type of screw and how it can be used. Suppliers and manufacturers provide tables that allow users to find different bolt sizes using numbers or known resources. These measurements may include the major or minor diameter, which represents the size of the female threads along the stem. These charts may also include the pitch, which represents the number of threads per inch or centimeter measured along the length of the rod. By combining two or more of these measurements, users can identify a loose screw.
The major diameter of a stud or bolt can be measured using a hand tool known as a micrometer. Depending on the region, users may need a metric or non-metric micrometer tool. To get an accurate measurement with this tool, it is critical to only measure around the widest part of a bolt’s threads. In some cases, excessive wear may have reduced the size of the threads, resulting in inaccurate measurements. Burrs or gaps along the edges of the wires can also affect the accuracy of the reading.
Using the main diameter and other measurements, workers can identify the type of bolt used on a specific project. This is useful for combining existing screws to create a secure and cohesive connection. With so many screw shapes and sizes available, knowing the main diameter and other measurement makes it much easier to choose the correct screw at the store or shop.
Although people around the world use many different systems to identify screw types, two main systems serve as the most widely used methods of identifying screws. This includes the Unified Thread Standard (UPS) and the International Organization for Standardization (ISO). In accordance with UPS identification standards, screws are identified by a number that can be used to identify the size and pitch of the screw. To find the main diameter of a UPS screw, multiply the identification number by 0.13 and add 0.60, which gives the diameter in inches. According to ISO identification standards, the main diameter is indicated as the first number in a sequence of numbers used to identify each bolt.