The main diameter is a measurement used to identify the size of a bolt 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 part of the threads or the head of the fastener. Major diameter plays a key role in most common bolt identification systems, including metric and non-metric systems.
Using different measurements on any given screw, users can identify the type of screw and how it can be used. Vendors and manufacturers provide charts that allow users to find different bolt measurements using known figures or resources. These measurements can include the major or minor diameter, which represents the size of the female threads along the shank. These charts may also include 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 bolt.
The main diameter of a bolt or bolt can be measured using a hand tool known as a micrometer. Depending on the region, users may require a metric or non-metric micrometer tool. To get an accurate measurement with this tool, it’s 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, cohesive connection. With so many screw shapes and sizes available, knowing the main diameter and another measurement makes it much easier to choose the right screw in the shop or workshop.
Although people all over the world use many different systems to identify types of screws, 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 Standards (ISO). According to UPS identification standards, screws are identified by a number that can be used to identify the size and slope of the screw. To find the main diameter of a UPS screw, multiply the ID number by 0.13 and add 0.60, which gives the diameter in inches. In accordance with ISO identification standards, the main diameter is given as the first number in a sequence of numbers used to identify each bolt.