The caliper is an indispensable assistant in the work. Calipers. Types and device. Measurements and applications Calipers with digital display

It just so happened (at least for the author) that the accuracy of measurements is made: with a ruler up to centimeters and a half, with a caliper up to millimeters, but tenths and hundredths of a millimeter are “caught” exclusively with a micrometer. What prevents using a caliper to measure tenths of a millimeter, because it is intended for this, and it will be difficult to answer “offhand”. Often, even those who know the device of this measuring tool will be careful not to indicate the size fixed by a caliper to within tens - because the scale (vernier) is “responsible” for determining tenths of a millimeter. I admit that it is for this reason that part of the calipers began to be produced equipped with a dial scale and even equipped with an electronic display (electronic).

And what prevents you from upgrading the caliper already in use and thereby bringing the accuracy of its measurements closer to those of the dial and, for example, equipping it with a magnifying glass? I sat down to the computer and began to draw a device that had already visited the imagination.

Refinement scheme

The sketch was made in a section, where the number:

1 - the caliper bar is indicated
2 - movable caliper frame
3 - holder frame, it is installed on a movable frame
4 - screw fixing the frame to the frame
5 - a screw that secures a frame with a magnifying glass to the frame
6 - magnifying glass frame
7 - spring pressing the frame to the head of the fixing screw
8 - magnifying glass

In accordance with the finished sketch, I collected the most suitable components of the future holder “by the bottom of the barrel”.

In a textolite cube (in the past, some part of the body electronic device, and in the future frame of the holder) increased the existing groove with a file to the dimensions corresponding to the movable frame of the caliper and drilled a hole with a diameter of 3 mm in the center for the fastening screw.

On the side there is an M4 threaded hole for the mounting screw of the frame with a magnifying glass. With the end of the manufacture of the frame, labor-intensive operations that require precision and careful fitting end.

A frame was made from a piece of soft plastic (in addition to the existing one). There are two holes drilled in the plastic plate. The smaller one is for the mounting screw of the frame, the larger one is for the existing frame (into which it is screwed along the thread, which makes it possible to adjust the sharpness).

Device assembled, according to the drawing, form. I didn’t specially cut the thread in the additional frame, it was made by the thread of the old (metal) frame during the first screwing. For this, a soft plastic plate was selected, and the hole was made 0.5 mm smaller than necessary. It is clearly seen that the risks of the vernier (the name of the scale for determining tenths of a mm) are increased to the size of a more comfortable observation. This makes it possible to confidently determine the measured size with an accuracy of "tens". And even more - now you can easily distinguish a wire with a size of 0.85 mm from 0.80 mm using measurement.

Procedure for taking caliper readings

count the number of whole millimeters, for this they find on the scale of the rod the stroke closest to the left to the zero stroke of the vernier;
fractions of a millimeter are counted, for this, a stroke is found on the vernier scale that is closest to zero division and coincides with the stroke of the rod scale - its serial number will mean the number of tenths of a millimeter;
add up the number of whole millimeters and fractions.

The fixture is easy to install and remove and can only be used when needed. Project author - Babay from Barnaula.

Discuss the article UPGRADE THE CALIPERS

As you will see from this article, modifying an electronic digital caliper is a very simple procedure, but it must be done carefully so as not to damage the instrument. The design of the electronic caliper provides 4 special contacts. These contacts, for example, can be used to connect an external power supply, control functions, etc.

The pin assignments are (from left to right): negative terminal, data, clock, and positive terminal.

To activate the hidden options of the electronic digital caliper, pins 2 and 4 must be connected together.

Perhaps different electronic calipers have some differences, but in general, their modification is carried out in the same way.

The first step in finalization is to find the screws holding the case together. On our caliper, they are located under a plastic sticker. Their location can be seen in the photo.

After opening the plastic case containing the circuit board, display and several metal elements, you need to unscrew a few screws to remove printed circuit board.

Special care must be taken when handling printed circuit board and display.

The display is connected to the printed circuit board by means of a conductive rubber gasket. Be careful not to detach the display from the board, as this will make it difficult to align the connections during reassembly. And when wrong location the display may turn off spontaneously and strange characters appear on it.

After removing the printed circuit board of the electronic caliper, we get access to the necessary contacts.

Now you can solder 2 thin wires (the thinner the better). Solder one to pin number 2 and the other to pin number 4.

To close these terminals, it is best to use a micro button, for example, from an old computer mouse. The pins of the button need to be bent at a 90º angle (as in the picture) so that it fits snugly into the slot and therefore is held firmly in place.

