# Pararallel Projections by TR59h6Z

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```									                                ISO128
Engineering Drawing Essentials

2012/4/25                                    1
Further Reference

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
positioned
 Each view shall be
identified by a capital
letter and a reference
arrow
 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
method
 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
outlines
 Simplified representations
of true intersection lines
may be applied provide
that they do not affect the
comprehensibility of the
drawing
Symmetrical parts
Interrupted Views and Simplified
Representation
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
non-transparent
 Colour and texture
specified in separate
document

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