Figs. 273, 274, 275.
Fig. 276.
It is necessary to be able to adjust the piece to be cut, as regards its height, above the lathe bed. This is effected in part by the position of the movable shelf—fixed by pins—and partly by guide or set screws, which regulate the traverse of the slides. Suppose the bar adjusted as in [Fig. 276], the groove to be cut being brought opposite to the drill. The set screws—two of which are seen at x, x, [Fig. 275]—acting on the handle, regulate the precise length of each groove. A similar stop, connected with the horizontal part of the machine, regulates the advance of the wood towards the drill, and thus the depth of the cut. Hence it is only necessary to set these carefully at starting—the pins on the guide plate insuring the proper width between the grooves—and the lathe being put in motion, any number of precisely similar grooves can be drilled with the utmost rapidity and neatness.
An inspection of the drawings will show what numberless purposes may be served by this simple apparatus, which may be modified in its details, while its principle of action is maintained. The drill should have a chisel and be kept to a keen edge. The lathe should be put in rapid motion, and if the required cut is to be deep, it should be cut at twice. The lower slide should return to its place by means of a spring when the foot is raised, the vertical slide being movable in both directions by means of the slotted part of the handle.
Note.—The above being taken from an apparatus for a steam lathe, the stirrup action maybe used, as the foot is at liberty. A foot lathe would require a slight modification. In [Fig. 275], the depressing handle is shown as if the chamfered bars were fixed to the sole plate, and the plate A, were movable, as is sometimes the case. When made according to the above description, the handle would, of course, be pinned to the fixed vertical plate, A, to which also the stops would be attached, and the pin which passes through the slot of the handle, must project from one of the chamfered bars. Either plan may be followed, but the pattern described is calculated for a stronger apparatus; inasmuch as the vertical plate can be secured more firmly to the chamfered horizontal slide than the mere pair of guide bars—the two might, in fact, be made in one casting, if preferred.