What tool is generally used to set a divider to an exact dimension?

The tool that is generally used to set a divider to an exact dimension is the machinist scale. A machinist scale consists of graduated measurements that allow for precise adjustments and can aid in marking or measuring specific dimensions accurately. It often features different units of measurement, such as inches and millimeters, making it versatile for various tasks in machining and fabrication.

In contrast, while calipers are designed for measuring internal and external dimensions as well as depths, they typically do not serve the same purpose as a machinist scale for setting dividers to a specified distance. A protractor is primarily used for measuring or drawing angles, and a ruler, although useful for linear measurements, may not provide the level of precision needed when setting a divider for detailed work. The specific design and functionality of a machinist scale make it the ideal tool for ensuring exact dimensions when working with dividers.