Scale and its Types

SCALE AND ITS TYPES

The proportion by which all the dimensions of an object are either enlarged (or) reduced suitably for the convenience and clear representation to be shown on a drawing sheet is known as `drawing to scale' (or) simply 'scale'.

It generally relates the drawing size to actual size of an object. Based on the proportion of drawing size to actual size. ie., Drawing size : Actual size, the scale is generally classified into three types as

i) Full size scale 

ii) Reduced scale, and 

iii) Enlarged scale 

(i) Full size scale : The scale in which the actual measurements of the object are drawn is known as Full size scale.

In Full size scale the drawing size and the actual size are equal.

ie., Drawing size : Actual size = 1:1

(ii) Reduced scale : The scale in which the actual measurements of the object are reduced to some proportion is known as reduced scale. ie., In reduced scale, the drawing size is less than the actual size. 

Example : Drawing size : Actual size = 1 : 2, ie., The actual size is two times of the drawing size, or drawing size is made to Half of the actual size. 

(iii) Enlarged scale : The scale in which the actual measurements of the object are enlarged to some proportion is known as enlarged scale. ie., in enlarged scale, the drawing size is greater than the actual size.

Example : Drawing size : Actual size = 2:1, ie., The actual size is half of the drawing size, or drawing size is made twice the actual size.

To distinguish between the different types of scales an object which is drawn in actual, reduced and enlarged scale is shown below in Fig. 5.1.

Note : While drawing an object in either enlarged or reduced scale, the dimensions are enlarged or reduced accordingly. But while dimensioning the object only the actual measurements are to be marked in the drawing irrespective of their drawing size.