Fig. 485.
It is obvious that when work is turned by hand tools, the parallelism of the work depends upon the amount of metal cut off at every part of its length, which to obtain work of straight outline, whether parallel or taper, involves a great deal of testing and considerable skill, and to obviate these disadvantages various methods of carrying and accurately guiding tools are employed. The simplest of these methods is by means of a slide rest, such as shown in [Fig. 485].
The tool t is carried in the tool post p, being secured therein by the set screw shown, which at the same time locks the tool post to the upper slider. This upper slider fits closely to the cross slide, and has a nut projecting down into the slot shown in the same, and enveloping the cross feed screw, whose handle is shown at c, so that operating c traverses the upper slider on the cross slide and regulates the depth to which the tool enters the work, or in other words, the depth of cut.
The cross slide is formed on the top of the lower slider, which has beneath a nut for the feed screw, whose handle is shown at a, hence rotating a will cause the lower slider to traverse along the lower slide and carry the tool along the work to its cut. To maintain the fit of the sliders to the slides a slip of metal is inserted, as at e and at c, and these are set up by screws as at f, f and b, b.
The lower or feed traverse slide is pivoted to its base b, so that it may be swung horizontally upon the same, and is provided with means to secure it in its adjusted position, which is necessary to enable it to turn taper as well as parallel work. To set this lower slide to a given degree of angle it may be marked with a line and the edge of base b may be divided into degrees as shown at d.
Fig. 486.
