CE En 112 Engineering Drawing with CAD Application

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CE En 112 Engineering Drawing with CAD Application

• Chapter 3 Section and Auxiliary Views (Lecture
  B)
• Auxiliary Views

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Lecture Outline

• Auxiliary view projection theory (3.5)
• Fold-line method (3.5.1)
• Constructing an auxiliary view (3.5.2)
• Partial and half auxiliary views (3.5.33.5.4)
• Secondary auxiliary views
• Curves in auxiliary views
• Auxiliary view applications
• Next class

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Auxiliary View Projection Theory

• Auxiliary view An orthographic view that is
  projected onto any plane other than one of the
  six principal views
• In a multiview drawing, a true size and shape
  plane is shown only when the line of sight (LOS)
  used to create the view is perpendicular to the
  projection plane

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Auxiliary View Theory (cont)

• Oblique lines, inclined planes, and oblique
  planes are never shown in their true size and
  shape as one of the six principal views

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Auxiliary View Theory (cont)

• A 3-D view of this same object shows best how the
  auxiliary view projection theory works

The inclined plane is never shown in its true
size and shape in the six principal views
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Auxiliary View Theory (cont)
Notice that in this alternative, the auxiliary
view is shown perpendicular to the included plane
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Fold-Line Method (3.5.1)

• Fold-line method An auxiliary plane is
  generated that is perpendicular to and hinged to
  the frontal plane, creating a fold line between
  the front and auxiliary views

Note that the fold lines are parallel to the edge
lines of the planes. This means that the fold
line is perpendicular to the projection lines
(lines of sight)
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Fold-Line Method (cont)

• An alternative to the traditional fold-line
  method is the Reference Plane Method

The two methods are essentially the same. In the
reference plane method, the folding line moves to
the edge or inside of the object to a location
that makes it more convenient to draw an
auxiliary line
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Auxiliary view applications

• Auxiliary views are used to determine the true
  size and shape of features that would appear
  foreshortened in any of the principal views. The
  Applications for auxiliary views can be grouped
  into the following five areas
• Reverse construction
• Truer Length of a line
• Point view of a line
• Edge view of a plance
• Tru size of a plane.

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Constructing an Auxiliary View (3.5.2)

• Step 1 Draw fold line F-1 using a phantom line
  parallel to the edge view of the inclined
  surface
• Step 2 Draw fold lines between the front and
  top, and front and right side views
  perpendicular to the projectors between the two
  views and at distance X from the rear edge of the
  views
• Step 3 Project the length of the inclined
  surface from the front view to the auxiliary view
  perpendicular to the edge view

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Constructing an Auxiliary View (cont)

• Step 4 Transfer the depth of the inclined
  surface from the top view to the auxiliary view
  (distance X from the fold line)
• Step 5 From point C in the auxiliary view, draw
  a line perpendicular to the projectors. Depth
  dimension Y is transferred from the top view by
  measuring the perpendicular distance from the
  fold line to point A. This can then be
  transferred to the auxiliary view
• Step 6 Darken the lines in the auxiliary view
• Note that only the inclined plane is shown in the
  auxiliary view. This is referred to as a partial
  auxiliary view.

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Partial and Half Auxiliary Views (3.5.33.5.4)

• Partial auxiliary view When only the details
  for the inclined surface are projected and drawn
  in the auxiliary view saves time and produces a
  drawing that is much more readable

Note Hidden lines are not shown in an auxiliary
view unless absolutely necessary
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Partial and Half Auxiliary Views (cont)

• Half auxiliary view Used for symmetrical
  objects in which only half of the object is shown

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Secondary Auxiliary Views

• To find the true size of an oblique line or plane
  a secondary auxiliary view is required

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Curves in Auxiliary Views

• Curves in auxiliary views are handled similar to
  the offset coordinate method used with pictorial
  views

These lines are parallel
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Auxiliary View Applications

• Reverse construction Used when an auxiliary
  view must be created to draw a principal view

It is very difficult to draw this right-side view
without having an auxiliary view (this uses the
offset coordinate method to transfer the circle
to the right-side view)
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Auxiliary View Applications (cont)

• Dihedral angles A dihedral angle is the angle
  between two planes
• To draw and measure the angle between two planes,
  create a point view of the line of intersection
  between the two planes (meaning that the fold
  line is perpendicular to the line of
  intersection between the two planes)

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Auxiliary View Applications (cont)
Sample 1 (inclined plane)
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Auxiliary View Applications (cont)
Sample 1 (cont)
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Auxiliary View Applications (cont)
Sample 2 Inclined place with a curve
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Auxiliary View Applications (cont)
Sample 2 (cont)