Introduction and Overview of Drill and Tap Sizes
– A comprehensive chart for all drill and tap sizes, imperial and metric
– Covers sizes up to 36.5 millimeters (1.44in) in diameter
– Used to determine the proper tap drill for a certain thread size or the proper tap for an existing hole
– Helps in producing threaded holes for female screw threads
– Includes drill sizes that are slightly larger than the minor diameter of the mating male thread
– The tap drill size yielded by the rules of thumb and major minus pitch technique is generally suitable for general use
– The 85% and 90% rules work best in the range of 14–1in (6.4–25.4mm)
– Some sizes outside that range may have different ratios
– The article’s factual accuracy is disputed, and relevant discussions can be found on the talk page
– The chart may not be complete, and missing items can be added to improve its usefulness
Rules of Thumb for Tap Drill Sizes
– For standard V threads, a good tap drill is 85% (± 2 pp) of the major diameter for coarse threads
– For fine threads, a good tap drill is 90% (± 2 pp) of the major diameter
– For metric V threads, the major minus pitch technique yields a good tap drill diameter
– The major minus pitch technique also works for inch-based threads
– These rules of thumb provide tap drill sizes that are generally suitable for most applications
Examples of Tap Drill Sizes
– Example (inch, coarse): A size 7/16 screw with 14 threads per inch needs a tap drill with a diameter of about 0.371 inches
– Example (inch, fine): A size 7/16 screw with 20 threads per inch needs a tap drill with a diameter of about 0.393 inches
– Example (metric, coarse): An M7.0×1.0 screw needs a tap drill with a diameter of about 5.95mm
– Example (metric, fine): An M7.0×0.5 screw needs a tap drill with a diameter of about 6.30mm
– The major minus pitch technique can be used to determine tap drill sizes for both inch and metric threads
Chart Details and Information
– The chart provides inch-sized drills, increments of 1/64in
– It includes drills specified in decimal inches, number series (1-80), and letter series (A-Z)
– The chart also lists standard metric drill sizes used for metric taps
– It provides information on drill bit diameter, fractional size, drill wire gauge, tap size, clearance, thread depth, and outer diameter
– The chart is a useful reference for selecting the appropriate drill and tap sizes
External Resources and Related Topics
– External links to tap drill sizes and calculators
– External links to tap and clearance drills for common screws
– Additional resources for machining and computing, such as computer-aided engineering, CAD, CAM, and G-code
– Information on drilling and threading, including die head, drill bit, drill bit shank, and drill bit sizes
– External links to tap drill sizes, metric tap drill sizes, tap and drill chart, and BTA drill tube reference chart Source: https://en.wikipedia.org/wiki/Drill_and_tap_size_chart
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.
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. 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. 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. Such an appropriately sized drill is called a tap drill for that size of thread, because it is a correct drill to be followed by the tap. Many thread sizes have several possible tap drills, because they yield threads of varying thread depth between 50% and 100%. Usually thread depths of 60% to 75% are desired.
People frequently use a chart such as this to determine the proper tap drill for a certain thread size or the proper tap for an existing hole.
