Fig. 1593. Fig. 1594.
This is mainly important when the tool is required to carry a deep vertical cut, in which case it is important to keep the tool point as close in to the holder as possible so that it may not bend and spring from the pressure of the cut.
The tool or holder may be held still closer to the edge of the head, and therefore brought still closer to the work, when the apron embraces the outside of the tool box, as was shown in [Fig. 1585], and referred to in connection therewith.
Fig. 1595.
Fig. 1596.
A sectional side view and a top view of [Fig. 1588] through the centre of the head is given in [Figs. 1595] and [1596], exposing the mechanism for the self-acting feed traverse, and for the vertical feed. For the feed traverse the feed screw (m, [Fig. 1588]) passes through the feed nut n. For the vertical feed the feed rod (n, [Fig. 1588]) drives a pair of bevel-gears at p, which drives a second pair at q, one of which is fast on a spindle which passes through the vertical feed screw, and is secured thereto by the set screw e. The object of this arrangement is that if the self-acting vertical feed should be in action and the tool or swing frame s′ should meet any undue obstruction, the set screw e will slip and the feed would stop, thus preventing any breakage to the gears at p or q. The feed screw is threaded into the top of s′. At e is the pin on which the tool box pivots to swing it at an angle.