Engineering Drawing

Yash ParikhM.Tech (Computer Integrated Manufacturing)

Assistant Professor

Department of Mechanical Engineering

Unit - 02

Orthographic Projections

Prof. Yash Parikh SIT Pune

Multiview Drawing

4/33

Introduction The purpose of a “Multiview Drawing” is to

represent a three dimensional object on a two dimensional sheet of paper or in a two dimensional drawing space.

Multiview Drawings are used by Engineers, Architects and Contractors to Design and build tiny objects such as microchips or large objects such as buildings, shopping centers, bridges etc.

5/33

Example..!!!

6/33

Bus is represented by six views, the front, top, sides, back and bottom.

7/33

Orthographic Projections Ortho is a Greek word, which means “Perpendicular”.

Orthographic Projections – here the line of sight is perpendicular to the viewer.

By definition, for each element of a orthographic projection drawing you required three dimensions.

Height (H)

Width (W) / Length (L)

Depth (D)

But while drawing, only two of the three dimensions can be shown.

8/33

6 Principle Views The 6 principle views are created by looking at the object,

straight on, in the directions indicated.

9/33

Orthographic Projection Views

When constructing an orthographic projection, we need to include enough views to completely describe the true shape of the part. Complex part = more views Simple part = less views

The standard views used in an orthographic projection are;

Front view

Top view

Side view (Right or Left Side View)

The remaining 3 views usually don’t add any new information.

Always pick the view which will help in describing the object with highest clarity.

10/33

Projection Method Third angle projection is normally used in the US while Europe uses the

First Angle projection. Note the symbols at the bottom of each one will tell you which projection

that you are viewing.

Third-angle Projection

First-angle Projection

11/33

Different Views for this????

12/33

Each of the view show only 2 out of 3 dimensions (Height, Length, Depth)

13/33

Glass Box Approach..!!! Most powerful technique to understand orthographic

projections is a method known as Glass Box Approach.

Here the object is suspended inside the transparent glass box with the help of strings.

After this the views are freeze from each direction,

(each of the six sides of the box).

At the end the box is unfold to get the views.

14/33

The object is placed & image is projected on the sides of a box.

15/33

The box is unfolded & three views are visible on plane of paper.

16/33

17/33

View Alignment

The front and top views are aligned vertically and share the same width dimension.

The front and side views are aligned horizontally and share the same height dimension.

THANK YOU