Orthographic Projection:

anintroduction

What is Orthographic Projection?

Orthographic Projection

Lesson ObjectivesBy the end of the lesson:• Everyone will be able to produce a

simple 3rd Angle Orthographic drawing .

• Most will be able to identify the 3rd Angle Orthographic.

• Some will understand hidden detail lines and their use.

Orthographic Projection

Third Angle Orthographic Projection is the most common method of producing a working drawing, made by creating at least three separate 2D views of an object:• Front view• Plan view (above or birds-eye)• End or side view

But what does this look like?

Orthographic Projection

Like this..

See it’s easy, now your turn. No? Too complex?

Orthographic Projection

Imagine you are viewing an object in a glass box, like this TV for example.

Let me explain…

Orthographic Projection

Let me explain…

If you view the TV from this angle, what would you see?

Orthographic Projection

Let me explain…

This is what you would see and this is the FRONT VIEW.

Orthographic Projection

Now view the TV from this angle, what would you see? The PLAN or BIRDS EYE VIEW.

Orthographic Projection

And finally view the TV from this angle, what would you see? The END or SIDE VIEW.

Orthographic Projection

Now imagine you could open up the glass box and see all three images in the exact 2D format and scale you have been looking at each one.

Orthographic Projection

Now imagine you could open up the glass box and see all three images in the 2D format and scale you have been looking at each one.

You would have all three 2D drawings on a single plane or surface, creating a THIRD ANGLE ORTHOGRAPHIC DRAWING. This is what you would see.

Orthographic Projection

Front View

Plan View (Top)

End View (Side)

Now look at this example using a set of steps, I have included the dimensions on the ISOMETRIC DRAWING.

Front View

Orthographic Projection

Front View

Plan View (Top)

End View (Side)

Now look at this example using a set of steps, I have included the dimensions on the ISOMETRIC DRAWING.

Note how the three drawings are laid out, all in line with each other and each has been drawn to scale.

Orthographic Projection

Front View

Plan View (Top)

End View (Side)

Now look at this example using a set of steps, I have included the dimensions on the ISOMETRIC DRAWING.

Note how the three drawings are laid out, all in line with each other and each has been drawn to scale.

All of this means the drawing meets the required standard and should have the symbol for 3RD ANGLE ORTHOGRAPHICPROJECTION.

Orthographic Projection

This is the symbol for Third Angle Projection drawings and you need to remember it.

It is showing that we project our images to the right of the plan

Orthographic ProjectionNow it’s your turn. In your books go to a new page and in a landscape format sketch freehand the shape shown below in the top right hand corner of your page. You have three minutes.

Orthographic ProjectionNow using your knowledge create a Third Angle Orthographic Projection drawing of the object, the arrow indicates the front view and again this should be done freehand. You have five minutes to complete the work.

Plan View

Front View

End View

Orthographic ProjectionSo how did you do? Does your drawing look like the one below? Do the three 2D drawings line up correctly? Have you created a Third Angle Orthographic Projection? Did anyone draw the hidden detail line?

Plan View

Front View

End View

Orthographic Projection

On a Third Angle Orthographic Projection there may often be hidden details, this is shown with a dotted line and indicates where features of an object are that can not be seen in a particular 2D view but which are important when manufacturing the object.

Orthographic Projection

On a Third Angle Orthographic Projection there may often be hidden details, this is shown with a dotted line and indicates where features of an object are that can not be seen in a particular 2D view but which are important when manufacturing the object. The recess

shown in the isometric drawing can only be seen in the plan and side view but not in the front view.

Orthographic Projection

On a Third Angle Orthographic Projection there may often be hidden details, this is shown with a dotted line and indicates where features of an object are that can not be seen in a particular 2D view but which are important when manufacturing the object. The recess

shown in the isometric drawing can only be seen in the plan and side view but not in the front view.This hidden detail is always shown and

is done so using a dotted line in the correct location.

Orthographic ProjectionNow using your knowledge, create a third angle orthographic projection drawing of the object you have been given.

Front View

Please note the front view.

And this time you will draw the object to scale using grid paper and a ruler.

You have ten minutes to complete the drawing.

Orthographic Projection

So how did you do? Are all the dimensions correct? Have you included all the hidden detail?

Orthographic Projection

Now lets make things a little harder, you have been given a new object to draw.

Front View

You have 10 minutes to complete this drawing.

Please note the diameter of the hole is 10mm and it is centrally located.

Orthographic Projection

So how well did you do this time? Are all the dimensions correct again? Have you included all the hidden detail this time? Is the hole the right diameter?

Orthographic Projection

Have you achieved the main learning objective? Are there any questions?