After soldering the wires, the assembly of the electronic digital caliper is carried out in reverse order. After assembly, soldered wires should stick out of the socket.

After that, solder the button and place it in the slot.

Because the button legs have been pre-bent, they spring the button and hold it firmly in place. Here's what it looks like.

By pressing a new button, we get access to some modes that were previously not available.

When the button is pressed for the first time, the electronic caliper enters the mode fast reading(FT), by pressing the "ZERO" button, we can freeze the measured value (H).

When the button is pressed again, the electronic caliper will enter the minimum value (MIN) mode. In this mode, the display shows the smallest measured value.

If you press the "ZERO" button again, we will again switch to the mode of fixing the measured value (H).

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In the home workshop, in addition to a variety of measuring tools, there should also be a caliper, which is often needed where a tape measure or ruler does not fit.

Below we will consider what such a measuring tool is, what types are found and how to use it correctly in order to obtain the most accurate measurement data.

Purpose of caliper

This measuring tool is mainly used to obtain the most accurate data when determining the outer and inner diameters of pipes, their wall thickness, to calculate the center distance in holes, the dimensions of cylindrical parts, the thickness of wire and metal sheet, as well as other materials of small dimensions and small products.

With such a device it is convenient to measure the depth of grooves, holes and grooves, various recesses with great accuracy in the most hard-to-reach places. The accuracy of the caliper during measurements reaches tenths and hundredths of a millimeter, which cannot be provided by such a simple tool as a ruler or tape measure.

The tool, according to GOST 166-89, is made of stainless or carbon steel coated with a chrome composition. Comprises:

a rigid metal ruler called a barbell (hence the name of the tool - caliper);
measuring protrusions - sponges;
an auxiliary frame with a vernier scale, otherwise called a vernier, which allows measurements to be made with an accuracy of tenths and hundredths of a millimeter, depending on the type of instrument;
a movable depth gauge ruler rigidly connected to the jaws.

The vernier caliper scale can have a different length and number of divisions. 10 divisions on the vernier scale make it possible to measure with an accuracy of up to 0.1 mm, 20 divisions give a measurement accuracy of up to 0.05 mm:

Sponges can be upper and lower. On the surface of the bottom - the minimum size of the measured parts is indicated. The ends of the lower jaws are made in the form of rectangles. The upper ones are pointed and beveled vertically, which allows them to mark on any materials and parts, without the use of other marking devices (i.e., you can draw a line exactly in size due to sharp ends directly with sponges).

Using the upper jaws, the internal dimensions of holes, pipe diameters, grooves, and various recesses are measured. The lower jaws are used to measure external parameters. For measuring length deep holes a depth gauge ruler is used, which extends from the main stem:

To fix the movable frame with a vernier scale on the ruler, there is a special fixing screw. Some models of calipers are equipped with a round scale and a movable frame, the scale of which is designed to measure in inches. At the same time, the vernier scale of such an instrument allows measurements to be made with an accuracy of 0.128 inches.

Caliper Types and Specifications

The classification of such measuring instruments is carried out according to several parameters - the method of taking readings, the type of scale, the location of the jaws. All these differences are reflected in the labeling of the device.

At different types calipers for taking measurement readings, the following types of scales can be used:

vernier scale;
scale located on the dial;
using a digital display board.

According to their design, calipers are divided into the following types:

Single-sided tools made of carbide steel and marked with ShTsT.
Mechanical models with one- or two-sided arrangement of jaws, marked as ShTs-I, ShTs-II, ShTs-III, on which measurements can be taken using a vernier scale.
A device equipped with a circular scale is marked SHIK or SCC and allows more accurate measurements than devices with a vernier scale. Fractional readings are shown on the circular scale, whole numbers on the bar itself.
The latest generation electronic caliper with a digital display showing the distance between the inner surfaces of the jaws is marked with SCC and can work in symbiosis with a PC. it the best device, which allows you to quickly, without unnecessary calculations, see the measurement data, which are carried out with a high accuracy of up to 0.01 mm.

The ShTs-II tool differs from the ShTs-I model in that it has an additional frame equipped with a locking screw and connected to the main frame. The fixed additional frame allows you to bring the ends of the jaws for a more accurate measurement of the internal dimensions of the holes.

The ShTs-III device differs from the ShTs-II model in that it does not have one pair of upper marking jaws. Used for measuring large parts.

How to use a caliper correctly

Before using the tool, it is necessary to check it for serviceability and accuracy. To do this, you need to inspect it and remove the existing contamination on all parts. It is also necessary to check whether the zero marks on the main scale and the vernier scale coincide with the tight connection of the lower jaws.

