### ISOMETRIC PROJECTION RATHER DRAWING

```ISOMETRIC PROJECTION
RATHER DRAWING
DEEPAK SAMEER JHA
LOVELY SCHOOL ENGINEERING
WHAT DO YOU UNDERSTAND
LOOKING AT THE FIGURES SHOWN
BELOW?
SQUARE
PLANE
C
Y
L
I
N
D
E
R
RECTANGULAR
PLANE
C
O
N
E
CIRCULAR
DISC
WHAT DO YOU UNDERSTAND BY?
CUBE
CUBOID
WHAT DO YOU UNDERSTAND BY?
IT IS NOT VERY EASY AND SIMPLE TO INTERPRET AND
UNDERSTAND THE ACTUAL COMPONENT BY LOOKING AT
THE ORTHOGRAPHIC PROJECTION ALONE.
SO WHAT DO WE NEED?
DESIGNER’S
MIND
MODEL
PRODUCER’S
VIEW
PRODUCER’S
INTERPRETION
OF THE
DRAWING
PROJECTIONS: FOUR BASIC TYPES
Note:
Isometric is a
special case of
Axonometric
Orthographic
Projections
Axonometric
Pictorials
Oblique
Perspective
WHAT IS ISOMETRIC PROJECTION?
Isometric projection is a type of an axonometric projection (or
pictorial projection).
 Isometric means ‘equal measure’.
As the name suggests, in isometric projection, all the mutually
perpendicular plane surfaces of an object and the edges formed
by these surfaces are equally inclined to a POP.
 In isometric projection, only one view on a plane is drawn to
represent the three dimensions of an object. This provides a
pictorial view with a real appearance.
PRINCIPLE OF ISOMETRIC PROJECTION
CUBE
• Isometric means equal measure
• All planes are equally or proportionately shortened and
tilted
• All the major axes (X, Y, Z) are 120 degrees apart
A VIDEO TO UNDERSTAND WHAT
CONCEPT ARE WE ATTEMPTING
TO UNDERSTAND
TERMINOLOGY
Isometric axes
The three lines GH, GF and GC meeting at point G and
making 120° angles with each other are termed isometric axes. Isometric
axes are often. The lines CB, CG and CD originate from point C and lie
along X-, Y- and Z-axis respectively. The lines CB and CD make equal
inclinations of 30° with the horizontal reference line. The line CG is
vertical.
HEIGHT
LETS STANDARDIZE THE AXES
CHARACTERISTICS OF ISOMETRIC PROJECTION
Isometric lines The lines parallel to the isometric axes are called isometric
lines or isolines. A line parallel to the X-axis may be called an x-isoline. So
are the cases of y-isoline and z-isoline.
Non-Isometric lines The lines which are not parallel to isometric axes are
called non-isometric lines or non-isolines. The face-diagonals and body
diagonals of the cube shown in Fig. 18.1 are the examples of non-isolines.
Isometric planes The planes representing the faces of the cube as well as
other faces parallel to these faces are called isometric planes or isoplanes.
Note that isometric planes are always parallel to any of the planes formed
by two isometric axes.
Non-Isometric planes
The planes which are not parallel to isometric
planes are called nonisometric planes or non-isoplanes (or non-isometric
faces).
Origin or Pole Point The point on which a given object is supposed to be
resting on the HP or ground such that the three isometric axes originating
from that point make equal angles to POP is called an origin or pole point.
Making an Isometric Sketch
• Defining Axis
60o
30o
60o
30o
Isometric Axis
NOTE
NO ISOMETRIC VIEW SHALL BE DRAWN
WITHOUT DRAWING THE ORTHOGRAPHIC
VIEWS
ISOMETRIC PROJECTION OF
STANDARD FIGURES
RECTANGLE
TRIANGLE
PENTAGON
CIRCLE
IRREGULAR SHAPES
Using construction lines to construct
a cube.
Key rules!
All diagonal lines
are at 30°.
