Line Conventions, Continued
Extension lines
Extension lines are thin lines that extend from the object outline or point on
the object to a place outside the image area. Extension lines define areas for
dimensions. You should leave a 1/16" gap between the object outline or
point on the object and the beginning of the extension line.
Extension lines
project 1/8" beyond the outermost dimension line. Extension and dimension
lines are drawn at right angles to each other.
Figure 3-12 shows extension and dimension lines.
Figure 3-12.—Extension and dimension
lines.
When extension lines must cross each other or object outlines, break the
extension lines.
Figure 3-13 illustrates the correct and incorrect use of extension lines.
Figure 3-13.—Extension lines drawn correctly and
incorrectly.
Continued on next page
3-17
