How to Connect Metal by Threading with a Tap

While welding is one of the go-to methods to connect metal, it’s not the only option available. If you don’t want to worry about wearing a welder’s mask and igniting a blow torch, there are other less extreme options. For a safe and effective method of connecting metal, consider tapping.

What is Tapping?

A tap is essentially a type of drill bit with grooves or threads. You can tap via drill or by hand with a tap wrench. The tapping tool creates permanent threads in the metal where you can screw in a bolt. If you plan to tap a high number of holes, use a tap drill for its speed and efficiency. However, if you’re tapping just a few holes, use a tap wrench. The tap wrench gives you more control over the process and results in a smoother hole.

Supplies for Tapping

Tap Drill
Tap Wrench
Oil or Tapping Fluid
Hand Taps
The appropriate screw to match your thread

Steps for Tapping with a Tap Wrench

Hand taps typically come in a set of three that includes the taper tap, plug tap, and bottoming tap. Each has a different number of chamfered threads to match a range of metal depths. We recommend that you begin the process with a taper tap, as it requires the least amount of force.

You will need a tap wrench or T-bar to attach the square shank of the tap. Then, you're ready to begin the process.
Spray oil or tapping fluid over the hole in the metal to help lubricate the wrench.
Grab the T-bar and place the tap into the hole at a vertical angle.
Rotate the T-bar two clockwise revolutions.
Rotate one-half turn in the reverse direction (reversing creates the thread after the tap is etched).
Repeat steps 3 and 4 a few times until the majority of chamfered threads are through.
Rotate the T-bar clockwise until the tap gets through the piece of metal.
Screw in the bolt.

Steps for Tapping with a Tap Drill

Drill tapping demands a straight tap and a proper torque. A slanted tap will result in an awkward angle, in which the screw will not completely fit. Minimal torque will prevent the tap from piercing through the metal, while too much torque can cause the drill to jam.

We recommend that you set your drill to low or moderate torque. It's easier and less risky to increase the revolution speed as you go, rather than drill incorrectly and not be able to fix your mistake. Once you’ve attached the tap to the drill, begin the process:
Spray oil or tapping fluid over the hole in the metal to help lubricate the wrench.
Place the drill vertically in the hole.
With the drill set to forward position, gently press the trigger to apply light pressure.
Rotate a few revolutions clockwise, then measure the tap with a square ruler to ensure it enters straight.
Reverse the drill until the tap is nearly released.
Repeat steps 4 and 5.
Proceed in a clockwise motion until the tap goes all the way through the metal.
Screw in the bolt.

Of course, the project goes to waste if you fit the hole for the incorrect screw size. That's why the drill, tap, and screw dimensions must be in unison for everything to go right. This chart should guide you in the right direction.

Tapping is relatively straightforward, and you can complete the process in just a handful of minutes. It's a safe and efficient way to connect metals. Find the right metal for the job via Industrial Metal Supply Co. Choose from aluminum, steel, brass, copper, and more.