1. ELEC 106 FUNDAMENTALS OF ELECTRICAL ENGINEERING Engineering Drawing

2. Visualization and Graphics Graphical communication skills essential for learning most of the concepts in all engineering disciplines Visualize information and translate it into visual products such as sketches and drawings Represent a three-dimensional object in a two- dimensional medium The prevalence of computers intensifies the need for visualization and graphical communication skills

3. The Theory of Projection Four specific components: 1) an object 2) an observer 3) a projection plane or picture plane 4) visual rays (lines of sight) The projection plane placed between the object and the observer Visual rays passing through the plane from the object to the observer creating a two-dimensional image of the object on the plane

4. The Theory of Projection Central perspective: - the size of the image a bit smaller than the true size of the object - due to a finite distance between the observer and the object Orthographic projection: - the image on the picture plane same size as the object - the visual rays parallel to each other and perpendicular to the picture plane

5. Central Perspective

6. Orthographic Projection

7. Fundamental principle upon which all engineering drawing is based The “glass box theory” The basis of how a three-dimensional object can be represented by its two-dimensional orthographic views: top view, front view, side view Top view: the width and depth Front view: the width and height Side view: the height and depth

8. The Glass Box Theory

9. Orthographic Multi-Views

10. The Meaning of Lines: Visible Lines Solid lines (0.7 mm thick) drawn to represent - the edge view of a surface - the intersection of two surfaces - the limiting element of a curved surface Elements : infinite number of lines drawn parallel to the axis of the cylinder The limiting element : the last element that one can see before the curve begins to turn back on itself

11. The Meaning of Lines

14. Hidden Lines & Centerlines Hidden lines - dashed lines (0.5 mm thick) - show the details of the object that appear hidden (i.e., blocked from the observer’s view by the object) Centerlines - solid thin lines (0.35 mm thick) - circular feature - a cross hair with a small + - a small gap (about 1/16 in) place on each side of + with a longer line extending 1/8 in beyond the curve - axis of symmetry - a long line broken in the middle

15. The Meaning of Lines

16. Centerlines for Cylindrical Features and Radii

17. Line Precedence Visible lines, hidden lines, and centerlines are all the same degree of darkness, but they vary with regard to their thickness.

18. Orthographic Multi-views

20. Pictorial Sketching Involves creating a view of the object in which all three dimensions shown Helps with visualization, i.e., ability to formulate in our mind’s eye what the object looks like Three types: Axonometric (isometric)Oblique Perspective

21. Isometric Sketches Quickest & easiest to draw and most commonly used Most common orientation – the observer looking down on the object (bird’s eye view) Isometric axes: two receding axes measured 30  from the horizontal reference plus a vertical axis

22. Isometric Grid Paper

23. Isometric Sketching Example

24. Sketching Example

25. Step 1: Generate ‘isometric prism’ to box in the entire object Step 2: Locate points 1, 2, 3, 4 on the top surface. Then, draw a line connecting 1-2 and 3-4 to create the slot

26. Step 3: Sketch a vertical construction line through 1, 2, 3, 4. Then, measure 1.5 units down each construction line to locate points 5, 6, 7, 8 for the depth of the slot. Step 4: Draw a line connecting 1-5, 5-6, 5-7, 3-7, 6-2, and 6-8 to complete the slot. Step 5: Erase lines 1-3, 2-4, and part 0f 6-8.

27. Another Example

29. Cylindrical Features in Isometric Sketch Circle appear as ellipse whose orientation depends on which orthographic view (top, front, side)

30. How to create an ellipse on the top isometric surface

31. How to create an ellipse on the front isometric surface

32. How to create an ellipse on the Right-side isometric surface

33. Scales Most technical drawings are drawn to some scale Drawing scale = the ratio that the drawing has to the real world object or other drawing Use of scale depends on the size of the drawing media Common drawing scales used in engineering: full scale (1:1), half scale (1:2), quarter scale (1:4), and tenth scale (1:10)

34. Isometric Coordinate System Used when sketching three-dimensional object on two-dimensional media without isometric grid