Line Conventions, Continued
Arrowheads
Arrowheads indicate the extent of the dimension. All arrowheads on a
drawing should be uniform in size and style. Arrowheads are usually solid
and are from 1/8" to 1/4" long. Their length is approximately three times
their width. Although many draftsmen recommend using templates to draw
arrowheads, you should be able to draw them freehand. Carelessly drawn
arrowheads make drawings look unfinished and unprofessional.
Figure 3-16 illustrates the proper construction of arrowheads.
Figure 3-16.—Constructing arrowheads.
Leader lines
Notes or dimensions that pertain to surfaces or parts are lead to that surface
or part by leader lines. Leader lines are thin, solid lines that terminate in an
arrowhead or dot. Use arrowheads when leader lines terminate at the outline
of an object. Use dots when leader lines terminate within the outline of the
object or on the surface of the object.
Figure 3-17 shows examples of properly used leader lines.
Figure 3-17.—Leader lines
referring to: A. Dimensions, and B.
Surface finish.
Continued on next page
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