Orthographic Projections, Continued
In third-angle projection, the plane of projection is always presumed to be
between the object and the observer regardless of which view you are
considering. Each view of the surface of an object is a view of that surface
as it would appear to an observer looking directly at it. You should be able
to determine what each line in a particular view represents.
A multiview projection should contain only as many views required to
describe the object fully. Most objects can be described in two or three
views. One-view drawings are objects that can be completely defined by that
view. Features such as thickness or length is listed as a dimension or note.
Many objects have no definite top or bottom. With objects of this kind,
select a surface and call it according to convenience. When eliminating
views, here are four rules to remember, (1) show an object in the position it
customarily occupies, (2) a top view is preferable to a bottom view, (3) a
right-side view is preferable to a left-side view, and (4) a view with a visible
line is preferable to a view with the same line shown as a hidden line.
Figure 6-29 show a one-view drawing of a washer.
Figure 6-29.A one-view drawing.
Continued on next page