1. Orthographic Projection
Engineering Drawing
BDU 10303

2. Objectives
To understand the basic principles of orthographic projection
To be able to draw simple objects using orthographic projection

3. Orthograpic Projection
A collection of multiple two-dimensional drawings that work together to get an accurate representation of an object.

4. Orthographic projection

5. Orthographic projection

6. Conventional orthographic view
All views must be properly aligned!

7. Guidelines Pick front view that is most descriptive of object.
Position the object in its natural position.
Choose the view that shows minimum hidden lines.
Longest dimension is normally chosen as width.
Usually only three views are used:
Front, top and side views

8. First and Third Angle Projection
Orthogonal plane
First angle projection
Third angle projection
ortho = perpendicular

9. Orthogonal plane

10. First angle projection
Symbol:

11. First angle projection

12. First angle projection

13. First angle projection

14. First angle projection

15. First angle projection

16. Third angle projection
Symbol:

17. Line types what is phantom lines?
Phantom  lines  are  used  most  frequently  toindicate an alternate position of a moving part.

18. Drawing Layout
All engineering drawings should feature a title block that include:
Title
Name
Checked
Version
Date
Notes
Scale
Company name
Projection

19. Exercise 4
Draw an orthogonal projection of the following object using the third-angle projection

20. Dimensioning

21. Dimensioning
shows two common methods of dimensioning a circle. One method dimensions the circle between two lines projected from two diametrically opposite points. The second method dimensions the circle internally
is used when the circle is too small for the dimension to be easily read if it was placed inside the circle.

22. Section views
Shortcoming: Orthographic view may shows all hidden lines but may not clear enough to describe an object’s INTERNAL details.
To overcome this, imagine the part of the object has been cut and shown in cross-section view.

23. Type of section views Full section view
Offset section view (Multiple offset views)
Half section view
Broken section view
Aligned and revolved section view
Removed view

24. Full section view

25. Offset section view

26. Multiple offset sections

27. Half section view

28. Broken section view

29. Example 1
2xΦ8

30. Example 2

31. Exercise 5
orthographic projection of the following object with full section view
R4.0
5.0 A
8.0 A
2.0
2.0

32. Quiz 3
2. Draw the orthographic projection of the following object with full section view
Φ1.54
Φ1.08