Isometric Drawing1
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ME 101
ENGINEERING GRAPHICS
Dr. Ouzhan YILMAZ (Assist.Prof.)Mechanical Engineering Department
Room: 319
http://www.gantep.edu.tr/~oyilmaz
The University of Gaziantep
Isometric Drawing
Faculty of Engineering
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Introduction and Objectives
ME 101
Dr. Ouzhan Ylmaz
Isometric Drawing
This lecture introduces the concept of Isometric projection and Isometricdrawing of an object.
Followings will be highlighted to be able to explain the Isometric drawing:
Axonometric projection
Isometric projection
Isometric drawing Isometric and non-isometric lines (Boxing and offset methods)
Angles in isometric drawing
Curves in isometric drawing
Circles in isometric drawing (Four center ellipse)
Isometric circle arcs
Students are required to understand the fundamentals of isometric drawing
and the technical and practical details while drawing of an object.
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Axonometric Projection
ME 101
Dr. Ouzhan Ylmaz
Isometric Drawing
AB
CD
Parallel & normal
to picture plane
Line
of
sight A
B
CD
Is a parallel projection technique
used to create a pictorial drawing of an
object by rotating the object on an axis
relative a projection or picture plane.
Axonometric projection is one of the
four principal projection techniques:
multiview, axonometric, oblique and
perspective
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Axonometric Projection
ME 101
Dr. Ouzhan Ylmaz
Isometric Drawing
In Multi views andaxonometric
projections, the
lines of sight are
perpendicular to the
plane of projection;
therefore, both are
considered
orthographic
projections
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Axonometric ProjectionType of axonometric drawing
a
b c2. Dimetric Two angles are equal.
b
a
c3. Trimetric None of angles are
equal.
a
b c1. Isometric All angles are equal.
A
B
CDA
B
C
D
Axonometric axis
Axonometric axis
Axonometric axis
ME 101
Dr. Ouzhan Ylmaz
Isometric Drawing
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Isometric Projection
ME 101
Dr. Ouzhan Ylmaz
Isometric Drawing
Rotate 45
about vertical axis
Tilt forward(35o16)
All edges foreshortenabout 0.8 time.
An isometric projection is a
true representation of the
isometric view of an object.
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Isometric Drawing
ME 101
Dr. Ouzhan Ylmaz
Isometric Drawing
Isometric projection(True projection)
Isometric drawing(Full scale)
Forshorten
Full scale
Isometric drawing is a drawing drawn on an isometric axes using ful l scale.
Isometric drawings are almost always preferred over isometric projection forengineering drawings, because they are easier to produce
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Isometric Axes
ME 101
Dr. Ouzhan Ylmaz
Isometric Drawing
An isometric drawing is an axonometric pictorial drawing forwhich the angle
between each axis equals 120 degrees and the scale used is full scale
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Positions of Isometric axes
ME 101
Dr. Ouzhan Ylmaz
Isometric Drawing
Regular
isometricReverse 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.
Isometric axes can be arbitrarily positioned to create different views of a
single object.
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Selection of Isometric axes
ME 101
Dr. Ouzhan Ylmaz
Isometric Drawing
View (a) is preferred as it reveals more detail than the others
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Isometric and Non-isometric lines & planes
ME 101
Dr. Ouzhan Ylmaz
Isometric Drawing
In an isometric drawing, true length
distances can only be measured alongisometric lines, that is, lines that run
parallel to any of the isometric axes.
Any line that does not run parallel to an
isometric axis is called a non-isometric
line
Non-isometric lines include inclined and
oblique lines and can not be measured
directly. Instead they must be created by
locating two end points.
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ME 101
Dr. Ouzhan Ylmaz
Isometric Drawing
Isometric and Non-isometric lines & planes
The three faces of the isometriccube are isometric planes, because
they are parallel to the isometric
surfaces formed by any two
adjacent isometric axes.
Planes that are not parallel toany isometric plane are called non-
isometric planes
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Isometric and Non-isometric lines & planes
ME 101
Dr. Ouzhan Ylmaz
Isometric Drawing
Isometr ic l ineis the line that run parallelto any of the
isometric axes.
Isometric axes
True-length distances are shown along
isometric lines.
Nonisometric linesIsometric lines
Isometric planes
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ME 101
Dr. Ouzhan Ylmaz
Isometric Drawing
Isometric drawing
The Boxing-in Method for Creating Isometric Drawings
Thefour basic steps for creating an isometric drawing are:
1. Determine the isometric viewpoint that clearly depicts the features of the
object, then draw the isometric axes which will produce that view-point.
2. Construct isometric planes, using the overall width (W), height (H), and depth(D) of the object, such that the object will be totally enclosed in a box.
3. Locate details on the isometric planes.
4. Darken all visible lines, and eliminate hidden lines unless absolutely
necessary to describe the object.
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ME 101
Dr. Ouzhan Ylmaz
Isometric Drawing
Isometric sketching
from multi-view drawing
Top View
Front View
Side View
Bottom
Front
Side
Side
Front
Top
Regular
Reverse
WD
H
H
DW
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ME 101
Dr. Ouzhan Ylmaz
Isometric Drawing
Isometric drawing
STEPS
1. Positioning object.
2. Select isometric axis.
3. Sketch enclosing box.
4. Add details.
5. Darken visible lines.
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ME 101
Dr. Ouzhan Ylmaz
Isometric Drawing
Isometric drawing
1. Positioning object.
2. Select isometric axis.
3. Sketch enclosing
box.4. Add details.
Note In isometric sketch/drawing), hidden lines are omit ted
unless they are absolutely necessary to completely
describe the object.
STEPS
5. Darken visible lines.
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ME 101
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g
Isometric drawing: object has inclined surfaces
W
H
D
y
x Front View
y
x
Nonisometric line
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ME 101
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g
Isometric drawing: object has inclined surfaces
Nonisometric line
A
A x
y
x
xB
B
AB
C
C
C
x
y
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g
Isometric drawing
A
A
B
B
C D
E
D
EF
F
x
y
Front View
Regular
C
Reverse
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Drawing of Circle and Arcs
In isometric drawing, a circle appears as an ellipse.
2. Construct an isometric square.3. Sketch arcs that connect the
tangent points.
Sketching Steps
1. Locate the centre of an ellipse.
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Drawing of Circle and Arcs
3. Construct a perpendicular
bisector from each tangent point.
4. Locate the fourcentres.
5. Draw the arcs with these centres
and tangent to isometric square.
Sketching Steps
Four-centremethod is usually used when drawn an
isometric ellipse with drawing instrument.
2. Construct an isometric square.
1. Locate the centre of an ellipse.
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Drawing of Circle and Arcs
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Drawing of Circle and Arcs
Half circleQuarter circle
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Drawing of Irregular curves in Isometric drawing
1. Construct points along the
curve in multiview drawing.
2. Locate these points in theisometric view.
3. Sketch the connecting lines.
Steps
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Hidden lines in Isometric drawing
In isometric drawings, hidden lines areomitted unless they are absolutely
necessary to completely describe the
object. Most isometric drawings will not
have hidden lines.
To avoid using hidden lines, choose themost descriptive viewpoint.
However, if an isometric viewpoint
cannot be found that clearly depicts all the
major features, hidden lines may be used.
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Center lines in Isometric drawing
Centerlines are drawn only for showing symmetry or fordimensioning.
Normally, centerlines are not shown, because many isometric drawings are usedto communicate to nontechnical people and not for engineering purposes