Metric & Imperial Taps
Modern Taps come in many different shapes and sizes, The three main types are Taper ( or First ), Second ( or Plug Tap ) and Bottom ( or third tap), All three have a specific task,
- Taper or First tap This small tap is similar to a Second tap but has a more pronounced taper to the cutting edges. This feature gives the taper tap a very gradual cutting action that is less aggressive than that of the plug tap. General use is New threads and cutting threads in soft material.
- Second or Intermediate tap This tap has tapered cutting edges, which assist in aligning and starting the tap into an untapped hole. The number of tapered threads typically ranges from 3 to 5. Plug taps are the most commonly used type of tap they are commonly known in Britain as second taps.
- Bottoming or Plug tap has a continuous cutting edge with almost no taper — between 1 and 1.5 threads of taper is typical. This feature enables a bottoming tap to cut threads to the bottom of a blind hole. A bottoming tap is usually used to cut threads in a hole that has already been partially threaded using one of the more tapered types of the tap; the tapered end ("tap chamfer") of a bottoming tap is too short to successfully start into an unthreaded hole