PRIN. OF DRAFTING AND SHOP DRAWINGS - OD1641 - LESSON 1/TASK 1
studying each view, try to imagine or visualize the appearance of the object.
Figure 1 on page 2 indicates how the views are pulled from the object.
c. Auxiliary Views. Objects having inclined faces, or other features that are not
parallel to any of the three principal planes of projection, require auxiliary
views to show the true shape of such features. The auxiliary view is arranged as
though the auxiliary planes were revolved into the plane of the paper by
considering it hinged to the plane with which it is perpendicular (figure 3).
FIGURE 3.
AUXILIARY VIEWS.
d. Principal Plane Line. Drawings are divided into zones. Each zone contains one
orthographic view, together with all information pertinent to that view. The zones
are separated by crossed (90,) construction lines called principal plane lines
which are similar to a mathematical coordinate system.
They are omitted on
finished drawings, but their presence is understood.
Principal plane lines are
defined in figure 4 (on the following page).
Figure 5 (on the following page)
shows how principal plane lines were initially developed.
4
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