In addition to a variety of measuring tools, a home workshop should also have a caliper, which is often needed where a tape measure or ruler is not suitable.
Below we will look at what such a measuring instrument is, what types are found and how to use it correctly in order to obtain the most accurate measurement data.
Purpose of a caliper
This measuring instrument is mainly used to obtain the most accurate data when determining external and internal diameters pipes, the thickness of their walls, to calculate the center distance in holes, the dimensions of cylindrical parts, the thickness of wire and metal sheets, 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 a caliper in measurements reaches tenths and hundredths of a millimeter, which cannot be achieved 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-plated composition. Consists of:
- a rigid metal ruler called a rod (hence the name of the tool - caliper);
- measuring protrusions - jaws;
- 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;
- movable ruler of the depth gauge, rigidly connected to the jaws.
The vernier caliper scale can have different lengths 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 provide a measurement accuracy of up to 0.05 mm:
Sponges can be upper and lower. On the surface of the lower - indicated minimum size measured parts. 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., directly with the sponges, you can draw a line exactly in size due to the sharp ends).
With the help upper lips The internal dimensions of holes, pipe diameters, grooves, and various recesses are measured. To measure external parameters, lower jaws are used. To measure the length of deep holes, a depth gauge ruler is used, which extends from the main rod:
To fix the movable frame with a vernier scale on the ruler, there is a special fastening screw. Some caliper models are equipped with a scale round shape and a movable frame, the scale of which is designed to take measurements in inches. At the same time, the vernier scale of such a device allows measurements with an accuracy of up to 0.128 inches.
Types of calipers and technical characteristics
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 markings of the device.
U different types The following types of scales can be used for taking measurement readings:
- vernier scale;
- scale located on the dial;
- using a scoreboard with a digital indicator.
According to their design, calipers are divided into the following types:
- Single-sided tools made of carbide steel and marked ШЦТ.
- Mechanical models with one- or two-sided arrangement of jaws, marked as ШЦ-I, ШЦ-II, ШЦ-III, measurements on which can be taken using a vernier scale.
- A device equipped with a circular scale is marked ShIK or ShTsK and allows for more accurate measurements than devices with a vernier scale. The circular scale shows fractional readings, while the bar itself shows whole numbers.
- The latest generation electronic caliper with a digital display showing the distance between the internal surfaces of the jaws is marked SCC and can work in symbiosis with a PC. This the best device, which allows you to quickly, without unnecessary calculations, see measurement data that is carried out with high accuracy 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. A fixed additional frame allows you to bring the ends of the jaws in for 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, you must check it for serviceability and accuracy. To do this, you need to inspect it and remove any existing dirt from all parts. It is also necessary to check whether the zero marks on the main scale and the vernier scale coincide when the lower jaws are tightly connected.
It is best to fix the part being measured in a stationary state, but you can also hold it in your left hand, the main thing is to prevent it from moving during the measurement process. If you need to measure external dimensions any part, you need to spread the jaws and tightly cover the object being measured with them. In this case, the part must be in the correct position, without distortion and should not move. The next step is to fix the part in the caliper by screwing in the mounting screw, without excessive force. Only after this can you start reading the readings.
When using the ShTsTs device, you do not need to calculate the dimensions of the part being measured; all this is shown on the display. It is also not difficult to take measurements when working with the ShCK device. Integer numbers on the bar are indicated by the edge of the movable frame; hundredths or tenths of a millimeter are indicated by a dial scale.
But with mechanical toolШЦ-I, ШЦ-II and ШЦ-III will need to compare the values of the main scale and the vernier scale. First, the size is determined in whole numbers, i.e., the reading on the main scale, which is determined by the position of the first mark 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 top scale to see how many whole millimeters fit.
- On the lower scale we look at which division coincides most closely with the division on the upper scale (as if it turns into one line) - these are tenths and hundredths of a millimeter.
