The implementation of most types of construction and installation works is impossible without the use of a special tool - a goniometer. As can already be judged by the name, this device is used to measure the angles of structures. The most popular at the moment are mechanical tools of this variety. Such goniometers are inexpensive, it is not difficult to use them, and measurements using them can be made quite accurate.
Tool history
The mechanical protractor was invented a very long time ago. Along with the ruler, this is one of the oldest tools on earth. Scientists believe that he first appeared in Egypt and Babylon. After all, the construction of such grandiose structures as, for example, the pyramids, without a goniometer would be simply impossible.
The design of this simple device over the past century has not changed. Modern goniometers look exactly the same as those used by the ancient engineers of Egypt. The only thing in our time for the manufacture of such tools are other materials. Of course, the scope of modern goniometers is much wider.
Intended classification
There are many types of this popular tool. Goniometers are classified mainly for their intended purpose. Modern manufacturers produce the following options for this tool:
Construction. Tools of this group are usually used for marking or installation operations. Mechanical building protractor can also be used in the development of drawings of projects of buildings and structures.
Carpentry Such tools are simply indispensable when performing various kinds of work with wooden blanks.
Mountain. Used in surveying surveys.
Nautical. They are used to determine geographical latitude.
Locksmiths. Such tools are used when performing work of the corresponding specialization. The mechanical goniometer usually has a rather high degree of measurement accuracy.
Training. These tools are used by students in the classroom and when doing homework.
Artillery. This variety of tools is also highly accurate. Goniometers of this type are used when installing artillery guns.
Universal. This group of devices can be used to measure angles when performing a variety of jobs.
Types of use
All mechanical tools existing on the market today can also be divided into groups according to such criteria as the size and type of error. In addition, such devices are classified by scope. A modern mechanical angle meter can be used:
For measuring external angles. Such models are marked with the letters UM.
For measuring internal angles (UN).
Design features
The unit of measurement of any angle, as you know, is, degree - 1/360 of the diameter of the circle. He is the step of the goniometer. Degrees, in turn, are divided into minutes and seconds. A common design element of all instruments of this type is the base in the form of a movable arc, on which a scale with degrees and minutes is applied. The latter is movably fixed on a special ruler, which serves as a starting point for measurement. Very often, the design of such tools instead of a ruler includes a square. It is fixed on a support level. It is possible to fix the obtained measurement result in such devices using a special screw.
Mechanical pendulum goniometers additionally have a special structural element that assumes a vertical position when the angle of inclination of the measured part changes. Such tools are more convenient to use than conventional ones. They are used most often when working with dimensional products. For example, with their help, the actual angles of arrangement of nodes and mechanisms of agricultural machinery are measured.
Goniometers are most often made of tool steel. This material is durable and resistant to damage. The steel angle gauge is mechanical for a very long time. In some cases, tools of this variety can also be made of wood or plastic. Such models are most often used when performing various kinds of repair work indoors (for example, when installing wall panels or mounting baseboards). Sometimes devices of this type are also made of lightweight aluminum.
Goniometer with Vernier
This is one of the most convenient types of tools. Nonius is the auxiliary scale installed on the goniometer. This small additional element is fixed above the upper edge of the arcuate base and remains stationary during operation. It serves to more accurately determine the number of fractions of division on the main scale. The principle of the vernier is based on the fact that the human eye much more accurately notices the coincidence of divisions than the location of one of them between the others. A mechanical goniometer, supplemented with such an element, is, of course, much more convenient in operation than a regular one. In addition, the measurements themselves with its use can be made much better.
Instructions for use
The question of how to measure angles with a mechanical goniometer is quite simple. Using such a device, of course, is more difficult than an electronic option. However, you can still learn how to work it quite quickly. Measurements using mechanical devices are made by selecting various combinations of the position of their elements. For example, the external angles when using the universal tool of Semenov are checked as follows:
The square is pressed to one side of the corner of the product.
The scale of the arcuate base is applied to another.
Carefully check the junction of the tool and the sides of the corner of the product for any gaps.
Screw the instrument to the item being measured.
They look at what value on the scale coincides with the edge of the square.
It is even easier to measure the angle between the converging or diverging opposite sides of the workpiece. In this case, you can also use the goniometer mechanical design Semenov. For measurement, one of the sides is simply assigned a horizontal bar of the tool on which the square is fixed, and to the other - the scale of the arcuate base.
Reviews of goniometers "Quadrant Fit"
Among the most popular models of such devices, in addition to the Semenov instrument, consumers include the “Quadrant Fit” and Mitutoyo. The first brand of tools is usually made of plastic. Its main advantages include fairly high measurement accuracy and good build quality. As the owners of these goniometers note, all their elements are fastened securely and do not hang out. The drawbacks of consumers include only a certain fragility of the material used for their manufacture. However, there are also “Quadrant Fit Profi” aluminum models on sale. The main distinguishing feature of the protractors of this brand is the presence of an elongated ruler. They can also be used for measuring overall products. Not too high cost - this is also why this angle meter has earned popularity among consumers. The price of the "Quadrant Fit" plastic models, depending on the supplier, ranges from 150-250 rubles. Models "Pros" cost 400-500 p.
Mitutoyo brand tools: reviews
Mitutoyo produces both electronic and mechanical goniometers. The latter are also referred to as fairly accurate and of high quality. This brand is produced in Japan and costs, of course, more expensive than the Chinese Quadrant Fit products. Mitutoyo goniometers are highly praised for being equipped with a special magnifying glass above the sector scale. Of course, this small addition greatly facilitates the measurement.
Malki "Bison"
Thus, both brands described above, with a classic design, are rated by consumers as quite worthy. However, sometimes a tool of this type is necessary to perform the simplest jobs. In this case, a special kind of goniometers is usually used - small. Their main distinguishing feature is the simplicity of design.
To carry out such work as measuring the angles of an apartment during installation of skirting boards, mechanical bendometers, quite popular with consumers, are often used, for example. They consist of only two elements - a metal bar and a ruler with a scale movably fixed on it.