Introduction to orthographic projections

Engineering Drawing
Yash Parikh
M.Tech (Computer Integrated Manufacturing)
Assistant Professor
Department of Mechanical Engineering

Unit - 02
Orthographic
Projections

Prof. Yash Parikh SIT Pune
Multiview Drawing

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.
4

Bus is represented by six views, the
front, top, sides, back and bottom.
6

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.
7

6 Principle Views
 The 6 principle views are created by looking at the object,
straight on, in the directions indicated.
8

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.
9

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.
10
Third-angle
Projection
First-angle
Projection

Different Views for this????
11

Each of the view show only 2 out of 3
dimensions (Height, Length, Depth)
12

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.
13

The object is placed & image is
projected on the sides of a box.
14

The box is unfolded & three views are
visible on plane of paper.
15

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.
17

Introduction to orthographic projections

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Introduction to orthographic projections