Transcript Principles of Organization

Multi-view Drawing
Gamal Prather
Multi-view Drawings
• Pictorial sketches are great for engineers to explain
ideas and communicate what the final part will look
like to the customer.
• Unfortunately, pictorial drawings have some
disadvantages.
– Foreshortened views and distorted features do not allow
for accurate prototyping.
– Many times, for parts to be accurately depicted, you need
straight on views of each surface.
Orthographic Drawings
• These straight-on views are called
ORTHOGRAPHIC PROJECTIONS
– aka MULTIVIEW DRAWINGS
– These views are perpendicular to a line of
sight
• There are 6 of these views to any
object
Orthographic Drawing
The arrows represent the
line of sight associated
with each view.
View the Orthographic
Drawings for this object
Orthographic
Principal Views
Note how the views
are oriented. Each view is
adjacent to the other as
if they were unfolded
from a 3D shape.
ISO
Front,
Top and Right views
are used most often. You can
see how other views resemble
these three except they are not
as clear due to hidden lines.
Orthographic Angle of
Projection
• The example you have just seen is
shown in THIRD ANGLE projection
– This is the standard in the United States
and Canada
• The rest of the world draws in FIRST
ANGLE projection
Orthographic
Spatial Quadrants and
Planes
This sketch shows the
quadrants where the angles
of projection are made from
In 3rd angle projection,
the projection planes used
to create views are
as shown in red.
Top
Front
Right Side
Orthographic
Views
are projected
onto planes
3rd
Angle
Projection
that exist on the face of that view.
Arrows show the direction of the
projection
ISO Symbol
Orthographic
Spatial Quadrants
and
Planes
Side
Top
In 1st angle projection
the projection planes used to
create the views are
as shown in red.
Front
Orthographic
1stViewsAngle
Projection
are projected onto planes
that exist on the opposite face of the
view you want to display. The
arrows show the direction
of the projection.
ISO Symbol
View Selection
• Finding the best view of a part can be
tricky
– Two or more sides may look like the best
solution for a front view.
– On the next slide is a list of
characteristics that you should use in
choosing your views.
View Selection Criteria
• The front view should show the ...
–
–
–
–
Shows best shape and characteristic contours
Longest dimensions
Fewest hidden lines
Most stable and natural position
View Selection
No hidden lines
in any views
Best shape
description
Longest
Dimension
Most natural position
for isometric view
Selecting Number of Views
• How many views do you need?
– Usually not more than 3, but you may only
need one or two.
One View Selection
Uniform shape.
All dimensions easily
shown on one view
Two views
will be identical
One View Selection
It is also possible to
have one view drawings
of objects that are flat
and have even thickness.
Gauges and gaskets are
two such objects. We
have a gauge here on the
left.
Two View Selection
Symmetrical parts. A third view
would be identical to the other
views
Second view is necessary for
depth.
Line Precedence
• Different line types frequently must be drawn in the
same space
– LINE PRECEDENCE helps us decide which lines to draw
• Generally you should draw …
– Object lines over hidden lines and centerlines
– Hidden lines over centerlines
– Cutting plane lines over centerlines
Precedence of Lines
An object line here takes precedence
over the center line. However we
draw short thin lines beyond the
object to show there is a center line
underneath the object line.
Precedence of Lines
Object lines took precedence over
the hidden lines you would see
from the hole. The center line in
the top view would show the depth
of the hole as well as the right
side view.
References
• Madsen, David A., Shumaker, Terence M., Stark, Catherine, Turpin, J.
Lee, Engineering Drawing and Design Second Edition,Delmar
Publishers, 1996, ISBN 0-8273-6720-1.
• Brown, David, You Can Draw, North Light Books, Cincinnati, Ohio,
1986, ISBN 0-89134-216-8.
• Olivo, Dr. C. Thomas, Olivo, Thomas P., Basic Blueprint Reading and
Sketching Sixth Edition, Delmar Publishers Inc., 1993, ISBN 0-82735740-0.
• Johnson, Cindy M., Lockhart, Shawna D., Engineering Design
Communication, Prentice Hall, 2000, ISBN 0-201-33151-9.
• Spencer, Henry Cecil, Dygdon, John Thomas, Novak, James E; Basic
Technical Drawing 6th Edition; Glencoe McGraw Hill; New York, New
York,1995, ISBN 0-02-685660-3.
Do you want to be a good
sketcher?
First Slide