How to use the protractor
A goniometer is a tool used to measure the angles between two planes. The principle of measuring with an angle gauge is similar to an ordinary joiner's corner, which is used only when determining right angles. The device can calculate various angles, since its design is based on an adjustable swivel joint of moving parts.
There are both simple and complex angle measuring tools. In this article, we will consider their basic principle of operation.
Device
With this precise measuring tool, the geometric values of the parts are compared, that is, the values of the angles in terms of the circumference and the graduated scale. It can be linear or rounded. The linear scale is not used to calculate degrees, their values are determined only by rounded variants, movable due to the hinge mechanism. The total circumference is 360°, and each unit is defined by 1/360th of the entire circumference; this is one angular degree. In precision instruments, the angle is measured in fractional parts of degrees. There are special angle gauges (template) to determine only one angle.
Simple models are mechanical goniometers, which have a fixed circular scale measured in degrees and a movable ruler connected to it at one end. They move along the surface, due to which the angles are measured. Let's consider how to measure correctly with an angle finder:
- the base of the scale is attached to one plane;
- the movable scale is combined with the second plane;
- at the intersection of the scale with the ruler, the value of the angle value is determined.
Advanced tools have additional nodes that simplify reading on the scale. They act as fixing guides to help identify distant corner points. The devices also perform other functions, depending on the purpose in a particular area.
Angle measuring devices are high—precision tools. They are made of alloy steels, bronze and other alloys. Building models with electronic modules in their construction are made of aluminum. They are easy to damage, so special care should be taken when using them, to avoid falling both the device itself and any objects on it.
Measuring the angle with a laser goniometer is based on the formation of a spatial picture of the measured parts, where you can see the reference points with coordinates measured by a laser rangefinder. The angles based on these coordinates are calculated on a computer by an electronic type of goniometer.
Scope of application
You can use angle meters not only in technical industries, but also in everyday life. For example, for self-leveling of raw plastered surfaces of window openings, niches and other shaped elements during construction. Along with a simple square, this tool is used by carpenters, carpenters, locksmiths, installers. Different types and types of goniometers are also used:
- in military affairs;
- in sewing industries;
- on special vehicles;
- in scientific fundamental and applied research;
- in education: art, physics and astronomy.
Angle gauges are used not only in the construction of structures, but also to control angles in existing nodes, units to ensure proper operation. Specialists use them to carry out verification work and diagnostics of various mechanisms. Let's consider the types of angle measuring devices separately.
Educational. Designed for use in educational institutions, used in the calculation of geometric quantities in various sciences. With the help of an educational tool, students begin to understand in practice how to use various types of angle gauges correctly. The simplest version of the tool is a linear one. It consists of two hinged sliding rulers. The linear goniometer can measure external and internal angles in the measurement range with an accuracy of one degree.
Locksmiths. These models are characterized by increased accuracy. They are compact, with sensitive adjustment, because they perform calculations in fractions of degrees, when even minimal deviations from standards are unacceptable.
A variety of locksmith goniometers include indicator nutrometers designed to tighten bolt fasteners. They are necessary in the repair of internal combustion engines to tighten the bolts with the necessary force to ensure sufficient sealing between the parts without tearing the thread. In such cases, the goniometers are combined with torque wrenches on a graduated scale (pre-turn). With their help, the tightening force of the threaded fasteners is determined by turning the bolts to a certain degree. For more correct and accurate use of the indicator nutrometer when measuring angles in internal spaces, ready-made calculations are used.
Construction.These devices are divided into digital, mechanical and laser devices. They are used in marking, designing, during the installation of building structures — foundations, walls, ceilings, inclined elements of buildings.
Quadrant goniometers. A quadrant is a part of a circle. This goniometer also refers to the construction type of devices, measurements are calculated in degrees. How to use a protractor of this type is taught in advanced training courses.
Small angle gauges.Another type of construction tool is a base in the form of a wooden or metal bar, at the end of which there is a manual wrench. A graduated ruler with a longitudinal groove moves along the threaded rod. This tool is used to calculate angles on walls and other building structures.
Mountain. Using these optical goniometers, surveying surveys are carried out. In their design, there are inclinometers that measure the angles of inclination of surfaces. Mining angle gauges are used in cases of calculation at a distance, measuring the angles of the internal spaces of ore mines and mines. Such mechanical tools allow for measurement error, they have already been replaced by more accurate devices.
Astronomical. This type of device has nothing to do with construction. Astronomical goniometers are used to calculate the azimuths of celestial objects. They calculate the angles between bodies in the firmament and the horizon of the earth's surface, determine the trajectories of movement, the speed of movement. Astronomical goniometers are for the most part components of telescopes.
Seaworthy. This type of goniometers determines the geographical latitude of the vessel. In the calculation process, the position of the sun, moon and stars relative to the horizon, that is, the angle in height, is used. An example of a nautical protractor is a sextant, which was used by seafarers in the past. Now they have been replaced by electronic navigation devices using satellite technologies, but the rules of navigation safety prescribe the mandatory presence of a mechanical nautical protractor on the ship in case of electronic failure.
Artillery. Are used to aim guns at the target. More precisely, it would be correct to say that they were used, since now they have already been replaced by computer guidance systems.
