Goniometer. Types and types. Design and operation. Application and how to choose

Models of inclinometers and inclinometers differ in their operating principles and capabilities. The main selection criteria that you should focus on when choosing a measuring device:

Type.

There are electronic and mechanical devices on display. The former have higher measurement accuracy, the results of which are displayed on a digital display. But the latter are significantly cheaper and can be used for domestic needs - where an error of 0.5-0.7° is not important.

Tool dimensions.

The length of the meter is usually in the range of 10-40 cm, but there are also more compact models. Dimensions are important when measurements need to be taken in confined spaces.

Degrees.

The range of degrees depends on the scale, or how far apart the sides of the protractor are. The maximum measurement angle is within 90-360 degrees.

Bubble level.

Some models have it (with 1-3 eyes), but in others it is missing. The level is convenient when you need to hang a TV, a picture or arrange furniture evenly; when installing doors and tiling, this option is also necessary.

Weight.

Inclinometers and inclinometers weigh between 70-2000 g. For work at heights, this parameter is also important.

History of appearance

The goniometer was invented many centuries ago. Experts say that this device was first used in Babylon and Egypt. Because the construction of huge and incredibly beautiful buildings is completely impossible without the use of a goniometric device.

Over the long period of its existence, its design has not undergone significant changes. Modern devices have almost the same appearance. The difference from ancient devices lies only in the material from which they are made. Of course, the scope of use of a modern instrument is much wider.

Electronic protractors - their application and reliability

Digital devices are popular, but not because they have high measurement accuracy, but due to the simplicity and speed of taking readings. Their main advantage is that measurements are carried out automatically and displayed. Even beginners know how to use electronic protractors, since this is the simplest type of tool. To do this, you need to attach the support bars to perpendicular surfaces, and then take the finished readings from the LCD display. Measurements are displayed taking into account tenths and hundredths of degrees, which depends on the accuracy class of the device.

The main disadvantage of electronic meters is that despite the low error values ​​​​claimed by manufacturers, they are much inferior to mechanical devices.
It is only worth noting that not all devices have low accuracy, since branded models from well-known manufacturers prove their accuracy in practice. However, the cost of such devices is twice as high as conventional electronic inclinometers from China. It is rational to buy a Chinese device only if high data accuracy is not important. Otherwise, it is better to use a mechanical device with a vernier. This is interesting! In addition to the large error, digital devices have additional disadvantages, such as the need to constantly replace the battery, store in a warm and dry room, and avoid mechanical stress.

Top 5. ADA instruments Pro-Digit MICRO

Rating (2021): 4.30

37 reviews from resources were taken into account: All tools, Yandex.Market

The most versatile device measures both angles and inclination. With high measurement accuracy, it is ideal as a professional tool. And the compactness of the protractor allows you to always have it at hand.

• Characteristics

  Average price: 2990 rub.

• Country: Hong Kong (manufactured in China)
• Type: electronic
• Measurement: Angle, Tilt
• Measurement accuracy: 0.2°
• Bubble level: no
• Level length, cm: 5.7

This electronic model from a popular brand is liked by customers for its versatility. A protractor and an inclinometer in one compact metal case are used in carpentry, when installing guides for wall cladding, for suspended ceilings and in solving other problems. There is a mode for measuring the angle between surfaces in the range from 0 to 360 degrees. To determine the angle of deviation from the vertical or from the horizon, the instrument must be placed on a horizontal surface or attached to a vertical one. Easy fixation is ensured by magnets. The inclinometer is powered by 2 AAA batteries, and to save battery power, the device automatically turns off after 5 minutes of inactivity. Buyers like the compactness and functionality of the device, its price and measurement accuracy. But some people think its body is a bit thick.

Advantages and disadvantages

• Multifunctionality
• Fixation with magnets
• Auto shutdown
• Affordable price

• The body is a bit thick

Other protractors

Of course, goniometric techniques are not limited to those listed above. In fact, this class of measuring instrument has an ancient history. Phoenician sailors also used sextants, the oldest goniometer instruments. In addition to sextants, sailors also use such a device as a nautical octant; as a measuring scale, it has a scale that covers only 45 degrees. But this is enough to observe the stars and thereby determine your location in space. Using a vernier scale allows for more accurate calculations.

Goniometer sextant instrument

Goniometer tool octant

When carrying out construction work, a protractor inclinometer is widely used. It is used to measure the location of building structures in space and relative to each other. When making furniture work, it is also important to maintain certain angles, for example, between the walls of a cabinet or bedside table.

