Engg.graphics

Engg.graphics

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  Lecture 3 Monday10 December 2012 1 ENGINEERING GRAPHICS 1E7 Lecture 3: Orthographic Projections
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  Lecture 3 Monday10 December 2012 2 Projections (1) • Projections transform points from n (here, n = 3) dimensional space into a space of dimension less than n (here, n = 2) • Points to be considered, – Location of object – Location of observer – Plane of projection – Projectors
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  Lecture 3 Monday10 December 2012 3 Projections (2) Projections Parallel/ Perspective/ Cylindrical Conical Oblique Orthographic One-Point Two-Point Three-Point Cabinet Multi-view Cavalier First-angle Fourth-angle Third-angle Second-angle Other Axonometric Isometric Di-metric Trimetric (30°)
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  Lecture 3 Monday10 December 2012 4 Perspective Projections
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  Lecture 3 Monday10 December 2012 5 Parallel Projections
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  Lecture 3 Monday10 December 2012 6 Parallel Projections • Projectors are parallel to each other but not perpendicular to projection plane • Effective in pictorially representing objects
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  Lecture 3 Monday10 December 2012 7 Parallel Projections • Projectors are parallel to each other and perpendicular to the projection plane • Effective in technical representation of objects
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  Lecture 3 Monday10 December 2012 8 Axonometric The object is tilted with all three coordinate axes are visible in any one view (PP projection plane)
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  Lecture 3 Monday10 December 2012 9 Orthographic (Orthogonal) The object is at rest and two coordinate axes are visible in any one view (PP projection plane)
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  Lecture 3 Monday10 December 2012 10 Multiview Projections
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  Lecture 3 Monday10 December 2012 11 Multiview Projections • Front surfaces of object is parallel to plane of projection • Projectors or line of sights are perpendicular to projection plane • Projectors are parallel to each other and originate from any point on object
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  Lecture 3 Monday10 December 2012 12 The six views
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  Lecture 3 Monday10 December 2012 13 Angles • First angle projection – European System • Third angle projection – American System
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  Lecture 3 Monday10 December 2012 14 Sketching Views (1) STEP 1: • Measure the overall width, depth and height of the object Front View Top View STEP 2: • Draw the construction (thin) lines following the number sequence Right Side View
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  Lecture 3 Monday10 December 2012 15 Sketching Views (2) STEP 3: • Draw all the details using blocks STEP 4: • Sketch the circles and corners using compass
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  Lecture 3 Monday10 December 2012 16 Sketching Views (3) STEP 4: • Draw the centre lines, hidden lines •Lighten the construction lines and thicken the final lines.
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  Lecture 3 Monday10 December 2012 17 First Angle Projection
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  Lecture 3 Monday10 December 2012 18 First Angle Projection 1 How to draw plan and elevation?
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  Lecture 3 Monday10 December 2012 19 First Angle Projection 2 How to draw end view?
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  Lecture 3 Monday10 December 2012 20 First Angle Projection 3 Points to remember: • The ‘front view’ (or elevation) is the view with maximum information. •The ‘plan’ is below the ‘elevation’ (in projection). •The ‘end view’ is placed on the right if viewed from left side of object and on the left if viewed from right side. •‘End view’ and plan face inwards from ‘elevation’.