These are straight flute general purpose taps that can be used by machine or by hand or as drill bits. They are generally the most cost-effective tool for use on production runs, but they work best on materials that produce chips or swarf that break easily. Other types of taps, especially coarse threads, may be required when tapping deep holes in materials that produce stringy swarf.
Taper taps: At 5 degrees per side, TAPER TAPS have a lead of 7–10 threads. The cutting force is dispersed over a wide area by the taper lead, and the thread starts more easily thanks to the taper shape. As a result, they can be utilised for through holes, to begin a thread before the use of second or bottom leads.
Second Taps: At 8 degrees per side, SECOND TAPS have a lead of 3-5 threads. They are the most common and can be used for through or blind holes where the thread does not have to go all the way to the bottom.
Bottom taps: BOTTOM TAPS have a chamfer (lead) of 1-2 threads, with an angle of about 18 degrees per side. They’re used to make threads near the bottom of blind holes.