Which tool is best for cutting precise threads on a metal rod?

The lathe is the best tool for cutting precise threads on a metal rod because it is specifically designed for shaping and machining cylindrical objects. When using a lathe, the workpiece is rotated while a cutting tool is applied to it, allowing for accurate and controlled removal of material. This method enables the creation of finely detailed threads that are essential for components that must fit together tightly or require specific dimensional tolerances.

In contrast, a drill is primarily used for making round holes and does not provide the necessary mechanism for producing threads. A band saw, while useful for making straight cuts in materials, lacks the capability to generate threaded features. Similarly, a router is designed for hollowing out an area in the face of a piece of material but is not suited for cutting threads. Together, these characteristics reinforce the lathe as the optimal choice for this specific threading task.