Which file is typically used for general purpose filing?

A mill file is designed for general-purpose filing and is one of the most commonly used types of files in various applications. It has a flat surface with a single-cut pattern, allowing for efficient removal of material while providing a smooth finish on the workpiece. The teeth on a mill file are spaced evenly, which helps in shaping and finishing metal, wood, and other materials effectively.

In addition, the flat edge allows the user to file edges and surfaces with precision, making it versatile for many tasks in pipe fitting and other trades. Mill files can be used to sharpen tools and prepare surfaces for fitting, which aligns perfectly with the needs of an apprentice in pipe fitting.

Other types of files have more specialized uses; for instance, a half-round file provides both flat and curved surfaces but is less versatile than a mill file. A knife file is useful for fine detail work and in tight spaces, while a rasp file is designed primarily for rapid material removal with its coarse teeth, making it less suitable for situations requiring a fine finish.