Auxiliary Drawings
(Text Chapter 11)
UAA ES A103
Week #9 Lecture
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Introduction
There are times when the six principal views
will not completely describe an object.
This is especially true when there are
inclined or oblique planes or features on an
object. For these cases, a special
orthographic view called an auxiliary view
can be created.
Additionally, auxiliary views are used to
show an object from an odd angle for any
of a variety of reasons.
Definition
• An auxiliary view is an orthographic view
which is projected onto any plane other
than the frontal, horizontal, or profile
plane.
• An auxiliary view is not one of the six
principal views.
• One of the principle reasons for drawing
auxiliary views is to show a surface at true
size and shape.
The Six Principle Views
• None of the views gives an accurate
depiction of surface ABCD.
Finding the True Shape
• A viewing
plane parallel
to the surface is
required to get
true size and
shape.
Fold Lines
• Fold lines
represent the edges
of the “glass box”
• Orthographic lines
are projected from
adjacent views
across fold lines.
• Object distances
from fold lines are
obtained from
related views.
Reference Planes
• Reference Planes are a
variation on the glass box.
• They appear as edges in
the auxiliary & related
views.
• Lengths perpendicular to
the fold line are measured
relative to the reference
plane
Using Miter Lines to Transfer
Distances between Related Views
• The author does
not cover this,
but it is an easy
way to transfer
dimensions
between related
views.
• We have been
using this in
multi-view
drawing
anyway.
Classification of Views
• Auxiliary views are created by positioning a new
line of sight relative to the object. It is possible to
create any number of auxiliary views, including a
new auxiliary view from an existing auxiliary
view. Therefore, auxiliary views are first
classified as: primary, secondary, or tertiary.
– A primary auxiliary view is a single view projected
from one of the six principal views.
– A secondary auxiliary view is a single view projected
from a primary auxiliary view.
– A tertiary auxiliary view is a single view projected
from a secondary or another tertiary auxiliary view.
More Classifications
• Auxiliary views are also classified by the space
dimension shown in true size in the primary
auxiliary view.
– A depth auxiliary is an auxiliary view projected from
the front view, and the depth dimension is shown true
length.
– A height auxiliary view is an auxiliary view
projected from the top view, and the height dimension
is shown true length.
– A width auxiliary view is an auxiliary view projected
from the profile view, and the width dimension is
shown true length.
Partial & Half Auxiliary Views
• In auxiliary views, it is normal practice not to project
hidden features or other features that are not part of the
inclined surface.
• When only the details for the inclined surface are
projected and drawn in the auxiliary view, the view is
called a partial auxiliary view. A partial auxiliary view
saves time and produces a drawing that is much more
readable. The full auxiliary view is harder to draw, read,
and visualize.
• Symmetrical objects can be represented as a half
auxiliary view, that is, only half of the object is drawn.
Applications of Auxiliary Views
•
•
•
•
•
Reverse Construction
True Length of a Line
Point of View of a Line
Edge View of a Plane
True Size of a Plane
Reverse Construction
• This is
where the
auxiliary
view is
drawn first.
• Note the use
of a
reference
plane
Drawing the True Length
of an Oblique Line
• The oblique line needs to be defined in two
adjacent views.
• The auxiliary view that shows the true
length of the line is perpendicular to the
line in either of the given views.
Point
of
View
of a
Line
• The
auxiliary
view
projected
parallel
to the
true
length
view line
Edge of
a Plane
• Auxiliary
view
projected
parallel to
a true
length
line
True Size
of a Plane
• The auxiliary
view
projected
perpendicular
to the edge
view.
True Angles
• Project so that
root axis line
appears as a
point
• The auxiliary
view in the
direction of
the line
formed by the
intersection of
the two planes.