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Auxiliary ViewsAuxiliary Views
ObjectiveObjective
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
OutlineOutline
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
Auxiliary Vs. Principle ViewsAuxiliary 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
Review: Fold Line MethodReview: 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
Example: Fold Line MethodExample: 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.
Primary Auxiliary ViewPrimary 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
Example: Primary Auxiliary Example: Primary Auxiliary ViewsViews 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
Projection PlanesProjection 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
LinesLines
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
LinesLines
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
SurfacesSurfaces
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
Secondary Auxiliary ViewsSecondary Auxiliary Views An oblique surface
requires a secondary auxiliary view to show the surface in true shape
Secondary Auxiliary ViewsSecondary 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
Example: Secondary Auxiliary Example: Secondary Auxiliary ViewView
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
Example: Secondary Auxiliary Example: Secondary Auxiliary ViewView 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
Example: Secondary Auxiliary Example: Secondary Auxiliary ViewView
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
Example: Secondary Auxiliary Example: Secondary Auxiliary ViewView
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
Example: Secondary Auxiliary ViewExample: 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
Example: Secondary Auxiliary ViewExample: 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
Memorize These Statements Memorize These Statements Before The QuizBefore 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”
Another ExampleAnother 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
ExampleExample
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
Example: Secondary Auxiliary Example: Secondary Auxiliary ViewView 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
Example: Secondary Auxiliary Example: Secondary Auxiliary ViewView
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
Example: Secondary Auxiliary Example: Secondary Auxiliary ViewView
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
Example: Secondary Auxiliary Example: Secondary Auxiliary ViewView 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)
Helpful Visualization ToolsHelpful 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
