1. Engineering Graphics III – Pictorial Projections Prof. Jon Southen October 15, 2008

2. Pictorial Projections Text Reference:  Bertoline-Wiebe, Fundamentals of Graphics Communication, Chapter 7

3. Orthographic Projections Multiview Drawings  Discussed last class  Show two dimensions at a time (with proper size and shape)  Images must be mentally combined to form full 3-D description of object Pictorial Views  Show all three dimensions at once, making visualization easier

4. Pictorial Views Pictorial views show all three dimensions in one view Common projections:  Perspective  Oblique (Cabinet)  Axonometric (Isometric)

7. Perspective Views

10. Oblique Projection Front view is true size and shape Not a true projection – CAD can’t generate them Other dimensions are greatly distorted

11. Oblique Projection

13. Practice - Oblique View

14. Axonometric Projection

17. Axonometric (isometric) All lengths to same scale Not true shape Angles equal CAD can generate isometric views 60º

18. Scale and Axes “Full-scale”:  All dimensions same as those on equivalent multiview drawings Coordinate axes separated by 120 degrees (2:1 on squared paper)

19. Creating Isometric Drawings Determine viewpoint that most clearly depicts features of object Construct isometric box that contains the object Locate details on isometric planes Darken visible lines

20. Front Top Side

21. Practice – Isometric View

22. Isometric Circles

24. Standards for Isometric Drawings Show hidden lines only if absolutely necessary to describe the object Show centerlines only to show symmetry or for dimensioning Isometric view not normally dimensioned Guidelines for sketching other features (ellipses, curves, etc.) may be found in the text

25. Isometric Sketching

27. Example: Sketch Isometric View

28. Sketch Isometric View http://pergatory.mit.edu/2.007/resources/drawings/index.html

29. Multiview Drawing Visualization Reading an engineering multiview drawing requires one to form a clear 3-D mental image of the object.

30. To improve visualization skills Study existing drawings Construct physical models Contrast similar shapes

35. What is Isometric View?

36. Possible Solutions

37. Adjacent Areas Surfaces which reside next to each other Boundary between surfaces represented by line indicating change of planes No two can lie in same plane

38. Adjacent Areas represent 1. Surfaces at different levels 2. Inclined or oblique surfaces 3. Cylindrical surfaces or arc 4. A combination of these

40. Next Class Other Views Dimensioning and Tolerancing