How to measure with a caliper

Measuring with a caliper requires a certain skill that comes with experience. Therefore, in order to avoid mistakes, it is recommended in the initial attempts to make two or three measurements without haste. Before you start working with a caliper, you need to familiarize yourself with its design and understand the principle of operation.

Diagram of a caliper

Diagram of the device calipers.

The tool is made of steel, the surfaces in contact with the measured parts are hardened and have a high degree of hardness. It ensures the durability of the device and allows you to put risks on the measured parts. But there are stationery calipers made of plastic.

Work with a caliper

The basic basis of the device has a ruler or bar - hence the name. The frame is equipped with a frame of special design, on which there is a Nonius scale. On the rod and on the moving part there are sponges for internal and external measurements. In the groove of the rod moves the depth gauge rod rigidly attached to the moving structure. A clamping screw is attached to the moving part.

Four kinds of measurement with a caliper

Four kinds of measurement with a caliper.

Depending on how the readings are taken, the instruments are equipped with a nonius, convenient dial or digital indicator. There are devices that have a micrometric head attached to a movable sponge. The readings are taken in mm, but in some instances there is an inch scale at the top of the frame. The screw for clamping the movable structure is applied after the sponges are pressed against the measured part, but the reading is difficult due to the inconvenient location. In this case, it is possible to shift the frame at the moment when the caliper is taken away from the measured place. The screw is clamped in the case when you want to set a predetermined size.

It is very convenient to measure correctly with a caliper equipped with a dial or a digital indicator, and will not be a problem. The accuracy will be 0.01 mm. The same accuracy will be when equipping the micrometer head. If you measure with a vernier caliper, you first mark the number of whole mm, and the size of the next fractional mm is determined by what division of the vernier coincides with the millimeter scale on the rod. If a vernier is provided for an accuracy of 0.1 mm, then the numbers on the scale are missing. If the accuracy is 0.05 mm, then there are numbers on the vernier scale. When measuring, the device is usually held in the right hand so that the thumb rests on the ledge with notches on the moving frame. Use your left hand to move the measuring jaws to the part until you touch it lightly.

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Check before work

Before measurements, check the caliper for coincidence with zero division in the absence of a gap between the jaws. Depth gauge check on a flat surface to the full deepening of the measuring rod. A zero-division mismatch may occur when the surface is worn in contact with the part being measured. In this case, the size of the mismatch is taken for error and subtracted when measuring.

Before use, you must ensure that the tool is clean. It should be more often wipe it with a clean cloth. Measured parts and hands must also be clean. During operation, avoid striking the device and prevent it from falling; do not lay the device on heated surfaces and avoid scratches.

The accuracy of the device is usually taken equal to half the price of division.

With a graduation price of 0.1 mm, the result should be depicted, for example, as 30.7 plus or minus 0.05.

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