Post on 16-Dec-2015
Unit 5Multiview Drawings
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Learning Objectives
• Define spatial visualization.• Explain the relationship between an orthographic
projection and a multiview drawing.• Identify and define the three dimensions of an
object.• Define the six principal views and the three
regular views.• Identify the three principal projection planes.
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Learning Objectives
• Explain three visualization principles for multiview drawings.
• Identify the three types of flat surfaces.• Explain characteristics of cylindrical surfaces.• Explain characteristics of fillets, rounds, and
runouts.• Identify differences between third-angle and first-
angle projection.• Discuss computer-generated views.
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The Role of Spatial Skills
• Spatial visualization can be defined as the mental visualization of 2D and 3D shapes and objects, including such tasks as imagining objects in the mind as they are rotated, moved, or reflected in a mirror
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Spatial Visualization Tools
• Visualization of rotations
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Spatial Visualization Tools
• Mental rotation with two correct rotations
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Spatial Visualization Tools
• Surface development test
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Spatial Visualization Tools
• Mental visualization of folding and unfolding
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Orthographic Projection
• Created by projecting the points of a three-dimensional object onto a two-dimensional plane
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Multiview Projection
• Orthographic projection consisting of systematically arranged views to describe an object
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Definition Summary
• Orthographic projection, multiview projection, and multiview drawing are interchangeable terms
• Represents the main type of drawing views used in industrial prints
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Selection of Views
• Six principal views:– Front– Back– Top– Bottom– Right side– Left side
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Selection of Views
• Three “regular” views commonly used in education:– Front– Top– Right side
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Selection of Views
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Dimensions of an Object
• Height is how tall the object is, as measured on the front view
• Width is how wide the object is, as measured on the front view
• Depth is how deep the object is from front to back• Each dimension appears twice in the three
regular views• “Length” and “breadth” are terms not used
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Dimensions of an Object
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Three Orientation Possibilities• Perpendicular• Parallel• Inclined
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Three Projection Possibilities• Edge view• True size and shape• Foreshortened shape
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Three Principal Planes of Projection• Frontal plane• Horizontal plane• Profile plane
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Three Types of Flat Surfaces
• Normal
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Three Types of Flat Surfaces
• Inclined
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Three Types of Flat Surfaces
• Oblique
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Cylindrical and Curved Surfaces
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Meanings of a Multiview Line
• A—Edge view of a flat or curved surface
• B—Intersection of two surfaces (just an edge)
• C—Maximum contour of a curved surface
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First-Angle and Third-Angle Projection• Dividing space into quadrants
– Historical development of projection theory used two planes to divide space
– After projections, the two planes are revolved into one, with quadrants two and four “collapsed”
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First-Angle and Third-Angle Projection
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Third-Angle Projection
• Used in the United States
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First-Angle Projection
• Used in Europe
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Computer-Generated Views
• The benefits of creating views directly from the 3D model include: – Ease of construction– Ease of change– Accuracy in representing geometry– Intelligent association between the model and the
annotations
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Computer-Generated Views
• Views created by the CAD program may need:– Individual line adjustment
for weight or dash spacing– The representation of
fillets, rounds, and runouts adjusted (see A versus B to the right)
– Conventional practices reviewed
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What do you see?
Print supplied by Sunnen Products Company.