What does a sine plate do in machining?

A sine plate is a precision tool used in machining and fabrication to set specific angles for cutting, which is why the chosen answer is correct. The sine plate is designed to provide accurate angular adjustments and definitions based on the sine principle. By positioning the workpiece at a desired angle, the sine plate allows machinists to set up their processes for cutting, grinding, or milling angled features with high precision.

The sine plate can be used in combination with measuring tools, such as sine bars or protractors, to achieve the required angle setup. This capability is vital in producing parts that require precise angular features, which are common in many engineering applications.

While measuring angles, indicating level surfaces, and aligning parts are important aspects of machining, the sine plate's primary function centers around setting those angles for cutting operations, making it an essential tool when precise angles are necessary.