File (tool) - Types

Types

Files come in a wide variety of materials, sizes, shapes, cuts, and tooth configurations. The cross-section of a file can be flat, round, half-round, triangular, square, knife edge or of a more specialized shape. There is no unitary international standard for file nomenclature; however, there are many generally accepted names for certain kinds of files.

The cut of the file refers to how fine its teeth are. They are defined as (from roughest to smoothest): rough, middle, bastard, second cut, smooth, and dead smooth. A single-cut file has one set of parallel teeth while a cross-cut or double-cut file has a second set of cuts forming diamond teeth. In Swiss-pattern files the teeth are cut at a shallower angle, and are graded by number, with a number 1 file being coarser than a number 2, etc. Most files have teeth on all faces, but some specialty flat files have teeth only on the face or only on the edge, so that the user can come right up to another edge without damaging the finish on it.

Some of the common shapes and their uses:

• Crossing files are half round on two sides with one side having a larger radius than the other. Tapered in width and thickness. For filing interior curved surfaces. The double radius makes possible filing at the junction of two curved surfaces or a straight and curved surface.
• Crochet files are tapered in width and gradually tapered in thickness, with two flats and radiused edges, cut all around. Used in filing junctions between flat and curved surface, and slots with rounded edges.
• Knife files are tapered in width and thickness, but the knife edge has the same thickness the whole length, with the knife edge having an arc to it. Used for slotting or wedging operations.
• Pippin files are tapered in width and thickness, generally of a teardrop cross section and having the edge of a knife file. Used for filing the junction of two curved surfaces and making V-shaped slots.
• Square files are gradually tapered and cut on all four sides. Used for a wide variety of things.
• Three square files, also called triangular files, have a triangular cross-section, which usually gradually tapers. Some files taper all the way to a point (especially small ones). Three square files are used for many cuts, such as cutting angles less than 90 degrees. They are often employed for sharpening the teeth of wood saws.It has been pointed out that there's no such thing as a "three square". Triangular files have 60 degree angles, whereas "square" is 90 degrees. All this is true, but triangular files are nevertheless commonly called "three square". Natural language does not always follow the most apparent logic.
• Round files, also called rat-tail files, are gradually tapered and are used for many tasks that require a round tool, such as enlarging round holes or cutting a scalloped edge.
• Round parallel files are similar to round files, except that they do not taper. Shaped like a toothed cylinder.
• Equalling files are parallel in width and thickness. Used for filing slots and corners.
• Slitting files are parallel in width with a diamond shaped cross section. Thinner than knife files and use for filing slots.
• Nut files are fine, precise files in sets of graduated thickness, used by luthiers for dressing the slots at the end of the neck which support the strings of guitars, violins etc., in the correct position.
• Pillar files are parallel in width and tapered in thickness for perfectly flat filing. Double cut top and bottom with both sides safe, these are long, narrow files for precision work.
• Warding files are parallel in thickness, tapered in width, and thin. Like a hand or flat file that comes to a point on the end. Used for flat work and slotting.
• Dreadnought (curved teeth) and millenicut (straight teeth) files both have heavily undercut, sharp but coarse teeth. Both can be used for rapidly removing large quantities of material from thick aluminum alloy, copper or brass. Today, the millenicut and dreadnought have found a new use in removing plastic filler materials such as two-part epoxies or styrenes such as those commonly used in automobile body repairs.
• Farrier Rasp files are tanged horse rasps used mainly by horseshoers and blacksmiths. They are flat with rasp cut on one side (upstanding teeth arranged in rows with curved cutting edges of generally pyramidal shape and have a cutting face with a positive rake or slope) and a double cut file on the reverse side.

Steel files are made from high carbon steel (1.0 to 1.25% carbon) and may be through hardened or case hardened.