1. Orthographic Projection
Auxiliary Views

2. Auxiliary View
To accurately view the true dimensions of an inclined surface, one must create a view at 90 degrees from that inclined face. This is referred to as an Auxiliary View. This allows us to view the surface in its true size and shape.

3. Primary Auxiliary View
In order to see a feature in it’s true size and shape,
we must look at it straight on or perpendicular
to the plane in which the feature exists. Note
that in this view (the auxiliary view) the slotted
hole is true size and shape.
To obtain this view the auxiliary must be drawn
from the view that allows the line of sight to be
perpendicular to the desired feature.
Line of sight.
Many times a feature on a part cannot
be seen in true size and shape. When this
is the case we use an auxiliary view.

4. Secondary Auxiliary View
Sometimes you may have a feature that
is oblique in all three views. This type of
feature needs two auxiliaries to obtain
a perpendicular line of sight on that
surface.
We now can view a true length line
and project with a line of sight perpendicular
to the face we would like to see in true
size and shape.
Line of sight.
In the first auxiliary we will try
to obtain a view that is looking at
the end of one line. Once this auxiliary
is projected we then have a true length
line
Line of sight.