CHAPTER 3. MULTI-VIEW DRAWING 1.pptx

ADDIS ABABA SCIENCE AND
TECHNOLOGY
UNIVERSITY
Collage of Electrical and Mechanical
Engineering
Department of Mechanical Engineering
COURSE :ENGINEERING DRAWING [Meng1011]

TOPICS
SYSTEM OF PROJECTION
CHOICE OF VIEWS
LAYING OUT DRAWINGS AND RELATION BETWEEN
HEIGHT, DEPTH AND WIDTH
ONE VIEW, TWO VIEW AND THREE VIEW DRAWINGS
PROJECTION OF CURVE ,INCLINDE, OBLIQUE AND
INTERSECTION AND TANGENTS
LINE CONVENTION

A plane of projection (POP) is a plane on which a particular
view is projected.
Three such planes, perpendicular to each other, are called
principal planes or reference planes (RP).
 When the observer looks at the object from the front, the
view obtained is called the front view or elevation and is
seen on the vertical plane (VP)/ frontal plane (FP).
 When the observer looks at the object from above, the view
obtained is called top view or plan and is seen on the
horizontal plane (HP).
 When the observer looks at the object from side, i.e., from
his left-hand side or right-hand side, the view obtained is
called side view and is seen on the profile plane (PP).

First Angle Projection: the object is placed in the first
quadrant. This means that the Vertical Plane is behind the
object and the Horizontal Plane is underneath the object.
 The object lies in between the observer and the planes
of projection.
Third Angle Projection: The Object is placed in the Third
Quadrant. This means that the Vertical Plane is in front of
the object and the Horizontal Plane is above the object.
 The Plane of projection lie between the object and the
observer.

1. First angle system
2. Third angle system
First Quadrant
Third
Quadrant
- European country
- ISO standard
- Canada, USA,
Japan, Thailand

1st angle system 3rd angle system

Folding
line
Folding
line
Folding
line
Folding
line

Front View
Front View
Right Side View
Right Side View
Top View
Top View

First angle system Third angle system
Projection Symbols

d 1.7d
2.2d
Suggested proportion
Projection Symbols

CHOICE OF VIEWS
16
 Most commonly used views
 Front View
 Top View
 Right Side View
 Steps for Choice of views
 Orient the object to the best position
 Select the front view
 Select adjacent views

STEP 1 : Orient the Object
The object should be placed in its natural position.
NO !
The object should presents its features in actual size and
shape in orthographic views.
GOOD
17
CHOICE OF VIEWS

STEP 2 : Select a Front View
The object’s longest dimension should be presented as a width.
Inappropriate
First choice
GOOD
Second choice
Waste more space
18
CHOICE OF VIEWS
Most descriptive view is typically designated as the Front View

Inappropriate
The adjacent views that are projected from the selected
front view should appear in its natural position.
19
CHOICE OF VIEWS

Choose the view that have the fewest number of
hidden lines.
GOOD Inappropriate
20
CHOICE OF VIEWS

STEP 3 : Select an Adjacent View
GOOD
Inappropriate
Inappropriate
GOOD
Choose the view that have the fewest number of hidden lines.
21
CHOICE OF VIEWS

Choose the minimum number of views that can represent
the major features of the object.
Necessary
Necessary
Hole’s location can be specified
on the same view.
Difficult to interprete.
Easy to understand
22
CHOICE OF VIEWS

Choose the views that are suitable to a drawing space.
POOR
Not enough space
for dimensioning.
23
CHOICE OF VIEWS

Choose the views that are suitable to a drawing space.
GOOD
24
CHOICE OF VIEWS

Example : View selection
Shape description
Size description
F.V.
W D

W
H

D
mislead to…




F.V. & T.V. Three views F.V. & R.S.V.
H
25
CHOICE OF VIEWS

3.3
ONE VIEW, TWO VIEW AND
THREE VIEW DRAWINGS

ONE-VIEW DRAWING
Thin objects can be described with only one view:
Depth is given in a note
eg. Flat part having a uniform thickness.
Unnecessary These 2 views provide only information
about the part thickness !
1 Thick
27

ONE-VIEW DRAWING
Simple objects can be described with one views
eg. Cylindrical-shaped part.
Unnecessary
Repeat !
Unnecessary
28

TWO-VIEW DRAWING
There exists an identical view.
Repeat !
Unnecessary
29

The 3rd view has no significant contours of the object.
TWO-VIEW DRAWING
Unnecessary
30

TWO-VIEW DRAWING
Unnecessary
The 3rd view has no significant contours of the object.
31

32
Necessary
Necessary
Hole’s location can be specified
on the same view.
Difficult to interprete.
Easy to understand
THREE-VIEW DRAWING
Complex objects require three views to describe its
shape

