Auxiliary Drawings(Text Chapter 11)

UAA ES A103Week #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 Lengthof 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.