Basic Technical Drafting - Auxiliary Views and Revolutions 1
Auxiliary Views and Revolutions -
Sacramento City College
Engineering Design Technology
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Pictorial Drawing
Objects are generally described with three Normal Views (orthographic views):
Front view.
Top view.
Right Side view.
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Pictorial Drawing
As long as the object has surfaces that align with one of the principal planes, the Normal views are sufficient.
Front view.
Top view.
Right Side view.
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Pictorial Drawing
For objects with inclined surfaces, such as the separator, the three Normal Views are not sufficient!
For objects with inclined surfaces, the three Normal Views are:
Hard to draw.
Show the circles as ellipses.
Are hard to understand.
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Auxiliary Views
When an object has an inclined surface, none of the regular views show the inclined part in its true size and shape.
Front
Top
Right Side
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Inclined surface
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Auxiliary Views
ONLY a View on a plane parallel to the inclined surface shows the true size and shape.
An Auxiliary View is used to show the true size and shape of an object that has surfaces that are not parallel to a principal plane.
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Auxiliary Views
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Auxiliary Views
An auxiliary view is a projection on an auxiliary plane that is parallel to an inclined surface.
See Figure 7-3.
Auxiliary views provide a clear, undistorted image of the inclined surface on an object.
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Auxiliary View
The auxiliary view looks directly at the inclined surface in a direction that is perpendicular to the surface.
See Figure 7-4a, 7-4b and 7-4c.
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Figure 7-3a
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Figure 7-3b
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Figure 7-3c
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Figure 7-3d
Hinge
Point
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Figure 7-4a
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Figure 7-4b
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Auxiliary View
Figure 7-4C completely describes the object and only two views are required.
Front view
Auxiliary view
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Figure 7-4c
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Auxiliary Views
Auxiliary views are classified according to which of the three regular planes from which they are developed.
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Auxiliary Views
Three auxiliary views exist
Front View
Top View
Right Side View
Each is developed by projecting as a primary reference the
Height
Width
Depth
obtained from a normal view.
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Figure 7-5a
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Figure 7-5b
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Figure 7-5c
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Auxiliary Views
1. Front Auxiliary View
When an auxiliary view is hinged on the Front View, the view is known as the Front Auxiliary View.
The primary reference of the front auxiliary view is depth.
See Figure 7-6A.
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Figure 7-6a
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Auxiliary Views
2. Top Auxiliary View
When an auxiliary view is hinged on the Top View, the view is known as the Top Auxiliary View.
The primary reference of the top auxiliary view is the height of the object.
See Figure 7-6B.
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Figure 7-6b
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Auxiliary Views
3. Right Side Auxiliary View
When an auxiliary view is hinged on the Right Side View, the view is known as the Right Side Auxiliary View.
The primary reference of the right side auxiliary view is the width of the object.
See Figure 7-6C.
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Figure 7-6c
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Constructing an Auxiliary View
To construct any primary auxiliary view
1. Examine the normal views and look for the view that has the inclined surface.
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Constructing an Auxiliary View
2. Find the view that shows the edge view of the inclined plane.
The plane associated with this view is the reference plane, from which the auxiliary plane will be developed.
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Constructing an Auxiliary View
3. In this view, draw a light construction line at right angles to the inclined surface.
This line is the line of sight.
This line is the “hinge”.
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Constructing an Auxiliary View
4. Think of the auxiliary plane as being attached by hinges to the view from which it is developed.
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Constructing an Auxiliary View
5. From all important points on the reference view, draw projection lines at right angles to the inclined surface.
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Constructing an Auxiliary View
6. Draw a reference line parallel to the edge view of the inclined surface.
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Constructing an Auxiliary View
7. Transfer the depth dimension to the reference line.
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Constructing an Auxiliary View
8. Project the important points and connect them in sequence to form the auxiliary view.
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Auxiliary Views
Symmetrical Objects
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Constructing an Auxiliary View
For symmetrical objects, the center-plane method is used.
Refer to Figure 7-8.
Procedure Steps:
1. Use a center plane as a reference plane.
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Constructing an Auxiliary View
2. Find the edge view of the inclined plane.
In Figure 7-8, the edge view of this plane appears as a centerline, XY, on the top view.
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Constructing an Auxiliary View
3. Label the points on the Top View for reference.
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Constructing an Auxiliary View
4. Transfer these points on the edge view of the inclined surface on the Front View.
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Constructing an Auxiliary View
5. Parallel to this edge view and at a convenient distance from it, draw the line X’ Y’.
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Constructing an Auxiliary View
6. In the Top View, find the distances from the numbered points to the centerline.
These are the depth measurements.
Transfer them onto the corresponding construction lines which you just drew.
Measure them off on either side of line X’ Y’
The result will be a set of points on the construction lines.
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Constructing an Auxiliary View
7. Connect and number the points on the construction lines to finish the Front Auxiliary View of the inclined surface.
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Example:
Figure 7-31
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Assignment:
Figure 7-55
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Revolutions
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Revolutions
When the true size and shape of an inclined surface do not show on a drawing, we can make an auxiliary view to find true lengths.
Use new reference planes to look at objects from new directions.
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Revolutions
Another solution is to revolve (turn) the object.
The resulting drawing is called a Revolution.
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The Axis of Revolution
In a revolution, use the regular reference planes X, Y and Z.
The Axis of Revolution
Imaging the object has been revolved to an angle that makes the principal features parallel to these planes.
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The Axis of Revolution
To “revolve” the object:
Imagine that a shaft or an axis has been passed through it.
