As you know, nothing lasts forever, and even the tools of branded manufacturers break, not to mention the so-called "consumer goods". And the grinder (angle grinder) is no exception. By the way, they began to call the angle grinder "Bulgarian" during the time of the Union, because then this tool was produced in Bulgaria and the first models were supplied from there. The grinder, as a tool, has become very widespread due to its versatility and ease of use. There are also many varieties and models of angle grinders, however, the principle of operation and the device are not fundamentally different. Therefore, considering the structure of the tool, possible faults and repair methods, they can be applied to any model of grinder.

Bulgarian device relatively simple. The basis of the tool is its body, inside which there is an electric motor, a starter and a gear transmission to the spindle, on which various nozzles are mounted.

The case is made of strong impact-resistant plastic. Depending on the power, there are various dimensions and shape of the tool. Some models have an angular speed regulator, which is designed for optimal selection of revolutions, when various types work.
Another component can be a reducer. The gearbox is designed to create optimal conditions for the transfer of rotation from the rotor of the electric motor to the cutting or grinding wheel. This reduces the number of revolutions on the output shaft of the gearbox. Properly selected rotation speed and circle diameter is the key to the most efficient operation of the tool.

The button for replacing the working disk, when pressed, locks the disk in a certain position, preventing it from scrolling when removed.

The safety clutch serves as a limiter in the event of a sudden reactive torque. In another way, when the disc is jammed in the material, the grinder itself starts to rotate sharply, which can lead to injury to the worker. This clutch does not allow this rotation.

The electric motor normally consists of a stator and a rotor. The stator is located in the guide tides of the plastic body of the grinder. On the back of the stator there is a special device called a brush mechanism. It contains copper-graphite brushes. Brushes are needed to transmit voltage to the rotor through the collector assembly.

The rotor is located inside the stator and is fixed in the housing in bearing assemblies, which are inserted directly into the tool housing. The front bearing assembly is usually made in a metal plate, or this plate can be made of aluminum alloy.

The gearbox housing of the angle grinder is almost always made of aluminum alloy and has several threaded holes for attaching an additional handle. By screwing the handle into various holes, you can change the plane of location during operation.

The gearbox consists of two gears, with the help of which the direction of the output shaft is changed by 90 degrees and the rotation speed is reduced. The ratio of the number of teeth on the primary gear to the number of teeth on the secondary gear is called the gear ratio.

Typical malfunctions of angle grinders and diagnostic and repair methods

Bulgarian suddenly stopped working.
The first thing to do - disconnect physically from the network and manually rotate the disk. If the disc does not spin or spins very tightly, immediately disassemble the tool for visual inspection. If it turns easily, then the most likely thing is that electricity does not reach the brushes of the electric motor. That is, the problem lies either in the power plug, or in the wire itself, or in the Start button mechanism. It is enough to disassemble the case and "ring" the cable with a conventional tester, or in some other way, for a break. After eliminating the break or replacing the wire, the grinder will work.

The wire and plug are guaranteed to be intact, but the tool still does not work.
It is necessary to disassemble the trigger, and it is desirable to mark the contacts to be removed - if they are subsequently connected incorrectly, the winding may burn out or the armature may jam. It is not often possible to repair the trigger mechanism - it is easier and more reliable to replace the trigger button with any similar one with suitable power parameters. Such a button is not so expensive and you can buy it in any store of the corresponding profile.

The start button and the power wire are in working condition, the grinder does not work.
Check brushes and brush holders. There may be a break or complete wear of the brushes. The resource of these devices is usually limited to several years, of course, it all depends on the intensity of use. Repair break or replace brushes.

More serious malfunctions follow, respectively, and repair requires certain knowledge and skills.

Breakage or licking of the gear teeth of the gearbox;
- jamming of bearings;
- failure of the armature or stator;
- failure of the control electronics;
- failure of the collector;
- deformation of the hull;

When determining the mechanical defects of the grinder, more attention should be paid to the condition of the plonitary (large gear), shank (gear on the shaft) and bushings. Uneven wear of the teeth or the shank of the shafts indicates the immediate replacement of worn parts.

Breaking out the spindle lock button.
The reason is just one careless movement, namely pressing (intentionally or accidentally) on the button when the disk is spinning. Sometimes breakdowns occur due to attempts to remove a jammed disk using a button. Many grinders on the spindle, where the disk is attached, have slots especially for a regular open-end wrench, look at your grinder, most likely you have one. So, it's better to use them and an open-end wrench than a disk lock button.

Chipped gear teeth.
Usually occur due to jamming (in such a situation, a tool breakage is not the worst thing that can happen). A sign of a malfunction is a rumble in the gearbox. If the gear has lost two or three teeth, then the tool will not be able to cut.
In this case, it is necessary to change the gears in a pair and the gear itself and the bevel wheel. When you go to the store for gears, do not forget to write down the name of your grinder and its power.

Failure of the electric motor.
This often happens with tools that work in dust and are forced to rest in sand or on the ground: the sucked-in dust wears down the winding. However, you can ruin the motor without dust - by strong overloads, especially if the tool is low-power. Therefore, in small grinders, not only the anchor, but also the stator often burns out. Small angle grinders also have a breakdown of the electronic speed control unit. If you use a grinder to cut very dusty materials, in particular slate, a stocking put on the ventilation slots in the case helps to protect the instrument.

