workshoptools/files

Files are often sold without handles, but they shouldn’t be used until a handle of the right size has been fitted. The handle should be checked before use. It can come loose, and it may need a sharp rap to tighten it up.

Clean hands will help avoid slipping. Hands should always be kept away from the surface of the file and the metal that’s being worked on. Filing can produce small slivers of metal which can be difficult to remove from a finger or hand, and acids and moisture from the skin can cause corrosion.

Depending on how hard or soft a material is, a special file may be needed. It’s no good trying to file something if the file is softer than what is being filed - softer metals like copper and aluminum can clog a conventional file.

What makes one file different from another is not just it's shape but how much material it’s designed to remove with each stroke. That depends on the teeth. The following are both flat files, the most common general purpose type, but their teeth are different.

The teeth on this coarse grade file (left) are longer, with a greater space between them. Filing this piece of mild steel removes a lot of material with each stroke. A coarse file leaves a rough finish.

On the right is a flat file, but its shorter teeth remove much less material on each stroke, and the finish is much smoother.

On a job, the coarse file is used first to remove material quickly, then a smoother file gently removes the last of it and leaves a clean finish to the work.

The full list of grades in flat files, from rough to smooth, is:

• rough
• coarse bastard
• second cut
• smooth, and
• dead smooth

Some flat files are available with one smooth edge, called safe edge files. They allow filing up to an edge without damaging it. Flat files are fine on straightforward jobs but files need to be able to work in some awkward spots as well.

A warding file is thinner than normal, for working in narrow slots.	A square file has teeth on all 4 sides, so you can use it in a square or rectangular hole.
A square file can make the right shape for a squared metal key to fit in a slot. This is a three square file. It's triangular in section, so it can get into internal corners.	Curved files are either half-round, or round. This is a half round. Its shallow convex surface can file in a concave hollow, or in an acute internal corner. The fully round file, sometimes called a rat-tail file, can make holes bigger. Or it can file inside a concave surface with a tight radius.
Files should be cleaned after use. If they’re clogged, they can be cleaned by a tool that's really part of the family called a filecard or filebrush. This is a thread file. It cleans clogged or distorted threads. It has 8 different surfaces that match different thread dimensions so the right face must be used.