This imaginary axis is perpendicular to one of the three principal planes.
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Figure 7-16
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The Axis of Revolution
Refer to Figure 7-16.
The axis the object is revolved around is called the axis of revolution.
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Figure 7-16
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The Axis of Revolution
Refer to Figure 7-16.
The axis the object is revolved around is called the axis of revolution.
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Figure 7-16
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The Axis of Revolution
An object can be revolved
to the right (clockwise)
to the left (counterclockwise)
about an axis perpendicular to either the vertical or the horizontal plane.
See Figure 7-16.
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Figure 7-16
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Figure 7-16
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Figure 7-16
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The Rule of Revolution
The Rule of Revolution has two parts:
1. The view that is perpendicular to the axis of revolution stays the same except in position.
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Figure 7-17
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Figure 7-17
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The Rule of Revolution
The Rule of Revolution has two parts:
2. Distances parallel to the axis of revolution stay the same.
Refer to Figure 7-17.
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Figure 7-17
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Revolution About An Axis
Perpendicular to the Vertical Plane
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Revolution - Axis Perp to Vertical Plane
Refer to Figure 7-18A.
The revolution axis is perpendicular to the vertical plane.
The front view is the same in size and shape.
The front view has a new position.
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Figure 7-18a
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Revolution - Axis Perp to Vertical Plane
The front and top views are shown in their normal positions.
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Revolution - Axis Perp to Vertical Plane
The new front view is then shown, after the object has been revolved 45 degrees counter clockwise about an axis perpendicular to the vertical plane.
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Revolution - Axis Perp to Vertical Plane
The new front view is the same in size and shape, except that it has a new position.
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Revolution - Axis Perp to Vertical Plane
The new top view has been made by
Projecting up from the new front view and
Projecting across from the old top view.
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Revolution - Axis Perp to Vertical Plane
The depth remains the same from one top view to another.
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Revolution About An Axis
Perpendicular to the Horizontal
Plane
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Revolution - Axis Perp to Horizontal Plane
Refer to Figure 7-18B.
The revolution axis is perpendicular to the horizontal plane.
The top view is the same in size and shape.
The top view has a new position.
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Revolution - Axis Perp to Horizontal Plane
The front and top views are shown in their normal positions.
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Revolution - Axis Perp to Horizontal Plane
The top view is then shown, after the object had been rotated 60 degrees clock wise about an axis perpendicular to the horizontal plane.
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Revolution - Axis Perp to Horizontal Plane
The new top view is the same in size and shape, as the old top view.
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Revolution - Axis Perp to Horizontal Plane
The new right-side view has been made by
Projecting down from the new top view and
Projecting across from the old front view.
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Revolution - Axis Perp to Horizontal Plane
The height remains the same from the original front view to the revolved front view.
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Revolution About An Axis
Perpendicular to the Profile Plane
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Revolution - Axis Perp to Profile Plane
Refer to Figure 7-18C.
The revolution axis is perpendicular to the profile plane.
The right-side view is the same in size and shape.
The right-side view has a new position.
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Revolution - Axis Perp to Profile Plane
The front and right-side views are shown in their normal positions.
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Revolution - Axis Perp to Profile Plane
The right-side view is the same in size and shape, except that it has a new position.
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Revolution - Axis Perp to Profile Plane
The new right-side view has been made by
Projecting down from the top view and
Projecting across from the new front view.
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Revolution - Axis Perp to Profile Plane
Note that the width remains the same from one front view to the other.
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Revolution - Axis Perp to Profile Plane
The depth remains the same from one top view to another.
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Revolving an Object About the
Horizontal Axis
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Figure 7-19
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Revolving an Object About A
Vertical Axis
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Figure 7-20
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Revolving an Object Through a 45
Degree Angle
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Figure 7-21
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Partially Revolved Views
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Figure 7-22
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Successive Revolutions
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Successive Revolutions
After an object is revolved about an axis perpendicular to one plane, it can be revolved again about an axis perpendicular to another plane.
This process is called successive revolutions.
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Figure 7-23
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Industrial Applications
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Figure 7-24
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Figure 7-24
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True Size and Shape
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True Size and Shape
The true size of an inclined surface can be shown by:
An auxiliary view. The observer changes position.
OR
A revolved view. The object changes position.
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True Size and Shape
In a revolved view:
The inclined surface is turned until it is parallel to one of the principal planes.
It is as if the object has changed position.
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True Size and Shape
In the auxiliary view:
The observer has changed position to look at the object from a new direction.
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True Shape of an Oblique Plane
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True Shape of an Oblique Plane
A surface shows its true shape when it is parallel to a plane.
Successive revolutions can be used to find the true shape of a surface.
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True Length of A Line
Since an auxiliary view shows the true size and shape of an inclined surface, it can be used to find the true length of a line.
Refer to Figure 7-29.
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True Shape of an Oblique Plane
In D, the oblique plane 1-2-3-4 is shown.
It is oblique because it is inclined to all three of the normal planes.
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Figure 7-29
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True Length of A Line
You can revolve a line in any view to make it parallel to any one of the three principal planes.
Projecting the line on the plane to which it is parallel shows its true length.
Refer to Figure 7-30 F, G, H.
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Single Revolution
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Single Revolution
An axis of revolution can be perpendicular to the vertical, horizontal or profile plane.
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Summary
Use either the Auxiliary View or the Revolved View to find true length lines.
In the auxiliary view, it is as if the observer changed positions.
In the revolved view, it is as if the object changed positions.
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