Files are classified according to shape, cut and length. The cross-sectional shape of a file may be circular, rectangular, triangular, diamond-shaped or a combination of flats and rounds.
- The mill file has straight edges and a series of tiny parallel teeth. It's good for sharpening and smoothing surfaces as well as for straight filing and draw filing.
- The double-cut file is used for faster cutting and when a rougher finish is acceptable. On this file, a second, opposing row of diagonal teeth is cut over the first row. The first row of teeth is called the overcut; the second row is called the upcut .
- The rasp has teeth that form individual points rather than lines. This reduces clogging and makes for fast work but a rough finished surface. The rasp can be used to trim almost any material, including metal.
- The combination file is a four-in-one tool. The 8" long file has both round and flat surfaces, and each side of the file has a double-cut and a rasp-cut end. The top of the file is curved for working on corners.
- The round file is the standard file for cleaning up or enlarging holes and shaping tight internal curves. It may be used on metal or wood.
To remove debris from a file, brush it in one direction across the bristles of a file-card brush.