76 Print Reading for Industry
In educational settings, the front, top, and
right side views are typically used to describe an
object. This type of drawing can be referred to as a
three-view drawing. Yet, many objects made of flat
sheet metal require only one view, while cylindrical
objects may only require two views. The following
rules will help in the selection of views.
Only views clearly describing the shape of
the object should be drawn.
Select views containing the fewest hidden
lines. For reference, compare the two side
views in Figure 5-3.
If practical, draw the object in its functioning
(operating) position.
If practical, draw the view best describing
the shape of the object as the front view.
Dimensions of an Object
One of the keys to reading a multiview drawing
is familiarity with the terminology used for the
dimensions of an object. It is critical to discuss the
scientific explanation of projections using standard
terms. As you have probably noticed, each projected
view is two dimensional, even though the object is
three dimensional.
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Throughout the field of drafting, three terms
predominantly used for the three dimensions of an
object are height, width, and depth. The height and
width of the object are shown in the front view, but
not the depth. The width and depth of the object
are shown in the top view, but not the height. The
height and depth of an object are shown in a side
view, but not the width.
Height is defined as the top-to-bottom
measurement for an object, as you look at the front
view. Remember, the front of the object is not always
selected as the front view! Width is defined as the
left-to-right measurement of an object, as you look at
the front view. Depth is defined as the front-to-back
distance of the object, as based on the orientation
of the object for the views. Standardizing the terms
used for the measurements is critical to studying
print reading and for completing the exercises in
this unit.
Visualization of Objects
Another necessary step on the road to successful
print reading is understanding how views are
created by projection. You will examine how flat, or
planar, surfaces are oriented in space and how they
appear in a multiview drawing. At this stage, three
Front
Top
Right
side
Top
Right
side
Front
Figure 5-4.
Looking at a three-dimensional object, you must be able to see the orthographic views of the object.