Drafting – Product Design & Architecture Orthographic Projection Alphabet of Lines Short Break Line: A freehand Object Line: Thick lines Hidden Line: Lines used.
Download ReportTranscript Drafting – Product Design & Architecture Orthographic Projection Alphabet of Lines Short Break Line: A freehand Object Line: Thick lines Hidden Line: Lines used.
Slide 1
Drafting – Product Design & Architecture
Orthographic Projection
Slide 2
Alphabet of Lines
Short Break Line: A freehand
Object Line: Thick lines
Hidden Line: Lines used to
drawn line that shows where a part is
.6mm(.032in) that show
show interior detail that is not visible broken toabout
reveal detail behind the part or
the visible edges of an object.
Center
Line: of
Lines
from
the outside
the that
part.define to shorten a long continuous part. (See
Section
Lines are
used to
the center
of Lines:
arcs, circles,
or symmetrical
parts.
example of Long Break Line
define
there
is as
material
They
arewhere
half as
thick
an object line.
on the next slide.)
after a part of the object is cut away.
Construction Line: Very lightly
drawn lines used as guides to help draw
all other lines and shapes properly.
Usually erased after being used.
Slide 3
Alphabet of Lines
Dimension
that
used Line:
to
Cutting
Plane
A line used to
Long Break
Lines:Lines:
BreakLines
lines
are are
used
show detail
distance.
are
on thea part has been cut
to either show
or asArrows
in thisdesignate
casedrawn
theywhere
can
Lines:
Lines
used
to see
show
where
ends
toExtension
show
where
the dimension
line
starts
and The
ends.
detail.
arrows should
be used
to shorten
very
longaway
objects
that
a dimension
and located
stops
on
object.
The
actual
distance
isstarts
usually
ininan
the
middle
of that
this you are
point
the
direction
do not
change
in detail.
Notice
that
this
part
with
dimension
lines
properly
dimension
line
to letlong
youhowever
know thewe
distance
beinglooking
communicated.
at the cutout.
isUsed
12”
havetoshortened
object.with
The
line
1/16”to
from the
Dimension
lines
areislines
used
inaway
conjunction
thean
drawing
break
use
part our
as to
notextension
get
confused
the object lines
with
lineswith
to properly
space
more
efficiently.
dimension objects.
Leader Lines: Leader lines are used to
show dimensions of arcs, circles and to help
show detail. An arrow head is used to point
to the part you are dimensioning and the line comes
off the arrow point usually at a 45 degree angle.
At the end of this line a horizontal line is drawn
with a note at the end telling information
How many lines from the
about what is being pointed at.
previous slide can you identify
here?
Slide 4
Alphabet of lines
Phantom Lines: Phantom lines are used
to identify alternate positions that a part my
take up. In this example we are using Phantom
lines to show that the door handle may only move
45 degrees from it’s horizontal
position.
How many lines from the
previous 2 slides can you
identify here?
Slide 5
Orthographic
(Multiview 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.
Slide 6
Orthographic
(Multiview Drawings)
In order to obtain these straight line
views we have a type of drawing
called Orthographic Projection also
known as Multiview drawings.
Orthographic projection is a way to
project a view based on a line of sight
that is perpendicular to that view.
There are six of these views to any
object as shown in the next slide.
Slide 7
Orthographic
(Multiview Drawings)
The arrows represent the
line of sight associated
with each view.
Use the button
below to jump
between this
view and the ortho
view on the next
page.
ORTHO
Slide 8
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.
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.
Click to go back
to ISO view.
ISO
Slide 9
Orthographic View Selection
Finding the best view of a part can be
difficult. 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.
Slide 10
Orthographic View Selection
Steps in selecting the front.
Most natural position or use.
Shows best shape and characteristic contours.
Longest dimensions.
Fewest hidden lines.
Most stable and natural position.
Relationship of other views
Most contours.
Longest side.
Least hidden lines.
Best natural position.
Slide 11
Orthographic View Selection
Longest Dimension
Most natural position.
Best shape description.
No hidden lines.
Slide 12
Orthographic View Selection Numbers
Another decision on view selection
you need to make is how many views.
