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## ENGINEERING GRAPHICS 1E7

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**ENGINEERING GRAPHICS1E7**Lecture 3: Orthographic Projections**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**Parallel Projections**• Projectors are parallel to each other but not perpendicular to projection plane • Effective in pictorially representing objects**Parallel Projections**• Projectors are parallel to each other and perpendicular to the projection plane • Effective in technical representation of objects**Axonometric**The object is tilted with all three coordinate axes are visible in any one view (PP projection plane)**Orthographic (Orthogonal)**The object is at rest and two coordinate axes are visible in any one view (PP projection plane)**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**Angles**• First angle projection – European System • Third angle projection – American System**Front View**Top View Right Side View Sketching Views (1) STEP 1: • Measure the overall width, depth and height of the object STEP 2: • Draw the construction (thin) lines following the number sequence**Sketching Views (2)**STEP 3: • Draw all the details using blocks STEP 4: • Sketch the circles and corners using compass**Sketching Views (3)**STEP 4: • Draw the centre lines, hidden lines • Lighten the construction lines and thicken the final lines.**First Angle Projection 1**How to draw plan and elevation?**First Angle Projection 2**How to draw end view?**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’.