1. Unit 16 Engineering Drawing

2. Unit 16 Engineering Drawing
Aims:-
Introduce Orthographic Projection.
Present the 1st and 3rd angle projection.
Identify isometric and oblique projections.
Objectives:-
Recognise orthographic projections.
Know the difference between 1st & 3rd angle projections.
Explain the difference between isometric and oblique projections.

3. FIRST ANGLE ORTHOGRAPHIC PROJECTION
Orthographic Projection is a way of drawing an object from different directions. Usually a front, side and plan view are drawn so that a person looking at the drawing can see all the important sides. Orthographic drawings are useful especially when a design has been developed to a stage whereby it is almost ready to manufacture.
IMPORTANT: There are two ways of drawing in orthographic - First Angle and Third Angle. They differ only in the position of the plan, front and side views.

4. The Orthographic Projection 1st angle is viewed as shown below, plan, side and front projection

5. Plan

6. Front

7. Side

8. First Angle Projection
The final arrangement of the views are shown.

9. The final arrangement of the views are shown in the drawing below
The final arrangement of the views are shown in the drawing below. Notice how the symbol for first angle orthographic projection has been added and the paper has a title block and borderline.

10. First Angle projection: The object placed in the first quadrant Third Angle projection: The object placed in the third quadrant

11. Example of third angle orthographic projection is shown below
Example of third angle orthographic projection is shown below. Follow the blue, red and green guidelines as the front, side and plan view are constructed.

12. The final arrangement of the views are shown in the drawing below
The final arrangement of the views are shown in the drawing below. Notice how the symbol for third angle orthographic projection has been added and the paper has a title block and borderline.

13. You're task is to sketch this object in 1st angle