ISOMETRIC DRAWINGS LECTURE NO. - 02

What is PROJECTION?

PROJECTION METHOD Perspective Parallel Oblique Orthographic

MEANING Orthographic projection is a parallel projection technique in which the parallel lines of sight are perpendicular to the projection plane 1 2 5 3 4

ORTHOGRAPHIC VIEW Two dimensions of an object is shown. Orthographic view depends on relative position of the object to the line of sight. Rotate Two dimensions of an object is shown. Tilt More than one view is needed to represent the object. Multi-view drawing Three dimensions of an object is shown. Axonometric drawing

OBJECT REPRESENTATION Orthographic projection technique can produce…. Axonometric projection ~ that shows all three dimensions of an object in one view. Multiview projection ~ that each view show an object in two dimensions. Both drawing types are used in technical drawing for communication.

PROJECTION METHOD Perspective Parallel Oblique Orthographic Axonometric Multiview

Fundamentals of Projection

PROJECTION SYSTEMS - European country - ISO standard First Quadrant 1. First angle system - European country - ISO standard First Quadrant VP 2. Third angle system HP - Canada, USA, Japan, Thailand HP VP Third Quadrant

ORTHOGRAPHIC PROJECTION 1st angle system 3rd angle system

ORTHOGRAPHIC VIEWS Folding line Folding line Folding line Folding line 1st angle system 3rd angle system Folding line  Folding line Folding line  Folding line

ORTHOGRAPHIC VIEWS Top View Right Side View Front View Top View 1st angle system 3rd angle system Top View Right Side View Front View Top View Front View Right Side View

PROJECTION SYMBOLS First angle system Third angle system

Projection Symbol

Projection Symbol - explained

AXONOMETRIC DRAWING Why have you drawn ORTHOGRAPHIC VIEWS? Right Side View Front View Is it easy to visualize that the actual object of the given orthographic views looks like this? To give idea about shape of the final object. Top View AXONOMETRIC DRAWING

Axonometric Projection Because even a simple drawing can be better visualized by this drawings. C D A B D F G C A B G E F C D

Axonometric Projection Line of sight D Parallel & normal to picture plane C A B D How can the Axonometric Drawing be explained? A C B How exactly can the cube be placed ?

Axonometric Projection Type of axonometric drawing A B C D a b c 1. Isometric All angles are equal. A B C D a b c 2. Dimetric Two angles are equal. b a c 3. Trimetric None of angles are equal.

Isometric Projection Non-Iso Lines Isometric axis TERMINOLOGIES b c Non-Iso Lines Isometric axis TERMINOLOGIES Iso-Lines

All edges foreshorten about 0.8 time. But there is a PROBLEM!!! All edges foreshorten about 0.8 time. We can not take measurements directly from the figure.

Isometric drawing / View Isometric drawing is a drawing drawn on an isometric axes using full scale. Isometric projection (True projection) Isometric drawing / View (Full scale) Foreshortened Length Full scale

Positions of Isometric Axes Before we start learning how to draw isometric views / projections, there is one more concern…

Positions of Isometric Axes Isometric axes can be arbitrarily positioned to create different views of a single object. Regular isometric Reverse axis isometric Long axis isometric View point is looking down on the top of the object. View point is looking up on the bottom of the object. View point is looking from the right (or left) of the object.

To explain the method let us take the example of cube again... Isentropic Projection How to draw Isentropic Views? A C B D C To explain the method let us take the example of cube again... B D C H F E G F G E A D B A F Vertical iso-lines are drawn either along vertical isometric axis or parallel to it. Horizontal iso-lines are drawn either along inclined isometric axis or parallel to it. C B D C

Let us start with a plane Regular isometric Isentropic View Let us start with a plane A B D 300 c’, (b) d’, (a) C y x a b TV of a SQUARE B C A D c d

Isentropic View In case of a rectangle? TV Regular isometric A D B c’, (b) d’, (a) C y x b a TV B C A d c D

Isentropic View FV of a SQUARE Regular isometric B a' b' A C c' d' D x y a, (d) b, (c)

C/W: Sketch from multi-view drawing: FV FV TV TV FV & TV

Circle & Arc in Isometric In isometric drawing, a circle appears as an ellipse. Sketching Steps 1. Locate the centre of an ellipse. 2. Construct an isometric square. 3. Sketch arcs that connect the tangent points.

Circle & Arc in Isometric Four-centre method is usually used when drawn an isometric ellipse with drawing instrument. Sketching Steps 1. Locate the centre of an ellipse. 2. Construct an isometric square. 3. Construct a perpendicular bisector from each tangent point. 4. Locate the four centres. 5. Draw the arcs with these centres and tangent to isometric square.

Sketch from multi-view drawing of SOLIDS 1. Interpret the meaning of lines/areas in multi-view drawing. 2. Locate the lines or surfaces relative to isometric axis.

Example 1 : Object having only normal surfaces D b‘, (c’) Top a‘, (d’) A Front View H H Front C Side B p‘, (s’) W q‘, (r’) P W R c, (r) D d, (s) Top View D Q a, (p) b, (q)

Example 1 : Object having only normal surfaces Top Side View Front View H H Front Side D W W D Top View

Example 2 : a' b' (e’) c' d' p' q' (t’) r' s' e, (t) d, (s) a, (p) c, (r) b, (q)

Example 3 : o' p' q' (t‘) r' s' t p s o r q

Example 4 :

Example 4/A :

Example 5 :

Example 6 : D Nonisometric line q H y y x W x Front View

Example 7 : x x B x Nonisometric line y A C x B A y C B A

Example 8:

Irregular Curve in Isometric Example 9: Irregular Curve in Isometric Steps 1. Construct points along the curve in multiview drawing. 2. Locate these points in the isometric view. 3. Sketch the connecting lines.

ISOMETRIC VIEW Composite Solids

Objects are decomposed into solid geometric primitives. BASIC IDEA Objects are decomposed into solid geometric primitives. Some of familiar solid objects Rectangular prism Cylinder Negative cylinder (Hole)

Objects are decomposed into solid geometric primitives. BASIC IDEA Objects are decomposed into solid geometric primitives. Some of familiar solid objects Cone Pyramid Sphere

Example 10:

Example 11:

Example 12:

simple machine components Isometric Views for simple machine components 1. Orient yourself with the views given. (Choose the viewing direction.) 2. Read the individual surfaces that appeared in each view and related to each other. 3. Create a proper solid geometric primitive from each reading. 4. Assembly all of solid geometric primitive according to orthographic views.

EXAMPLE -13: Composition Given Rectangular prism Hole Front View

EXAMPLE -14: Given Composition Rectangular prism Cylinder Front View

Example 15 B A C D F E x Front View y B D C E F A

EXAMPLE -16: Composition Given Cylinder with a blind hole. L-shaped with round end Hole

EXAMPLE -17: Composition Given Wedge

EXAMPLE -17: Composition Given Wedge L-shaped block

Example 18

Example 18