56 Welding Print Reading Copyright Goodheart-Willcox Co., Inc. May not be reproduced or posted to a publicly accessible website. An additional or auxiliary view is used to show the true shape and size of the angular surface, Figure 5-10. Because of the extensive use of angled surfaces, sheet metal and press-break drawings often use auxiliary views. The auxiliary view is always projected at right angles (90°) from the principal view on which the angular surface appears as a line. Quite often with aux- iliary views, it is possible to eliminate one of the prin- cipal views, as in Figure 5-11. To avoid confusion and unnecessary sections of the part, some auxiliary views are drawn as partial auxiliary views. Only the angular surface is shown in the auxiliary view, and break lines indicate where part of the view was removed. Sectional Views When an object is relatively simple in design, its shape can be described on a drawing without dif- ficulty, Figure 5-12. For a complex object with many features obscured from view, however, it is often not easy to show its internal structure without a “jumble” of hidden lines, Figure 5-13. The draw- ing is hard to understand and interpret. Figure 5-8. A block with ISO symbols is normally on a print to identify the angle of projection. THIRD ANGLE PROJECTION FIRST ANGLE PROJECTION Figure 5-9. The regular top, front, and side views do not show true shape and size of angular or slanted surfaces. True width of angular surface but not true length True length of angular surface but no width given True width but not true length Figure 5-10. Dimensions of an angular surface are given by an auxiliary view. 1 4 3 2 2 1 3 4 2 1 3 4 1-2 3-4 90° Direction of sight Auxiliary view