When an object is shown in true projection, it is drawn in all views as it actually appears. However, in some cases, one view of the object may be shown as it does not actually appear. For example, in a revolved view, a portion of the object is rotated in order to obtain a straight axis, Figure 7.14(b). In this position, the true shape of the object can be determined. This is done to give a more complete description of the object and to make the drawing easier to read. Although this is considered a violation of true projection, it is nevertheless preferred as shown in Figure 7.14.
FIGURE 7.12 ■ Developed views of sections required for the fabrication of an elbow.
(a) TRUE PROJECTION
FIGURE 7.14(a, b) ■ Revolved projection.
NOTE: In Figure 7.14(a), there is considerable detail shown where the angle iron and the small pipe join the larger pipe. Also, the hole in the angle iron is not shown in its true shape. In Figure 7.14(b), there is much less detail where the parts are joined and the hole is shown in its true shape, thus simplifying interpretation of the lower view.