ES 101 Engineering Graphics Gaurav Srivastava Assistant Professor Civil Engineering (gauravs@iitgn.ac.in) Fall 2017

Last time [5.1] bisecting a line [5.2] to draw perpendiculars [5.3] to draw parallel lines [5.4] to divide a line [5.6] to bisect an angle [5.10] to construct equilateral triangles [5.11] to construct square [5.16] to draw tangents

Types of Lines Types of Lines Applications Example Thick Continuous Line Visible Edges and Surface Boundaries Thin Continuous Line Extension and Dimension Lines, Section Lines Construction Line in light stroke Dashed Line Hidden Outline and Edges 10 mm

Types of Lines Types of Lines Applications Example Dash-dot Line or alternating Long-Short dash Center Line, Line of symmetry Dash with pair of dots Line Phantom Lines Continuous zig-zag Line Partial Views Discontinuation Line

Example: Center Lines

Example: Hidden & Center Lines

Example: Construction Lines

Example: Many Lines 1 Viewing-plane line Dimension Line 3 4 Center Line 2 Extension line 5 Hidden Line 6 Break Line Cutting-plane Line 7 8 Visible Line 9 Center Line (of motion) 10 Leader Chain Line 14 Phantom Line 13 Section Line SECTION A-A 12 VIEW B-B 11 ES-101: Engineering Graphics - Amit Prashant ES101: Lecture 2 (28 August 2014) Source: http://www.genium.com/pdf/dmpc.pdf

Scale Dimensions of large objects must be reduced to accommodate on standard size drawing sheet. Similarly in case of tiny objects dimensions must be increased. 1: 2 1: 0.5 Large Objects Ex: Table or chair Drawing Size 1:1 Ex: Keyboard of a computer Small Objects Ex: Circuit of a mobile phone

Scale Representative Fraction, RF:   RF = 0.2 or 1/5 means the actual object is five times larger than the size shown on drawing Scale = 1:5 RF = 5 or 5/1 means the actual object is five times smaller than the size shown on drawing Scale = 1:0.2

Scale 1 : R Hence, the Scale is written as (Drawing : Real) i Full Scale 1:1 Reduced Scale 1:R R>1.0 Enlarged Scale 1:R R<1.0 on Right is the Real size

Plane Scale For dimensions up to ONE decimal Example: Scale of 1 cm = 1m to read decimeters Maximum distance of 6 m Show distance of 4 m and 6 dm What is the R.F.? 4 m 6 dm 10 METER 1 2 3 4 5 DECIMETER

Diagonal Scale For dimensions up to TWO decimals Example: Scale of 1 cm = 1m to read centimeters Maximum distance of 6 m Show distance of 4 m and 46 cm 5 10 CENTIMETER 4 m 46 cm 10 METER 1 2 3 4 5 DECIMETER

Diagonal Scale: Example Construct a diagonal scale of R.F. =1/500 to read up to 60 meters and to read millimeters on it. Show a length of 40.802 meters on it. 5 10 MILLIMETER 40.802 m 100 METER 10 20 30 40 50 CENTIMETER

Curves Sections of Cone at various inclinations result into different plane geometries - Curves Circle Ellipse Parabola Hyperbola

Geometric construction [3.1] lines [4.2] scales [6.1.1] ellipse [6.2.1] cycloid [6.3] involute [6.5.1] Archemedian spiral [3.3-3.8] dimensioning

Ellipse – Rectangle Method Very useful in making inclined views of ellipses/circles in isometric/perspective projections

Parabola – General Method Focus

Parabola – Rectangle Method RISE SPAN

Cycloid C1 C2 C3 C4 C5 C6 C7 C8 7 6 5 4 3 2 1 8

Involute 1 2 3 4 5 6 7 8 D D D

Spiral

Dimensioning – good practices Should be complete but not redundant Should be placed outside views/objects Avoid crossing of dimension lines Should be placed at a reasonable distance from the object/feature Use uniform arrow type (typically 3:1 ratio between length:depth)