1. ISOMETRIC DRAWINGS
LECTURE NO. - 02

2. What is
PROJECTION?

3. PROJECTION METHOD
Perspective
Parallel
Oblique
Orthographic

4. MEANING
Orthographic projection is a parallel projection technique in which the parallel lines of sight are perpendicular to the projection plane 1 2 5 3 4

5. ORTHOGRAPHIC VIEW Two dimensions of an object is shown.
Orthographic view depends on relative position of the object to the line of sight.
Rotate
Two dimensions of an
object is shown.
Tilt
More than one view is needed
to represent the object.
Multi-view drawing
Three dimensions of an object is shown.
Axonometric drawing

6. OBJECT REPRESENTATION
Orthographic projection technique can produce….
Axonometric projection ~ that shows all three dimensions of an object in one view.
Multiview projection ~ that each view show an object in two dimensions.
Both drawing types are used in technical drawing for communication.

7. PROJECTION METHOD Perspective Parallel Oblique Orthographic
Axonometric
Multiview

8. Fundamentals of Projection

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

10. ORTHOGRAPHIC PROJECTION
1st angle system
3rd angle system

11. ORTHOGRAPHIC VIEWS Folding line Folding line Folding line Folding line
1st angle system
3rd angle system
Folding
line 
Folding
line
Folding
line 
Folding
line

12. ORTHOGRAPHIC VIEWS Top View Right Side View Front View Top View
1st angle system
3rd angle system
Top View
Right Side View
Front View
Top View
Front View
Right Side View

13. PROJECTION SYMBOLS
First angle system
Third angle system

14. Projection Symbol

15. Projection Symbol - explained

16. AXONOMETRIC DRAWING Why have you drawn ORTHOGRAPHIC VIEWS?
Right Side View
Front View
Is it easy to visualize that the actual object of the given orthographic views looks like this?
To give idea about shape of the final object.
Top View
AXONOMETRIC DRAWING

17. Axonometric Projection
Because even a simple drawing can be better visualized by this drawings. C D A B D F G C A B G E F C D

18. Axonometric Projection
Line of
sight D
Parallel & normal
to picture plane C A B D
How can the Axonometric Drawing be explained? A C B
How exactly can the cube be placed ?

19. Axonometric Projection
Type of axonometric drawing A B C D a b c
1. Isometric
All angles are equal. A B C D a b c
2. Dimetric
Two angles are equal. b a c
3. Trimetric
None of angles are equal.

20. Isometric Projection Non-Iso Lines Isometric axis TERMINOLOGIESb c
Non-Iso Lines
Isometric axis
TERMINOLOGIES
Iso-Lines

21. All edges foreshorten about 0.8 time.
But there is a PROBLEM!!!
All edges foreshorten about 0.8 time.
We can not take measurements directly from the figure.

22. Isometric drawing / View
Isometric drawing is a drawing drawn on an isometric axes using full scale.
Isometric projection
(True projection)
Isometric drawing / View
(Full scale)
Foreshortened
Length
Full scale

23. Positions of Isometric Axes
Before we start learning how to draw isometric views / projections, there is one more concern…

24. Positions of Isometric Axes
Isometric axes can be arbitrarily positioned to create different views of a single object.
Regular
isometric
Reverse axis
isometric
Long axis
isometric
View point is looking
down on the top of
the object.
View point is looking
up on the bottom of
the object.
View point is looking
from the right (or left)
of the object.

25. To explain the method let us take the example of cube again...
Isentropic Projection
How to draw Isentropic Views? A C B D C
To explain the method let us take the example of cube again... B D C H F E G F G E A D B A F
Vertical iso-lines are drawn either along vertical isometric axis or parallel to it.
Horizontal iso-lines are drawn either along inclined isometric axis or parallel to it. C B D C

26. Let us start with a plane
Regular isometric
Isentropic View
Let us start with a plane A B D
300
c’, (b)
d’, (a) C y x a b
TV of a SQUARE B C A D c d

27. Isentropic View In case of a rectangle? TV Regular isometric A D B
c’, (b)
d’, (a) C y x b a TV B C A d c D

28. Isentropic View FV of a SQUARE Regular isometric B a' b' A C c' d' D xy
a, (d)
b, (c)

29. C/W: Sketch from multi-view drawing:FV FV TV TV
FV & TV

30. Circle & Arc in Isometric
In isometric drawing, a circle appears as an ellipse.
Sketching Steps
1. Locate the centre of an ellipse.
2. Construct an isometric square.
3. Sketch arcs that connect the tangent points.

31. Circle & Arc in Isometric
Four-centre method is usually used when drawn an isometric ellipse with drawing instrument.
Sketching Steps
1. Locate the centre of an ellipse.
2. Construct an isometric square.
3. Construct a perpendicular bisector from each tangent point.
4. Locate the four centres.
5. Draw the arcs with these centres and tangent to isometric square.

32. Sketch from multi-view drawingof
SOLIDS
1. Interpret the meaning of lines/areas in multi-view drawing.
2. Locate the lines or surfaces relative to isometric axis.

33. Example 1 : Object having only normal surfacesD
b‘, (c’)
Top
a‘, (d’) A
Front View H H
Front C
Side B
p‘, (s’) W
q‘, (r’) P W R
c, (r) D
d, (s)
Top View D Q
a, (p)
b, (q)

34. Example 1 : Object having only normal surfaces
Top
Side
View
Front View H H
Front
Side D W W D
Top View

35. Example 2 : a' b' (e’) c' d' p' q' (t’) r' s' e, (t) d, (s) a, (p)
c, (r)
b, (q)

36. Example 3 : o' p' q'
(t‘) r' s' t p s o r q

37. Example 4 :

38. Example 4/A :

39. Example 5 :

40. Example 6 : D
Nonisometric line q H y y x W x
Front View

41. Example 7 : x x B x
Nonisometric line y A C x B A y C B A

42. Example 8:

43. Irregular Curve in Isometric
Example 9:
Irregular Curve in Isometric
Steps
1. Construct points along the curve in multiview drawing.
2. Locate these points in the isometric view.
3. Sketch the connecting lines.

44. ISOMETRIC VIEW
Composite Solids

45. Objects are decomposed into solid geometric primitives.
BASIC IDEA
Objects are decomposed into solid geometric primitives.
Some of familiar solid objects
Rectangular prism
Cylinder
Negative cylinder (Hole)

46. Objects are decomposed into solid geometric primitives.
BASIC IDEA
Objects are decomposed into solid geometric primitives.
Some of familiar solid objects
Cone
Pyramid
Sphere

47. Example 10:

48. Example 11:

49. Example 12:

50. simple machine components
Isometric Views
for
simple machine components
1. Orient yourself with the views given. (Choose the viewing direction.)
2. Read the individual surfaces that appeared in each view and related to each other.
3. Create a proper solid geometric primitive from each reading.
4. Assembly all of solid geometric primitive
according to orthographic views.

51. EXAMPLE -13:
Composition
Given
Rectangular prism
Hole
Front View

52. EXAMPLE -14:
Given
Composition
Rectangular prism
Cylinder
Front View

53. Example 15 B A C D F E x
Front View y B D C E F A

54. EXAMPLE -16: Composition Given Cylinder with a blind hole.
L-shaped with round end
Hole

55. EXAMPLE -17:
Composition
Given
Wedge

56. EXAMPLE -17:
Composition
Given
Wedge
L-shaped block

57. Example 18

58. Example 18