You usually do not need more than
three but you may only need one or
two. The following slides will show
when to make a decision between
one, and two view drawings.
Slide 13
One View Selection
Uniform shape.
Two views
will be identical
All dimensions easily
shown on one view.
Slide 14
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.
Slide 15
Two View Selection
Symmetrical parts. A third view
would be identical to the other
views
Second view is necessary for
depth.
Slide 16
Precedence of Lines
In multiple view drawings, many times different line
types will take up the same space, therefore, we
have line precedence. The following is an
explanation of which lines exist over others.
Object lines over hidden and center.
Hidden over center.
Cutting plane lines over center lines.
The following slide will show an example.
Slide 17
Precedence of Lines
An object line here takes preced
over
theprecedence
center line.over
However
Object lines
took
draw
short
lines
the hidden
lines
youthin
would
seebeyond th
to show
there
from the object
hole. The
center
lineisina center
underneath
the depth
object line.
the top view would
show the
of the hole as well as the right
side view.
Slide 18
Do you want to be a good
sketcher?
First Slide
Slide 19
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
Slide 20
Multiview Drawing
A system that allows you to make a
two-dimensional drawing of a threedimensional object
Slide 21
Viewing Objects
A box is formed by
six mutually
perpendicular
planes of projection
that are located
around the object
Slide 22
Viewing Objects
Lines are formed on the planes by
projecting the edges of the object onto
the planes
These images are
called “views”
There are six views
formed by the
planes of a box
Slide 23
Viewing Objects
Unfolding the box produces an
arrangement of the six views
TOP
BACK
L.SIDE
FRONT
BOTTOM
R.SIDE
Slide 24
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
Slide 25
Angles of Projection
Third-angle projection
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
TOP VIEW
FRONT VIEW
RSIDE
Slide 26
Viewing Objects
Each view is placed in
a constant location
relative to the other
views
Each view must be
placed in its correct
position
Views and features
must be aligned
Slide 27
Choosing Views
Most commonly used
views
2.00
TOP VIEW
Front View
Top View
Right Side View
Most descriptive view is
typically designated as
the Front 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
Slide 28
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
Slide 29
Choosing the Views
Objects described in two views
Third view would add nothing to the
description of the object
Carefully select views to describe
shape of objects accurately
Slide 30
Curved Surfaces
Some
curved
surfaces do
not show as
curves in all
views
CYLINDER
CONE
WHEEL
FRUSTRUM
Slide 31
Object Dimensions
All objects have 3
dimensions
HEIGHT
Height
Distance from top
to bottom
Width
Distance from side
to side
Depth
Distance from the
front to back
WI
DT
H
H
PT
E
D
Slide 32
Object Dimensions
Front View
Shows width &
depth
TOP VIEW
WIDTH
Side View
Shows height &
depth
DEPTH
HEIGHT
Top View
DEPTH
Shows width &
height
FRONT VIEW
R. SIDE
VIEW
Slide 33
Drawing Views of Objects
Depth can be projected between
views by using a 45° miter line
TOP VIEW
FRONT VIEW
R. SIDE
Slide 34
Line Types - Visible
Edges that can be seen in a given view
areVisible or Object lines
Visible lines are thick and dark
.028” or .7mm
F or HB lead
FRONT VIEW
Slide 35
Line Types - Hidden
Edges that cannot be seen
from a given view are indicated
by Hidden lines
TOP VIEW
Slide 36
Line Types - Hidden
Drawing hidden lines
.125” (3mm) dashes
.0625” (1mm) spaces between dashes
Thin: .020” (.5mm)
Dark: F or HB lead
.125"
.0625"
Slide 37
Line Types - Hidden
Follow rules for hidden line placement
Alphabet of Lines
Drawings produced with CAD may violate
hidden line rules
Slide 38
Line Types – Center
Center lines indicate
axes of symmetry
TOP VIEW
Slide 39
Line Types – Center
Perpendicular lines for circular objects
Small dashes cross at the center point of
