An object positioned in space may be imagined as surrounded by six mutually perpendicular planes. So, for any object, six different views may be obtained by viewing at it along the six directions, normal to these planes. Figure 3.5 shows an object with six possible directions to obtain the different views which are designated as follows:
1. View in the direction a = view from the front
2. View in the direction b = view from above
3. View in the direction c = view from the left
4. View in the direction d = view from the right
5. View in the direction e = view from below
6. View in the direction f = view from the rear
Figure 3.6a shows the relative positions of the above six views in the first angle projection and Fig.3.6b, the
distinguishing symbol of this method of projection. Figure 3.7 a shows the relative position of the views in the third angle projection and Fig. 3.7b, the distinguishing symbol of this method of projection.
NOTE A comparison of Figs. 3.6 and 3.7 reveals that in both the methods of projection, the views are identical in shape and detail. Only their location with respect to the view from the front is different.
MACHINE DRAWING
Third Edition
Dr.K.I. Narayana
Dr.P. Kannalah
K. Venkata Reddy
NEW AGE INTERNATIONAL (P) LIMITED, PUBLISHERS
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