It is best to fix the measured part in a stationary state, but you can also hold it in your left hand, the main thing is to prevent its mobility during the measurement process. If you want to measure the external dimensions of any part, you need to dilute the sponges and tightly cover the object being measured with them. In this case, the part must be in correct position, not skewed and should not move. The next step is to fix the part in the caliper by screwing in the mounting screw, without undue force. Only after that you can start reading the testimony.

When using the SCC device, you do not need to calculate the dimensions of the measured part, all this is shown on the display. It is also not difficult to take dimensions when working with the SCC device. Integer numbers on the rod are indicated by the edge of the movable frame, hundredths or tenths of a millimeter are shown by a circular scale.

But with a mechanical tool ShTs-I, ShTs-II and ShTs-III, it will be necessary to compare the values of the main scale and the vernier. First, the size is determined in integers, i.e., the indication on the main scale, which is determined by the position of the first risk of the vernier scale. Then, depending on the type of caliper, the size is determined in tenths or hundredths of a millimeter.

Total, Measurement algorithm:

We look at the upper scale, how many whole millimeters fit.
On the lower scale, we look at which division maximally coincides with the division on the upper scale (as if it turns into one line) - these are tenths and hundredths of a millimeter.

Consider in the picture how the measurement of 28.55 millimeters is obtained:

When using a tool, one should take into account the error of the caliper, which may occur due to improper storage, mechanical damage, contamination of the tool, and the temperature state of the measured part. Optimum temperature for measurements, this device is a range within 10-40 degrees above zero. To obtain the most reliable measurement data when working with a caliper, it is recommended to take several measurements and calculate the average arithmetic value. At the end of the measurements, the device must be wiped dry and stored in a case.

This is where the article ends. Today we learned what a caliper is, what types it is and how to use it to make measurements.

Determination of indications by vernier

To determine the readings of the caliper, it is necessary to add the values of its main and auxiliary scales.

The number of whole millimeters is counted on the rod scale from left to right. The zero stroke of the vernier serves as the pointer.
To count fractions of a millimeter, it is necessary to find that stroke of the vernier, which most closely matches one of the strokes of the main scale. After that, you need to multiply the serial number of the found vernier stroke (not counting zero) by the division value of its scale.

The measurement result is equal to the sum of two quantities: the number of whole millimeters and fractions of a mm. If the zero stroke of the vernier exactly coincided with one of the strokes of the main scale, the resulting size is expressed as an integer.

The figure above shows the readings of the ShTs-1 caliper. In the first case, they are: 3 + 0.3 = 3.3 mm, and in the second - 36 + 0.8 = 36.8 mm.

The scale of the device with a division value of 0.05 mm is presented below. For example, two different indications are given. The first is 6 mm + 0.45 mm = 6.45 mm, the second is 1 mm + 0.65 mm = 1.65 mm.

Similarly to the first example, it is necessary to find the strokes of the vernier and the rod, which exactly coincide with each other. In the figure, they are highlighted in green and black, respectively.

Mechanical caliper device

The device of a double-sided caliper with a depth gauge is shown in the figure. The measuring range of this tool is 0-150mm. With it, you can measure both external and internal dimensions, the depth of holes with an accuracy of 0.05 mm.

Main elements

Barbell.
Frame.
Sponges for external measurements.
Sponges for internal measurements.
Depth gauge line.
Locking screw for fixing the frame.
Nonius scale. Used to read fractions of millimeters.
Barbell scale.

Sponges for internal measurements 4 have a knife-like shape. Thanks to this, the size of the hole is determined by the scale without additional calculations. If the jaws of the caliper are stepped, as in the ShTs-2 device, then when measuring grooves and holes, their total thickness must be added to the readings obtained.

Nonius reading value y various models tool may vary. So, for example, for ShTs-1 it is 0.1 mm, for ShTs-II it is 0.05 or 0.1 mm, and the accuracy of devices with a vernier reading of 0.02 mm approaches the accuracy of micrometers. Structural differences in the device of calipers can be expressed in the form of a movable frame, measurement limits, for example: 0–125 mm, 0–500 mm, 500–1600 mm, 800–2000 mm, etc. The accuracy of measurements depends on various factors: the value of the vernier reading, work skills, the good condition of the instrument.

Measurement procedure, serviceability check

Check before work technical condition caliper and adjust if necessary. If the device has skewed jaws, it must not be used. Also nicks, corrosion and scratches on working surfaces are not allowed. It is necessary that the ends of the rod and the depth gauge ruler coincide with the combined jaws. The scale of the instrument must be clean and legible.

