1. Multi-view Projection Drawing
CHAPTER 5

2. Content Projection Theory Multi-view Projection [Planes | Lines]
Multi-view [6 principle views | View placement]
Projection angle [1st angle | 3rd angle]
Detail drawing [1-view | 2-view | 3-view drawing]
Creating multi-view drawing
View selection
Line convention
Common feature in multi-view drawing

3. 5.1 Projection Theory
Engineering and technical graphics are dependent on projection methods
2 methods primarily used
Parallel: object positioned at infinity & viewed from multiple points on an imaginary line parallel to the object
Perspective: object position at finite distance & viewed from a single point
Parallel
Perspective

4. 5.1 Projection Theory
Projection theory comprises of the principles used to graphically represent 3D objects on 2D media
Based on 2 variables:
Line of Sight (LOS): an imaginary ray of light between and observer’s eye and an object. Parallel – all LOS are parallel; perspective – all LOS start at a point
Plane of projection: an imaginary flat plane where the image created by LOS is projected.

5. 5.1 Projection Theory
Orthographic projection: a parallel proj. technique where the proj. plane is placed between observer and object and is perpendicular to the parallel lines of sight
Changing view point

6. Perspective Projections
5.1 Projection Theory
Projections
Perspective Projections
Parallel Projections
Linear Perspective
Aerial Perspective
Oblique
Projections
Orthographic
Projections
Axonometric
Projections
Multiview
Projections

7. 5.1 Projection Theory: Multi-view

8. 5.1 Projection Theory

9. 5.2 Multi-view projection
Multiview projection is an orthographic projection for which the object is behind the plane of projection, and the object is orientated such that only two of its dimensions are shown.
object
Projection plane
Orthographic projection – Front View

10. 5.2 Multi-view projection
Multiview drawings
Employ multiview projection technique
Generally three views of an object are drawn
Each view is a 2D flat image

11. 5.2 Multi-view projection
Right side view
Top view

12. 5.2 Multi-view projection
Multiview drawing of an object

13. 5.2 Multi-view: Lines
Lines in multi-view projection

14. 5.2 Multi-view: Lines

15. 5.2 Multi-view: Planes

16. 5.2 Multi-view: Planes

17. 5.3 Multi-view: The 6 principal views
The 6 principal views are the six mutually perpendicular views that are produced by six mutually perpendicular planes of projection
Imagine an object is suspended in a glass box, the 6 sides become projection plane showing the six views

18. 5.3 Multi-view: The 6 principal views
The views are front, rear, top, bottom, left and right
Front view
the 1st to be established
Shows the most features
All other views are based on the orientation chosen for the front view

19. 5.3 Multi-view: The 6 principal views
The views are laid flat by “unfolding the glass box”
This forms the basis of two important multiview drawing standard
Alignment of views
Fold lines
Top, front and bottom views are all aligned vertically & share the same width dim.
Rear, left, front and right side are aligned horizontally & share same height dim.

20. 5.3 Multi-view: The 6 principal views
Fold lines – are the imaginary hinged edges of the glass box
The fold line between the top & front views is labeled H/F
The distance from a point in front view to the H/F is the same as the distance from the corresponding point in the top view to the H/F fold line

21. 5.4 Multi-view: View Placement
The three-view drawing is the standard used in engineering, as normally other three principal views are mirror images
The standard views – top, front & right
The width dim. are aligned between the front & top view using vertical projection lines
The height dim. are aligned between the front & right side view, using horizontal projection lines
The depth dim. are aligned between top & right side view, using scale, miter line or compass

22. 5.4 Multi-view: View Placement

23. 5.4 Multi-view: View Placement
The arrangement of views may vary as shown, where the top view is considered the central view
Alternate view arrrangement

24. 5.4 Multi-view

25. 5.5 1st- and 3rd-angle projection
There are two standard arrangement of all six views of an object
First-angle projection
Third-angle projection
Each uses a different symbol
The names are derived from the method used to view the object being drawn

