# How to get first and third angle projections

• Slides: 16

How to get first and third angle projections

OBSERVER MOVE AROUND Top view Front view Right side view

THE GLASS BOX CONCEPT Rear view Left side view Bottom view

Depth History Width Height

PROJECTION SYSTEMS 1. First angle system - European country - ISO standard First Quadrant 2. Third angle system - Canada, USA, Japan, Thailand Third Quadrant

ORTHOGRAPHIC PROJECTION 1 st angle system 3 rd angle system

ORTHOGRAPHIC VIEWS 3 rd angle system 1 st angle system Folding line

ORTHOGRAPHIC VIEWS 3 rd angle system 1 st angle system Right Side View Front View Top View Front View Right Side View

PROJECTION SYMBOLS First angle system Third angle system

PROJECTION SYMBOLS Suggested proportion d 1. 7 d 2. 2 d

WRITING STEPS 1. Select the necessary views 2. Layout the views. 3. Project the views. 4. Dimension the views.

1. SELECT THE NECESSARY VIEWS

2. LAYOUT THE VIEWS A 4 152 64 25 45 152 Choose an appropriate scale 1: 1

PROJECT THE VIEWS

DIMENSION THE VIEWS y y x x x y y x z PART NAME NOTES 1. Dimensions in millimeters. 2. ….

Difference in first and third angel projection First-angle Projection Method Ø In first-angle projection, an object is 16 placed in the first quadrant, i. e. , above the HP and in front of the VP. Ø The object lies in between the observer and the plane of projection. Ø The plane of projection is assumed to be non transparent and views drawn on it. Ø Front view is above the reference axis and top view lies below the reference axis exactly bellow the front view. Ø Right hand side view is drawn to left of front view and Left hand side view is drawn to the right of front view. Ø Symbol Third -angle Projection Method In third-angle projection, an object is placed in the third quadrant, i. e. , below the HP and behind the VP. Ø The plane of projection lies in between the observer and the object. Ø The plane of projection is assumed to be transparent and views drawn on it. Ø Front view is below the reference axis and top view lies above the reference axis exactly above the front view. Ø Right hand side view is drawn to right side of front view and Left hand side view is drawn to the left side of front view. Ø Symbol 16