Home 9 CNC Machining 9 Thread Taps: A Complete Guide on the Cutting Tool

Thread taps are a type of cutting tool. Thread taps are used to work on metals, making threaded holes in them. If you’ve ever wondered what tool is used to make the holes in bolts and the threads on nuts, you’ve finally found the answer to your question.

Manufacturers use materials like alloy, high-carbon, and high-speed steel to make thread taps. To use them, you have to either use them with a wrench or tap handle. However, combining them with drills is the easiest way to use them.

Various types of thread taps

Thread Taps 

Thread taps commonly have three parts: the tang, the shank, and the body. The tang is usually the part attached to the drill or wrench, while the shank holds the inscriptions regarding the tap’s properties. The body is the most important part, holding the threads which do the actual drilling.

Now that we’ve briefly introduced thread taps, let’s review the various types available.


Types of Thread Taps

In this section, we’ll go through the various types of thread taps, their unique features, and their advantages. There are 10 types of taps, namely:

1. Hand Taps

A hand-tap set

These are the most common type of thread taps. However, they’re not advisable to use for CNC machining procedures as they do not produce the best threads. Hand taps usually come in a set of three taps known as the taper tap, the second/intermediate/plug tap, and the bottoming/finish tap.

  • Taper Taps

When using hand taps, this is the first tap used on the workpiece. It has 8 – 10 threads on its body, which do the actual threading work. It is common so you might find this in any machine shop.

  • Second/Intermediate/Plug

This is used after the taper tap. It has 3 – 5 threads on its body which function to shape and give depth to threads made by the taper tap.

  • Bottoming/Finishing Tap

This is the last tap of the hand tap set. It comes in use after the intermediate tap and has 1 – 1.5 threads on its body. The bottoming tap is best suited for threading holes that do not go completely through the workpiece. However, if the hole goes through both sides, machinists use only the taper and the intermediate taps.

2. Machine Tap

An example of a machine tap

A machine tap

Machinists use this tap in combination with a tap drill machine. The tap drills usually have a special holder for the machine drills to allow easy attachment.

3. Gas Tap

Two Gas Taps

Gas Taps

Just like the name implies, this thread tap functions in drilling gas-type threads. These threads are suitable for fittings where gas or liquid pipes are meant to pass through. This tap has 1.5 of its thread at the lower portion chamfered and ¾ taper per foot. They are also known as pipe thread taps.

4. Extension Tap

An Extension Tap

Extension Tap

These taps are just like hand taps, but they have a longer shank. Machinists use them for making threads in deep spots such as pulley hubs.

5. Form Taps

A Form Tap

Form Tap

This tap is different from others in that it doesn’t have flutes on its body but has threads all over. It is also different in mode of operation such that it doesn’t cut the metal but pushes and compresses it. They are better for use in softer metals like aluminum and brass. They are also known as fluteless taps.

6. Master Tap

Master Tap

This is another tap similar to the hand tap; however, it has more flutes due to more threads. This tap thread is used to cut the threads in thread ring gauges.

7. Machine Screw Tap

A set of five machine screw taps

Machine Screw Thread Tap

This tap is used when cutting cut threaded holes with less than ¼ diameter. On its lower portion, it has two to four chamfered threads.

8. Stay Bolt Tap

A set of two stay bolt taps

Stay Bolt Tap

The stay bolt tap is a special type of thread tap. It is a multipurpose tap with its part divided into three areas. The lower part has the same diameter as the hole, which it drills to help keep its tab straight. The middle portion has a reamer which helps to clean the hole. The tap itself is at the last part and makes the thread.

9. Punch Tap

A golden-bodied punch tap

Punch Tap

This tap is a technology made by Audi to make threading faster. These taps can run 75% faster than the normal forming tap.

10. Spiral Flute Tap

A spiral flute thread tap

Spiral Flute Thread Tap

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Spiral taps are similar to the end mill in shape. They are also a good choice for threading blind holes because they can eject cut metal up and out of the hole.

Some taps are also used for special functions, such as the ACME thread taps. There are also some custom thread taps machinists get made to suit themselves. Some taps could also be hand-oriented, e.g., right or left-handed thread taps.


How to Tap A Thread

If you want to machine a threaded hole, here’s the process to follow:

  • First, bore a hole using a tap drill of the appropriate size for the thread.
  • File the thread tap while attached to the drill.
  • Clamp down the workpiece.
  • Then, the taper thread tap is up next. This tap is used to make the thread.
  • After moving through a few threads, check if the tap is still moving in a straight line.
  • Ensure adequate lubricant is applied while tapping.
  • After using the taper tap, use the intermediate and finishing tap to complete the process as the case requires.
  • If it’s a blind hole, take out the tap occasionally to dispose of chips.


However, it is vital to ensure that the drilled hole is appropriate for the tap is vital. Also, the machinist should move the thread tap forward and backward during the process.


Find Thread Tap Size with a Chart

This chart shows different tap sizes with their diameter and other properties.

Tap SizeMajor Diametermm per threadDrill size
M1.6 x 0.351.6mm.351.25mm
M2 x 0.42mm.41,6mm
M2.5 x 0.452,5mm.452,05mm
M3 x 0.53mm.52,5mm
M3.5 x 0.63,5mm.62,9mm
M4 x 0.74mm.73,3mm
M5 x 0.85mm.84,2mm
M6 x 16mm15mm
M8 x 1.258mm1.256,8mm
M8 x 18mm17mm
M10 x 1.510mm1.58,5mm
M10 x 1.2510mm1.258,8mm
M12 x 1.7512mm1.7510,2mm
M12 x 1.2512mm1.2510,8mm
M14 x 214mm212mm
M14 x 1.514mm1.512,5mm
M16 x 216mm214mm
M16 x 1.516mm1.514,5mm
M18 x 2.518mm2.515,5mm
M18 x 1.518mm1.516,5mm
M20 x 2.520mm2.517,5mm
M20 x 1.520mm1.518,5mm
M22 x 2.522mm2.519,5mm
M22 x 1.522mm1.520,5mm
M24 x 324mm321mm
M24 x 224mm222mm
M27 x 327mm324mm
M27 x 227mm225mm

Thread Tap Size Chart


Applications of Thread Taps

The use of thread taps spread to various procedures. Some examples of these applications include:

  1. Bolts and Nuts: Thread taps are vital in the manufacturing of threaded bolts and nuts.
  2. Gas Fittings: Thread taps are also vital in making fittings through which gas pipes are passed.


Leave the Tapping to Us at Prolean

While it’s fun learning about these tools, in theory, using them is a different game entirely. This is why you should leave these types of jobs to the experts. You would save yourself the stress and time that comes with doing it yourself.

This is why you should work with us at Prolean. We have various machining specialists that understand how to use these various tools for the right applications. If you need any type of tapping services, do not hesitate to contact us.



Identifying the various types of thread taps and their uses could be quite confusing. However, with this guide, you should easily be able to tell these taps apart.


How are thread sizes measured?

To measure a thread size, you can use a vernier caliper to measure the outside diameter. After getting the measurement, you can compare the measurement to the figures on the chart above. This way, you can easily measure and identify any thread tap.


Which thread tap is the best to use?

Thread taps come in different types because they have different applications. Hence, there’s no particular one that is best as they all have their various uses.

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