Taps are used to create a metric coarse thread in a variety of metals, with three types available - Taper, Second and Plug. A taper tap has pronounced taper to the cutter allow for the gradual forming of the thread, which is useful when dealing with tough material such as alloy steel or the hole is a small diameter and the tap is liable to break. Second taps have less of a taper and can be used to start and form the thread, these are the most popular type of tap. A plug tap has very little taper and is used to form the thread to the bottom of a blind hole. The hole will have previously been partially tapped with a taper or second tap. Always use a cutting lubricant when tapping.
