Hand taps are cutting tools that produce helical grooves in a hole in order to insert a fastener. Taps are used in multiple industries and trades.
Hand taps have a straight flute and come in a taper, plug or bottoming chamfer. The tapering of the threads distributes the cutting action over several teeth.
How do taps work?
A conventional hand tap works as a cutting tool by removing material from a work piece. This is done using sharp teeth. The tap is spun down a hole within a work piece. The hole is referred to as a pilot or tap hole and is sized according to the desired thread and the material to be tapped. As the tap scrapes along the sides of the hole, it cuts away a spiraling ramp making the female thread. A tap can be used to create a thread for the first time or it can be run into an already tapped hole to help repair damaged threads.
When a tap is used it only cuts in one direction, typically clockwise for standard threads. As the tap is spun it will progressively work its way deeper into the hole as it cuts new threads. If the tap is spun counter-clockwise it will back itself out of the hole, similarly to backing out a threaded fastener.
Hand taps are usually paired with a tap wrench, see Figure 3. This allows a user to align the tap with the pilot hole and allows the user to spin the tap in both directions. There are a variety of wrench styles and they are sized to fit a range of taps. They consist of a clamp which secures the tap and an elongated handle to give the user leverage.