feature
One center line drawn to indicate longitudinal
axis of cylinder or hole
FRONT VIEW
R. SIDE
VIEW
Slide 40
Line Types - Center
Draw center lines using a series of
long and short dashes
.125” (3mm) short dash @ the center
.75”- 1.5” (20mm-40mm) long dash
.0625” (1mm) spaces between dashes
Thin: .02” (5mm)
Long dash extends .125” to .25”
beyond feature
.125"
.75" - 1.5"
.0625"
Slide 41
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
Slide 42
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
Slide 43
Steps for Centering a
Drawing
Add:
Width
Space
Depth
Horizontal
TOP VIEW
5.13
1.50
2.00
8.63
2.00
5.13
2.88
1.63
1.25
Ø2.22
Height
Space
Depth
Vertical
3.00
1.50
2.00
6.50
45°
3.00
2.00
1.75
1.50
FRONT VIEW
R. SIDE
VIEW
Slide 44
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"
Slide 45
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
Slide 46
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
Slide 47
Multiview Drawing
Slide 48
Straight Edges
6
5
B
2
1
A
4
Edges that are
perpendicular to a
plane of projection
appear as a point
3
1
6
2
4
B
5
5
6
3
2
A
1
5
5
6
4
1
1
A
2
4
B
B
2
6
3
3
A
1
5
5
6
4
1
1
A
2
4
B
B
2
6
2
A
4
3
A
1
6
5
B
2
4
1
1
A
B
2
A
4
Slide 49
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
NGT
H
POINT
VIEW
FORESHORTENED
FORESHORTENED
Slide 50
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
Slide 51
Normal Surfaces
Normal surfaces appear as an edge in
two opposite principal views, and
appear a surface in all other principal
views.
Slide 52
Inclined Surfaces
Inclined surfaces appear as an edge
in two opposite principal views, and
appear foreshortened (not true size)
in all other principal views.
Slide 53
Oblique Surfaces
Oblique surfaces do not appear either
as an edge or true size in any
principal view.
Slide 54
Intersections & Tangencies
Where a curved surface is tangent to
a plane surface, no line should be
shown where they join
NO LINE
NO
LINE
Slide 55
Intersections & Tangencies
Where a plane surface intersects a
curved surface, an edge is formed
LINE
LINE
Slide 56
Intersections & Tangencies
Where the plane surface is horizontal
or vertical, exceptions to these rules
may occur
LINE
VERTICAL
SURFACE
Drafting – Product Design & Architecture
Orthographic Projection
Slide 2
Alphabet of Lines
Short Break Line: A freehand
Object Line: Thick lines
Hidden Line: Lines used to
drawn line that shows where a part is
.6mm(.032in) that show
show interior detail that is not visible broken toabout
reveal detail behind the part or
the visible edges of an object.
Center
Line: of
Lines
from
the outside
the that
part.define to shorten a long continuous part. (See
Section
Lines are
used to
the center
of Lines:
arcs, circles,
or symmetrical
parts.
example of Long Break Line
define
there
is as
material
They
arewhere
half as
thick
an object line.
on the next slide.)
after a part of the object is cut away.
Construction Line: Very lightly
drawn lines used as guides to help draw
all other lines and shapes properly.
Usually erased after being used.
Slide 3
Alphabet of Lines
Dimension
that
used Line:
to
Cutting
Plane
A line used to
Long Break
Lines:Lines:
BreakLines
lines
are are
used
show detail
distance.
are
on thea part has been cut
to either show
or asArrows
in thisdesignate
casedrawn
theywhere
can
Lines:
Lines
used
to see
show
where
ends
toExtension
show
where
the dimension
line
starts
and The
ends.
detail.
arrows should
be used
to shorten
very
longaway
objects
that
a dimension
and located
stops
on
object.
The
actual
distance
isstarts
usually
ininan
the
middle
of that
this you are
point
the
direction
do not
change
in detail.
Notice
that
this
part
with
dimension
lines
properly
dimension
line
to letlong
youhowever
know thewe
distance
beinglooking
communicated.
at the cutout.
isUsed
12”
havetoshortened
object.with
The
line
1/16”to
from the
Dimension
lines
areislines
used
inaway
conjunction
thean
drawing
break
use
part our
as to
notextension
get
confused
the object lines
with
lineswith
to properly
space
more
efficiently.
dimension objects.
