MECHANICAL DRAWING
Different views of an object
Objects
may be drawn in different ways
Multiview
Pictorial
•Better for showing true size
and shape
•Better for visualizing the
object
•Each view only shows two
dimensions
•All three dimensions
shown on a single view
Multiview Drawing
Multiview Drawing
A multiview drawing is one that shows two
or more two-dimensional views of a threedimensional object.
Multiview drawings provide the shape
description of an object. When combined
with dimensions, multiview drawings serve
as the main form of communication
between designers and manufacturers.
Multiview Drawing
• Another name for orthographic projection is
multiview drawing
• Involves visualization and implementation
– Ability to see clearly in the mind’s eye an object
– Process of drawing the object
Angles of Projection
• First-angle projection
– Used by many European countries
– Object is projected onto planes
from the first angle or quadrant
• Front view projected to vertical plane
• Top view projected to horizontal plane
• Left-side view projected to profile
plane
Angles of Projection
• Third-angle projection
TOP VIEW
FRONT VIEW
– Standard for the United States
– Third quadrant is used for
projection
• Front view projected to vertical
plane
• Top view projected to horizontal
plane
• Right-side view projected to
profile plane
RSIDE
Choosing Views
• Most commonly used
views
– Front View
– Top View
– Right Side View
• Most descriptive view is
typically designated as
the Front View
2.00
TOP VIEW
2.88
1.63
Ø1.52
5.13
1.25
45°
3.50
2.50
2.25
1.50
FRONT VIEW
R. SIDE
VIEW
Choosing Views
• Complex objects require three views to
describe its shape
• Simple objects can be described with
two views
– Ex: Soda Can
• Thin objects can be described with
only one view
– Depth is given in a note
– Ex: Erasing Shield
Placement of Views
• Views should be visually balanced
within the working space
2.00
TOP VIEW
5.13
2.88
1.63
1.25
Ø2.22
45°
3.00
2.00
1.75
1.50
R. SIDE VIEW
FRONT VIEW
SPECIAL CAM
R. MIGLIORATO
5/9/03
SCALE 1:1 16-52
12
NBHS
Steps for Centering a Drawing
• Draw border and title block using light construction lines
• Draw diagonal lines from corners of border
.75
8.50
7.00
.25
.25
.50
.25
11.00
10.50
Layout of Views
Steps for Centering a Drawing
• Add:
–
–
–
–
TOP VIEW
Length
5.13
Space
1.50
Width
2.00
Horizontal 8.63
2.00
5.13
2.88
1.63
1.25
Ø2.22
–
–
–
–
Height
Space
Width
Vertical
3.00
1.50
2.00
6.50
45°
3.00
2.00
1.75
1.50
FRONT VIEW
R. SIDE
VIEW
Steps for Centering a Drawing
• Draw a box the size of all views
• Measure from the center:
– Half the width
– Half the height
3"
4.3"
4.3"
3"
Steps for Centering a Drawing
• Draw in views using light construction lines
2.00
TOP VIEW
1.50
3.00
R. SIDE
VIEW
FRONT VIEW
5.13
1.50
2.00
Adding Details
• Add holes and features
• Transfer horizontal and vertical features
• Use miter line to transfer depth
TOP VIEW
FRONT VIEW
SPECIAL CAM
R. SIDE VIEW
R. MIGLIORATO
5/9/03
SCALE 1:1 16-52
12
NBHS
Straight Edges
• Edges that are parallel to a plane of projection
appear as lines
• Edges that are inclined to a plane of projection
appear as foreshortened lines
TRUE LENGTH
TRUE LENGTH
TRU
E LE
N
POINT
VIEW
GTH
FORESHORTENED
FORESHORTENED
Curved Edges
• Curved edges project as straight lines on the plane
to which they are perpendicular
• Curved edges project as curved lines on the planes
to which they are parallel or inclined
Normal Surfaces
Normal surfaces appear as an edge in
two opposite principal views, and
appear a surface in all other principal
views.
Inclined Surfaces
• Inclined surfaces appear as an edge in two
opposite principal views, and appear
foreshortened (not true size) in all other
principal views.
Oblique Surfaces
• Oblique surfaces do not appear either as an
edge or true size in any principal view.
