Npt tap drill size chart

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Each standard size of female screw thread has one or several corresponding drill bit sizes that are within the range of appropriate size-slightly larger than the minor diameter of the mating male thread, but smaller than its pitch and major diameters. One of the most common ways to produce such threaded holes is to drill a hole of appropriate size with a drill bit and then tap it with a tap.

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In manufactured parts, holes with female screw threads are often needed they accept male screws to facilitate the building and fastening of a finished assembly. Below is a comprehensive drill and tap size chart for all drills and taps, imperial and metric, up to 36.5 millimetres (1.44 in) in diameter.

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