Medical. Few people have heard about this type of goniometer. They measure the angles of joint operability, that is, the maximum range of rotation of human body parts. There is a graduated scale on the device, according to which a medical specialist analyzes the amplitude of movements.
Types of goniometers
The classification of the goniometers is determined by the measurement method and the display of the readings. Let's look at the design features of each type of goniometer and how to use them.
Mechanical
Structurally, this is the simplest kind of tool. To measure the angle with an angle finder, it is applied to the surfaces, and thus their position is measured among themselves. Mechanical protractors do not belong to the high-precision tools category.
Pendulum
Pendulum protractors are a device with a round scale similar to a clock face. It is marked with a step of 1 degree. The angles of inclination of the surfaces are determined by the arrow. The goniometer is arranged according to the principle of a pendulum mechanism.
Optical
They are high-precision goniometers capable of measuring angles around the entire circumference by 360°. Due to the fact that the angles are calculated in fractions of degrees, they are quite difficult to consider, for this the device is equipped with a magnifying glass.
Laser
The device works on the basis of laser beams. They are directed to surfaces whose position is measured relative to each other.The laser goniometer is equipped with a built-in liquid crystal display. The advantage of laser models is that they can be used in dark places or at night. However, in bright light, the marks are almost invisible.
There are models of laser protractors in the form of a crossbow. They calculate the angles of the cutting edges when sharpening saws, knives, incisors.
In construction laser goniometer devices, two beams are emitted directed at the measured surfaces. The processor is responsible for calculations and analysis, and the data is displayed on the display. They are equipped with smartphones, this function works through a special application.
Electronic
Such goniometers are also called digital. The measurement principle is similar to mechanical devices, only the readings are determined not by a dial or scale, but are displayed on an LCD display. These are universal goniometers, belong to the high-precision category of measuring instruments. Digital views calculate tenths of degrees.
Vernier
With this mechanical tool, the geometric shapes of various structures are measured. There are models for measuring angles at a distance. The design has a mechanism for fixing the exact positions of the measured objects. The values of the angles are in minutes, and if there is an additional scale, in angular seconds.
Using a vernier protractor is easier than it might seem at first glance. It has a vernier scale connected to the base on a long ruler. Standard goniometers of this type, equipped with a 4-UM vernier, are the most common. They measure angles within a radius of 180 °. They are used in industry in the manufacture of parts, repairs, and diagnostics.
Measuring vernier goniometers are made of high-quality steels and belong to the category of high-precision tools. They differ in size, markings on the scales, and design. A movable ruler is attached to the center of the scale, measuring the magnitude of the angle of inclination of any plane. The vernier is located in the part of the device where the ruler runs. It allows you to calculate tenths of a degree. Verniers are not as sensitive to mechanical influences as electronic goniometers, so they are more durable.
How to choose a goniometer
We have described the types of goniometers, how they work and on what basis. With this information, you will be able to purchase the right tool for certain purposes, taking into account all the necessary criteria when choosing. If there is no need to calculate hundredths of a degree, then you should not buy an expensive electronic device. A mechanical tool is quite suitable for simple measurements. Electronic or laser goniometers are used for accurate angle calculations in production, diagnostic, and repair operations. It is advisable to buy expensive devices if they will justify their use in the future. When choosing, you need to pay attention to the following factors:
- The materials from which the working parts of the tool, housing, holders, and adjusting components are made. In high-precision expensive models, movable mechanisms are made of tool steels. There should be no backlash in the hinge joints, the measuring elements should move smoothly, evenly, without effort. A tool with plastic working parts is not suitable for production purposes, it is suitable for everyday life, has a relatively short service life.
- The quality of the scale graduation. The accuracy of the product is determined visually by comparing the indicators during trial measurements on other devices.
- Cost. The high price of a high-quality product should not be an obstacle to purchase. In principle, a good tool cannot be cheap because the best materials are used for its manufacture, new technologies are used. An expensive high-precision device justifies its cost by long-term operation and precision in operation.
To summarize, let's highlight the main thing. Every professional should have a high-quality, high-precision catch meter. An expensive tool is not needed for the home, because in everyday life there is no need to measure angles with an accuracy of hundredths or even tenths of a degree. At home, they are used mainly for repairs, for example, to align the corners of walls in window openings. If the tool is purchased for production, then it is not worth saving on its cost.
Useful tips on using the goniometer
It is possible to count on the most accurate measurement results only if the goniometer is operated and stored in the conditions recommended by the manufacturer. It should be stored in a case, within the permissible temperature and humidity limits. Like all precision instruments, it cannot be exposed to an aggressive environment — chemical vapors, acids, alkalis. Even the slightest deformation of the working parts can affect the accuracy of measurements.
To ensure good visibility of the laser goniometer marks in bright light, special reflectors and light beam amplifiers should be additionally purchased.
Electronic goniometers are powered by AAA batteries. If long-term use is expected, you should stock up on an additional set of batteries. When powering the device from a battery, it is recommended to take a charger with you, and not expect that a fully charged device will last for the entire duration of the work.
The device should be calibrated periodically. When taking measurements with an inclinometer, do not forget about safety precautions, especially if you work at height. In such cases, you need to take care of the reliability of the supports of building structures in advance.
Any goniometer, whether digital or mechanical, needs careful handling and appropriate storage. When using the device, it is necessary to follow the rules provided by the manufacturer in the user manual.