Measurement

The jaws of the caliper are pressed tightly with little effort, without gaps and distortions, to the part.
When determining the outer diameter of the cylinder (shaft, bolt, etc.), make sure that the plane of the frame is perpendicular to its axis.
When measuring cylindrical holes, the jaws of the caliper are placed at diametrically opposite points, which can be found by focusing on the maximum scale readings. In this case, the plane of the frame must pass through the axis of the hole, i.e. measurement along a chord or at an angle to the axis is not allowed.
To measure the depth of a hole, the bar is placed at its edge perpendicular to the surface of the part. The depth gauge ruler is pushed all the way to the bottom using a movable frame.
The resulting size is fixed with a locking screw and the readings are determined.

Working with a caliper, monitor the smoothness of the frame. It should sit tightly, without swaying, on the bar, while moving without jerking with a moderate effort, which is regulated by a locking screw. It is necessary that when the jaws are combined, the zero stroke of the vernier coincides with the zero stroke of the rod. Otherwise, reinstallation of the vernier is required, for which its fastening screws to the frame are loosened, the strokes are combined and the screws are re-fastened.

- it is universal measuring device to determine the linear dimensions of parts with a specified accuracy. With it, you can measure the external and internal dimensions of parts, as well as the depth of holes, provided that a retractable rod is available.

The device and application of calipers

The most popular areas of application of calipers are construction, repair of machinery and equipment, processing of metal and wooden products. The scope of application has virtually no restrictions - it can be used to determine dimensions with an accuracy of 0.1 or 0.05 mm (depending on the type of tool) in any field of activity - both in everyday life and in the aerospace industry. Application possibilities are limited only by the scale size and accuracy requirements (up to 0.01 mm for electronic calipers).

The caliper device is quite simple. The main element is a fixed bar with a scale and jaws for external and internal dimensions, to which movable and fixing elements are attached.

Mobile frame;
Movable jaws for definition inner size;
Movable jaws for determining the outer size;
Nonius scale;
Depth gauge rod;
Screw for fastening the frame.

In some models, it is possible to have a movable scale in the upper part with an inch measurement system.

How to take readings with a caliper

Before starting work, it is necessary to check the caliper for accuracy. To do this, it is necessary to completely reduce the sponges and check the coincidence of zeros on both scales. If there is no match, then, depending on the required accuracy, it is necessary either to take another tool, or to take into account the existing error.

For measurement outer dimension open the jaws of the caliper, place the object and connect them.
Measurement of the internal size is made by placing the corresponding upper jaws inside the measured area and diluting them to the stop
Sponges should rest against the edges of the part. If the surface is hard, then you can squeeze it a little for a tight fixation; for a soft one, this should not be done, because you can distort the result.
Check the position of the caliper relative to the workpiece to be measured for distortion. To do this, the jaws must be located at the same distance from the edge of the part.
Fix the vernier with the fixing screw.
Determine the whole number of millimeters on the main scale.
We find the coincidence of the stroke on the vernier with the zero of the main scale and count the number of divisions.
We multiply the number of divisions of the vernier by the division price and sum it with the value of the main scale.

Types of calipers

In general, all types of calipers can be divided into mechanical and electronic depending on the type of scale. The main types, according to GOST 166-89 are:

ШЦ-I - a tool with 2-sided placement of sponges for measuring external and internal values and a depth gauge.
ShTsK - equipped with a circular scale for determining the exact size. Easier to use than a vernier caliper.
ШЦТ-I - one-sided sponges for measuring outer linear dimensions. Differs in high resistance to wear.
ШЦ-II - equipped with two jaws for external and internal measurement and marking, as well as a micrometric feed frame.
ШЦ-III - one-sided sponges for determining the external and internal dimensions.
ШЦЦ - electronic caliper with digital indication.

Technical condition and verification of calipers

One of the most important requirements ensuring the accuracy of the tool is its cleanliness. A magnetized layer of metal filings, preservative grease, dirt - all this can significantly distort the measurement result. Also, the result is affected by tool wear, its deformation, and violations of settings. To avoid this, annual verification of the caliper by a specialized service center with repairs and adjustments. The simplest verification of the correctness of the readings is the coincidence of zero strokes when the jaws are completely closed.

Current GOSTs

The production and verification of the instrument is regulated by a number of state standards. Yes, it defines specifications on calipers GOST 166-89. The procedure for checking the tool is defined in GOST 8.113-85.