1. Orthographic Projection
Created by Steven Colgan

2. What is Orthographic Projection?
Orthographic Projection is a method of representing a three dimensional object on paper using several two dimensional views.
It is the international language of Engineers and Designers

3. How does it work?
We look directly at the different faces of the object (90˚ to the face) and draw the lines that we see.
Click here to view the movie

4. How many views? One view is never enough to describe an object.
We need at least two views to accurately describe even the most simple of objects.
Generally we se three views and arrange them as shown in the movie
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You can use as many views as the object requires.

6. Is it really an international language?
Yes. However America and Australia arrange the views differently.
This arrangement of views is called third angle projection.
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8. How do I know which method is being used?
Each method has its own symbol and they are as follows
First angle projection
Third angle projection

9. How do I draw this symbol?
The recommended proportions for the symbol are as follows

10. How did they get their names?
The name first angle is derived from the objects position in the first quadrant of the planes of reference.
The name third angle is derived from the objects position in the third quadrant of the planes of reference.

12. Is that it?
Sometimes features of an object are hidden (for example they are at the back of the object)
To show these features we add dashed lines in their place.
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If a dashed line meets a thick line leave a gap as shown

14. There’s too many dashed lines!
If there is too much hidden detail and the drawing becomes confusing use a sectional view
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Draw the Hatching lines at 45˚ as shown
Always place the section line (the dashed line that ends in arrows) exactly were you are cutting the object.
To see more types of Sectional views click here

16. Anything else? Make sure you keep your drawing neat.
Recommended proportions are shown below.
Keep construction lines light and finished lines heavy