The simplest design of a protractor

The design of a protractor in its simplest form consists of two plates (rulers). They are fixed together on one side, fixed with an axis that allows you to change the angle between them. On the surface of the instrument there is a scale expressed in degrees. It can be ruled or rounded. There are both fully movable protractors and those with fixed measurements. The latter are used in cases where only the measurement of the most important angles is required - 90, 45 and 30 degrees. This tool falls more into the category of templates.

How does a pendulum protractor work?

Structurally, the device resembles an analog clock, as it is presented in the form of a round dial with markings applied in 1-degree increments. The peculiarity of the instrument is that the arrow on the dial always has a strictly vertical position, and works on the principle of a pendulum. The device has two scales graduated in degrees, red and black.

• The red scale determines values ​​if vertical surfaces are measured
• The black scale calculates readings when measuring a horizontal surface

Now let's figure out how to use a pendulum inclinometer correctly. To do this you need to do the following:

1. Place the tool on the plane to be measured using a special support base.
2. Press the locking ring of the device, which is located in the upper part
3. Wait until the needle stops oscillating and then release the locking ring.
4. The arrow will remain at the corresponding value, and now you can read the degrees, which will not cause any difficulties. The main thing is not to confuse when to shoot on the red and black scale of a pendulum goniometer

The main feature of the device is that it allows you to measure the angle of a surface without using an additional plane, as is typical for mechanical devices. The disadvantage of a pendulum protractor is its tendency to mechanical damage. To eliminate such consequences, you need to use the device carefully and store it in a special case.

Top 3. BISON 34747

Rating (2021): 4.50

The most accurate Electronic inclinometer with the highest measurement accuracy - 0.05°. Professional level for solving a wide range of problems.

• Characteristics

  Average price: 8918 rub.

• Country: Russia (manufactured in China)
• Type: electronic
• Measurement: Tilt
• Measurement accuracy: 0.05°
• Bubble level: 3 eyes
• Level length, cm: 12

The electronic level for measuring the angle of inclination is intended for professional use: installation of window and door structures, driving piles, for installing billiards, tennis tables, in shipbuilding and other areas. The inclinometer is equipped with three bubble levels; it levels and controls both the horizontal and vertical planes. The measurement results are displayed on the display in graphs and numbers. The backlit screen allows results to be read in low-light areas. Maximum measuring angle: 90°. Buyers like the functionality of the device and the accuracy of measurements, ease of control and a variable form of displaying information. The price is a little high for a home, but for a professional instrument it is quite justified.

Advantages and disadvantages

• High measurement accuracy
• Results in graphics and numbers
• Backlit display
• 3 bubble levels

• The price is a bit high

Mechanical protractor and features of its application

The mechanical type goniometer is classified into three types - simple, with a protractor and with a vernier. The simplest mechanical goniometer (malk) is designed for template angle measurement. What does this mean? It cannot be used to find out the angle in degrees, since it does not have a built-in protractor. The measured angle is transferred to the template and then used to make similar parts. As mentioned, the device is not highly accurate, but it is sufficient for carpentry work. Such a tool is also used in construction, for example, when installing slopes.

Now consider a model of a protractor with a protractor (it is called a quadrant), which allows you to find out the degrees of the measured angle with a slight error. Such a tool is made of steel or plastic, and consists of two adjacent bases in the form of slats, as well as a protractor and an index bar.

Using a quadrant goniometer is quite simple, and its error of 1-2 degrees allows it to be used in construction, for example, when covering roofs. The meter allows you to measure angles from 1 to 180 degrees.

Not many craftsmen know how to use a mechanical protractor with a vernier. The vernier scale of the device is needed in order to obtain high measurement accuracy. A device with a vernier is also called universal, since it can be used in different areas.

Universal goniometer with vernier design

The accuracy class of a mechanical device is very high, and if you compare the readings of a mechanical and electronic one, the first option will show more accurate results despite its age.
This is interesting! If you need to measure the exact angle of two perpendicular planes, it is recommended to use a protractor with a vernier scale.
Using the tool is quite simple. For this purpose, the device has two scales - in degrees (protractor) and vernier. The vernier division price is 2 degrees. It can be used to measure up to 320 degrees. The principle of measurement is that the whole number in degrees is read on the protractor scale, and the fractions on the vernier.

To do this, you need to find exactly matching marks on two scales and take the readings. Devices with vernier are produced according to GOST 5378-88 standard. More details on how to use the vernier scale are described in the material “How to use a vernier caliper.” The video shows the design and features of using a mechanical protractor with a vernier.

