Transcript Sketching – the language of engineers

Engineering
Graphics III –
Pictorial Projections
Prof. Jon Southen
October 15, 2008
Pictorial Projections
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Text Reference:
 Bertoline-Wiebe,
Fundamentals of Graphics
Communication, Chapter 7
Orthographic Projections
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Multiview Drawings
 Discussed
last class
 Show two dimensions at a time (with proper
size and shape)
 Images must be mentally combined to form
full 3-D description of object
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Pictorial Views
 Show
all three dimensions at once, making
visualization easier
Pictorial Views
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Pictorial views show
all three dimensions
in one view
Common projections:
 Perspective
 Oblique
(Cabinet)
 Axonometric
(Isometric)
Perspective Views
Perspective Views
Oblique Projection
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Front view is true size
and shape
Not a true projection –
CAD can’t generate them
Other dimensions are
greatly distorted
Oblique Projection
Oblique Projection
Practice - Oblique View
Axonometric Projection
Axonometric Projection
Axonometric (isometric)
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All lengths to same
scale
Not true shape
Angles equal
CAD can generate
isometric views
60º
60º
Scale and Axes
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“Full-scale”:
 All
dimensions same
as those on equivalent
multiview drawings
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Coordinate axes
separated by 120
degrees (2:1 on
squared paper)
Creating Isometric Drawings
Determine viewpoint that most clearly
depicts features of object
 Construct isometric box that contains the
object
 Locate details on isometric planes
 Darken visible lines
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Top
Front
Side
Practice – Isometric View
Isometric Circles
Isometric Circles
Standards for Isometric Drawings
Show hidden lines only if absolutely
necessary to describe the object
 Show centerlines only to show symmetry
or for dimensioning
 Isometric view not normally dimensioned
 Guidelines for sketching other features
(ellipses, curves, etc.) may be found in the
text
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Isometric Sketching
Example: Sketch Isometric View
Sketch Isometric
View
http://pergatory.mit.edu/2.007/resources/drawings/index.html
Multiview Drawing Visualization
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Reading an engineering multiview drawing
requires one to form a clear 3-D mental
image of the object.
To improve visualization skills
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Study existing
drawings
Construct physical
models
Contrast similar
shapes
What is Isometric View?
Possible
Solutions
Adjacent Areas
Surfaces which reside next to each other
 Boundary between surfaces represented
by line indicating change of planes
 No two can lie in same plane
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Adjacent Areas represent
1.
2.
3.
4.
Surfaces at different levels
Inclined or oblique surfaces
Cylindrical surfaces or arc
A combination of these
Next Class
Other Views
 Dimensioning and Tolerancing
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