Fig. 1589.
[Figs. 1588] and [1589] represent the sliding head of the large planer at the Washington Navy Yard, the sectional view, [Fig. 1589], being taken on the line x x in [Fig. 1588]. c is the cross bar and s the saddle, f being the swing frame or fiddle, as some term it, and s′ the vertical slider; b is the tool box, and a the apron.
The wear of the cross slider is taken up by the set screws a, and that of the vertical slide by the screws b.
Fig. 1590.
The graduations of the degrees of a circle for setting over the swing frame f, as is necessary when planing surfaces that are at an angle to the bed and to the cross slide, are marked on the face of the saddle, and the pointer (f, [Fig. 1578]) is fastened to the edge of the swing frame. When the swing frame is vertical the pointer is at 90° on the graduated arc, which accords with English practice generally. In American practice, however, it is customary to mark the graduations on the edge of the swing frame as in [Fig. 1590], so that the pointer stands at the zero point o when the swing frame is vertical, and the graduations are marked on the edge of the swing frame as shown, the zero line o being marked on the edge of the saddle.
In the English practice the swing frame is supposed to stand in its neutral or zero position when it is vertical, and all angles are assumed to be measured from this vertical zero line, so that if the index point be set to such figure upon the graduated arc as the angle of the work is to be to a vertical line, correct results will be obtained.