How to choose the right protractor and inclinometer

The best tool is the one that copes with the tasks necessary for a particular master. Therefore, before purchasing, you need to assess the volume and complexity of the upcoming measurements, as well as the required measurement accuracy.

Mechanical protractors

convenient to use for carpentry and joinery work, for a number of topographic measurements. Inclinometers allow you to lay heat-insulating and finishing materials evenly, make markings, and check the work of hired craftsmen. At its core, a protractor is a regular protractor with a ruler, and an inclinometer is a bubble level. Multifunctional devices have replaceable rulers, a square and a vernier, which is fixed with a stopper. The elbow length of mechanical models is 30-60 cm, the measurement limit is 180 degrees, the gradient accuracy is 0.5°.

Electronic devices

It makes sense to buy when high-precision measurements with minimal error are required. The measurement range of these models is up to 360 degrees. But electronic protractors are heavier than mechanical ones - their weight is approximately 1-2 kg, while protractors weigh no more than 500 g. The length of such devices is 30-80 cm. Important parameters when choosing are the presence of a laser module, display size, and the presence of a connector for fixing to a tripod , error level and range. When purchasing, you should pay attention to the presence of a cover that protects the instrument from dirt and water, and also find out whether there is a warranty from the manufacturer and for how long.

Scope of use

The scope of application of goniometers is practically all areas of human activity. They are required wherever the design of products, the construction of their drawings and the marking of workpieces are carried out. Angular measurements are carried out in such industries as:

• construction;
• industry (from mining to clothing);
• warfare;
• education;
• transport;
• basic science;
• applied research;
• art;
• education.

An inclinometer is used in various fields, including in construction.
Angles surround a person everywhere; he uses inclinometers everywhere.

Characteristics of inclinometers

By definition, an inclinometer is a device designed to construct a plane parallel to the horizon. If the device has additional elements, it can be used to determine vertical lines, in accordance with the readings of a plumb line, or specified inclination angles. This device is otherwise called a level and is divided according to its design type into:

• bubbly;
• optical;
• aquatic;
• laser

It is noteworthy that to increase functionality, some instruments use elements that characterize two types of inclinometer. An example is a bubble level equipped with a laser pointer (or two), which allows you to mark a given point (or line) instantly and at a considerable distance.

The equipment of individual inclinometers includes several measuring instruments at once, which makes it possible to increase their functional characteristics. Such devices are used to make complex calculations with several input parameters. They find their application in the construction of structures of complex geometric configurations.

Top 2. ADA instruments AngleMeter 30

Rating (2021): 4.60

The best combination of price and functionality Inexpensive electronic model with good measurement accuracy, two bubble levels and quick calibration. The option when opportunities are combined with accessibility.

• Characteristics

  Average price: 3490 rub.

• Country: Hong Kong (manufactured in China)
• Type: electronic
• Measurement: Angle
• Measurement accuracy: 0.3°
• Bubble level: 2 eyes
• Level length, cm: 30

The goniometer is intended for carpentry and joinery work. In parallel with the digital display on which measurements are displayed, a bubble level with 2 eyes helps with the work. It can be used to control the initial position of the level, to apply markings on horizontal and vertical surfaces and for other operations. The start of the countdown can be set at different positions of the folding arm - the Zero button is used for this. The tool is lightweight (380 g per package) but strong. The goniometer is not afraid of falls, since its body is made of anodized aluminum. The length of the larger side is 30 cm, the measurement range is from 0 to 225 degrees. The device runs on 1 battery, and the protractor automatically turns off to save battery power. In reviews, buyers talk about the ease of use of this model, but some believe that the measurement error here is slightly higher than the stated 0.3 degrees.

Advantages and disadvantages

• Easy to measure
• Easy
• Rugged housing
• Affordable price

• The error is slightly higher than stated

See also:

• 20 best laser rangefinders from AliExpress

Choosing a protractor or what you need to know before buying

Based on the above description, you can make an appropriate decision about which type of tool is preferable to buy. Often the choice falls on mechanical or digital devices, followed by laser ones, and pendulum and optical devices are the least popular among home craftsmen. To choose the right meter, you need to consider the following criteria:

1. The material of manufacture can be plastic, aluminum or steel. You should choose aluminum devices as a last resort, since they have a short service life
2. The quality of the scale and the performance of the instrument as a whole - we visually determine how high quality this device is. If it was assembled not at the factory, but in a basement in a hurry, then this will be clearly visible. You should not choose such models
3. Price - a good device will cost accordingly. If it is a mechanical instrument made of plastic, then you can buy it for 500-600 rubles; with a vernier, devices made of steel cost at least 1,500 rubles, and the most expensive ones are electronic and laser meters

To summarize, it should be noted that the type of measuring instrument in question should be in the arsenal of every master. With its help, you can not only measure the angle between two perpendicular surfaces or a specific part, but also produce high-precision workpieces and mechanisms.

