Lecture 3 Sunday, 03 May ENGINEERING GRAPHICS 1E7 Lecture 3: Orthographic Projections

Lecture 3 Sunday, 03 May 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

Lecture 3 Sunday, 03 May Projections (2) Projections Parallel/ Cylindrical Oblique Cabinet Cavalier Other Orthographic Multi-view First-angleFourth-angleThird-angleSecond-angle Axonometric Isometric (30°) Di-metricTrimetric Perspective/ Conical One-PointTwo-PointThree-Point

Lecture 3 Sunday, 03 May Perspective Projections

Lecture 3 Sunday, 03 May Parallel Projections

Lecture 3 Sunday, 03 May Parallel Projections Projectors are parallel to each other but not perpendicular to projection plane Effective in pictorially representing objects

Lecture 3 Sunday, 03 May Parallel Projections Projectors are parallel to each other and perpendicular to the projection plane Effective in technical representation of objects

Lecture 3 Sunday, 03 May Axonometric The object is tilted with all three coordinate axes are visible in any one view (PP projection plane)

Lecture 3 Sunday, 03 May Orthographic (Orthogonal) The object is at rest and two coordinate axes are visible in any one view (PP projection plane)

Lecture 3 Sunday, 03 May Multiview Projections

Lecture 3 Sunday, 03 May 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

Lecture 3 Sunday, 03 May The six views

Lecture 3 Sunday, 03 May Angles First angle projection – European System Third angle projection – American System

Lecture 3 Sunday, 03 May Sketching Views (1) Measure the overall width, depth and height of the object STEP 1: Draw the construction (thin) lines following the number sequence STEP 2: Top View Front View Right Side View

Lecture 3 Sunday, 03 May Sketching Views (2) Draw all the details using blocks STEP 3: Sketch the circles and corners using compass STEP 4:

Lecture 3 Sunday, 03 May Sketching Views (3) Draw the centre lines, hidden lines STEP 4: Lighten the construction lines and thicken the final lines.

Lecture 3 Sunday, 03 May First Angle Projection

Lecture 3 Sunday, 03 May First Angle Projection 1 How to draw plan and elevation?

Lecture 3 Sunday, 03 May First Angle Projection 2 How to draw end view?

Lecture 3 Sunday, 03 May 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’.