# chapter 4 sketching and orthographic projection. 2 links for chapter 4 sketching shapes sketching...

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Chapter 4

Sketching and

Orthographic Projection

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Links for Chapter 4

Sketching Shapes

Sketching Procedures

Orthographic Projection

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Sketching Tools & Materials

• Soft lead pencil with H or HB lead

• Type of paper is not critical as long as the idea can be conveyed

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Sketching Lines

• Create lines with short connected segments

• Keep lines light so they can easily be erased

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Sketching Circles• Trammel method

– Mark the radius of the circle on the trammel– Place pencil on one point while holding the

other point at the center of the circle– Rotate trammel around the center

• Hand compass method– Use your hand as the center and rotate paper

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Measurement and Proportion

• Proportion of lines to each other are more important then the size of the sketch itself

• The first line sketched determines the scale of the drawing

• Make sure the direction and position of lines are accurate

• Use your pencil to establish measurements

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Sketching Procedures

• Before sketching try to visualize the object

• Sketch very light lines of the outline

• Add details being careful to keep the proportion correct

• Darken in the desired lines of the final sketch

• Use a grid to create irregular shapes

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Multiview Sketches

• Block out views and 45° line

• The 45° line is used to project lines from the top and right side view

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Isometric Sketches

• Isometric sketches are a three-dimensional pictorial representation of the object

• Begin by drawing– Horizontal ground line

– Perpendicular line

– Two 30° lines

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Isometric Sketches

• Determine best view for the front

• Set up isometric axes

• Sketch overall block

• Add details

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Isometric Details

• Nonisometric lines are not parallel to one of the three original axes and are not true length

• Circles and arcs appear as ovals– Use the four-center method to construct

– Be sure they lie on the proper plane

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Orthographic Projection

• Any projection of features onto an imaginary perpendicular plane– Lines of sight are perpendicular to the plane

– Objects are true size if they are parallel to the plane

– Objects are foreshortened if they are not parallel to the plane

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Multiview Projection

• In architecture, two-dimensional exterior drawings are referred to as elevations

• Use a glass box to help visualize the six views

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Multiview Details

• Use the front, left side, right side, and back as elevations

• Top view is the roof plan

• Project circles and inclined lines using the 45° line projection method