Manual of Engineering Drawing, 3rd Edition

Chapter 4. Principles of first and third angle orthographic projection

First angle projection

Assume that a small block is made 35 mm × 30 mm × 20 mm and that two of the corners are cut away as shown below in three stages (Fig. 4.1).

Fig. 4.1

Figure 4.2 illustrates a pictorial view of the block and this has been arranged in an arbitrary way because none of the faces are more important than the others. In order to describe the orthographic views, we need to select a principal view and in this case we have chosen the view in direction of arrow A to be the view from the front.

Fig. 4.2

The five arrows point to different surfaces of the block ...