Title: Auxiliary Views
1Auxiliary Views
- Engineering Graphics
- Stephen W. Crown Ph.D.
2Objective
- To understand how to generate views that show
inclined and oblique surfaces in true shape in
multiview drawings - To better understand the manipulation of 3-D
objects using successive 90 degree rotations in
preparation for solid modeling
3Outline
- Definition and Use
- Fold Line Method
- Primary Auxiliary Views
- Review of descriptive geometry
- Example Inclined surface
- Secondary Auxiliary Views
- Example Oblique surface
- Example A surface with no true length lines
4Auxiliary Vs. Principle Views
- Principle planes
- Horizontal (Top and bottom view)
- Frontal (Front and back view)
- Profile (Left and right side view)
- Auxiliary views
- Definition An orthographic view that is
projected into a plane that is not parallel to
any of the principle planes - Purpose To show the true shape of a detail that
does not lie in on of the principle planes
5Review Fold Line Method
- A fold line (hinge) may be placed between
adjacent views to aid in the construction and
interpretation of multiview drawings - Projection lines are always perpendicular to fold
lines - The distance from a fold line to any specific
point on an object is the same for any related
views (ex. top and side view) - Fold lines represent a 90 degree rotation in
viewpoint
6Example Fold Line Method
- Distances from the fold line in View A are equal
to the distance from the fold line in View C - Follow projection lines to keep track of vertices
- Use offset when creating View C from View A B
- Note that the projection lines are always
perpendicular to fold lines.
7Primary Auxiliary View
- Definition Any view that is projected from
(adjacent to) one of the principle views and
which is not parallel to any of the principle
planes - A primary auxiliary view is perpendicular to only
one of the principle planes - Any inclined surface may be shown in true shape
in the appropriate primary auxiliary view - If the fold line for an auxiliary view is
parallel to the edge view of an inclined surface
the inclined surface will appear in true shape in
the auxiliary view
8Example Primary Auxiliary Views
- Use the UCS command to rotate about the Z axis
and align the x axis up with the inclined surface - Project perpendicular projection lines from the
inclined surface (ORTHO) - Determine the depth of each point from related
views (OFFSET) - Use DDOSNAP to quickly select features
9Projection Planes
- A fold line represents the projection plane for
the adjacent view - A line appears true length if it lies in a plane
parallel to the projection plane - A line which is not parallel to the projection
plane appears foreshortened - A line which is perpendicular to the projection
plane appears as a point
10Lines
- A line which is parallel to a fold line will
appear true length in the adjacent view - A true length line which is perpendicular to a
fold line will appear as a point in the adjacent
view - Line 1-3 is parallel to the fold line in the
right side view and true length line in the front
view - Line 1-2 is true length in the right side view
and is a point in the front view
11Lines
- All views adjacent to a point view of a line will
show the line in true length - A line which does not appear true length in any
of the principle views is called an oblique line
12Surfaces
- A Surface appears in true shape (undistorted)
if it is parallel to the projection plane - A surface appears as an edge parallel to the fold
line in all views adjacent to the true shape view
of the surface - If any line on a surface appears as a point then
the surface will appear as an edge - A surface which does not appear as an edge in any
of the principle views is called an oblique
surface
13Secondary Auxiliary Views
- An oblique surface requires a secondary auxiliary
view to show the surface in true shape
14Secondary Auxiliary Views
- Definition A secondary auxiliary view is any
view which is not perpendicular to any of the
principle views - Purpose A secondary auxiliary view is used to
show the true shape of an oblique surface - A secondary auxiliary view is constructed as an
auxiliary view to a primary auxiliary view using
fold lines and perpendicular projectors
15Example Secondary Auxiliary View
- The top view shows the oblique surface
- A secondary auxiliary view is needed to show the
surface in true shape - The lengths of sides and angles are distorted in
all other views - Perpendicular projection lines and reference
planes are used to construct the right side view
from the front and top view
16Example Secondary Auxiliary View
- A true length line on the oblique surface is
identified in the right side view - Placing a fold line which is perpendicular to the
true length line gives the edge view of the
surface - This auxiliary view is a primary auxiliary view
- The edge view of the surface is needed to obtain
the true shape view
17Example Secondary Auxiliary View
- A fold line which is draw parallel to the edge
view of the oblique surface gives the secondary
auxiliary view showing the surface in true shape - Perpendicular projectors are used to determine
the location of vertices - Often only the inclined or oblique surface is
shown in auxiliary views
18Example Secondary Auxiliary View
- Simplify the construction of drawings by starting
with only a portion of the drawing - The right side view is constructed by measuring
along projection lines in the top view - Vertices are numbered to help keep track of
correct distances from reference planes
19Example Secondary Auxiliary View
- A true length line is identified in the right
side view - line 2-4 is parallel to the fold line in the
front view, therefore line 2-4 is a true length
line in the right side view - A fold line perpendicular to the true length line
gives the edge view of the oblique surface
20Example Secondary Auxiliary View
- Use UCS to rotate about the Z axis and align the
X axis with the edge view of the oblique surface - Perpendicular projection lines are constructed
(ORTHO) - The distance along projection lines are measured
in relative views (OFFSET and DDOSNAP) - The secondary auxiliary view shows the oblique
surface in true shape
21Memorize These Statements Before The Quiz
- A fold line that is parallel to a line gives a
view that shows the true length of the line - A fold line that is perpendicular to a true
length line on a surface gives a view that shows
the surface as an edge. - A fold line that is parallel to the edge view of
a surface gives a view that shows the true shape
22Secondary Auxiliary Views(Finding the True
Shape View)
- A fold line that is parallel to a line gives a
view that shows the true length of the line - A fold line that is perpendicular to a true
length line on a surface gives a view that shows
the surface as an edge. - A fold line that is parallel to the edge view of
a surface gives a view that shows the true shape
23Another Example
- The top view and front view of a surface is shown
- Is an auxiliary view needed to show the surface
in true shape? - Yes The surface does not appear as an edge in
either view
24Example
- Construct the right side view using projection
lines and reference planes - Note that there are no true length lines in any
of the principle views
25Example Secondary Auxiliary View
- Since the surface does not appear as an edge in
any of the principle views the surface is oblique
and requires a secondary auxiliary view - A line is drawn on the surface which is parallel
to the fold line between the front and right side
view - This line appears as a true length line in the
right side view
26Example Secondary Auxiliary View
- The true length line is used to get an edge view
of the surface - A fold line perpendicular to the true length line
gives a point view of the line in the adjacent
view - Since the line is on the surface the surface will
appear as an edge
27Example Secondary Auxiliary View
- The secondary auxiliary view gives the true shape
of the surface - The secondary auxiliary view is constructed by
placing a fold line parallel to the edge view of
the surface
28Example Secondary Auxiliary View
- Fold lines are labeled by the name of the
principle plane or the level of auxiliary view - Primary auxiliary view (1)
- Secondary auxiliary view (2)
29Helpful Visualization Tools
- Label surfaces
- Label vertices - List nearest vertex first at
each location (1,2) - Follow construction lines to determine location
- Equal number of sides - A surface with 3 sides
will have three sides in every view - Parallel edges - If lines are parallel in one
view they will be parallel in every view