Technical Drawing

CHAPTER 1

By:Aznita

Abdullah

Why engineers use orthographic projection?

Engineers need to be able to explain and simplify complicated design ideas for others to understand.

Why engineers use orthographic projection?

To show complicated 3 dimensional (3D) object in two dimension (2D)

ORTHOGRAPHIC PROJECTION• the object is looked at from three views at 90

degrees to each other.

ORTHOGRAPHIC PROJECTION – 3 VIEWS

1. Plan 2. Front View 3. Side View (or End View)

ORTHOGRAPHIC PROJECTION

Viewed in 2 ways:• 1st Angle Projection• 3rd Angle Projection.

1st Angle Projectionused mainly in USA

END VIEW

ISOMETRIC

FRONT VIEW

PLAN

1st Angle Projection Symbol

FRONT VIEW SIDE VIEWFRONT VIEW

SIDE VIEW

3rd Angle ProjectionUsed in UK and in most countries of the world

END VIEW

ISOMETRIC

FRONT VIEW

PLAN

FRONT VIEW

SIDE VIEW

3rd angle Projection Symbol

SIDE VIEW

FRONT VIEW

DIFFERENCE BETWEEN 1ST ANGLE AND 3RD ANGLE

1st Angle Projection 3rd Angle Projection

MODULE OBJECTIVESBy the end of this module the student will be able to:

1.1 Describe orthographic projection1.2 State why engineers use orthographic projection1.3 Compare 1st degree angle and 3rd degree angle

MODULE OBJECTIVES 1.4 By the end of this module the student will be able to:

Correctly sketch two-dimensional views from three dimensional drawings.

END VIEW

PLAN VIEW

FRONT VIEW

MODULE OBJECTIVES 1.5 By the end of this module the student will be able to:

Correctly identify and draw different types of line.