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.

Important Terms

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.

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 drawing.

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

Axonometric projection

Trimetric.

Dimetric.

Isometric.

Axonometric projection

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’.

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

Isometric projection: scale

The tilt causes the edges & planes to become

foreshortened.

The projected length is approximately 80% of

the true length.

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

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.

*The figure below shows how the cases

can be executed.

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.

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

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)

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,

lines and surfaces on

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.

Isometric Projection

ORTHOGRAPHIC MULTI-VIEW PROJECTION ISOMETRIC PROJECTION

«Construction box»

How to draw an object containing rounded

parts

THANK YOU

Department : Mechanical M-1 (B-Batch).

Created by : Parth P. Prajapati.