CHAPTER 3. VIEW DRAWING

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

2. CHAPTER 3
MULTI-VIEW DRAWING

3. 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

4. 3.1
SYSTEM OF PROJECTION

5. SYSTEM OF PROJECTION
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).

6. SYSTEM OF PROJECTION

7. SYSTEM OF PROJECTION

8. 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.
SYSTEM 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.

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

10. 1st angle system 3rd angle system
SYSTEM OF PROJECTION

11. 1st angle system 3rd angle system
Folding
line
Folding
line
Folding
line
Folding
line
SYSTEM OF PROJECTION

12. 1st angle system 3rd angle system
Front View
Front View
Right Side View
Right Side View
Top View
Top View
SYSTEM OF PROJECTION

13. First angle system Third angle system
SYSTEM OF PROJECTION
Projection Symbols

14. SYSTEM OF PROJECTION
d 1.7d
2.2d
Suggested proportion
Projection Symbols

15. 3.2
CHOICE OF VIEWS

16. 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

17. 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

18. 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

19. Inappropriate
The adjacent views that are projected from the selected
front view should appear in its natural position.
STEP 2 : Select a Front View
19
CHOICE OF VIEWS

20. STEP 2 : Select a Front View
Choose the view that have the fewest number of
hidden lines.
GOOD Inappropriate
20
CHOICE OF VIEWS

21. 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

22. Choose the minimum number of views that can represent
the major features of the object.
STEP 3 : Select an Adjacent View
Necessary
Necessary
Hole’s location can be specified
on the same view.
Difficult to interprete.
Easy to understand
22
CHOICE OF VIEWS

23. Choose the views that are suitable to a drawing space.
STEP 3 : Select an Adjacent View
POOR
Not enough space
for dimensioning.
23
CHOICE OF VIEWS

24. Choose the views that are suitable to a drawing space.
STEP 3 : Select an Adjacent View
GOOD
24
CHOICE OF VIEWS

25. 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

26. 3.3
ONE VIEW, TWO VIEW AND
THREE VIEW DRAWINGS

27. 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

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

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

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

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

32. 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. 33
THREE-VIEW DRAWING
Complex objects require three views to describe its shape

34. 3.4
LAYING OUT DRAWINGS

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

36. 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. 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. 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. 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. 40
Construct the views : add hidden lines and darken final lines.
STEP 4
1st Angle
Projection

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

42. 1st Angle Projection
LAYING OUT DRAWINGS

43. 3rd Angle Projection
LAYING OUT DRAWINGS

44. 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

45.  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
R/N B/N HEIGHT, DEPTH AND WIDTH

46. 46
Top View
Front View RS.View
Width
Height
Depth
Width
Height
Depth
R/N B/N HEIGHT, DEPTH AND WIDTH

47. 3.5.
LINE CONVENTION

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

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

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

51. Hidden line should intersect to form L and T
corners.
Correct
No !
L T
HIDDEN LINE PRACTICE

52. Hidden arcs should start on a center line.
HIDDEN LINE PRACTICE

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

54.  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..
HIDDEN LINE PRACTICE

55. 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

56. 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

57. 3.6.
PROJECTION OF CURVE
,INCLINDE, OBLIQUE AND
INTERSECTION AND TANGENTS

58. 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

59. 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

60. 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

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

62. 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

63. PROJECTION OF INTERSECTIONS &
TANGENCIES
• Where a plane surface intersects a curved
surface, an edge is formed
LINE
LINE

64. PROJECTION OF INTERSECTIONS &
TANGENCIES
• Where the plane surface is horizontal or
vertical, exceptions to these rules may occur
LINE
VERTICAL
SURFACE

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

66. 1ST ANGLE PROJECTION
80
75
60

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

68. 1ST ANGLE PROJECTION
60
50
40

69. END
OF
CHAPTER
THREE