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CHAPTER 14

CHAPTER 14. Pictorial Drawings and Technical Illustrations. Learning Objectives. Draw three-dimensional objects using 3-D coordinates Construct objects using isometric, diametric, or trimetric methods Construct objects using oblique drawing methods. Learning Objectives.

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CHAPTER 14

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  1. CHAPTER 14 Pictorial Drawings and Technical Illustrations

  2. Learning Objectives • Draw three-dimensional objects using 3-D coordinates • Construct objects using isometric, diametric, or trimetric methods • Construct objects using oblique drawing methods

  3. Learning Objectives • Draw objects using one-, two-, or three-point perspective • Apply a variety of shading techniques to pictorial drawings • Given an orthographic engineering sketch of a part or assembly, draw the part in pictorial form using proper line contrasts and shading techniques

  4. Pictorial Drawings • Often accompany 2-D orthographic multiviews • Provide a realistic 3-D view • Help improve visualization • Now created using CADD or illustration programs • ASME Y14.4M, Pictorial Drawing standard

  5. Pictorial Drawings • Useful for a variety of applications • Clarify basic and complicated engineering designs • Help designers and engineers work out spatial problems • Most often the basis for technical illustrations

  6. Pictorial Drawings

  7. Uses of Pictorial Drawings • Design • Instruction manuals • Parts catalogs • Advertising literature • Technical reports • Presentations • Assembly • Construction

  8. Isometric Projections and Drawings • Equal (iso) measure (metric) • Simplest form of axonometric projection • Single scale for all axes

  9. Isometric and Nonisometric Planes

  10. Regular Isometric • Most common • View the top of the object and the object from either side

  11. Reverse Isometric • View the bottom of the object

  12. Long-Axis Isometric • Common for long objects

  13. Isometric Construction: Box or Coordinate Method • Most common form of isometric construction • Used on objects that have angular or radial features

  14. Isometric Construction: Centerline Layout Method • Used on objects with many circles and arcs • Circles in isometric are isometric ellipses

  15. Isometric Circles and Arcs

  16. Establishing Isometric Intersections

  17. Drawing Isometric Sections

  18. Drawing Isometric Threads • Equally spaced elliptical arcs • Detailed thread representation

  19. Drawing Isometric Spheres

  20. Dimetric Pictorial Representation • Form of axonometric projection • Two different scales for measurement • Missing image – go to page 566

  21. Trimetric Pictorial Representation • Most involved form of axonometric projection • Three different scales for measurement

  22. Exploded Pictorial Drawings • Exploded assembly • Show the relationship of parts in a realistic manner • Commonly used in: • Parts catalogues • Owner's manuals • Assembly instructions

  23. Exploded Pictorial Drawings • Isometric drawings most common • Can include centerlines between part and subassembly axes • Can use solid extension lines between non-cylindrical features, parts, and subassemblies • Can include balloons

  24. Exploded Pictorial Drawing

  25. Oblique Drawing • Shows three faces of the object • Useful if one face of an object needs to be shown flat

  26. Cavalier Oblique

  27. Cabinet Oblique

  28. General Oblique

  29. Perspective Drawings • Most realistic pictorial illustration • Show depth and distortion perceived by the human eye • Objects appear smaller the farther away they are until they vanish at a point on the horizon • One-point or parallel perspective • Two-point or angular perspective • Three-point perspective

  30. General Perspective Drawing Concepts

  31. One-Point Perspective • Plan view is oriented so the front surface of the object is parallel to the picture plane • Elevation view is placed below and to the right or left of the plan and rests on the ground line • Used most often when drawing interiors of rooms

  32. Two-Point Perspective • Two principal planes are at an angle to the picture plane • Two vanishing points provide another dimension to the depth of the perspective • Most popular form of perspective drawing • Exteriors of houses and small buildings • Civil engineering projects • Machine parts (occasionally)

  33. Three-Point Perspective • Time consuming to construct • Often occupy a considerable area on the drawing sheet • Used to illustrate objects having great vertical measurements, such as tall buildings

  34. Drawing Circles and Curves in Perspective • Circles in perspective typically appear as ellipses • Any circle on surface parallel to the picture plane appears as a circle • Construction using the coordinate method

  35. Basic Shading Techniques • Line-contrast shading • Straight-line shading • Block shading • Stipple shading

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