Two files may be required by the beginner, an eight inch flat mill file and a three inch three cornered taper saw file.

The mill file (Fig. 149) will be used in sharpening compasses, the gauge spur, and similar work. The saw file (Fig. 150) will be used for filing saws. Files are so shaped that the teeth cut but one way, and therefore they should be pressed against the work only on the forward stroke. When learning to use a file, it is better to lift it entirely from the work on the return stroke. Always hold the file firmly and move it as nearly the entire length as the work will permit. In filing saws or any light, thin material, be very careful to have the work held firmly. For ordinary work the file is moved lengthwise, but sometimes it is moved side-wise, as in sharpening the scraper (Fig. 186).

Fig. 149. Mill File.

Fig. 150. Taper Saw File.