All other lines are
vertical.
Keep all
construction lines
very faint.
Using a cube to create right angle
triangles
Other examples
SOLIDS
PRISM
PYRAMID
OPPOSITE
ENDS
ARE
EQUAL
JOINED
BY
RECTANGULAR PLANES
A PLANE ON ONE SIDE AND
AN APEX ON THE OTHER
JOINED BY TRIANGULAR
PLANES
Rectangular Prism (Cuboids)
PENTAGONAL PRISM
HEXAGONAL PRISM
CYLINDER
Rectangular Pyramid
PENTAGONAL Pyramid
HEXAGONAL Pyramid
CONE
HEXAGONAL PRISM
EDGE: 20MM AND 50 MM HEIGHT
CYLINDER OF DIA 60 MM AND
HEIGHT 80 MM
STEP 2 – ELLIPSE ON FRONT FACE
- Corner to corner to get center
- Lines to tangent points
Tangent Points
Lines to Tangent
Points
STEP 3 – ELLIPSE ON FRONT FACE
Sketch in Arcs
Tangent Points
STEP 3 – ELLIPSE ON BACK FACE AND PROFILE
Repeat for ellipse on rear face
Draw Tangent Lines for Profile
Complete Visible Part of Back Ellipse
A PENTAGONAL PYRAMID OF EDGE
30MM AND HEIGHT 60MM
A CONE OF DIA 60 MM AND HEIGHT 80 MM
Object for Practice
Blocking in the Object
Begin with Front Face
Front Face
Height
Width
Blocking in the Object: Add Side
Face
Side Face
Height
Depth
Blocking in the Object: Add Top Face
Top Face
Adding Detail Cut Outs – Part 1
Adding Detail Cut Outs – Part 2
Adding Detail Cut Outs – Part 3
Darken Final Lines - Part 4
Note:
All visible edges
will be darkened
CHAPTER 4 : ISOMETRIC DRAWING
1. Three views of shaped block are shown in Figure 1. Draw a
full size
isometric view of the block in the direction of arrows
shown. The size
of grid is 10 mm x 10 mm. All hidden
details need not be shown.
FIGURE
1
LOCAL PUBLICATIONS (001427383-A)
Sketch from an actual object
STEPS
1. Positioning object.
2. Select isometric axis.
3. Sketch enclosing box.
5. Darken visible lines.
Sketch from an actual object
STEPS
1. Positioning object.
2. Select isometric axis.
3. Sketch enclosing
box.
5. Darken visible lines.
Note In isometric sketch/drawing), hidden lines are omitted
unless they are absolutely necessary to completely
describe the object.
Sketch from multiview drawing
1. Interprete the meaning of lines/areas in
multiview drawing.
2. Locate the lines or surfaces relative to isometric
axis.
Example 1 : Object has only normal surfaces
Top
Regular H
Top View
Front
Side
W
W
Bottom View
H
Front View
D
Side View
D
Reverse
Front
Bottom
Side
D
Example 2 : Object has inclined surfaces
Nonisometric line
y
H
y
x
Front View
x
W
Example 3 : Object has inclined surfaces
x
C
B
A
x
x
x
B
A
y
C
y
C
B
A
Nonisometric line
Example 4
Regular
x
y
C
E
D
B
F
Front View
A
B
C
A
Reverse
D
F
E
Circle & Arc in Isometric
In isometric drawing, a circle appears as an ellipse.
Sketching Steps
1. Locate the centre of an ellipse.
2. Construct an isometric square.
3. Sketch arcs that connect the
tangent points.
Circle & Arc in Isometric
Four-centre method is usually used when drawn an
isometric ellipse with drawing instrument.
Sketching Steps
1. Locate the centre of an ellipse.
2. Construct an isometric square.
3. Construct a perpendicular
bisector from each tangent point.
4. Locate the four centres.
5. Draw the arcs with these centres
and tangent to isometric square.
Example 5
```