Pararallel Projections by TR59h6Z


            Engineering Drawing Essentials

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Further Reference

Download your copy of ISO 128/129 from:

Accessible by PolyU staffs and students
 on campus only
Relative position of views

 First angle projection      Third angle projection
Overriding Default View Positions
 The use of reference
  arrows permits the
  various views to be freely
 Each view shall be
  identified by a capital
  letter and a reference
 The identifying capital
  letters shall be placed
  immediately below or
  above the relevant views
Special Views
 Direction of viewing
  different from those of
  standard projection
 View cannot be placed in
  its correct position
 Partial views may be
  used may be used where
  complete views would not
  improve the information
  to be given
Choice of Views
Principle view:
  Most informative
  Functioning position
  Main position of manufacturing or mounting
Other views:
  As few as possible
  As few sections as possible
  Avoid the need of hidden outlines and edges
  Avoid unnecessary repetition of details
Layout of Views on Paper
Types of Lines
            Section Views

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Section Views
 The object is imagined to be cut by a plane & the portion nearer to
  observer is removed.
 The interior is exposed & shown in continuous lines
 Hatching is applied at the plane of cutting

                                         The object is cut with the front
                                                 part removed
Section Views
 Use a thin chain line w/ thick continuous lines at both ends to
  represent the imaginary cutting plane
 Label the sectional view
 Draw cutting line on a view adjacent to the sectional view
 Add label & viewing direction
 Since sectional cutting is imaginary, all other views remain uncut

                                                  Normal top & side views,
                                                  plus a sectional front view

                               SECTION A_A
Cutting Plane Variations
Special Cases
Half Sections and Local Sections
True and Imaginary intersections
 Imaginary intersection
  lines such as fillets or
  rounded corners may be
  indicated in a view by
  means of continuous thin
  lines not touching the
 Simplified representations
  of true intersection lines
  may be applied provide
  that they do not affect the
  comprehensibility of the
Symmetrical parts
Interrupted Views and Simplified
Close-up Views and Initial Outlines
Texture and Materials
 The use of colours on
  technical drawings is
  not recommended
 All object made of
  transparent material
  should be drawn as
 Colour and texture
  specified in separate

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