A caliper is a device used to measure the distance between two opposing sides of an object.
These are designed to measure outside dimensions. The accuracy in caliper measurment depends upon the inspector’s sense of feel. When a caloper has to be set from the scale to control the dimension of any component theb leg of the caliper must be held firmly against the end of the proper dimension by adjusting nut with the thumb abd forefinger.
When calliper is used to measure the outside diameter of a cylinder, then it must be held in hand with its nut between forefinger and thumb, and one end og leg touching with the surface of cylinder. The other leg is moved to and from on the opposite surface so that other leg just passes through the cylinder. The caliper reading is transferred to the scale by holding one leg of the caliper against the scale firmly and the reading taken at other end of leg. For accurate settings. the distance between the outside calipers may be set by slip gauge or by micrometer anvils sometimes it may be required to transfer this dimension to caliper.
Inside caliper :
While using inside calipers, the use of hook scale to measure the distance between its legs is desirable. With ordinary scale, one leg of inside caliper must be coincided with a vertical brace and second leg adjusted accordingly. It will be best if the legs of the inside caliper are adjusted with a micrometer.
Vernier caliper :
The vernier, dial, and digital calipers give a direct reading of the distance measured to high accuracy. This vernier caliper can make measurements using both inside ( for holes ) and outside (shafts) anvils. A major feature of the vernier caliper is the auxiliary scale metric scale on the top, a metric vernier plate. and an scale on the bottom with vernier