ENGINEERING DRAWING

SKKK 1021

ISOMETRIC DRAWING

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Agus Arsad, Azizul Azri Bin Mustaffa

LEARNING OUTCOMES

ISOMETRIC DRAWING

It is expected that students will be able to:

• Understand the significance of

isometric drawing

• Apply the basics method of isometric

drawing

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ISOMETRIC DRAWING

• INTRODUCTION

• SIGNIFICANCE

• TRUE LENGTH

• BASIC METHOD

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INTRODUCTION

• Isometric drawing method shows the

drawing in 3-D

• The real shape of an object can be

easily interpreted by using isometric

drawing

• The construction of an isometric

drawing can be made by viewing the

object from certain angle and

directions. 10/2/2012 4

SIGNIFICANCE

• In this Chapter, you will be constructing isometric

drawings from given orthographic projections of an

object.

• Isometric drawing is important to engineering

designers as the drawing shows clearly what that has

been designed

• It is also useful for equipment designers as they can

easily interpret the method of construction of an

object or equipment.

• This type of drawing also can cope with beginners of

someone who has no basics in engineering drawing

unlike orthographic drawing.

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TRUE LENGTH

• Every measurements that are transferred to

the isometric drawing is in its true length of

the object

• However, only vertical & horizontal lines in

orthographic drawing can be transferred

directly to isometric drawing.

• Inclined, oblique lines, circles and others

however cannot be transferred directly and

must be drawn using certain techniques

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Distance in Isometric Drawing

Isometric line is the line that run parallel to any of

the isometric axes.

Isometric axes

True-length distances are shown along

isometric lines.

Nonisometric lines

BASIC METHODS

• Isometric drawing is built on 3 main axis

namely the vertical axis and two 30 degrees

axis from a horizontal line to the left and

right of the vertical axis

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Vertical Axis

30 degrees axis

30 degrees axis

Horizontal line

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Isometric Drawing and Scale

Isometric drawing is a drawing drawn on an isometric

axes using full scale.

Isometric projection (True projection)

Isometric drawing (Full scale)

Foreshorten

Full scale

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2. Define an isometric axis.

3. Sketching the enclosing box.

4. Estimate the size an and relationship of

each details.

5. Darken all visible lines.

1.Place the object in the position which its

shape and features are clearly seen.

Sketch from an actual object

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1. Positioning object.

2. Select isometric axis.

3. Sketch enclosing

box.

4. Add details.

Note In isometric sketch/drawing), hidden lines are omitted

unless they are absolutely necessary to completely

describe the object.

Sketch from an actual object

STEPS

5. Darken visible lines.

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Front View

Top View

Side View

Example 1 : Object has only normal surfaces

Bottom View

Side Front

Top

Regular

Reverse

W D

H

H

D W

Bottom

Front Side

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Example 2 : Object has inclined surfaces

W

H

D

y

x Front View

y

x

Nonisometric line

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Nonisometric line

A

A x

y

x

x B

B

A B

C

C

C

x

y

Example 3 : Object has inclined surfaces

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A

A

B

B

C D

E

D

E F

F

x

y

Front View

Regular

C

Example 4

Reverse

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Circle & Arc in Isometric

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 center of an ellipse.

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Circle & Arc in Isometric

3. Construct a perpendicular

bisector from each tangent point.

4. Locate the four centers.

5. Draw the arcs with these centers

and tangent to isometric square.

Sketching Steps

Four-center method is usually used when drawn

an isometric ellipse with drawing instrument.

2. Construct an isometric square.

1. Locate the center of an ellipse.

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Example 5

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Irregular Curve in Isometric

1. Construct points along the

curve in multiview drawing.

2. Locate these points in the

isometric view.

3. Sketch the connecting

lines.

Steps

END

OF

CHAPTER 5

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