This document discusses orthographic projections, which are a method of producing multiple two-dimensional views of a solid object from different angles to fully represent it. Orthographic projections involve projecting points and lines on an object orthogonally onto planes to create two-dimensional views at right angles to each other. There are two forms of orthographic projection depending on the positioning of the object: first angle projection and third angle projection.

1. Engineering
Graphics
Course No. ME 193
Orthographic Projections
of
Machine Parts

2. • A method of producing a number of separate two-
dimensional inter-related views.
• These views are drawn mutually at right angle to each
other.
• It is used to represent solid objects by two dimensional
views, as many as are necessary to give all the
information needed, clearly and accurately.
• Depending on the positioning of the object, there are
two forms of orthographic projection:
(i) First angle orthographic projection
(ii) Third angle orthographic projection
Definition

3. Example

4. • A point or line is said to be projected
orthographically if the projector is normal to the
plane. Therefore the word orthographic stands for
drawing at right angle.
• Solids consist of points linked by lines. Using a system
of parallel projectors from their boundaries, the lines
(or points) may be projected orthographically on to
any planes.
The principle

7. Difference between Ist and IIIrd angle projection