Design features and operating principle

The geometric principle of operation of any goniometer device is based on comparing the value of the measured angle with part of the circumference. A full circle corresponds to an angle of 360 degrees; the unit of measurement for an angle is defined by scientists as 1/360 of a full circle - 1 degree (angular). With increasing accuracy of measurements, they began to talk about fractional parts of a degree - decimal fractions or 1/60 of its part - an arc minute and 1/360 - an arc second.

The simplest mechanical protractors consist of a semicircular scale measured in degrees and a movable ruler fixed at one end. The measurement is carried out as follows:

• one side of the angle being measured is aligned with the base of the scale;
• the other with a movable ruler;
• At the intersection of the ruler and scale, the angle value is read.

More advanced models are supplemented with units that make it easier to read scale readings, fix the position of the device relative to the horizon, allow you to fix the direction to distant points on the sides of corners, and others.

Top 1. BOSCH PAM 220

Rating (2021): 4.80

The most thorough Electronic protractor has the longest length among the models in our rating - 42.5 cm. The tool is equipped with a bubble level (2 eyes) and is packaged in a convenient zippered case.

• Characteristics

  Average price: 8259 rub.

• Country: Germany (manufactured in China)
• Type: electronic
• Measurement: Angle
• Measurement accuracy: 0.2°
• Bubble level: 2 eyes
• Level length, cm: 42.5

The manufacturer's thorough approach can be seen in this protractor at first glance. A long arm contributes to more convenient and accurate calculations, a bubble level with 2 eyes helps to control the initial position of the device, takes part in marking for fixing guides, heat insulation, tiles, and in other works. The measurement results are displayed on a digital display, and the Hold function allows you to keep the current readings in memory. The inclinometer comes with a convenient zippered cover that protects it from dust and moisture. Buyers like the measurement accuracy (0.2° in the range from 0 to 220 degrees), ease of use and build quality, but the price for this model is quite high.

Advantages and disadvantages

• Measurement accuracy
• Long ruler
• Case included
• Memory function

• High price

See also:

• 10 Best Cheap Laser Levels

to the beginning of the rating

What is a mechanical angle meter?

The most affordable option is mechanical inclinometers. They allow you to obtain accurate data, but are characterized by less accuracy. When choosing a protractor, attention is paid to the following points:

1. What regulatory document was used as standards during production?
2. What is the accuracy of the angle measuring tool.
3. Features of device operation.

There are various versions of mechanical measuring instruments on sale; construction protractors have become widespread. The vernier type is represented by the following design:

1. Frame.
2. Disc fixed to a nut.
3. Base with scale and vernier.
4. Ruler and shank.

Vernier protractor

Vernier type protractor device
Optical versions are characterized by a more complex design. A separate group includes mechanisms that are in fact templates.

Recommendations

Inclinometer designs equipped with automatic systems allow you to navigate faster and perform more complex actions even in cramped conditions. For example, an electronic protractor is ready to report the measurement result immediately after the rulers touch the surface. At the same time, the optics need to be initially installed on a horizontal surface to avoid level errors. And mechanical devices additionally require certain knowledge from the performer in order to be able to make calculations.

For this reason, the most popular and widely available are inclinometers equipped with a large number of different options. When purchasing any measuring instrument, it is necessary to check the regulatory documents in order to be able to check or adjust it.

How to use a vernier protractor

How to use a vernier protractor? Mechanical type goniometer equipment is quite simple. It can be used on any surface and can measure both external and internal angles. When installing the device, distortions must not be allowed; this can lead to a significant error.

The device is equipped with a special scale, which allows you to increase the accuracy of measurements by an order of magnitude. In some ways they are similar to a traditional caliper. For example, to measure an external angle, it is enough to attach a ruler located at the base of the device to one of the planes, and bring the moving part connected to the scale to the other. As a result, it will be possible to find out the desired angle. For more detailed information, see the operating instructions for the angle measuring device. It, like the passport, is included in the delivery package.

The basic scale shows degrees; in appearance it looks like a school protractor, and measuring angles with a protractor with a vernier is not difficult even for a beginner.

