Line Conventions, Continued
Viewing or
cutting plane
lines
To give a clearer view of obscure or oblique planes and interior or hidden
features of an object that cannot be clearly observed in a conventional outside
view, use viewing or cutting plane lines respectively. Viewing or cutting
plane lines are the thickest of all lines. Viewing or cutting plane lines are
solid lines. Only when the cutting plane line is offset does the line appear as
thick, short dashes.
VIEWING PLANE LINES: Viewing plane lines indicate the plane or planes
from which a surface or several surfaces are viewed.
CUTTING PLANE LINES: Cutting plane lines indicate a plane or planes
exposed by cutting and removing an imaginary section of the object. The
exposed plane is called the sectional view and the line used to cut the object
is referred to as the cutting plane line. Hidden lines behind the plane of
projection are customarily omitted, while lines visible behind the plane of
projection must be included in the sectional view.
Figure 3-21 illustrates a cutting plane line.
Figure 3-21.—Viewing and cutting plane lines.
Continued on next page
3-23
