How to use a caliper

How to use a caliper, and what kind of device? Caliper - measuring tool for determining small distances, depth, diameter of parts. To understand how to use it, you need to carefully examine its structure.


Caliper - a device for measuring small distances, depth, diameter of parts.

Measurements by this device are obtained with an accuracy of 0.1-0.01 mm. Outer and inner diameters are measured by wide lower and inner auxiliary jaws.

There are these types of tools:

  • nonius
  • dial;
  • electronic.

The principle of construction is the same, but the type of reading device is different.

Device structure

Figure 1 shows the shts-1 caliper with a vernier, which has the following components:

  1. Barbell
  2. Tool frame.
  3. Scale of divisions.
  4. Internal sponges.
  5. External sponge.
  6. Depth gauge
  7. Vernier.
  8. Screw.
Device caliper SHTs-1

Figure 1. Device caliper SHC-1: 1 - bar, 2 - tool frame, 3 - scale of divisions, 4 - internal jaws, 5 - external jaws, 6 - depth gauge, 7 - nonius, 8 - screw.

The bar is a measuring ruler with a gradation of 1 mm, whose length is 150 mm. That is, the maximum size of the measured surface should not exceed 15 cm. But there are also such calipers, the rod length of which is more than 15 cm.

The frame of the caliper is movable and is designed to move the jaws. With the help of a frame, they can be expanded or narrowed to the required size. Screw (pos.8) frame can be fixed. This is necessary so that after the measurement of the part does not lose the desired position of the frame.

Small sliding elements measure the internal size of a cavity: the internal diameter of the sleeve, the internal size between the planes of the mating parts.

With the help of large sliding elements measure the outer dimensions of products: outer diameter, length, width, height of small parts. To do this, the sponge must be diluted on both sides of the measured surface and close tightly.

The depth gauge measures the depth of the products. It is a thin retractable ruler. This device determines the depth of the holes, various protrusions that are difficult to measure by standard methods.

Nonius is a subsidiary scale on a caliper. The nonius has 10 divisions with a size of 1.9 mm. Thus, the total length of the scale is 19 cm. The auxiliary scale is used to find out the size with an accuracy of 0.1 mm.

When using the device, you should be careful: the tool has sharp edges.

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Terms of use of the measuring device

Before starting the measurements, the new instrument should be cleaned on the working surfaces and checked for its accuracy. To do this, combine the main sponge. At the same time, the initial marks of the two scales should coincide: a fixed worker, with millimeter divisions and a movable vernier.

Instructions for determining the external dimensions:

Diagram of measuring a part with a caliper

The scheme of measurement details with calipers.

  1. Take the tool in the right hand and the part in the left.
  2. Spread the outer jaws and tightly clamp the part between them. To do this, move the frame with your thumb until the desired expansion of the jaws.
  3. When the sliding parts of the tool are in close contact with the extreme points of the measured part, this position must be fixed with a fixing screw.
  4. Before you take the results of testimony, you must ensure that there are no distortions.
  5. The detail is set aside and start reading the results.

Measurements of internal dimensions:

  1. Close the inner sliding parts of the instrument and place in the measured cavity.
  2. Dissolve the jaws until they touch the outer points of the inner surface of the part with their outer edges.
  3. This position of the caliper is fixed with a screw.
  4. Remove the part to the side and start reading the results.

To determine the depth of the hole, it is necessary to lower the depth gauge into the hole cavity. The outer lips move apart until the depth gauge rests on the bottom of the surface. This position is fixed with a screw and proceed to the removal of the results.

In order to take readings correctly, the caliper should be held right before your eyes. If you look at the scale from the side, it will lead to measurement errors.

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Definition of evidence

Determination of external, internal dimensions and depth produced by one algorithm.

Four kinds of measurement with a caliper

Four kinds of measurement with a caliper.

The measurement value determines the relative position of the two scales: the main and the vernier. The surface of the vernier scale has a bevel for better alignment with the main scale.

To begin with, it is necessary to estimate an integer mm on the main scale, which is located to the left of the initial mark of the nonius. For example, if the zero point of the vernier stopped between the 33 mm and 34 mm divisions, then the integer in mm is 33.

Next, determine the number of tenths of measuring units. To do this, on the nonius scale, a stroke is found which clearly coincides with any mark on the main scale. It is exactly the exact match that is important here! The value of the matching bar on the division of the Vernier is a tenth of mm.

If there are several such coincidences, then they take into account the figure that is closer to the zero point of the nonius. For example: on the vernier scale, two matching lines: at levels 3 and 4. Take into account the value "3".

Adding the whole part and the tenths, receive measurements readings. So, in the described example, we obtain the total measurement result: 33.3 mm.

It is very easy to read the readings with the help of an arrow instrument. The integer size is determined by the main dial of the device. On the auxiliary graduated dial, the hand indicates tenths and even hundredths of measuring units.

Digital device - the easiest and most convenient. The readings are displayed on the instrument display.

Vernier caliper is an indispensable device in engineering and design. With it, control the accuracy of manufacturing parts.

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