Top 3. BISON 34292

Rating (2021): 4.57

7 reviews from resources taken into account: Yandex.Market

Best for home Cheap, but high-quality mechanical protractor with a measurement accuracy of 0.5°. Simple, does not require the purchase of batteries or a specific temperature regime.

• Characteristics

  Average price: 440 rub.

• Country Russia
• Type: ruler
• Measurement: Angle
• Measuring accuracy: 0.5°
• Bubble level: no
• Level length, cm: 10

The simpler the design, the more durable the device. There is practically nothing to break in this mechanical protractor: the battery will not run out, it is not afraid of frost, and understanding the measurement process is as easy as shelling pears. This is a very convenient and compact tool for home use. In the professional field, it is not suitable for everyone, since a measurement error of half a degree is not always acceptable. The ruler is 10 cm long, the entire structure is made of durable stainless steel - it does not bend like school aluminum protractors. Buyers also like the device's affordable price and engraved rather than painted values ​​that are unlikely to ever be erased. But the reliability of the rivet that connects the rulers to each other raises doubts.

Advantages and disadvantages

• Inexpensive
• Durable
• Does not require batteries

• The error is higher than in electronic

Types of goniometers based on measurement principle

Depending on the method of angular measurements used, devices are divided into several types:

Mechanical

Mechanical protractors, widely used in plumbing and carpentry, are divided into two subtypes:

• simple, representing an angular scale-protractor and a ruler fixed at one end at the origin;
• equipped with a vernier - an additional scale for more accurate reading.

Mechanical goniometer
Measurements of flat angles are carried out using the contact method - the tool should be pressed tightly to the surface.

Pendulum

In addition to determining the angle between two directions, it is also possible to make angular measurements relative to the horizon. In ancient designs, a plumb line, a rectangle, or a gimbal were used for this; in modern ones, a design is used that stabilizes its position in space due to the rapid rotation of a rotor-gyroscope. The device allows you to quickly determine the slope of a surface, the slopes of the sides of complex structures, etc. Some laser rangefinders can determine the position of the horizon line by processing GPS satellite signals

Optical

In this type of device, one (or both) sides of an angle are marked using an optical system aimed at a marker point on the object being measured. This is a remote sensing tool. These include navigation, mining, astronomical and many construction instruments.

Laser

These are the most advanced devices to date. Usually they are combined with a laser rangefinder, angular measurements are an additional function of most of them. Two or more laser beams are directed at points lying on the sides of the angle being measured. The processor calculates the angular values ​​and displays them on the device display. It can measure angles in any plane and count them from a user-specified coordinate system.

The simplest devices use a mechanical scale on which the operator turns a dial with a laser pointer installed. Advanced ones process the reflected laser signal independently.

Laser protractor

Widely used for marking construction sites and industrial structures. If the illumination spot from the laser beam is difficult to see in bright sunlight, additional amplifiers and reflectors are used.

Electronic

The values ​​are calculated by the built-in processor. The measurement results are displayed. The devices allow you to remember the results of the latest measurements and carry out calculations based on them: for example, the difference between two measured angles. Such devices are actively used when marking workpieces in mechanical engineering and woodworking industries, and when cutting sheet and roll materials.

In addition, in study, production, construction and in everyday life, constant angle goniometers are widely used - these are templates made with a fixed angle of 90, 30, 45, 60. With their help, you can determine whether the measured angle is equal or not to the value fixed in the template.

Top 5. Kraftool 1-34851

Rating (2021): 4.25

The simplest and easiest to maintain. The inclinometer-ruler with a bubble level is a reliable and understandable device for everyone. A smart choice for home use.

• Characteristics

  Average price: 890 rub.

• Country: Japan
• Type: ruler
• Measurement: Tilt
• Measurement accuracy: 0.7°
• Bubble level: 1 eye
• Level length, cm: 20

Calculating the angle of inclination with this tool is simple. You just need to attach the ruler to the surface: when measuring a horizontal surface, the level eye will be at 0, when measuring a vertical surface, it will be at 90° (this is the maximum possible measurement angle). For the convenience of the master, the case has a convenient handle and magnetic fastenings. The measurement accuracy of this inclinometer is inferior to all other models and is 0.7° - such readings are not compatible with every professional field. But the price of this tool is much lower than that of electronic competitors. However, this model can be used in private construction and in some other areas where such an error is acceptable. The body is made of durable plastic, but it is still better not to drop the device.

