Metal cutting tools, their principles, action and construction

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1922 Excerpt: ...again has the full amount of clearance. If a cutter were required of an outline as shown in Fig. 154, there would be no clearance at the points A and further to the center because the clearance would be formed by the dotted line which meets the full line at A. However, it is possible to make such a cutter with clearance all around. To do this the form tool is made as shown in Fig. 155, and is placed on the toolslide of the backing-off machine in such a manner that its movement will first be in the direction of the arrow No. 1. After the left side of the cutter has been backed off, the toolslide is changed so as to move in the direction of arrow No. 2. The result will be that clearance will be provided as shown by the dotted line. This method solves the problem of providing clearance at all points but introduces a new problem. If we should imagine the cutter being ground away down to the dotted line, we would again have a cutter of the same general configuration, but not of the same size as the original cutter. The problem, however, is easily solved by making the cutter interlocking. Wherever a complicated cutter has somewhere a straight line in its contour and parallel with the direction of the arbor, this method can be employed. This method, then, could be employed on a convex cutter. On a concave cutter, such as is shown in Fig. 156, we can make it again interlocking, but we would not succeed in getting a perfect half circle. There are many cases where it is of more importance to have some clearance than to have a perfectly correct outline, and this method of giving side clearance and making the cutter interlocking can be used many times to good effect in practice. The beneficial effect of rake on form cutters was mentioned before. This good effect is not...