Firm joint and spring joint calipers

 The commonly used calipers 

. name the commonly used calipers

.compare the features of firm joint and spring joint calipers

. state the advantages of spring joint calipers.

Calipers are simple measuring instruments used to transfer measurements from a steel rule to objects,, and vice versa.

Calipers are of diffent types depending on the type of the joint and the shape of the leg.

Types of joints

The commonly used calipers are firm joint calipers and spring joint calipers

Firm joint calipers

In the case of firm joint calipers, both leg are pivoted at one end. To take measurements of a workpiece, the caliper is opened roughly to the required size. Fine setting is done by tapping the caliper lightly on a wooden surface.

Spring joint calipers

For this type of calipers, the legs are assembled by means of a pivot loaded with a spring. For opening and closing the caliper legs, a screw and nut are provided.

Spring joint calipers have the advantage of quick setting. The setting made will not change unless the nut is turned. The size of a calipers is specified by its length, which is the distance between the pivot centre and the tip of the leg. The accuracy of the measurement taken depends very much on the sense of 'feel' or 'touch' while measuring the job, you should get the feel when the legs are just touching the surface.

Types of leg

Outside and inside calipers are differentiated by the shape of the legs.

Calipers used for outside measurements are known as outside caliper.The calipers are used for internal measurements are known as inside calipers.

Inside caliper

Outside caliper

Calipers are used along with steel rules, and the accuracy is limited to 0.5mm, parallelism of jobs etc. Can be checked with higher accuracy by using calipers.