Leader Lines: Leader lines are used to
show dimensions of arcs, circles and to help
show detail. An arrow head is used to point
to the part you are dimensioning and the line comes
off the arrow point usually at a 45 degree angle.
At the end of this line a horizontal line is drawn
with a note at the end telling information
How many lines from the
about what is being pointed at.
previous slide can you identify
here?
Slide 4
Alphabet of lines
Phantom Lines: Phantom lines are used
to identify alternate positions that a part my
take up. In this example we are using Phantom
lines to show that the door handle may only move
45 degrees from it’s horizontal
position.
How many lines from the
previous 2 slides can you
identify here?
Slide 5
Orthographic
(Multiview 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.
Slide 6
Orthographic
(Multiview Drawings)
In order to obtain these straight line
views we have a type of drawing
called Orthographic Projection also
known as Multiview drawings.
Orthographic projection is a way to
project a view based on a line of sight
that is perpendicular to that view.
There are six of these views to any
object as shown in the next slide.
Slide 7
Orthographic
(Multiview Drawings)
The arrows represent the
line of sight associated
with each view.
Use the button
below to jump
between this
view and the ortho
view on the next
page.
ORTHO
Slide 8
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.
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.
Click to go back
to ISO view.
ISO
Slide 9
Orthographic View Selection
Finding the best view of a part can be
difficult. 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.
Slide 10
Orthographic View Selection
Steps in selecting the front.
Most natural position or use.
Shows best shape and characteristic contours.
Longest dimensions.
Fewest hidden lines.
Most stable and natural position.
Relationship of other views
Most contours.
Longest side.
Least hidden lines.
Best natural position.
Slide 11
Orthographic View Selection
Longest Dimension
Most natural position.
Best shape description.
No hidden lines.
Slide 12
Orthographic View Selection Numbers
Another decision on view selection
you need to make is how many views.
You usually do not need more than
three but you may only need one or
two. The following slides will show
when to make a decision between
one, and two view drawings.
Slide 13
One View Selection
Uniform shape.
Two views
will be identical
All dimensions easily
shown on one view.
Slide 14
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.
Slide 15
Two View Selection
Symmetrical parts. A third view
would be identical to the other
views
Second view is necessary for
depth.
Slide 16
Precedence of Lines
In multiple view drawings, many times different line
types will take up the same space, therefore, we
have line precedence. The following is an
explanation of which lines exist over others.
Object lines over hidden and center.
Hidden over center.
Cutting plane lines over center lines.
The following slide will show an example.
Slide 17
Precedence of Lines
An object line here takes preced
over
theprecedence
center line.over
However
Object lines
took
draw
short
lines
the hidden
lines
youthin
would
seebeyond th
to show
there
from the object
hole. The
center
lineisina center
underneath
the depth
object line.
the top view would
show the
of the hole as well as the right
side view.
Slide 18
Do you want to be a good
sketcher?