Let's look at the picture to see how the measurement of 28.55 millimeters is obtained:
When using a tool, you should take into account the error of the caliper, which may arise due to improper storage, mechanical damage, contamination of the tool, and the temperature state of the part being measured. Optimal temperature For measurements this device has a range of 10–40 degrees above zero. To obtain the most reliable measurement data when using a caliper, it is recommended to take several measurements and calculate the arithmetic average. Upon completion of 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 comes in and how to take measurements with it.
This device is used to measure internal and external measurements, as well as between the surfaces of parts, used to measure the depth of holes and protrusions. has very useful function Compared to a mechanical one, it is adjusted to zero at any point on the scale, thanks to which deviations can be observed in each area of the size. That is, you can reset it to zero at, say, 21.55 mm, and then count the length from it.
In modern high-precision mechanical production there is no way to do without it. convenient tool, where the measurement range is universal. In heavy and light industry, construction, and in all other branches of technical life, it is no longer possible to imagine work without the use of a digital caliper. If necessary, a computer can be connected to the ES, to which all data will be output during the size control process. For this purpose, the digital caliper has a special connector:
The digital caliper has a resolution of 10 microns with an accuracy of 30 microns. This accuracy is achieved using capacitive sensors. Capacitive sensors are very linear and immune to mechanical and electronic interference. However, they are sensitive to liquid. Accidentally entering liquid will unbalance the measuring bridges of the plates and increase the capacity.
How does a digital caliper work?
To begin with, let's take this meter and let's see how it works from the inside.
The principle of its operation is a capacitive digital vernier, here is the technical documentation. The operation of a digital caliper is based on a capacitive matrix - an encoder.
Simply put, two “ordinary” capacitors connected in series, i.e. the top plate as a common electrode.
Electronic calipers use multiple plates to form a capacitive array that can accurately sense movement. There is a stator and a slider (“rotor”) plate. The stator is located in a metal ruler. And the moving part with the LCD screen has a slider.
Diagram of signals from capacitive sensors
Stator template fabricated into top layer copper standard glass epoxy laminate and bonded to stainless steel caliper bar. The slider pattern shown is similarly fabricated on a PC laminate, drives a 100 kHz signal through the sin/cos stator electrode plates and picks up the AC voltage at two central pickup plates which describe the sin(displacement) and cos(displacement) signals.
Separate sin and cos signals are needed to determine the direction of movement. The combination of analog interpolations between plates and a digital data processing circuit gives up to 0.02mm errors. Digital micrometers are used to measure with even higher accuracy. The device's power supply (LR-44 round battery) is enough for 2-4 months of daily operation. Based on the decrease in the contrast of the LCD indicator, it is clear that it is time to change it to a new one.
Do-it-yourself apartment renovation always involves the need to take various measurements.
An ordinary ruler or tape measure cannot always provide the necessary accuracy, and in some cases they are simply impossible to use.
Vernier calipers are professional measuring instruments.
Our advice is designed to help the home craftsman choose it for performing many types of measurements and marking work in everyday life. Brief overview industrial products large assortment will allow you to more accurately determine the required model based on its technical characteristics.
The optimal choice is possible based on taking into account:
- accuracy classes;
- measurement limits;
- ease of use;
- simplicity of design;
- cost.
Purpose
A caliper of any model is designed to perform high-precision measurements of three types of distances:
- external dimensions;
- indentations on internal cavities;
- recesses from the base surface.
A home craftsman may need a caliper when:
- choosing the drill diameter;
- at ;
- turning parts on a lathe;
- other repair work.
Design features
The caliper device is represented by three types of separate measuring devices, which have a common accuracy class and uniform measurement limits.
Their results are displayed on a common bar and vernier scale.
Components of a caliper
Structurally, the mechanism consists of:
- base element - rod;
- moving part - frames with additional devices.
Barbell
All details are placed on it. It is made of a flat metal strip with fixed jaws and a scale of millimeter divisions.
Frame
Composite design with internal grooves - the movable frame moves along the rod. It has its own jaws, vernier scale and locking mechanism.
