1Chapter 7
Chapter 7Auxiliary Views
2Learning Objectives
L Explain the purposes of auxiliary views.L Identify auxiliary views and explain their relationship to principal
views.L Discuss terms related to auxiliary view projection.L Read prints that incorporate auxiliary views.L Discuss computer-generated auxiliary views.
Learning Objectives
3Auxiliary Views
L Created with a projection plane that is not in one of the principaldirections
L An orthographic view
Auxiliary Views
4Auxiliary View Purpose
L Can be used to show the true size and shape of an inclinedsurface
Auxiliary View Purpose
5Auxiliary View Purpose
L Used to show the true angle, or dihedral angle, of a groove
Auxiliary View Purpose
6Auxiliary Views in Education
L In education or standards, reference lines are often used to helpconstruct the auxiliary view
Auxiliary Views in Education
7Visualizing Auxiliary Views
L Turn the drawing to see the auxiliary view in a horizontal orvertical orientation
Visualizing Auxiliary Views
8Partial Auxiliary View
L Does not show the entire object
Partial Auxiliary View
9Primary Auxiliary View
L Projected from a principal viewL By dimension:T Height: projected from the top viewT Width: projected from the side viewT Depth: projected from the front view
Primary Auxiliary View
10Secondary Auxiliary View
L Projected from a primary auxiliary view
Secondary Auxiliary View
11Computer-Generated Auxiliary Views
Computer-Generated Auxiliary Views
12What do you see?
What do you see?
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14
15PROJECTION METHOD
PROJECTION METHOD
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PROJECTION METHOD
Perspective
ObliqueOrthographic
Axonometric Multiview
Parallel
Oblique
17PROJECTION THEORY
L The projection theory is used to graphically represent 3-D objectson 2-D media (paper, computer screen)
L The projection theory is based on two variables:T 1) Line of sightT 2) Plane of projection (image plane or picture plane)
PROJECTION THEORY
18Line of Sight
L Line of Sight is an imaginary ray of light between an observer’seye and an object
T There are 2 types of Line of SightO parallel O converge
Line of Sight
Line of sightLine of sight
Parallel projection Perspective projection
19Plane of Projection
L Plane of projection is an imaginary flat plane which the image iscreated
T The image is produced by connecting the points where the LOSpierce the projection plane.
Plane of Projection
Plane of projection
Parallel projection
Plane of projection
Perspective projection
20Disadvantage of
L Perspective projection is not used by engineers formanufacturing of parts, because
T 1) It is difficult to create.T 2) It does not reveal exact shape and size.
Disadvantage of Perspective Projection
Width is distorted
1
21Orthographic projection
L Orthographic" comes from the Greek word for "straight writing (ordrawing)."
T This projection shows the object as it looks from the front, right,left, top, bottom, or back, and are typically positioned relative toeach other according to the rules of either “First Angle” or“Third Angle” projection.
Orthographic projection
22Pictorial
L 3-dimensional representationsT One-point O one vanishing point O lines that are not vertical or horizontal converge to single point in distance
T Two-point or Three-point O two or three vanishing pointsû With two points, vertical or horizontal lines parallel, but not bothû With three-point, no lines are parallel
T IsometricO Drawing shows corner of object, but parallel lines on object are parallel in
drawingO Shows three dimensions, but no vanishing point(s)
Pictorial
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One-point
Two-Point
Three-Point or Oblique Perspective
24Symbols for Third Angle or First Angle
L First angle projection is the ISO standard and is primarily used in Europe.
T The 3D object is projected into 2D "paper" space as if you werelooking at an X-ray of the object: the top view is under the front view, the right view is at the left of the front view.
L Third angle projection is primarily used in the United States and Canada, where it is the default projection system according to BS 8888:2006, the left view is placed on the left the top view on thetop.
Symbols for Third Angle or First Angle
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26Orthographic projection
L Orthographic projection is a parallel projection technique inwhich the parallel lines of sight are perpendicular to theprojection plane
Orthographic projectionMEANING
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Object views from top
Projection plane
1
2
3
4
51 2 3
4
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Image of a part represented in First Angle Projection
28Orthographic / Multiview
L Draw object from two / three perpendicular views
Orthographic / Multiview
Orthographic
What it looks like pictorially
29Multiview Drawing
L AdvantageT It represents accurate shape and sizeL DisadvantageT Require practice in writing and readingL Example
Multiview Drawing
Multiviews drawing (2-view drawing)
30Axonometric (Isometric) Drawing
L AdvantageT Easy to understandL DisadvantageT Shape and angle distortion L Example
Axonometric (Isometric) Drawing
Circular hole becomes ellipse.
Distortions of shape and size in isometric drawing
Right angle becomes obtuse angle.
31Isometric projection
Isometric projection
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Sectional views
33Auxiliary Views
L Used to show true dimensions of an inclined plane
Auxiliary Views
Not True Size
True Size
34Auxiliary projection
Auxiliary projection
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1
36Isometric and Oblique Pictorials
Isometric and Oblique Pictorials
37Pictorial Drawing
L 2D illustration of a 3D objectT Shows three faces of an object in one viewT Provides a realistic view of an objectL Three typesT Isometric T ObliqueT Perspective
Pictorial Drawing
Isometric Oblique (Cavalier) PerspectiveOblique (Cabinet)
38Oblique Pictorials
L An Oblique pictorial starts with a straight-on view of one of theobject’s faces, which is often the front face
L Angled, parallel lines are drawn to one side to represent theobject’s depth.
T Common oblique angles include 30E, 45E, and 60E
Oblique Pictorials
39Oblique Pictorials
L Two common types of oblique pictorials: T Cavalier T CabinetL The difference between the two is how the depth of the object is
represented
Oblique Pictorials
Cavalier Oblique Cabinet Oblique
40Oblique Pictorials
Oblique Pictorials
Cavalier Oblique Cabinet Oblique
Object appears deeper than it actually is
More realistic view because depth does not appear distorted
41Isometric Pictorial
L Isometric means equal measure.L Three adjacent faces on a cube will share a single pointT Edges converge at one point will appear as 120 degree angles or
30 degrees from the horizon line
Isometric Pictorial
42Isometric Pictorial
L These three edges represent height, width, and depth
Isometric Pictorial
43View labels
View labels
Top, Front, Right Side view orientation
Top, Left Side, Front, view orientation
44View Selection
L Recommendations for how to select the front viewT Most natural position or useT Shows best shape and characteristic contoursT Longest dimensionsT Fewest hidden linesT Most stable and natural position
View Selection
45Orthographic View Selection
Best shapeDescription
Most natural position
No hidden edges
Longest Dimension
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