How to make a Thread Tap

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

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

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

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

Secure the bolt in a vice

Carefully cut the slots with a thin cutting disk.

Your angle grinder cuts should look something like this.

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.

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.

Then quench till it is a safe temperature to touch.

The bolt is now hard and somewhat brittle.

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

Start tapping the thread.

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

This would be a good enough substitute in some situations.

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and we would love to see you there ♥