Fig. 2245.
Fig. 2246.
Fig. 2247.
In using a half-round file to cross file it should at each stroke be swept first from right to left, and after a few strokes from left to right, so that the file marks appear first as in [Fig. 2245], running somewhat diagonal from right to left, and then, when the side sweep of the file is reversed in direction, the file marks will cross after the manner shown exaggerated in [Fig. 2247]. Unless this is done, the curve will be apt to have a wave in it as in [Fig. 2246], or in large curves there may be several waves, and the same thing may occur if the direction of side sweep is not reversed sufficiently often. The file should also be partly swept around the curve, so that if at the beginning of a stroke it meets the work at the upper position in [Fig. 2247], then at the end of the stroke it should be as at the lower one, which will also prevent the formation of waves. The larger the curve the less the amount of this sweep can be, the operator giving as much as convenient for the size of curve being filed.
In draw-filing the file should be slightly rotated, so that if at the beginning of a stroke it stands as at a, [Fig. 2247], at the end of that stroke it should stand as at position b, and it should at the same time be given sufficient end motion, so as to cause the file marks to cross as shown.