Vernier Caliper

How to use and read a vernier caliper？


An ordinary vernier caliper has jaws you can place around an object, and on the other side jaws made to fit inside an object. These secondary jaws are for measuring the inside diameter of an object. Also, a stiff bar extends from the caliper as you open it that can be used to measure depth.


The basic steps are as follows:



1. Preparation to take the measurement, loosen the locking screw and move the slider to check if the vernier scale works properly. Before measuring, do make sure the caliper reads 0 when fully closed. If the reading is not 0, adjust the caliper’s jaws until you get a 0 reading. If you can’t adjust the caliper, you will have to remember to add to subtract the correct offset from your final reading. Clean the measuring surfaces of both vernier caliper and the object, then you can take the measurement.



2. Close the jaws lightly on the item which you want to measure. If you are measuring something round, be sure the axis of the part is perpendicular to the caliper. Namely, make sure you are measuring the full diameter. An ordinary caliper has jaws you can place around an object, and on the other side jaws made to fit inside an object. These secondary jaws are for measuring the inside diameter of an object. Also, a stiff bar extends from the caliper as you open it that can be used to measure depth.



3. How to read the measured value:


1), Read the centimeter mark on the fixed scale to the left of the 0-mark on the vernier scale. (10mm on the fixed caliper)

2). Find the millimeter mark on the fixed scale that is just to the left of the 0-mark on the vernier scale. (6mm on the fixed caliper)

3). Look along the ten marks on the vernier scale and the millimeter marks on the adjacent fixed scale, until you find the two that most nearly line up. (0.25mm on the vernier scale)

4). To get the correct reading, simply add this found digit to your previous reading. (10mm + 6mm + 0.25mm= 16.25 mm)

4.Maintenance



Clean the surface of the vernier caliper with dry and clean cloth (or soaked with cleaning oil) and stock in a dry environment if it stands idle for a long time.

Digital Vernier Caliperse:

Least count:


The least count of any measuring equipment is the smallest quantity that can be measured accurately using that instrument.Thus Least Count indicates the degree of accuracy of measurement that can be achieved by the measuring instrument.



The Vernier scale consists of a main scale graduated in centimeters and millimeters. On the Vernier scale 0.9 cm is divided into ten equal parts. The least count or the smallest reading which you can get with the instrument can be calculated as under:


Least count = one main scale (MS) division - one vernier scale (VS) division.

= 1 mm - 0.09 mm

= 0.1 mm

= 0.01 cm


The least count of the vernier =  Value of  the smallest division on MS/Total number of divisions on VS
                                                     =  1 mm/ 10 = 0.1 cm/10 = 0.01 cm