Both the single-cut and the double-cut files vary as to coarseness. The most widely sold models are the grades referred to as bastard-cut. For use on wood, leather, lead and other soft materials, rasp-cut files (usually called wood rasps) are also available. They have individually shaped teeth and give a rough cut which removes stock rapidly. Home handymen will find them useful for shaping and smoothing lumber, as well as for trimming joints to a snug fit. Like the metal files, these wood rasps also come in various degrees of coarseness.
In addition to the type of cut, files vary in cross section and shape. The most frequently used shapes are rectangular (flat files or mill files), square, round or triangular. Each comes in various lengths, and as the files increase in length, they also become larger in cross section. They may be either tapered (narrower at one end) or blunt (uniform in thickness from end to end) .
The home handyman will find that two rectangular (flat) files will handle most of his metal-smoothing and sharpening jobs : an 8- or 10-inch mill file (these are single-cut) and a flat bastard file (these are double-cut) of about the same length. The mill file will be used for sharpening tools and for final smoothing of hard metals, while the double-cut bastard file will be used for all-around heavy work when large amounts of metal must be removed.