The fixation unit consists of a force adjustment screw with a spring-loaded plate, which creates uniform pressure when the frame moves along the entire length of the rod.
The working edges of the jaws of the frames and the rod have an angular sharpening. To perform external measurements, it is created with limiting stops, and internal ones - along the entire length of the working edge.
Measuring scales
The length of the part being measured in mm is measured using the rod scale, and subsequent clarification of their proportions is carried out using the vernier. Its accuracy class in mm is:
- 0,02;
- 0,05;
The vernier scale can be applied directly to the body of the moving frame, as shown in the bottom photo, or attached with screws to perform precise calibration of the instrument - top photo.
How vernier and rod scales work
Let's look at the example of a caliper with an accuracy class of 0.1.
The price of one division of the bar located on top is exactly 1.0 mm, while that of the vernier is 1.9. Therefore, its ten lower divisions occupy 19 mm.
For all measurements, the zero position of the vernier scale, set opposite the upper divisions, is used as an indicator of the size of the part being measured. In the presented figure, it is located at the origin of the rod and indicates 0 mm of length.
During measurement, the movable frame moves along the rod, moving away from the beginning of the scale, and is fixed in a certain position, for example, as shown in the figure below.
The zero of the vernier scale has passed two millimeters along the rod. It indicates the whole part of the measured number - 2.0 mm. Of all the other nine marks of the moving frame, the fourth one came closest to the upper calibrated divisions. It shows the size of the fractional part - 0.4 mm.
All that remains is to fold them: 2.0 + 0.4 = 2.4 mm. We received the result of measuring a caliper in its accuracy class.
Design overview
All models of calipers can be divided into two types of measuring devices:
- mechanical with scales;
- digital with display.
Mechanical calipers
This type includes devices of the ShTs-1, ShTs-2, ShTs-3, ShTs-K brands.
Model ШЦ-1
The simplest and most common brand of caliper with a vernier scale type. Standard price divisions - 0.1 mm. But there are devices for 0.05 and 0.02.
Model ШЦ-2
The device differs from the previous one in the presence of an additional frame with a locking screw and an adjusting mechanism, as well as a special design of the jaws.
Their lower part allows you to measure both external and internal dimensions two different work surfaces. The difference in reading between them in mm is marked directly on the body.
The protrusion line of the outer jaws is strictly parallel to the axis of the rod. This allows you to focus on them with the base surface of the part being measured: increased accuracy is created.
The upper jaws are pointed and perform two tasks:
Model ШЦ-3
The device completely repeats the design of the previous one, but it does not have the upper pair of marking and measuring jaws.
ShTs-2 and ShTs-3 are created with rods that make it possible to measure fairly extended parts.
Model ShTsK-1
The mechanism for counting fractions of mm is made of a mechanical device with a circular scale. These devices provide the highest accuracy class in their group: 0.02 or even 0.01 mm.
To move the movable frame when taking measurements, a rack and pinion transmission is used, controlled by rotation of the handle wheel. The head is also secured with a locking screw.
The disadvantages of this model include the need to maintain its rack and pinion rod mechanism and frame in constant cleanliness.
Calipers with digital display
One of the representatives of this class is the ShTsTs-1 model.
The additional letter “C” in the marking indicates the operation of the measuring device using digital technology. This makes it much easier to take the reading. ShTsTs-1 has the highest accuracy: class 0.01.
As with all similar devices, there are control buttons various modes And standalone source power supply located in a special compartment.
When thinking about the quality of work of such meters, one should not forget about all the disadvantages inherent in electronic devices:
- sensitivity to external electromagnetic fields;
- limited battery life, which is also sharply reduced at cold temperatures;
- the need for protection from humidity and mechanical influences;
- increased cost.
When not in use, electronic devices are kept in special cases. To measure the dimensions of the parts, they are removed and then placed there again. They require more careful handling than simple mechanical analogues.
Checking serviceability and preparing for measurement
The measurement accuracy of any caliper depends on its technical condition. The metrological characteristics of professional instruments are checked by specialists from the relevant laboratories.
