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Drill and Tap Specification Chart

In CNC machining, the usual process is to use a drill bit to drill a hole in the workpiece and then use a tap of the appropriate size to cut the desired threads in the hole. This ensures that the threads match the design requirements and can ensure that the threads fit correctly with other components.

These tools are used in custom CNC machining to create the required threads on a part in order to connect it to other parts or components.

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I. Introduction to Drill Bits and Taps

A drill is a tool used for drilling holes, usually made of steel, with a cutting edge and a shank. A tap is a tool used to form internal threads, also made of steel. When making threads, it is necessary to first drill a suitable hole with a drill bit, and then use a tap of the corresponding specifications to make deep cuts to form a threaded structure.

II. Drill and Tap Specification Chart

The following is a table of drill and tap specifications to make it easier to determine the matching relationship between drills and taps. When selecting the correct tap specification, please choose the appropriate drill specification according to the size of the threads to be made to ensure a proper matching relationship between the threads and the drill.

1. Tap specification table

Thread Specifications

TypeDrill DiameterTap Specification
Metric Coarse Thread (M)3.0mmM3
Metric Coarse Thread (M)3.5mmM4
Metric Coarse Thread (M)4.2mmM5
Metric Coarse Thread (M)5.0mmM6
Metric Coarse Thread (M)6.8mmM8
Metric Coarse Thread (M)8.5mmM10
Metric Coarse Thread (M)11.0mmM12
Metric Coarse Thread (M)14.0mmM16
Metric Coarse Thread (M)18.0mmM20
Imperial Coarse Thread (UNC)4.8mm1/4-20UNC
Imperial Coarse Thread (UNC)6.5mm5/16-18UNC
Imperial Coarse Thread (UNC)8.5mm3/8-16UNC
Imperial Coarse Thread (UNC)10.5mm7/16-14UNC
Imperial Coarse Thread (UNC)12.5mm1/2-13UNC
Imperial Coarse Thread (UNC)16.5mm5/8-11UNC
Imperial Coarse Thread (UNC)19.5mm3/4-10UNC
Imperial Coarse Thread (UNC)22.5mm7/8-9UNC
Imperial Coarse Thread (UNC)25.5mm1-8UNC
Imperial Fine Thread (UNF)4.2mm4-40UNF
Imperial Fine Thread (UNF)5.6mm6-32UNF
Imperial Fine Thread (UNF)6.8mm8-32UNF
Imperial Fine Thread (UNF)8.5mm10-24UNF
Imperial Fine Thread (UNF)10.5mm12-24UNF
Imperial Fine Thread (UNF)12.5mm1/4-28UNF
Imperial Fine Thread (UNF)16.5mm5/16-24UNF
Imperial Fine Thread (UNF)19.5mm3/8-24UNF
Imperial Fine Thread (UNF)22.5mm7/16-20UNF
Imperial Fine Thread (UNF)25.5mm1/2-20UNF

2. Drill and Tap Matching Chart

Metric Coarse Thread (M)

Thread SizeDrill Diameter
M32.5mm
M43.3mm
M54.2mm
M65.0mm
M86.8mm
M108.5mm
M1211.0mm
M1614.0mm
M2018.0mm

Unified National Coarse Thread (UNC)

Thread SizeDrill Diameter
1/4-20UNC0.2031in
5/16-18UNC0.2570in
3/8-16UNC0.3238in
7/16-14UNC0.3770in
1/2-13UNC0.4063in
5/8-11UNC0.5156in
3/4-10UNC0.6094in
7/8-9UNC0.7031in
1-8UNC0.8125in

Unified National Fine Thread (UNF)

Thread SizeDrill Diameter
4-40UNF3/32in
6-32UNF7/64in
8-32UNF9/64in
10-24UNF5/32in
12-24UNF11/64in
1/4-28UNF1/4in
5/16-24UNF5/16in
3/8-24UNF3/8in
7/16-20UNF7/16in
1/2-20UNF1/2in

IV. Summary

This article provides a table of drill and tap specifications, so that you can easily choose the correct tap specifications to avoid difficulties in the work. When using drills and taps, please follow the precautions to ensure the quality and accuracy of the threads.

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