What tool is specifically used for cutting new external threads?

The tool specifically designed for cutting new external threads is the thread die. A thread die is a cylindrical tool that has internal teeth which are shaped to match the profile of the desired thread. When a die is turned onto a rod or a bar of material, it cuts the material to create new threads on the outside, which can then accommodate nuts or fittings that have matching internal threads.

In contrast, a thread tap is used for cutting internal threads within a pre-drilled hole, creating threads inside materials such as metal or plastic. A pipe wrench is designed for grip and turning pipes or fittings rather than cutting threads, while a saw is meant for cutting through materials without threading capabilities. Thus, the thread die stands out as the correct tool for creating external threads.