Multiview Sketches
Transcript of Multiview Sketches
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Multiview Sketches
Engineering Graphics
Stephen W. Crown Ph.D.
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Objective
How to use sketching as an effective
tool in the engineering design process
How to represent a 3-D objecteffectively on a 2-D drawing surface
(multiview sketching)
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Overview
Sketching Definition
Tools / Instruments
Mechanics of sketching Lines and Curves
A Bounding Box
Multiview sketches How to create them
When to use them
Why use sketches? Creativity
Communication
Documentation
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Sketching
Definition: A rough freehand drawing
used to document, communicate, and
refine ideas developed in the ideation
phase of the design process
Beginners will benefit from instruments
Follows standard practices
A developed skill
Should be the first step of
any CAD drawing
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Tools
Pencils Use a mechanical pencil (0.5mm lead)
Practice using different pressure to produce
desired linetypes (construction lines)
Paper Unlined paper is the most useful
Square grid and tracing paper is often useful
Eraser A good eraser is worth the investment
Do not overuse your eraser (save some mistakes)
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Using Simple Instruments
The use of mechanical instruments is
recommended only for beginners. Break away
from reliance on tools that slow you down.
Helpful tools for beginners Compass
Triangles
Dividers
Ruler
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Drawing straight lines
Mark starting and ending point
Break long lines into short line
segments by marking the midpoint
Start with a light pass if necessaryand then darken
Use a loose comfortable grip
Reorient the paper to your
convenience test your skill with different orientations
an awkward orientation may
occasionally produce positive results
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Drawing curved lines
Break large arcs/circles into
small segments
Make guide marks for eachsegment
Circles and Ellipses
Sketch a light square/rectangle
Lightly sketch in diagonals
Mark contact points on
square/rectangle
Rotate the paper for each
segment
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Bounding Box and Construction Lines
Plan
choose proper scale and
orientation
dont crowd sketches Start with a bounding box
Use light straight
construction lines
Draw boundary lines of
internal features starting
with the largest features
Sketch dark object lines
using light boundary lines
as a guide
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Multiview Sketching
Represents a 3-D object
with a series of 2-D
views in contrast to
pictorials which showall three dimensions in a
single view
Also called orthographic
projection
Best understood by
engineers or technically
trained people
Multiview Drawing
Pictorial
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Parallel projection
Preserves true relationship
between features
The geometry is generally not distorted
Lines that are parallel on the object are
parallel on the drawing
Parallel projectors
The object is projected onto a
projection plane as a shadow is
projected where the rays form the lightsource are parallel.
Projection from one view to another is
accomplished with parallel projection
lines
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Parallel versus Perspective Projection
Parallel
Perspective
Parallel
Perspective
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Projection Planes versus Views
Projection planes:
Object formed from projection lines projected
perpendicularly onto a projection plane
Planes: Horizontal, frontal, and profile Each projection plane is perpendicular to adjacent
projection planes
Principle views
The object is rotated 90 degrees about the horizontalor vertical axis to give six principle views (top,
bottom, front, rear, left, and right side)
Common views: top, front, and right side
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Only use Necessary Views
One view drawings
Stamped, thin or extruded parts
Specify thickness with a note
Two view drawings
Cylindrical parts
Show the circular and
rectangular view Three view drawings
Usually sufficient for all other
drawings
Top, front, and right side view
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Orientation and Placement of Views
The most descriptive view
should be selected as the
front view
The natural orientation of
the part should be
preserved if possible
Views must be aligned Top view above front view
Right view to the right of
front view
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Hidden lines
Represented with
dashed lines
Precedence of lines
(visible, hidden, center)
Views should be
selected to minimize
the use of hidden linesmost descriptive view
should be selected as
the front view
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Third Angle Projection Associated with English
units
First Angle Projection Associated with SI units
First Versus Third Angle Projection
ANSI Symbol
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Fold Lines
Represents a 90 degree fold between views
Generally not shown on engineering
drawings except when views other than the
principle views (auxiliary views) are used.
Labeled as: H/F, F/P, F/1, 1/2
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Terminology to Relate Views
Adjacent view
A view that is separated by a fold line
The top view is an adjacent view to the front view
Central View A view that is between two adjacent views
The front view is the central view of the top, front,
and right side view
Related views
Two views that are adjacent to a central view
The top and right side view are related views
since they are both adjacent to the front view
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Constructing a New View
The top and front viewsof a surface are shown
The fold linerepresentsa 90 degree foldbetween the views
Parallelprojection lines
are perpendicular to thefold line
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Constructing a New View
A vertical fold lineis drawn at an
arbitrary distance from the front view
Parallelprojection linesare drawn
from each vertex The common depth between the top
and side view is used to locate each
vertex on the projection lines
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Sketching as Part of the Creative
Design Process
Quickly translate
thoughts to paper
An effective means
of communication
Stimulates creativity
and visualization
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Sketching Allows for the Quick
Translation of Thoughts to Paper
Commit thoughts to paper before you
lose an idea
Avoid the of use mechanical tools (drawing
tools are helpful for beginners)
Does not need to be an exact representation
objects may be simplified
parts may be missing
Avoid erasing
as new ideas are developed make new sketches
start with light lines and then darken with darker
lead or heavier strokes
Sk hi i A Eff i M
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Sketching is An Effective Means
of Communication
Understand your audience
Who is looking at the sketches?
What details are they interested in?
What type of sketch will they best understand?
Follow standard practices
You may not always accompany your sketches
Others may misinterpret your drawing Sketches provide a log of ideas that were
considered in a brainstorming session
Sk hi S i l C i i
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Sketching Stimulates Creativity
and Helps Visualization
The process of sketching ideas that are partially
developed often aids the design process
do not wait until you have a clear picture before you
start sketching allow yourself the freedom to make mistakes
Visualization of the entire design is essential but
often impossible without aid of sketches
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Appendix
Engineering Graphics
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Make a Quick Sketch
How many of the nine views consisted of asquare bounding box?
How many of the nine views are the same?
How many of the nine views consisted of onlyvertical or horizontal lines?
What is the volume of each object (Cube=8 in3)?
You will have ten seconds to make a
sketch of each object shown below
before being asked a few questions
about the objects.