Internal threads are cut with which tool?

• A. Lathe
• B. Saw
• C. Die
• D. Tap

Answer: (D)

Internal threads are created with a tap. A tap is a cutting tool designed to form the inside surface of a hole by removing material as you turn it, producing the helical thread profile inside the hole. The other tools don’t create internal threads: a die cuts external threads on rods, a saw isn’t used for threading, and a lathe typically cuts threads on a workpiece but the standard way to make internal threads in a drilled hole is tapping with a tap (hand tapping with a tap wrench or machine tapping). When tapping, you drill the hole to the correct tap drill size, apply cutting oil, and gradually advance the tap to the full depth.