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Multi-view Projection Drawing

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Multi-view Projection ... Missing views END OF CHAPTER 5 Multi-view Projection ... Projections Orthographic projection Front View Projection ... – PowerPoint PPT presentation

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Title: Multi-view Projection Drawing


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 observers 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
5.1 Projection Theory
Projections
Perspective Projections
Parallel Projections
Oblique Projections
Orthographic Projections
Linear Perspective
Aerial Perspective
Multiview Projections
Axonometric 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
  • Symbols

28
5.5 1st- and 3rd-angle projection
Third-angle projection
First-angle projection
29
5.6 One-view two-view drawings
One-view
Two-view
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 -gt Draw border -gt Title block -gt
etc.
Construct view (outline) -gt Using thin pencil -gt
Measure place view -gt Project all views -gt
Final lining hidden centre lines (thin), arcs
circles (thick)
Lining views -gt Line in the rest of the lines -gt
Start from top left -gt Construction lines may be
left if thin enough
Finish drawing -gt Dimension, notes, etc. -gt
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
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