Microsoft Word - lecnote_fm_engineering drawing

Figure 7.13 Oblique lines

In order to solve for true length of an oblique line, an auxiliary
view with a line of sight perpendicular to a view of the oblique
line must be projected from any existing view. The fold line
between these two views will be parallel to the oblique line.

Line 1-2 is an oblique line since it is not parallel to any
principal planes of projection and appears foreshortened in
every view. In order to locate an oblique in space, dimensions
must be taken from fold lines and projection lines extended
from an existing view. Dimension D1 and D2 locate the end
points of line 1-2 from the H/F and F/P fold line and represent
the distance line1-2 behind the frontal plane.