AIA NAS725:2021

This specification establishes the requirements for externally threaded fasteners of diameters from .30 UNM (.0118 in.) to 1.40 UNM (.0551 in.) inclusive, which fall within the classification of Miniature Screws and which are designed to be assembled with tapped holes or nuts and driven by means of a jeweler's type screwdriver. There is only one class of thread established: this is with zero allowance on all diameters. All tolerances governing limits of size are based on functions of the pitch only and apply to lengths of engagement from two-thirds to one and one-half times the nominal diameter.