26. 5.5 1st- and 3rd-angle projection
In first-angle projection, the object is placed in the first quadrant
In third-angle projection, the object is placed in the third quadrant

27. 5.5 1st- and 3rd-angle projection
Brief rules
1st angle projection
3rd angle projection
View from above is placed underneath
View from above is place above
View from below is placed above
View from below is placed below
View from left is placed on right
View from left is placed on left
View from right is placed on left
View from right is placed on right
Symbols

28. 5.5 1st- and 3rd-angle projection
Third-angle projection
First-angle projection

29. 5.6 One-view & two-view drawings
Three-view
One-view

30. 5.6 Two-view drawings
Examples
Two-view

31. 5.6 Two-view drawing
Creating 2-view sketching 1 2

32. 5.6 Two-view drawing 3 4

33. 5.6 Steps in creating multi-view drawing
SKETCH
DRAW
READ
Decide:
Projection angle, Location of view, Scale
Prepare paper
-> Draw border
-> Title block
-> etc.
TOP
FRONT
SIDE
height
depth y
y = (total length – height – depth)/3
Construct view (outline)
-> Using thin pencil
-> Measure & place view
-> Project all views
-> Final lining: hidden & centre lines (thin), arcs & circles (thick)
Lining views
-> Line in the rest of the lines
-> Start from top left
-> Construction lines may be left if thin enough
Finish drawing
-> Dimension, notes, etc.
-> Finish off title block, etc.

34. 5.6 3-view dwg Before start drawing, produce sketch on rough paper
Decide on front view and projection angle
Obtain the overall width, height and depth
Place the views (in block)
Determine approx. space between the views
Sketch the component, place dimensions

35. 5.6 Creating 3-view drawing
(1) Drawing of border/frame and location of view
(2) Light construction of view (inc. title block frame)
(3) Lining in the views
(4) Dimensioning and inserting of any subtitles and notes
(5) Drawing title block, parts list and revision table

36. 5.6 Creating 3-view drawing
(1) Draw border/frame, title block, etc.
Draw border, title block
Locating the view
should be approx. in centre
distance between view =
(total length available –
view length) / 3
Drawing projection lines

37. 5.6 Creating 3-view drawing
Projecting views

38. 5.6 Creating 3-view drawing
(2) Light construction of the views
Draw light/thin horizontal & vertical lines accordingly for front view
Draw center lines and hidden lines as final
Draw top (or side) view
Project top view (or side) from front view using thin, light construction line
Draw side (or top) view
Project side view (or top) from front view and top (or side) view
All arcs and circles should be lined (final) at this stage

39. 5.6 Creating 3-view drawing
(3) Lining in of the views
To darken all visible edges (lines that represent a hard edge)
Done using thick, black pencil (0.5mm, 2B)
Should be done systematically for 3 views
Start with horizontal line at the top of the top/plan view, working down the page using T-square
From left hand side, working across the page, line in all vertical lines, using T-square and set square
Projection lines may be left on the drawing if they are very light

40. 5.6 Creating 3-view drawing
(4) Write dimensioning, notes, annotation, etc.
Be aware of redundant dimensioning
(5) Complete drawing by writing the rest of title block, parts list & revision table, and others.

41. 5.7 View Selection 4 basic decisions
(1) Determine the best position. The object must be positioned in such a way that the surface of major features are either perpendicular or parallel to glass planes.
(1)

42. 5.7 View Selection
(2) Define the front view. Should show the object in natural state and show most features.
(2)

43. 5.7 View Selection
(3) Determine the minimum number of views needed to completely describe the object.
(4) Determine other views that have fewest number of hidden lines
(3)
(4)

44. 5.8 Line convention
Hidden lines
Centre lines
Hidden features

45. 5.8 Line convention
Hidden lines
Drawing conventions for hidden lines

46. 5.9 Primitive shape

47. 5.9 Primitive shape

48. 5.9 Runouts

49. 5.10 Exercise: Missing views

50. 5.10 Exercise: Missing views

51. END OF CHAPTER 5