ORTHOGRAPHIC PROJECTION

There is a pile of both. Which one do you choose and why?

NAME: ORTHOGRAPHIC PROJECTION DATE: ELEVATION END VIEW PLAN END VIEW

NAME: ORTHOGRAPHIC PROJECTION DATE: ELEVATION END VIEW PLAN END VIEW

What is Orthographic Projection? When we look at everyday objects we see them in a three dimensional (3-D) view. However we cannot see the true lengths of the different sides of the object. For instance when you are watching the television you can see the front screen, but you cannot see the back & sides of the T.V. set.

What is Orthographic Projection? Sometimes a view of the back and sides is needed. For example in the manufacturing industry, drawings need to have views of all sides of an object so that workers can read important dimensions and get an accurate view of what each side of the component should look like.

What is Orthographic Projection? In any object you will need to get a view of 3, occasionally 4 sides to get a good picture of the overall object. These views are: Elevation Plan End view

Orthographic Projection All planes of projection are then rotated into one plane allowing the three views to be transferred to a sheet of paper. The end elevation looking from the left lies directly to the right of the front elevation. The plan lies directly below the front elevation. The three views are said to be in projection in this arrangement.

Orthographic Projection

If the end elevation is looking from the right hand side then it will lie to the left of the front elevation. Lines which are hidden from the viewing direction are represented by dashed lines. This is called Hidden Detail.

Orthographic Projection The curved surface of a cylinder appears as a rectangle in elevation. In plan it appears as a circle.

Orthographic Projection The curved surface of a cone appears as a triangle in elevation. In plan it appears as a circle.

Elevation Elevation Vertical Plane (VP). When you look at the front of an object you are looking straight at it. This is reflected in the drawing. The front view or Elevation is drawn in the first quadrant or Vertical Plane (VP).

Elevation

Plan Plan Horizontal Plane (HP) When you look down on an object from above, you will naturally see the image below. What you are actually seeing is the Plan of the object. This is drawn in the Horizontal Plane (HP) which is directly below the elevation.

Plan

End View end view Auxiliary Vertical Plane When viewing the object from the side or ‘end’, you will see it at the same level as the elevation. This is why the end view is drawn directly across from the elevation in what is known as the Auxiliary Vertical Plane.

End view

Projection Lines When drawing the next stage of an orthographic projection drawing whether it be the plan or end view, you need to draw projection lines from the previous phase of the drawing.

Projection Lines These lines should be drawn as what is called ‘construction lines’. These line are very light and are drawn using fine pencils such as 2H or H.

Hidden Detail Features that cannot be seen in a given view are represented by a heavy, broken line. For instance a hole that can be seen in an elevation but not in the end view. So to tell the viewer that a hole does exist, the broken line is used

Hidden Detail It is important to note that a visible line always takes priority over a hidden detail. This is illustrated in the slide.

The Glass Box Approach

Hints for Orthographic Projection Identify the major features and overall dimensions of the object Do not use any straight-edge devices as a pencil guide when sketching by hand Start by drawing bounding boxes with light construction lines. Keep views aligned while sketching

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