Engineering Drawing, 2nd Edition

21

Computer-Aided Drafting

OBJECTIVES

After reading this chapter, you will be able to

• Draw straight lines, curved lines, arcs, circles, polygons, ellipses and elliptical arcs without using drawing instruments
• Prepare accurate drawings of machine parts and enlarge, reduce, copy and rotate them
• Change the type, thicknesses, and color of symbolic lines, and erase any selected line
• Dimension drawings to describe the size of the object perfectly

21.1 INTRODUCTION

The preparation of engineering drawings with the help of a drawing board, a minidrafter, set squares, dividers, compasses and other instruments is a laborious process. Computer-aided drafting (CAD) helps in preparing drawings without the use of the usual drawing instruments. The ...