Chapter 10 Dimensioning
253
to leaders. When grouping dimensions,
try not to extend extension lines for linear
distances more than halfway across any
given view, Figure 10-12. If this is required,
it is probably best to locate or give the
size of the feature along the nearer side
of the object.
4. Dimensions must be complete. No
measuring or scaling of the drawing
should be necessary for manufacturing
the object. It should be possible to
determine sizes and shapes without
assuming any measurements.
view in which the feature is not visible
(in other words, where it is hidden). In
most cases, dimensioning to hidden lines
is not an acceptable practice. Of course,
as with some rules, there are exceptions.
Your instructor will point these out when
appropriate.
2. Unless absolutely necessary, dimensions
should not be placed within the outlines
(outer visible lines) of the views,
Figure 10-9. Instead, extension lines
should be used to extend the profi les
and features of the object to around
the perimeter for the purpose of linear
dimensioning. Centerlines may be
extended and used as extension lines
since they are the same line weight,
Figure 10-10. Dimensioning within the
visible lines of views becomes acceptable
when objects are very complex. However,
the focus of this text is to teach basic
dimensioning. More complex examples
will be part of your future drafting studies.
3. If possible, dimensions should be
grouped together rather than scattered
about the drawing. See Figure 10-11. The
illustration shown is a good example of
grouping linear distances between views
or on two sides of a view. Grouping also
applies to sizes and information attached
Preferred Avoid
Goodheart-Willcox Publisher
Figure 10-9. Dimensions should not be placed within the visible lines of views. They should be placed with
extension lines around the perimeter.
Goodheart-Willcox Publisher
Figure 10-10. Notice how the centerlines are extended
and used as extension lines for dimensioning.
Copyright Goodheart-Willcox Co., Inc.