I will assume that you are talking about the length on a partially thread bolt. Typically the thread length provided is the length of the fully operational thread. Any run off or partial threads are not included in this length and it is typically a minimum length unless the run off is buried or eliminated by an undercut to ensure that thread completes cleanly. If you are talking about the length of the threads or more correctly depth of threads in a hole it is important that this standard be maintained. In both cases it relates to the holding strength of the final bolted joint. Niel Leon engineering.com |