1. Orthographic Projection – Multi-View Drawing

2. Orthographic Projection
a system of drawing views of an object using perpendicular projectors from the object to a plane of projection

3. Revolving an Object to Produce the Six Basic Views

4. Projection of an Object

5. The Glass Box
Imagine that the object you are going to draw is positioned inside a glass box, so that the large flat surfaces of the object are parallel to the walls of the box.
From each point on the object, imagine a ray, or projector perpendicular to the wall of the box forming the view of the object on that wall or projection plane.

6. The Glass Box

7. Unfolding the Glass Box

8. The Six Basic Views

9. The Standard Arrangement of Views
TOP
LEFT FRONT RIGHT
BOTTOM
REAR
Why must views be arranged so that they align?
To make it possible for someone to interpret the drawing.

10. Transferring Dimensions

11. Using a Miter Line to Transfer Depth1.
Draw miter line at 45 degrees
at a convenient distance to produce the desired view.

12. Sketch light lines projecting depth locations for points to miter line and then down into side view as shown. 2.

13. Project additional points, surface by surface.3.

14. 4.
Draw the view locating each vertex of the surface on the projection and miter line.

15. Symbols for 1st & 3rd Angle Projection
Third angle projection is used
in the U.S., and Canada

16. Other Visualization Tools
Number vertices in different views of multiview and isometric drawing
Practice

17. Multiview Sketching
Represents a 3-D object with a series of 2-D views in contrast to “pictorials” which show all three dimensions in a single view
Also called orthographic projection
Multiview Drawing
Pictorial

18. Parallel projection Preserves true relationship between features
Lines that are parallel on the object are parallel on the drawing

19. Parallel versus Perspective Projection

20. Projection Planes versus Views
Object formed from projection lines projected perpendicularly onto a projection plane
Planes: Horizontal, frontal, and profile
Each projection plane is perpendicular to adjacent projection planes
Principle views
The object is rotated 90 degrees about the horizontal or vertical axis to give six principle views (top, bottom, front, rear, left, and right side)
Common views: top, front, and right side

21. Only use Necessary Views
One view drawings
Sphere (Football)
Two view drawings
Cylindrical parts
Show the circular and rectangular view
Three view drawings
Usually sufficient for all other drawings
Top, front, and right side view

22. Orientation and Placement of Views
The most descriptive view should be selected as the front view
The natural orientation of the part should be preserved if possible
Views must be aligned
Top view above front view
Right view to the right of front view

23. Hidden lines Represented with dashed lines
Precedence of lines (visible, hidden, center)
Views should be selected to minimize the use of hidden lines most descriptive view should be selected as the front view

24. Fold Lines Represents a 90 degree fold between views
Generally not shown on engineering drawings except when views other than the principle views (auxiliary views) are used.

25. Terminology to Relate Views
Adjacent view
A view that is separated by a fold line
The top view is an adjacent view to the front view
Central View
A view that is between two adjacent views
The front view is the central view of the top, front, and right side view
Related views
Two views that are adjacent to a central view
The top and right side view are related views since they are both adjacent to the front view

26. Constructing a New View2
The top and front views of a surface are shown
The fold line represents a 90 degree fold between the views
Parallel projection lines are perpendicular to the fold line 1 3 1 3 2

27. Constructing a New View
A vertical fold line is drawn at an arbitrary distance from the front view
Parallel projection lines are drawn from each vertex
The common depth between the top and side view is used to locate each vertex on the projection lines 1 2 3

28. Sketching Allows for the Quick Translation of Thoughts to Paper
Commit thoughts to paper before you lose an idea
Avoid the of use mechanical tools (drawing tools are helpful for beginners)
Does not need to be an exact representation
objects may be simplified
parts may be missing
Avoid erasing
as new ideas are developed make new sketches
start with light lines and then darken with darker lead or heavier strokes

29. Summary
The six standard views are often thought of as produced from an unfolded glass box.
Distances can be transferred or projected from one view to another.
Only the views necessary to fully describe the object should be drawn.