For home handyman such an operation is unnecessary. It is enough to check the calibration certificate when purchasing and then maintain your instrument in good condition.
However, the possibility of falls, impacts and other unforeseen events should be taken into account. To this end, it is important to periodically perform three simple rules functionality checks:
- inspection of external condition;
- checking the zero reading;
- assessment of the quality of measuring surfaces.
External inspection
They evaluate “by eye” the quality of the geometry of all parts, the cleanliness of surfaces, the need for lubrication of grooves with light oils, the condition of the scales and the ease of reading them. Check the ease of movement of moving parts.
Identified minor defects can be eliminated with your own hands.
Checking the zero reading
The movable frame is moved all the way to the initial position and observed:
- setting both scales to zero;
- the location of the tenth division of the vernier at the 19 mm mark of the rod scale reading (for ShTs-1 accuracy class 0.1, as shown in the diagram above).
Assessment of the quality of measuring surfaces
The shifted jaws are placed towards the light source and the tightness of their fit is visually assessed. The picture above shows a similar test of one surface with a standard square.
Light rays will penetrate through defective cracks and indicate their location.
Pay attention to the position of the recess meter. When shifted, it should be in the same plane as the far end of the rod.
To do this, it is pulled out when the end of the rod is installed on the reference plane and the measurement is taken on the reference scale. Should be 0.
Measurement techniques
It is important to understand: no caliper itself measures the part. It simply displays the position of the moving frame scale relative to the origin in a certain accuracy class. It is a person who takes measurements and quite often it is he who makes serious mistakes.
External distance measurements
The planes of the working surfaces of the caliper must be brought tightly to the part being measured.
Its axis should be perpendicular to them.
Tilt of the body onto the measurement surface until it stops with a bar or the use of special protrusions on the jaws helps eliminate measurement errors.
On long workpieces, the surface of the part should be parallel to the axis of the caliper rod.
Internal distance measurements
The jaws of the caliper should fit snugly against inner surface and be located in a perpendicular plane.
Definition of recesses
All the rules described above also apply here. The photo below shows one of the typical mistakes, when the deviation of the meter from a plane parallel to the surface of the part being measured is violated.
For precise definition recesses are necessary:
- ensure the correct support of the end of the rod in the reference plane;
- pull out the movable frame, firmly pressing the end of the pointer onto the remote surface;
- ensure its shortest distance to the measurement point with parallel orientation relative to the surface of the part;
- fix the locking screw;
- take the count correctly.
We hope that short review and brief tips from the article will help you choose and buy a caliper of the model that is most suitable for its characteristics. Now let’s give a photo of the ShTs-1 model, 160 cm long and 0.1 mm class, which has been working in the author’s arsenal of tools for the third decade.
Most often it is used for:
At one time there was a passion for wood turning and for them I did it myself. That's when calipers were used very often.
Then I had to replace the drill with a . But after that, interest in turning work somehow faded away, and the machine stood idle...
As personal practice has shown, an accuracy class of 0.1 mm is quite sufficient for doing household work, and if you follow the operating rules, then such a device works for a very long time and reliably.
Although some will find this clearly insufficient and will want to buy an electronic caliper ШЦЦ-1 with a class of 0.01 mm for their needs. Decide for yourself.
Ask questions in the comments, share the material you read with your friends on social networks.
As you will see from this article, modifying an electronic digital caliper is a very simple procedure, but it must be done carefully to avoid damaging the instrument. The design of the electronic caliper provides 4 special contacts. These contacts can, for example, be used to connect an external power supply, control functions, etc.
The pin assignments are as follows (from left to right): negative terminal, data, clock and positive terminal.
To activate the hidden options of the electronic digital caliper, you need to connect pins 2 and 4 together.
Perhaps different electronic calipers have some differences, but in general their modification is carried out in the same way.
The first step in modification is to find the screws that hold the case together. On our caliper they are located under a plastic sticker. Their location can be seen in the photograph.