Intersections & Tangencies
• Where a curved surface is tangent to a plane
surface, no line should be shown where they
join
NO LINE
NO
LINE
Intersections & Tangencies
• Where a plane surface intersects a curved
surface, an edge is formed
LINE
LINE
What is Multiview drawing?
Drawing
more than one orthographic view of an object on the same
page
Ortho (straight) + graphic (drawing)
Object
An orthographic view is drawn looking
Projection plane
straight at one side of the object (at
90° to it)
Line of sight

Orthographic Projection
Orthographic projection is a technique
that is used to create multiview drawings.
Orthographic projection is any projection
of the features of an object onto an
imaginary plane of projection. The
projection of the features of the object is
made by lines of sight that are
perpendicular to the plane of projection.
Orthographic Projection
The best way
to understand
orthographic
projection is
to imagine an
object
contained
inside a glass
box.
Orthographic Projection
There is a total of
six glass walls
surrounding the
object. Each wall
represents a
projection plane
onto which a twodimensional object
view will be created.
Projection Plane
A projection plane, also referred to as a
plane of projection or picture plane, is an
imaginary surface that exists between the
viewer and the object.
The projection plane is the surface onto
which a two-dimensional view of a threedimensional object is projected and
created.
Orthographic Projection
Start by focusing
only on the front
projection plane.
A person standing in
front of the object
would see only the
five corners
identified in black.
2
3
1
4
5
Orthographic Projection
Projection lines are
used to project each
corner outward until
they reach the
projection plane.
Projection Lines
A projection line is an imaginary line that
is used to locate or project the corners,
edges, and features of a three-dimensional
object onto an imaginary two-dimensional
surface.
Orthographic Projection
The visible edges
of the object are
then identified on
the projection
plane by
connecting the
projected corners
with object lines.
Orthographic Projection
The orthographic
projection
process is then
repeated on the
other projection
planes.
A Question…
Each of the
blocks to the
right have the
same overall
dimensions
and colors.
What else to
they have in
common?
Answer ….
They all have
identical top
views!
HIDDEN LINES
MUTLIVIEW DRAWINGS
We place hidden lines
in a drawing to do the
following things:
1. Show hidden features
2. Clarify the position
and shape of features
3. Make the “plate” more
readable
(NOTE: The term
“plate” refers to a
finished drawing.)
How many views?
Cubes
(like these dice) have 6 sides
Since each side of the die
will have its own view…
then there must be SIX
possible orthographic views!
Front
How many views?
Cubes
(like these dice) have 6 sides
Since each side of the die
will have its own view…
then there must be SIX
possible orthographic views!
Front
Top
How many views?
Cubes
(like these dice) have 6 sides
Since each side of the die
will have its own view…
then there must be SIX
possible orthographic views!
Front
Top
Right Side
How many views?
Cubes
(like these dice) have 6 sides
Since each side of the die
will have its own view…
then there must be SIX
possible orthographic views!
The Front, Top, and Right
Side are the views that are
usually drawn.
Front
Back
Top
Bottom
Right Side
Left Side
Where do the views go?
All
the views MUST be arranged correctly
Imagine “unfolding” the cube
to get proper view alignment.
The back view can be placed
in any of these four locations.
How does this work on other
objects?
Place
the object in a glass box
Then “unfold” the box
Front view is always central
Top view goes above
R.Side view goes to the right
What about details you can’t
see?
Hidden
lines show details that are not seen in all views
Project from hidden detail to
the other views
Draw hidden lines (dashed)
to show the detail
ANIMATED EXAMPLES
http://dossin.weebly.com/3-multi--view-orthographic-projectiondrawing.html
Multiview Drawing REVIEW
An
orthographic view is drawn looking straight at one side of the
object (at 90° to it)
There
are 6 possible orthographic
views: Front, Back, Top, Bottom,
Left Side, Right Side
The
Front, Top, and R.Side views
are usually all that are drawn
Hidden
lines show details you
can’t see in all views
Centering a Multiview Drawing Review
Make a sketch of the views needed for the drawing.
The space between the views is 1 ½”
What are the measurements needed to center the drawing?
What is the overall size of the box for the views?
Centering a Multiview Drawing Review
3.50
1.5
6.75
1.75
6.50
11.50
1.5
3.50
Layout of the 6 Views
Sketch the layout of the 6 views of this object and label the views.
TOP
REAR
L. SIDE
FRONT
BOTTOM
R. SIDE