If this is a bolt, the 1-1/2" is the length from under the head to the tip of the bolt. It includes the shank. If this is a thread call out on a drawing, it means the thread is 1-1/2" long. You need to specify where you're seeing this call out.eurekameh said:What does the thread note 3/8'' - 24UNF 2B x 1-1/2'' mean? I know that the diameter of the thread is 3/8'', but what's the 1-1/2''? Is that the length of the thread?
In thread measurement, 3/8''-24UNF 2B x 1-1/2'' refers to the size, thread type, and thread length of a specific thread. The 3/8'' refers to the major diameter of the thread, 24UNF indicates the number of threads per inch and the thread form, and 2B refers to the class of fit for the thread. The 1-1/2'' measurement is the length of the threaded portion of the fastener or hole.
The thread class refers to the tolerance or fit of the thread. 2B is a standard thread class, where the internal thread (nut) is designed to fit with a 2A external thread (bolt). 3B is a closer tolerance class, where the internal thread is designed to fit with a 3A external thread, resulting in a tighter fit.
Thread pitch is measured by counting the number of threads per inch (TPI) or the number of threads per millimeter (TPM). For example, a 3/8''-24UNF thread has 24 threads per inch.
3/8''-24UNF threads are commonly used in fasteners and fittings that require a strong, reliable connection. They are commonly found in automotive and machinery applications, as well as in plumbing and electrical connections.
Thread diameter is measured by finding the distance between the crest (top) of one thread to the crest of the opposite thread. For example, a 3/8''-24UNF thread has a major diameter of 3/8'', but the minor diameter (the valley between threads) will be slightly smaller.