Which tool is specifically designed to cut internal threads?

The tool designed specifically to cut internal threads is the tap. Taps are precision tools that create threaded holes by cutting into the material, allowing for screws or bolts to be inserted into these internally threaded holes securely. This process is essential in mechanical engineering and fabrication because it forms the basis for connecting components in structures and machinery.

Drills are used primarily to create holes but do not form threads; they just remove material to create a circular opening. Reamers are used to refine and finish existing holes to achieve a precise diameter, but they do not cut threads. Countersinks are designed to create a conical hole that allows the head of a screw to sit flush with the surface but also do not cut threads. Thus, the tap is the specialized tool for creating the internal threads needed for fastening applications.