Metalwork - Bench Tools - Files
Most files are made from high carbon steel where the Length has been hardened and tempered, but the Tang has been left soft. Files are manufactured in a variety of shapes and sizes. They are known either by their cross-section, the general shape, or by their particular use. Which file you use is dependent on the type of work you are doing and the material you are using. Files are used to square ends, file rounded corners, remove burrs from metal, straighten uneven edges, file holes and slots, smooth rough edges, etc. Files have three distinguishing features, and are classified by these features:
You can discover more about these features below.
Files are usually made in two types of cuts, Single Cut and Double Cut. The Single Cut File has a single row of teeth extending across the face at an angle of 65° to 85° for the length of the file. The Double Cut File has two rows of teeth which cross each other. For general work, the angle of the first row is 40° to 45°, and the angle of the second row can be anywhere between 30° and 87°.
Files are also classified by the coarseness of the teeth. The bigger the teeth the rougher the feel of the File, and the quicker the File will remove material when you are using it. There are four main levels of coarseness that you may come across in the metalwork room and they are :
You should be familiar with the Rough and Smooth Files. If you cannot tell by looking at the File which it is, then just rub your finger gently along it and you should figure it out.
There are many different types of Files, some of which you will be famliar with. Below you can see a table containing the more common Files, their shape and their main uses.
Needle Files are slender files which are about 18cm in length. They come in a wide variety of shapes, (whihc you can see below). They do not have a Tang but their handle is knurled for grip. Needle Files are used on very small work, very accurate angle finishing and in model work.
There are several precautions that any good craftsman will take in caring for his files :
Particles of metal collect between the teeth of a file and besides the possibility that they may make deep scratches in the material being filed, they also reduce the efficiency of the file. When these particles of metal are lodged too firmly between the teeth and cannot be removed by tapping the edge of the file, remove them with a File Card or Wire Brush. Draw the brush across the file so that the bristles pass between the teeth. If you don't have a File Card or a Wire Brush handy, you could also get a scrap piece of sheet copper or brass and rub it across the file as you would a File Card.
Before attempting to use a file, make sure their is an undamaged handle on the tang of the file. This is essential for proper guiding and safe use. In order to Crossfile, (the usual method of filing), grasp the handle so that its end fits into and against the fleshy part of your palm with the thumb lying along the top of the handle in a lengthwise direction. Grasp the end of the file between the thumb and first two fingers. To prevent undue wear to the file, remove the pressure during the return stroke.
A file is sometimes used by grasping it at each end, crosswise to the work, (as you can see below), then moving it lengthwise with the work. When done properly, work can be finished much smoother cross-filing with the same file. You can use this method of filing to remove slight scratch marks left by cross-filing. To get a very smooth finish, apply some water or oil, depending on the material you are filing, to the work and continue to drawfile.
There are two types of curves that you may have to file smooth. With an internal curve, (which you can see below on the left), you should move the fie across the work while at the same time moving along the curve. As you are moveing the file along the curve change the angle of the file as you see in the diagram. For an external curve, (as in the diagram on the right), run the file along the curve while at the same time "rocking" the file so that the point of the file rises as you move forward.