A tap drill bit, a tool attachment that is specifically made for tapping metalwork techniques, is called a tap drill bit. To create a hole through a material that can hold a bolt, the tapping technique is used. This attachment can be used to repair or rethread damaged fixings. To create both internal and external threads, a tapping tool can be combined with a die to create them.

A tap drill bit is more like a long bolt thread. It is used to insert into a drillchuck to speed up the process of making an internal thread. These bits are typically made of hardened tungsten to make it possible to use the bit multiple times to form threads in different metals. Tap drill bits can form an inner thread. This is sometimes called the female section of a coupleling such as in a standard nuts.

The die bit is the companion attachment to a tap drilling bit. It's used to create an external thread or the male section of a coupling. Tap bits and die bits can be paired to ensure the correct joining of the male and female sections of the coupling. Each type of bit has a numbering system based on diameter to permit creation of matching pairs.

Metal machinists use three types of tap drill bits: the bottoming, intermediate and taper tap. The bottoming tap is the first type of bit. It has a flat head that has very little tapering between the tip and the shaft. These tap drill bits can create a fully threaded hole through metal where the hole does NOT exit the metal. An example of this is furniture whose legs must be attached to a platform or base. This type of bit is best used by a machine operator who uses a tapered bit to begin the threading process. The flat head of the bottoming tap can't achieve enough purchase in an unthreaded hole.

Both taper and intermediate taps have a tapered tip that is wider than the bottoming tap. Tap drill bits are most common. The intermediate tap is the most popular. These two types of bits have a tapered cutting edge that is designed to aid in alignment of the threads and the tap of unthreaded holes. The taper bit has a gradual tapering, which makes it more suitable to work with heavier materials such as steel alloy.