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THIRD ANGLE ORTHOGRAPHIC DRAWING

AN EXAMPLE (WORKING DRAWINGS)

V. Ryan 2008 - 2010

 

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A simple design for a clock is seen below. The design is based on a flower and consequently the clock dial has petals surrounding it. It has been drawn in three dimensions using CAD (Computer Aided design) software. This is one way is which a design can be presented.

However, designers also need to draw in traditional ways including orthographic projection. This type of drawing allows the designer to draw a design/object from different angles.

The animation below shows how a three dimensional drawing can be arranged to present the three important views seen in third angle orthographic drawing. These views, known as elevations are the Front Elevation, Side Elevation and Plan elevation.

The clock is drawn below, this time in orthographic projection (Third Angle Projection). Three views have been drawn and they are the front, side and plan elevations. This style of accurate drawing is needed when the item is to be manufactured.

PDF FILE - CLICK HERE FOR PRINTABLE ORTHOGRAPHIC DRAWING EXERCISE

Dimensions (measurements) are then added to the three elevations. This means that overall sizes can be seen. Working drawings usually have a minimum of six dimensions although normally more are required. A drawing of this type is always drawn either to the full size of to a scale. This means that any dimensions that have not been included can be measured directly from the paper.

When looking at an orthographic drawing it is very important to establish the ‘angle of projection’. The most popular system is third angle projection, as seen on this page. Another system is first angle projection (dealt with earlier). The symbol identifying third angle projection is seen opposite. This should be placed on every third angle projection orthographic drawing so that the person using the drawing understands immediately the system being applied.
Usually the scale of the drawing is written near the symbol, keeping important information together.

   

This amended working drawing  (below) has only two elevations of the clock. A plan elevation was not required because the front and side elevations have enough detail and information to make it possible to manufacture the clock.

A parts list has been added. Each part has been numbered on the drawing and listed in a table. A simple description has been added as well as material, overall dimensions and the finish to be applied. This gives the manufacturer all the information required to manufacture the clock.

The scale of the drawing and a simple diagram symbolising the type of orthographic projection used - have also been included.

 
 

Working drawings are normally presented in a very formal manner. This means that colour and shade are not used. Outline drawings are the usual mode of presentation. Colour can hide or mask detail.
A working drawing is a precise piece of work and colour or shade could make a drawing look more complicated than it actually is.

SAMPLE LAYOUT TO A WORKING DRAWING
 
 
EXAMPLE WORKING DRAWING AND PARTS LIST
 
 
 
 
 
 
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