Slotting machines with vertical cutting movement differ from planing machines in several respects, to which attention may be directed. In slotting, the tools are in most cases held rigidly and do not swing from a pivot as in planing machines. The tools are held rigidly for two reasons; because the force of gravity cannot be employed to hold them in position at starting, and because the thrust or strain of cutting falls parallel, and not transverse to the tools as in planing. Another difference between slotting and planing is that the cutting movement is performed by the tools and not by movement of the material. The cutting strains are also different, falling at right angles to the face of the table, in the same direction as the force of gravity, and not parallel to the face of the table, as in planing and [135] shaping machines.

The feed motion in slotting machines, because of the tools being h............