1.
Isometric projections
A cube shown with this type of
projection pivots 45º to show two
faces on the projection plane
instead of a single face.
It is then tilted frontward or
backward, allowing three
faces to be observed.

2.
Important Terms

3.
Content
 Overview.
 Pictorial projection
 Parallel projection
 Axonometric projection
 Isometric projection.
 Axes and selection
 Isometric lines and planes
 Isometric scale
 Isometric projection & Isometric drawing
 Producing Isometric sketches & drawing.
 Isometric lines & non-isometric lines
 Circles and arcs
 Irregular curves
 Oblique projection drawing.

4.
Pictorial projection
 Pictorial projection:
 Not intended to give exact
or true view.
 Not intended to transmit
dimensions, although
sometimes dimension is
useful.
 Useful when the
information and
instructions to be given to
non-technical and
untrained people.
 Hidden lines are not
shown in isometric

5.
Axonometric projection
 axon = axis; metric = measure, in Greek
 Axonometric projection is a parallel projection
technique to create a pictorial drawing of an object by
rotating the object on an axis relative to a projection or
picture plane

6.
 Axonometric projection
 Trimetric.
 Dimetric.
 Isometric.
Axonometric projection

7.
Isometric projection
 Isometric projection is a true representation of the
isometric view of an object.
 Isometric view is created by rotating the object 45
degree about vertical axis, and tilting it forward 35
deg 16’.

8.
Isometric projection: axes
 The 3 axis meet at A,B form equal angles of 120 deg
and they are called Isometric Axes
 OA is vertical, OB is inclined at 30deg to the right,
OC is inclined at 30deg to the left
 Any lines parallel to these – Isometric Line
 Any planes parallel – Isometric Planes

9.
Isometric projection: scale
 The tilt causes the edges & planes to become
foreshortened.
 The projected length is approximately 80% of
the true length.

10.
Draw the isometric projection of a rectangle of 100mm
and 70mm sides if its plane is (a) Vertical and (b)
Horizontal.
To draw the isometric projection of a square plane
Construction
Case:
Vertical plane
 Draw a line at 30° to the horizontal and mark the isometric
length on it.
 Draw verticals at the ends of the line and mark the isometric
length on these parallel lines.
 Join the ends by a straight line which is also inclined at 30°
to the horizontal.
 There are two possible positions for the plane.
Isometric Projection of Planes

11.
Case:
Horizontal plane
 Draw two lines at 30° to the horizontal and mark the
isometric length along the line.
 Complete the figure by drawing 30° inclined lines at
the ends till the lines intersect.
Note
 (i) The shape of the isometric projection or drawing of
a square is a Rhombus.
 (ii) While dimensioning an isometric projection or
isometric drawing true dimensional values only must
be used.

12.
*The figure below shows how the cases
can be executed.

13.
Isometric angles & non-isometric lines
 Example of producing non-
isometric lines.
 The position of point Z is
obtained in the isometric
view, by transferring the
distance of X and Y.

14.
Iso-circles and arcs: draw
 Drawing isometric circles and arcs using four-centre method.

15.
Drawing iso-circles
• To draw an iso-circle, on
left plane, Diameter
20mm
(a) Draw centre lines,
vertical & 30deg to left.
(b) Draw (construction line)
20mm “square box”. The
centre lines should
divide each side by half.
(c) Draw straight lines; 1-2 & 1-3 and 2-5 & 2-6.
(d) Point 7 is the intersection between line 1-2 & 2-5, and similarly point 8, 1-3 & 2-6 on the
other side.
(e) Set your compass to the distance 7-2, draw an arc with centre at point 7, from point 2 to
point 5. Do the same on the other side.
(f) Set your compass to the distance 1-2, draw an arc with centre (1), from (2) to (3).
(a)
12
3
4
5
6
7
8
2
5
4
5
6
(b) (c)
(d) (e) (f)

16.
Producing Isometric Projection
 Read multi-view
drawing given.
 Observe scale,
dimension, projection.
angle
 Determine front, side &
top view.
 Try to visualize how the
object looks like.
 Start with sketching, do
not draw straight away.
 If not sure, start with
sketching an isometric
box, enclosing the
whole object.
 You can label points,

17.
6.3 Sketching isometric cylinder
 Start by drawing the bounding box.
 The front end of the cylinder is sketched using the
previous technique.
 The far end of the cylinder is a partial iso-circle.
Sketch until meeting the tangent with the two straight
lines.

18.
Isometric Projection
ORTHOGRAPHIC MULTI-VIEW PROJECTION ISOMETRIC PROJECTION
«Construction box»
How to draw an object containing rounded
parts

19.
THANK YOU
Department : Mechanical M-1 (B-Batch).
Created by : Parth P. Prajapati.