ME2103 Engineering Visualization & Modeling Principles of Projections

Principles of Projections 1. Pictorial Drawings:

Axonometric Isometric View, Dimetric View, &

Trimetric View

Oblique & Perspective Views

2. Principles of Projections • 3rd Angle Projection

• 1st Angle Projection

3. Auxiliary View

4. True Length

Content:

Pictorial Drawings: Axonometric

Oblique Perspective

Pictorial Drawings

Axonometric

Oblique

Perspective Multi-view

There are three general classifications of pictorial drawings: Axonometric, Oblique & Perspective

Axonometric Projection Axonometric projection involves rotating the object so that the three principal faces can be seen from one viewing position

Examples of Axonometric Projection

Oblique Drawings An Oblique projection is a form of pictorial drawing in which the most informative view is treated as the front view and is placed parallel to the plane of projection

Oblique drawing angles

Cavalier Oblique Cabinet Oblique General Oblique

Oblique Images

Cavalier Oblique Cabinet Oblique

Perspective View

Perspective

A Perspective projection is a form of drawing that depicts a three - dimensional object on a flat plane as it appears to the eye

One point

Two point

Three point

Perspective and Oblique View

Principles of Projection

Angle of Projection

Angle of Projection

F

F

Angle of Projection

3rd Angle Projection

3rd Angle Projection

3rd Angle Projection

F F

Examples of 3rd Angle of Projection

Front Left

Plan

Front

Plan

Right

Examples:

Examples:

Right

Front

Plan

Plan

Front Right

Hidden lines not shown

Examples:

Examples:

Choosing the number of projection views

3 views

2 views

1 view

Symbols for Angle of Projection

1st Angle Projection

1st Angle Projection

1st Angle Projection

Comparison of 1st & 3rd Angle of Projection

3rd Angle 1st Angle

Comparison of 1st & 3rd Angle of Projection 3rd Angle 1st Angle

Adding Projection Symbol in SolidWorks for ME2103 (Step 1 : Annotation; Note; Add Symbol)

Adding Projection Symbol in SolidWorks for ME2103 (Step 2 : Add Symbol; Projection symbol; 3rd angle)

Types of Paper to Use Square Grid Paper Isometric Paper

Basic steps in Isometric construction

Build an enclosed box Add the details Darken the outlines

Examples of Isometric construction

Steps in Isometric Sketching

Examples of Orthographic sketching

Multi View Projection

Isometric Projection

Choices of Views

Choices of Views

Examples of Multi View Projection 1st Angle Projection

3rd Angle Projection

Examples of Multi View Projection 1st Angle Projection

3rd Angle Projection

Example: Lever Bracket 1st Angle Projection

3rd Angle Projection

Auxiliary Projection An object may have inclined surfaces that are not perpendicular, or right angle, to the principal planes of projection. These surfaces appear to be distorted and their true shapes are not shown in a regular view having orthographic projection. To reveal the true shape of these inclined surfaces with distortion, additional views (auxiliary views) are needed.

An auxiliary view is an orthographic view having a line of sight not perpendicular to the principal planes of projection

Auxiliary Plane parallel with the inclined surface

Auxiliary Projection

Auxiliary View

Orthographic, isometric and auxiliary projections of an inclined bracket

The main purposes of auxiliary view projection include:

• Finding the true length of a line. • Finding the true shape and size of a plane. • Dimensioning the auxiliary surface.

Example of Auxiliary Views Guide Bracket Angle Guide

Example of Auxiliary Views Control Bracket Tool Holder

True Length

Many inclined or oblique objects, or surfaces, require the true length of the surface edges to be determined. This is importance in the sheet metal development industry such as air-conditioning ducts making.

An inclined plane An oblique plane

Projecting true lengths and true surfaces

Principal views Auxiliary views E and F show the true lengths OA and OB

Revolving front view clockwise Revolving front view anti-clockwise

Revolving end view anti-clockwise Revolving only surface OAD

Projecting true lengths and true surfaces

Projecting true lengths

Revolving top view anti-clockwise Revolving top view clockwise

Revolving lines OA & OD in the top view

True Length

True Length

Thank You