Advantages and disadvantages

• Affordable price
• Ease of use
• Magnets for fixation

• Measurement error

Main types of goniometers

There are many types of this device. As a rule, they differ in purpose. The following models are on sale today:

• For installation and construction work. Devices of this type are used primarily for marking. A construction mechanical goniometer is also used in the process of developing design drawings.
• Carpentry. These devices are used to work with wood blanks.
• Mountain. Used for surveying surveys.
• Seaworthy. Used to identify geographic latitude.
• Mechanic's tools are used for specialized work. This device is characterized by a high level of measurement accuracy.
• Educational (school). These rulers and protractors are used in schools and universities.
• Artillery squares have the highest accuracy. Such devices are used in the installation and adjustment of artillery pieces.
• A universal tool that can be used for different jobs.

Modern devices may also vary in accuracy and size. In addition, devices can be designed to measure internal or external angles.

Top 2. ELITECH 2210.001000

Rating (2021): 4.60

The most affordable electronic inclinometer This electronic model is almost 2 times cheaper than the next similar inclinometer in our rating.

• Characteristics

  Average price: 2660 rub.

• Country: Russia (manufactured in China)
• Type: electronic
• Measurement: Tilt
• Measuring accuracy: 0.5°
• Bubble level: no
• Level length, cm: 5.7

A pocket-sized electronic device with a side of 5.7 cm and a weight of 205 g. The metal body of this device has a magnet for fixing to vertical surfaces, which facilitates measurements. The inclinometer calculates the angle of inclination with an accuracy of 0.5° within the range of 0-90°. Buyers like the build quality, compactness, ease of use of the device and good packaging in which it is convenient to store. Many appreciated the detailed instructions, which are rarely found in modern devices. The measurement accuracy seems sufficient to most, but not to everyone - it depends on the field of activity. For household needs, sharpening tools, monitoring hired workers and many other tasks, this inclinometer is quite sufficient.

Advantages and disadvantages

• detailed instructions
• Compactness
• Build quality

• Accuracy inferior to other electronic models

See also:

• 15 best calipers from AliExpress

Application

As already noted, goniometer devices have found their application in almost all sectors, industry, and transport.

In the construction industry, goniometers are used when performing installation work, marking and design work. With its help, they control the installation of building structures that are located at a certain angle relative to each other. Moreover, measurements can be carried out in three planes. In addition to the goniometer, plumb lines and levels are used in construction.

In addition, goniometric tools are used in carpentry, carpentry, and geodesy. Even in medicine, this instrument is used to control joints, spine, etc.

Popular protractors 2022 designed for narrow specialization

In addition to construction, protractors are used in many other specialties where the accuracy of plane alignment is important. Measurements with these devices are important in carpentry and carpentry, because deviations in the alignment of their products can lead not only to operational problems, but also to domestic injuries. In addition, goniometers are used by doctors, topographers and even astronomers.

However, in this situation, narrow specialists use devices of a different design. To measure them, there is no need to use multifunctional equipment. But the requirements for the accuracy of matching angles for this group of professionals are much higher. For this reason, they use devices that are not structurally related to inclinometers. Such devices are divided into several groups:

Vernier device

The measuring device is applied to the plane in the place where it is necessary to measure the desired angle, while the ruler and the body of the device are placed on the sides of the angle. Next, you need to count the degrees located on the main scale up to the point of contact with zero on the vernier field to determine the degrees. Then, moving along the vernier scale, they find the division that coincides with the desired mark on the main scale, lining it up in a common straight line to determine the minutes.

Optical device

There is a movable ruler here, which must be moved so that it forms the required angle with the fixed part. After this, a special ring is fixed, which is used for clamping. Next, it is necessary to take into account that both the disk and the device’s magnifying glass depend in their construction on the movable element, and, therefore, the desired position is determined from them. Through a magnifying glass, the movements of the disk markings are observed, aligning them with the mark on the plate, after which the instrument readings are taken.

Electronic protractor

This is a device that has a digital display necessary for measuring angles. For convenience, each arm of the device was equipped with markings that made it possible to set the exact value for the marks on the contact planes. The electronic device of the protractor has special functions that allow both resetting and freezing the results obtained, which adds convenience to the work. At the same time, the accuracy of the device is at a fairly high level, the error is only 0.3o (degrees).

Pointer protractor

This is the name given to a quadrant protractor equipped with an elongated guide on which a scale is applied. This device has found application when cutting large slabs. It is used to measure both internal and external angles from 0 to 180o (degrees). Such devices are made from stainless steel or ordinary steel with an anti-corrosion coating.