33
THREE-VIEW DRAWING
Complex objects require three views to describe its shape

35
LAYING OUT DRAWINGS
Hand Layout of a metric three-view drawing

36
LAYING OUT DRAWINGS
Views should be visually balanced within the working space
Draw border (20mm
from left and 5 mm
from each 3 sides) and
title block using light
construction lines
STEP 1
A4
Border line
20
5
28
5
5

37
Determine space desired between the front and right-side views (C), and front
and Top views (C) say 20 or 30 mm. Add
STEP 2
To set equal distances to the paper
edge, subtract this total from the
sheet width (Ws=185), and height
(Hs=259) then divide the remaining
number by two.
A = (Ws - H)/2
B = (Hs - V)/2

38
1st Angle
Projection
Set off vertical and horizontal spacing measurements with
light tick marks along the edge of the sheet and draw
construction lines
STEP 3
Dimension take
from the object

39
STEP 3
Set off vertical and horizontal spacing measurements with
light tick marks along the edge of the sheet and draw
construction lines
Dimension take
from the object
3rd Angle
Projection

40
Construct the views : add hidden lines and darken final lines.
STEP 4
1st Angle
Projection

41
Construct the views : add hidden lines and darken final lines.
STEP 4
3rd Angle
Projection

1st Angle Projection
LAYING OUT DRAWINGS

3rd Angle Projection
LAYING OUT DRAWINGS

44
The three-view drawing is the standard used in engineering,
as normally other three principal views are mirror images.
The standard views – TOP, FRONT and RIGHT.
All objects have 3 dimensions
 Height : Distance
from top to bottom
 Width : Distance
from side to side
 Depth: Distance
from the front to
back
R/N B/N HEIGHT, DEPTH AND WIDTH

 The width dimensions are aligned between the
front and top view using vertical projection lines.
 The height dimensions are aligned between the
front and side views, using horizontal projection
lines.
 The depth dimensions are aligned between top
and side views, using scale, miter line or compass.
45

46
Top View
Front View RS.View
Width
Height
Depth
Width
Height
Depth

PRECEDENCE OF LINE
Visible
line
Order of
importance
Hidden
line
Center
line

HIDDEN LINE PRACTICE
Hidden line should join a visible line, except it
extended from the visible line.
Correct
No !
Join
Leave
space

Correct No !
Hidden line should join a visible line, except it
extended from the visible line.
Leave
space
Leave
space

Hidden line should intersect to form L and T
corners.
Correct
No !
L T

Hidden arcs should start on a center line.

 Make a hidden line “jump” a
visible line when possible.
 Draw parallel hidden lines so
that the dashes are staggered,
as in bricklaying.

 When two or three hidden
lines meet at a point, join the
dashes, as shown for the
bottom of this drilled hole.
 The same rule of joining the
dashes when two or three hidden
lines meet at a point applies for
the top of this countersunk hole..

CENTER LINE PRACTICE
In circular view, short dash should cross at the
intersections of center line.
For small hole, center line is presented as thin
continuous line.
Center line should not extend between views.
Leave space Leave space

Leave the gap when centerline forms a
continuation with a visible or hidden line
Leave
space
Leave
space
Leave
space
Leave
space
Center line should always start and end with
long dash.
CENTER LINE PRACTICE

3.6.
PROJECTION OF CURVE
,INCLINDE, OBLIQUE AND
INTERSECTION AND TANGENTS

PROJECTION OF 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

PROJECTION OF NORMAL SURFACES
Normal surfaces appear as an edge in two
opposite principal views, and appear a
surface in all other principal views.
59

PROJECTION OF INCLINED SURFACES
• Inclined surfaces appear as an edge in two opposite
principal views, and appear foreshortened (not true size)
in all other principal views.
60

PROJECTION OF OBLIQUE SURFACES
• Oblique surfaces do not appear either as an
edge or true size in any principal view.
61

NO LINE
NO
LINE
PROJECTION OF INTERSECTIONS &
TANGENCIES
• Where a curved surface is tangent to a plane
surface, no line should be shown where they join

TANGENCIES
• Where a plane surface intersects a curved
surface, an edge is formed
LINE
LINE

TANGENCIES
• Where the plane surface is horizontal or
vertical, exceptions to these rules may occur
LINE
VERTICAL
SURFACE

Example 1. Using the first angle projection system,
draw the three principal view of the object whose
pictorial drawings are given below.

Example 2. Using the first angle projection system,
draw the three principal view of the object whose
pictorial drawings are given below.

CHAPTER 3. MULTI-VIEW DRAWING 1.pptx

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