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THIRD ANGLE - ORTHOGRAPHIC PROJECTION

FURTHER EXPLANATION

V. Ryan 2002 - 2010

 

Click here for an Introduction to Third Angle Orthographic Drawing

Click here for Third Angle Orthographic Drawing - an Example

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. Below is an example of third angle projection.

   
An L-shaped object.

The Plan View of the L-shape is drawn as a 'birds eye' view, a view from above.
The Front View is drawn as if stood in front of the L-shape.
The Side View is drawn as if stood at the side.
   
   
The correct position of each view is shown below. They have been drawn very accurately, using T-Squares and set squares.
   

 

   

Another 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.

   
PDF FILE - CLICK HERE FOR PRINTABLE FILE BASED ON EXERCISE 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.

   

   

Carefully study the symbols shown below. Normally when drawing in first or third angle projection a symbol is drawn which clearly shows which angle of projection has been used.

   

   
 
   

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