Thread Repair Tap EG - STI (for UNC Springs - American)

Tap taps are precision cutting tools used to create an internal thread in a hole (e.g. in nuts or holes in metal). This process is called tapping and requires the use of a special tap wrench or machine (drill/CNC).

• Main Categories:Hand (3-piece set): Consists of the taper (conical), the intermediate and the bottoming tap. They are used sequentially to distribute the cutting load and ensure perpendicularity.Machine: Designed for a single pass. They are divided into Spiral Point (push the chip forward - for through holes) and Spiral Flute (pull the chip out - for blind holes).
• Materials & Coatings: Usually made from HSS or HSS-E (Cobalt) for higher resistance to heat. They often have a TiN (gold color) coating to reduce friction.
• Important Rule: Before use, the appropriate hole must be drilled. The general formula for metric threads is:$D_{hole} = D_{nominal} - P$(Where $D$ is the diameter and $P$ is the thread pitch).