Which tool is specifically utilized to machine keyways in shafts or bores?

The tool specifically utilized to machine keyways in shafts or bores is a broach. Broaching is a machining process that removes material by using a toothed tool known as a broach, which can effectively create a keyway, a groove used for transferring torque between the shaft and the component mounted on it.

In this context, broaching is advantageous because it allows for precise control of the dimensions of the keyway, resulting in a smooth finish and accurate geometry. The tool designs, including straight and tapered broaches, facilitate machining keyways in various sizes and shapes, making it highly effective for this specific application.

In contrast, while a mill can also machine keyways by using milling cutters, it is typically less efficient for this specific purpose compared to a broach, especially for creating deeper or more intricate keyways. A lathe is mainly designed for turning operations and is not suited for shaping keyways directly. Lastly, a drill is used for making round holes and does not accommodate the specific dimensional requirements of keyways.