Files

Files are hardened tools that allow your to abrasively remove material from a workpiece. There are many different kinds of files, each suited to a specific job, but here we will cover the most common types of files commonly found in the shop or laboratory. Files are commonly used to perform fine sizing on a part, break sharp edges, or even produce odd shaped holes. Making a rectangular hole in a front panel for a switch or panel meter is an ideal example of where files would be used in the construction of laboratory equipment.

Types of Files

There is no standard or uniform rating system for files. They are generally manufactured in various shapes, roughnesses, and cuts. Common shapes for files include flat, round, half-round, triangular, knife edge, and square. The roughness of the file is classified as (from most aggressive to least): rough, middle, bastard, second cut, smooth, and dead smooth. Some Swiss files are number graded for roughness as well with lower numbers being more aggressive. Files can have grooves (teeth) cut in once angled direction (single-cut) or two directions (double-cut). To see all of these types of files explained, watch the video below.

When using a file, be sure to select the correct roughness for the job. Using a fine file of soft metal will load the file teeth with chips and quickly become ineffective and difficult to clean. Using a smooth file for roughing work will take much too long and excessively wear the file, while using a roughing file for finishing work will result in a poor surface finish and is likely to lead to the removal of excessive amounts of material.

Use

Using a file is as simple as firmly holding it from both ends and passing the cutting surface over the material with downward pressure. Do not file with excessive speed (about 1 pass/second is a good rule of thumb). Files should never be used without a handle - the tang of the file can be very dangerous. Before and after each use the file should be cleaned with a file-card and any stuck metal “pins” removed from the teeth. Files should be stored in such a way that their teeth are not scraping against each other and dulling all of the files in the drawer. For demonstrations of file use and care, see the video below.

Safety Precautions

When using a file, always make sure you are firmly gripping it and are not going to injure yourself when the file leaves the workpiece. Files must always be used with a proper handle or serious puncture wounds could result from the tang of the file. Other hazards include abrasions and cuts if the file slips and finds your hand, leg, etc. Always work on a firmly secured workpiece with eye protection.