After opening the plastic case containing the circuit board, display and several metal elements, you need to unscrew several screws to remove printed circuit board.
Particular care should be taken when handling the circuit board and display.
The display is connected to the printed circuit board via a conductive rubber gasket. Be careful not to disconnect the display from the board, as this will make it quite difficult to align the connections during reassembly. And if the position is incorrect, the display may spontaneously turn off and strange symbols may appear on it.
After removing the printed circuit board of the electronic caliper, we gain 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 short-circuit 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 an angle of 90º (as in the picture) so that it fits tightly into the slot and therefore is held firmly in place.
After soldering the wires, the electronic digital caliper is assembled in reverse order. After assembly, soldered wires should stick out from the socket.
After that, solder the button and place it in the slot.
Since the button legs have been pre-bent, they spring the button and it is held firmly in place. This is what it looks like.
When we press the new button, we gain access to some modes that were not previously available.
When you press the button for the first time, the electronic caliper enters the fast reading mode (FT), when you press the “ZERO” button, we can freeze the measured value (H).
When you press the button again, the electronic caliper will enter the minimum value (MIN) mode. In this mode, the display shows the lowest measured value.
If you press the “ZERO” button again, we will again go into the mode of fixing the measured value (H).
Voices)
Good day! Today we will talk about how to correctly take measurements using a universal measuring tool for this purpose - a caliper. With its help, you can determine the external/internal dimensions of parts, as well as the depth of holes.
The photo shows two instruments with vernier scale divisions of 0.1 and 0.02 mm.
Thanks to its special design, the tool allows you to fix the part, thus reducing the likelihood of an error occurring at the time of measurement.
Vernier caliper device:
- Barbell;
- Moving frame;
- Main scale;
- Sponges for measuring internal dimensions;
- Sponges for measuring external dimensions;
- Depth gauge;
- Vernier;
- Fixing (locking) screw.
When using a caliper, you should adhere to the following rules:
- The jaws must not be distorted.
- After the measurements have been taken, we fix the moving frame with a locking screw.
- While reading the readings, hold the caliper directly in front of your eyes.
- It is necessary to store the instrument in a special case, in a clean condition.
- After use, the tool must be wiped with a clean soft cloth.
Principles of measurement
Before starting measurements, we check the instrument for accuracy. To do this, let's bring the jaws of the caliper together. The zero marks, the tenth line on the vernier scale and the nineteenth line on the main scale must match.
Measuring external dimensions. Spread the caliper jaws a little more sizes the part being measured, and then bring them together until they stop, clamping the part.
Measuring internal dimensions. We set the tool to the zero position, then place the jaws in the required plane. Then we spread them all the way.
Depth measurement. We rest the end of the tool against the part and begin to move the moving frame until the depth gauge rests or reaches the desired point.
Performing markings. We set the specified value, fix the tool with a locking screw, rest one of the jaws against the edge of the part and apply markings to the surface of the workpiece (straight lines, notches, circles). But it is better to mark with tools specially designed for this purpose and spare the expense of an accurate, expensive measuring instrument.
Reading the caliper readings
Whole fractions of millimeters are counted on the main scale to the zero mark of the vernier, and tenths (hundredths) of a millimeter are counted on the vernier scale starting from the zero mark to the first mark that matches the main scale.
A few examples:
How to properly store a tool
It is best to store the instrument in the case in which it is sold. Do not allow dust or sawdust to enter. Avoid contact with moisture and avoid accumulation of condensation. Avoid impacts and scratches, which may deform the instrument and reduce measurement accuracy. After each use, wipe the surface with a dry cloth. The tool should be stored with the jaws spread apart (2-3 mm). Careful handling allows you to use it for many years and even decades.
In addition to the tools presented in this article, there are several other types of calipers:
Vernier calipers with a circular scale. In the recess located on the rod, there is a rack with a gear attached to it. The readings are read from a barbell and a dial scale.
Caliper with digital display.
I hope the information provided was useful! Thank you for your attention!
