Engineering Drawing Principles and Applications

Introduction

The previous chapters of the book have described the fundamental concepts of manual drawing, using various drawing instruments and producing a hardcopy of the drawing. This traditional drawing, however, still remains the foundation for engineering communication, as the subject of computer aided drafting (CAD) has been developed on the fundamentals of traditional drawing. So the advent of CAD does not necessarily eliminate manual engineering graphics.

There are several reasons for implementing a computer aided design system. A few of them are:

• • To increase the productivity of the designer

• • To improve the quality of design

• • To improve communication

• • To create a database for manufacturing

Computer Graphics

The term ‘computer graphics’ is very generic in the sense that it has different meanings for different disciplines of study. In the operation of the graphics system by the user, a variety of activities take place, which can be divided into three categories: interaction with graphics terminal to create and alter images on the screen; construction of a model of something physical and of the image on the screen; and entering the model into computer memory. In working with the graphics system, the user performs these various activities in combination rather than sequentially.

Requirements for Computer Graphics

The basic requirements are a CAD workstation and requisite software. CAD workstation comprises a common PC with minimum Pentium configuration, a video display, a mouse or pen, and a plotter or printer. The graphics software can be divided into three modules: the graphic package, the application program and the application database. Various requirements of graphics software are:

• • It should be easy to use.

• • The package should operate in a consistent and predictable way, for the user.

• • Graphics programs should be efficient.

• • It should not be too expensive to make its use prohibitive.

This chapter explores the AutoCAD package for its basic drafting capabilities.

Getting Started with AutoCAD

Start AutoCAD by clicking on the Windows start button placed at the bottom left, then move the mouse to programs, click on AutoCAD as shown in Fig. 19.1 or it can directly be opened by double clicking on the desktop icon of AutoCAD.