Plain scale is created to measure lengths in two units merely that are units and sub- units that like yards and meters or feet and centimeters or decimeters and millimeters. During other words, we can employ a plain scale for reading only up to the first decimal position, as like an example, decimeter and meter, millimeter and decimeter. The given are the significant steps used for the construction of a plain scale as :
(a) Evaluate RF, whether not given.
(b) Evaluate the length of the scale or L, with help of the formula as:
L = RF × Maximum length to be measured
(c) If the maximum length to be measured not specified in the problem, adopt L = 15 centimeter or minimum and or 30 centimeter or maximum. It is like per BIS.
(d) Draw a straight line of length L and divide it geometrically into a number of equivalent parts as essential. These are the major units.
(e) Draw another line parallel to, and just above, this line on a distance of 3 to 5 millimeter and of the similar length. Drawing vertical lines on the ending complete the rectangle. Draw vertical lines from all division to join mutually horizontal lines.
(f) From the left end write zero or "0" at the first division, and write as 1, 2, 3 major divisions on subsequent divisions on right side. Write units on the ending.
(g) Divide the first division into equivalent parts or geometrically that like the numbers are equivalent to sub-divisions. As an example, if the major divisions are meter, so then the first division should be divided into ten the same parts hence each sub-division represents 1/10th of a meter (m) of a decimeter (dm).
(h) Write down RF of the scale just above and on the middle length of the scale.