First Slide
Slide 19
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
Slide 20
Multiview Drawing
A system that allows you to make a
two-dimensional drawing of a threedimensional object
Slide 21
Viewing Objects
A box is formed by
six mutually
perpendicular
planes of projection
that are located
around the object
Slide 22
Viewing Objects
Lines are formed on the planes by
projecting the edges of the object onto
the planes
These images are
called “views”
There are six views
formed by the
planes of a box
Slide 23
Viewing Objects
Unfolding the box produces an
arrangement of the six views
TOP
BACK
L.SIDE
FRONT
BOTTOM
R.SIDE
Slide 24
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
Slide 25
Angles of Projection
Third-angle projection
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
TOP VIEW
FRONT VIEW
RSIDE
Slide 26
Viewing Objects
Each view is placed in
a constant location
relative to the other
views
Each view must be
placed in its correct
position
Views and features
must be aligned
Slide 27
Choosing Views
Most commonly used
views
2.00
TOP VIEW
Front View
Top View
Right Side View
Most descriptive view is
typically designated as
the Front 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
Slide 28
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
Slide 29
Choosing the Views
Objects described in two views
Third view would add nothing to the
description of the object
Carefully select views to describe
shape of objects accurately
Slide 30
Curved Surfaces
Some
curved
surfaces do
not show as
curves in all
views
CYLINDER
CONE
WHEEL
FRUSTRUM
Slide 31
Object Dimensions
All objects have 3
dimensions
HEIGHT
Height
Distance from top
to bottom
Width
Distance from side
to side
Depth
Distance from the
front to back
WI
DT
H
H
PT
E
D
Slide 32
Object Dimensions
Front View
Shows width &
depth
TOP VIEW
WIDTH
Side View
Shows height &
depth
DEPTH
HEIGHT
Top View
DEPTH
Shows width &
height
FRONT VIEW
R. SIDE
VIEW
Slide 33
Drawing Views of Objects
Depth can be projected between
views by using a 45° miter line
TOP VIEW
FRONT VIEW
R. SIDE
Slide 34
Line Types - Visible
Edges that can be seen in a given view
areVisible or Object lines
Visible lines are thick and dark
.028” or .7mm
F or HB lead
FRONT VIEW
Slide 35
Line Types - Hidden
Edges that cannot be seen
from a given view are indicated
by Hidden lines
TOP VIEW
Slide 36
Line Types - Hidden
Drawing hidden lines
.125” (3mm) dashes
.0625” (1mm) spaces between dashes
Thin: .020” (.5mm)
Dark: F or HB lead
.125"
.0625"
Slide 37
Line Types - Hidden
Follow rules for hidden line placement
Alphabet of Lines
Drawings produced with CAD may violate
hidden line rules
Slide 38
Line Types – Center
Center lines indicate
axes of symmetry
TOP VIEW
Slide 39
Line Types – Center
Perpendicular lines for circular objects
Small dashes cross at the center point of
feature
One center line drawn to indicate longitudinal
axis of cylinder or hole
FRONT VIEW
R. SIDE
VIEW
Slide 40
Line Types - Center
Draw center lines using a series of
long and short dashes
.125” (3mm) short dash @ the center
.75”- 1.5” (20mm-40mm) long dash
.0625” (1mm) spaces between dashes
Thin: .02” (5mm)
Long dash extends .125” to .25”
beyond feature
.125"
.75" - 1.5"
.0625"
Slide 41
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
Slide 42
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
Slide 43
Steps for Centering a
Drawing
Add:
Width
Space
Depth
Horizontal
TOP VIEW
5.13
1.50
2.00
8.63
2.00
5.13
2.88
1.63
1.25
Ø2.22
Height
Space
Depth
Vertical
3.00
1.50
2.00
6.50
45°
3.00
2.00
1.75
1.50
FRONT VIEW
R. SIDE
VIEW
Slide 44
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"
Slide 45
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
Slide 46
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
Slide 47
Multiview Drawing
Slide 48
Straight Edges
6
5
B
2
1
A
4
Edges that are
perpendicular to a
plane of projection
appear as a point
3
1
6
2
4
B
5
5
6
3
2
A
1
5
5
6
4
1
1
A
2
4
B
B
2
6
3
3
A
1
5
5
6
4
1
1
A
2
4
B
B
2
6
2
A
4
3
A
1
6
5
B
2
4
1
1
A
B
2
A
4
Slide 49
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
NGT
H
POINT
VIEW
FORESHORTENED
FORESHORTENED
Slide 50
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
Slide 51
Normal Surfaces
Normal surfaces appear as an edge in
two opposite principal views, and
appear a surface in all other principal
views.
Slide 52
Inclined Surfaces
Inclined surfaces appear as an edge
in two opposite principal views, and
appear foreshortened (not true size)
in all other principal views.
Slide 53
Oblique Surfaces
Oblique surfaces do not appear either
as an edge or true size in any
principal view.
Slide 54
Intersections & Tangencies
Where a curved surface is tangent to
a plane surface, no line should be
shown where they join
NO LINE
NO
LINE
Slide 55
Intersections & Tangencies
Where a plane surface intersects a
curved surface, an edge is formed
LINE
LINE
Slide 56
Intersections & Tangencies
Where the plane surface is horizontal
or vertical, exceptions to these rules
may occur
LINE
VERTICAL
SURFACE