Understanding Auxiliary Views: Generating True Shapes of Inclined Surfaces in 3D Drawing, Slides of Computer Graphics and Animation

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Auxiliary Views

Objective

 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

Auxiliary 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 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

Primary 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 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

Lines

 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 Docsity.com

Lines

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

Secondary Auxiliary Views

 An oblique surface requires a secondary auxiliary view to show the surface in true shape

Secondary 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 Docsity.com

Example: 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

Example: 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

Example: 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 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