Engineering Drawing, 2nd Edition

3

Geometrical Constructions, Loci and Engineering Plane Curves

OBJECTIVES

After studying this chapter, you will be able to

• Divide a line into equal parts

• Draw regular polygons

• Draw lines and arcs tangent to each other

• Draw curves used in engineering practice such as conics, cycloids, involutes and spirals

• Draw normals and tangents to a given engineering curve

• Draw the path of a point on a selected part of a machine that undergoes motion owing to the effect of another part

3.1 INTRODUCTION

The exact shape of a curve often decides the proper working of a machine and inaccuracy results in noisy or ineffective working. For example, the shape of gear teeth should be either a perfect involute or a cycloid. As the shapes of objects used in ...