Introduction: How to Make a Thread Tap

About: Hello, I'm Niki. I like to make things and save money while I am doing it.

How to make a quick and easy tap for cutting a thread.


  • High tensile steel bolt
  • Angle grinder (with cutting disk)
  • Bench vice
  • Butane torch
  • Tin can (for quenching)
  • Adjustable wrench

Step 1:

This tool is more of a last resort when you need to tap a thread
and you do not have immediate access to the actual necessary tool.

Step 2:

We take an existing bolt of the exact thread diameter and pitch required.

Step 3:

I recommend a high tensile steel bolt. But mild steel may work as well.

Step 4:

The idea is to make cuts along the bolt threads so that it somewhat resembles an actual thread tap.

Step 5:

Secure the bolt in a vice

Step 6:

Carefully cut the slots with a thin cutting disk.

Step 7:

Your angle grinder cuts should look something like this.

Step 8:

Make yourself a quenching bath, I am using a mixture of salt water.
But I have used old engine oil in the past.

Fire up your burner.

Step 9:

Heat the bolt to approximately 800 degrees Celsius,
or 1450 to 1500 degrees Fahrenheit. Which is expressed as a bright cherry red colour in carbon steel.

Step 10:

Then quench till it is a safe temperature to touch.

Step 11:

The bolt is now hard and somewhat brittle.

Step 12:

Now to test it.
Drill the required size hole in the piece that needs tapping and add some oil.

Step 13:

Start tapping the thread.

Step 14:

There you have it.
This quick tool was able to cut a pretty decent thread in 10mm 3/8 inch mild steel.

Step 15:

This would be a good enough substitute in some situations.

Step 16:

We have more DIY and Tips over on YouTube.

And we would love to see you there.

YouTube - Nikita Maree

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