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CHAPTER 14 - PowerPoint PPT Presentation

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

Pictorial Drawings and Technical Illustrations

• Draw three-dimensional objects using 3-D coordinates

• Construct objects using isometric, diametric, or trimetric methods

• Construct objects using oblique drawing methods

• 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

• 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

• 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

• Design

• Instruction manuals

• Parts catalogs

• Technical reports

• Presentations

• Assembly

• Construction

Isometric Projections and Drawings

• Equal (iso) measure (metric)

• Simplest form of axonometric projection

• Single scale for all axes

• Most common

• View the top of the object and the object from either side

• View the bottom of the object

• Common for long objects

• Most common form of isometric construction

• Used on objects that have angular or radial features

• Used on objects with many circles and arcs

• Circles in isometric are isometric ellipses

• Equally spaced elliptical arcs

• Form of axonometric projection

• Two different scales for measurement

• Missing image – go to page 566

• Most involved form of axonometric projection

• Three different scales for measurement

• Exploded assembly

• Show the relationship of parts in a realistic manner

• Commonly used in:

• Parts catalogues

• Owner's manuals

• Assembly instructions

• 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

• Shows three faces of the object

• Useful if one face of an object needs to be shown flat

• 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

• 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

• 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)

• 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

• 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