What is the tool used to create internal threads?

• A. Die
• B. Reamer
• C. Tap
• D. Chaser

Answer: (C)

A tap is the tool used to create internal threads because it is designed to cut threads inside a hole. When you insert a tap and turn it, the coaxial cutting flutes remove material as they progress, forming the screw threads that a mating bolt or screw will follow. Different taps are used in sequence: a taper tap to start the threads, then a plug tap to continue, and sometimes a bottoming tap to reach the full depth. Lubrication helps the tap cut smoothly and reduces breakage.

A die, by contrast, forms external threads on rods or bolts, not inside holes. A reamer is used to size and smooth a drilled hole but does not cut threads. A thread chaser is for cleaning and lightly repairing threads that already exist, rather than creating new ones from scratch.