Engineering Graphics, Class 9Auxiliary Views

Mechanical Engineering Department

Auxiliary Views

Inclined planes and oblique lines do not appear true length or true size in any of the principle planes of projection

To determine the true length of an oblique line or the true size of an inclined plane, an auxiliary view must be created.

Auxiliary Views

The base of the design for the bearing is shown in its true size, but the rounded upper portion is situated at an angle with the planes of projection and does not appear in its true size and shape in any of the three regular views

To show the true circular shapes, it is necessary to assume a direction of sight perpendicular to the planes of those curves. The resulting view is know as an auxiliary view

Definitions

Any view obtained by a projection on a plane other than the horizontal, frontal, and profile projection planes is an auxiliary view

A primary auxiliary view is projected onto a plane that is perpendicular to one of the principal planes of projection and is inclined to the other two

A secondary auxiliary view is projected from a primary auxiliary view into a plane that is inclined to all three principal projection planes.

The Auxiliary Plane

In the figure below, the object has an inclined surface that does not appear in its true size and shape in any regular view. The auxiliary plane is assumed parallel to the inclined surface P

The auxiliary plane is then perpendicular to the frontal plane of projection and is hinged to it. The inclined surface is shown in its true size & shape in the auxiliary view. The long dimension of the surface is projected directly from the front view and the depth from the top view

Depth Auxiliary Views

Auxiliary views are classified and named according to the principal dimensions of the object shown in the auxiliary view.

In depth auxiliary views the depth of the object is shown as a principal dimension. The depth is shown in all views that are projected from the front view

An infinite number of depth auxiliary views can be shown.

Depth Auxiliary Views

In the depth auxiliary views shown, the arrows indicate the directions of sight for the several views, and the projection lines are respectively parallel to these arrows. Actually, the projection lines determine the direction of sight, hence the arrows may not be needed.

Depth Auxiliary Views

Any one of these five plane is an auxiliary plane The principal dimensions shown in an auxiliary view is the one not shown in the adjacent view from which the auxiliary view was projected

Height Auxiliary Views

An infinite number of auxiliary views can be assumed perpendicular to , and hinged to, the horizontal plane of projection. These views show the principal dimension, height, therefore all the auxiliary views are height auxiliary views

Note that in the view projected from, which is the top view , the only dimensions not shown is height

Width Auxiliary Views

Also, an infinite number of auxiliary views can be assumed perpendicular to , and hinged to, the profile plane of projection. These views shows the principal dimension, width, therefore all the auxiliary views are width auxiliary views

Note that in the right-side view from, which the auxiliary views are projected, the only dimensions not shown is width

Uses of auxiliary views

Generally, auxiliary views are used to show the true shape or true angle of features that appear distorted in the regular views

Basically, auxiliary views have the following four uses:True length of linePoint view of lineEdge view of planeTrue size of plane

Hidden lines in auxiliary views

In practice, hidden lines should be omitted in auxiliary views, unless they are needed for clearness

The beginner, however, should show all hidden lines, especially if the auxiliary view of the entire object is shown.

Drawing Simplification by Auxiliary Views

The use of auxiliary view often makes it possible to omit one or more regular views and thus to simplify the shape description.

Partial Auxiliary Views

Three complete auxiliary view drawings are shown. To make such drawings takes a great deal of time, particularly when ellipses are involved.

The completeness of detail may add nothing to clearness or may even detract from it because of the clutter of lines. However, in these cases, some portion of every view is needed - no view can be completely eliminated.

Partial Auxiliary Views

Partial views are often sufficient, and the resulting drawings are considerably simplified and easier to read.

Partial regular views and partial auxiliary views are used with the same result.

Usually a break line is used to indicate the imaginary break in the views.

Partial Auxiliary Views

To clarify the relationship of views, the auxiliary views should be connected to the views from which are projected, either with a center line or with one or two projection lines.

This is particularly important for partial views, which are often small and appear to be “lost” and not related to any view

Half Auxiliary Views

If an auxiliary view is symmetrical, and it is necessary to save space on the drawing or to save time in drafting, only half of the auxiliary view may be drawn