Data required for construction of scales

DATA REQUIRED FOR CONSTRUCTION OF SCALES 

1. Representative fraction (R.F) of the scale. 

2. The maximum length of scale to be drawn on the drawing sheet. 

3. Least count of the scale, ie., the minimum length which the scale should measure.

For example, for the conventional 30 cm scale, most generally used in engineering drawing, 

i) Representative fraction is 1 (since the scale is full size scale) 

ii) Maximum length of scale is 30 cm (or) 300 mm. 

iii) Least count of the scale is 1mm. (since 1 cm is divided into 10 equal parts) 

The length of scale to be drawn on the drawing sheet is determined by the following expression,

Length of scale, Ls = R.F × Maximum length of object 

However, if length of scale and R.F are not given in the problem, it can be assumed suitably. (Normally the length of scale is assumed as 15 cm).