1. Orthographic Projections GMED Unit 1

2. Lecture Outline Objectives Projection methods (2.4)
Multiview projections (2.4.4)
Multiview sketches (2.6)
Visualization
Multiview representations
ANSI standards
Next class

3. Objectives
Learn the rules for reducing a 3D object onto a 2D multiview drawing
Learn some hints for visualizing a 3D object from a 2D multiview drawing
Covers material in Chapter 2, primarily Sections 2.4, 2.5, and 2.6 as well as material not in text

4. Projection Methods (2.4)
Locate multiview projections in the taxonomy of projections:
Projection  Parallel Projections  Orthographic Projections  Multiview Projections

5. Multiview Projections (2.4.4)
Line of sight
Projection plane
Object
Multiview is classified as parallel projection because lines of sight used to view the object are parallel

6. Multiview Projections (con’t)
Multiview projection is an orthographic projection for which the object is behind the plane of projection and oriented such that only two of its dimensions are shown

7. Multiview Projections (con’t)
Object suspended in a glass box, producing the six principal views
Six Principal Views See also Figure 2.35 in text

8. US (ANSI 3rd-angle projection) vs. ISO (1st-angle projection)
Multiview Projections (con’t)
US (ANSI 3rd-angle projection) vs. ISO (1st-angle projection)

9. Multiview Projections (con’t)
Choosing the views and orientation for a multiview object:
Determine the best position of the object
Try to make the surfaces of major features either perpendicular or parallel to the projection planes
Define the front view (the front view should show the object in its natural or assembled state)
Determine the minimum number of views needed to completely describe the object so it can be produced
Once the front view is selected, determine which other views will have the fewest number of hidden lines

10. Multiview Projections (con’t)
View Orientation
Bad orientation
Good orientation

11. Multiview Projections (con’t)
Most Descriptive Views

12. Multiview Sketches (2.6)
Multiview drawings can have from one to three or more views of an object (rarely are more than three views necessary)
One-view sketches: include simple objects such as a sphere, cylinder, or cube. Other applications include a thin gasket or printed circuit board (no depth)
Two-view sketches: include cylindrical, conical, and pyramidal shapes
Three-view sketches: used when an object is more complex and requires three views to communicate all aspects of the drawing (width, depth, and height)

13. Multiview Sketches (con’t)
One-View Sketches
Two-View Sketches

14. Multiview Sketches (con’t)
Creating a Three-view sketch:
Step 1: Block in the front, top, and right side views. Sketch the front view first using construction lines to project dimensions
Step 2: Lightly block the major features in views
Step 3: Use construction lines to project the location and size of features between views
Step 4: Finish adding the final lines

15. Visualization of Edges and Planes
Normal plane
Oblique plane
Inclined plane
Fundamental Views of Planes

16. Visualization (con’t)
Fundamental Views of Edges
Oblique line
Inclined line
Normal line (true-length)

17. Visualization (con’t)
Normal, Inclined, or Oblique?
A: parallel to frontal plane
B: parallel to horizontal plane
C: parallel to profile plane
D: inclined – on edge in front view
E: oblique – neither parallel or on edge in any plan or view

18. Multiview Representations
Practice makes perfect, without it, you will never learn this art of visualizing 3D objects from 2D multiview drawings
Some items to consider in multiview representation and visualization:
Projection studies
Physical model construction
Adjacent labeling
Missing lines
Vertex labeling
Analysis of solids
Analysis of surfaces

19. Multiview Representations (con’t)
Adjacent Areas
Possible Solutions

20. Multiview Representations (con’t)
There are several examples of multiview representations in this and other texts. The best method to learn the art of multiview representation of 3D objects is to draw by yourself, with tools or freehand, the objects in the Problems section of the text. We do not have time to cover all that are presented in the chapter. This section presents some examples of multiview representation.

21. Multiview Representations (con’t)

22. Multiview (con’t)

23. ANSI Standards for Multiview Drawings
Partial Profile Views to Describe an Object and Eliminate Hidden Lines
Partial View used on a Symmetrical Object

24. ANSI Standards (con’t)
Too “busy”
Revolution Conventions used to Simplify the Representation of Ribs and Webs

25. ANSI Standards (con’t)
Removed View
Make the drawings easy to understand!
Revolution Applications

26. Examples

27. Next Class
Worksheet - changing isometric drawings to orthographic drawings.
Copy of the worksheet can be found at
.com