Drawing Unit Orthographic Projection P. Hennessy 02-1-08.

Drawing Unit

Orthographic Projection

P. Hennessy

02-1-08

Orthographic Projection Defined

• Orthographic Projections are a set of 2-Dimensional drawings that work together to give an accurate overall representation of an object.

• The drawings are used by machinists, engineers, homeowners to make or assemble parts.

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Six Principle Views

The Most Common Views Used Are:

• Front View

• Right Side View

• Top

Views Used Less Frequently

• Left Side View

• Rear View

• Bottom View

Most Common Views

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What Views Are Needed?

General Guidelines• The Front View is the most descriptive of object • Normally the longest dimension is chosen as the

width of the front view• Most common combination of views is to use:

– Front, Top, and Side View• There are other views but those will not be address

now.

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The Relationship of the Dimensions

Top View shows Depth & Width

Front View

shows Height & Width

Right Side View shows Height & Depth 5

The Relationship of the Views

Top View

Front View

Right Side View

Notice how the Top View shows the top of the front view

Right Side View will show the right side of the front view.

Also that the Views Line Up

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Glass Box Approach

Imagine a glass box surrounding the object

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Glass Box Approach

See how the corners of the object are projected to the surface of the glass.

One is corner was not projected forward. Can you find it?

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Glass Box Approach

In this view the Top View corners have been projected up to the top of the glass box.

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Glass Box Approach

In this view the Right Side View corners have been projected horizontally to the side of the glass box.

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Glass Box Approach

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Glass Box Approach

From the Glass Box Animation

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Alphabet of Lines for Drawings

• A set of drafting standards has been set in order to make sure certain drawings are understandable.

• One such set of rules is the alphabet of lines.

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Starting your orthographic drawing

• Tape your paper down using the lines of the title box as a guide to align the paper with the T-Square.

• Be sure to use a sharpened pencil to draw the object.

• Do not free hand sketch. Use the T-Square for horizontal lines and one of the Triangles for all vertical lines.

• Measure all lines twice to check for accuracy.

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ORTHOGRAPHIC DRAWING

BLOCK DATE

YOUR NAME 1

Start the Front View of all your assignments ¾” over from the left border and ¾” up from the Title Box.

Position the Front View Drawing

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ORTHOGRAPHIC DRAWINGBLOCK DATEYOUR NAME 1

Draw The Front View

Draw the Front view.

Use the T-Square for horizontal lines.

And the T-Square and Triangle for Vertical lines.

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ORTHOGRAPHIC DRAWINGBLOCK DATEYOUR NAME 1

Draw The Right Side View

2”

Start the right side view 2” to the left of the front view.

Very light horizontal lines (construction lines) from the front view help to locate the base and height of lines in the Right Side View.

The dotted line is a line that is hidden from view. In this case it comes from the step which is in the back in the Right side view.

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ORTHOGRAPHIC DRAWINGBLOCK DATEYOUR NAME 1

Draw The Top View

1st Draw a 45º from the top right corner of the front view.

This line and the lines in the following steps should be draw light as they are construction lines.

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ORTHOGRAPHIC DRAWINGBLOCK DATEYOUR NAME 1

Draw The Top View

2nd Project the width of the Right Side View vertically to the line you drew at 45º.

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ORTHOGRAPHIC DRAWINGBLOCK DATEYOUR NAME 1

Draw The Top View

3rd Project horizontal lines from where the projected width lines intersected the 45º line.

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ORTHOGRAPHIC DRAWINGBLOCK DATEYOUR NAME 1

Draw The Top View

4th Project Vertical lines from each corner in the front view.

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ORTHOGRAPHIC DRAWINGBLOCK DATEYOUR NAME 1

Draw The Top View

5th Darken the lines that represent the Top View of the object and erase the construction lines.

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