Bearings.
Another sore spot for angle grinders (as well as other twisting power tools). Strong immunities against dust are distinguished by few machines, and high frequency rotation suggests rapid wear. In general, bearings are not the worst failure, they are easy to change. However, it is important to replace it on time, otherwise there is a high probability of a more serious breakdown, the repair of which is comparable to the purchase

stator
If, when turned on, the disk starts to gain momentum and accelerates too much, there is definitely a turn circuit on the stator winding. Stator repair is one of the most serious breakdowns and requires appropriate skills. If you are not confident in your abilities, then it is better to entrust it to professionals or use the services of a repair shop.

We begin repairing the stator of the grinder by cutting off the frontal parts of the winding, the remnants of which we take out. Next, we make a new winding using a template sandwiched between two large plates on an axis that can be inserted into an electric drill. The main thing is to achieve an identical number of turns made with the proper density and withstand the thickness of the wire. We insert two coils into the stator housing, draw conclusions from the same winding wire, insulating with flexible tubes of the appropriate diameter.

Reducer
In models with a power of up to 1100 W, spur gears mounted on an anchor are usually used, but angle grinders with more power, for example, by 1500 W, require helical gear wheels. Both variants have a conical shape, since the axis of the gearbox rod intersects with the armature shaft, and transmission is possible only by angular engagement of the teeth.
As a rule, the repair of the grinder gearbox consists only in the replacement of gears. If the disk gear is broken, then it will be very difficult to remove it for replacement; this assembly is best fixed in the gearbox.

speed controller
Almost all modern models of drills, jigsaws, screwdrivers have a speed control. But not all grinders (grinders) are equipped with such a mechanism. In principle, a regulator is not needed for cutting metal with a cutting stone, but it is simply not replaceable for grinding. The proposed circuit of a homemade regulator is very simple and reliable. There are not many parts and they are not expensive. If you already have an angle grinder without a regular speed controller, then you can easily improve it.

You can also assemble it separately in a box with a socket and use it as a carrier with a power regulator. And you can immediately assemble the regulator in the grinder case and bring out the resistor handle.

Rules for using the angle grinder and preventive maintenance

The power tool must not be allowed to work for a long time under load at a significantly reduced speed (this can be determined by ear) compared to idle speed, and even more so, the tool must not be clamped (blocked), otherwise it will burn out within a few seconds.

After working at low speeds, do not immediately turn off the power tool. To prevent local overheating, it is necessary that it work for some time (more than 1 min.).

It is important to strictly observe the terms for replacing (adding) lubricant and its quantity indicated in the operating instructions.

With increased noise during the operation of the grinder or with a deterioration in its performance, it is necessary to carry out a prof. service.

Prevention consists in the complete or partial disassembly of the tool, cleaning, lubrication and replacement (if necessary) of some parts.
Timely replacement of relatively cheap parts that wear out quickly will allow you to save more expensive durable components, which in the end will lead to savings in tool operation, eliminate premature repairs and greatly extend tool life.

Almost every craftsman who often works with metal knows the electrical circuit of an angle grinder. The grinder is a tool that is most often used for cutting metal. This tool is the source heightened danger, therefore, before each use, check the serviceability of the electrical and mechanical components of the structure.

The angle grinder, which in the post-Soviet territory is called the “Bulgarian”, was the dream of every home craftsman 3-4 decades ago. 30-40 years ago, this working tool was produced by one manufacturer, the Eltos-Bulgarian plant, located on the territory of Bulgaria in the city of Plovdiv. At the moment, manufacturers offer consumers various models and modifications of this tool, but the main components of the design have not changed much. Most of the structural elements on various models and modifications differ only in size.

The electrical component of the grinder design

For the entire period of its existence appearance instrument remained virtually unchanged. The grinder has an elongated body in which an electric drive and a gearbox are mounted. A handle is fixed on the side surface of the tool to hold the tool in the working position; additionally, to protect the master, a protective cover is fixed on the tool body, covering the working element.

The grinder, like any tool, can fail during operation. In most cases, to eliminate breakdowns, the simplest repair of working equipment, its electrical component, is required.

In order to make repairs, you need to know the device not only of the mechanical part, but also the electrical circuit of the tool. To carry out a quality repair, you should study the principle of operation of the angle grinder. The electrical circuit of the angle grinder includes the following structural elements:

anchor;
collector;
electric brushes;
reducer;
stator;
start and lock button;
power cable with a plug for connecting to a household network.

Each of the components is designed to perform certain functions in the electrical circuit, and a malfunction of any of them leads to a stop in the functioning of the device. For example, an armature is a rotating element of an electrical circuit. It provides the transmission of rotational motion to the grinding disc. In order for the tool to function properly, the armature must rotate at high speed. The higher the rotation speed of this structural element, the higher the power of the device.

Functions performed by the structural components of the angle grinder

The collector is an anchored platform to which all power and control cables are led. The task of the collector is to conduct the signals passing through the windings to the engine and the control unit. When removing the housing cover, the collector immediately catches the eye by the presence of polished plates, which are large in size.

Electric brushes in the design of the device are used to transmit electric current to the collector from power cable. In the process of operation, if the brushes are in a normal technical condition, then through the ventilation openings of the housing, a uniform glow is visible. If the glow in the process of turning on the device is not observed or has a pulsating character, then this is a sign of problems with this electrical component of the device.

The gearbox is one of the most important components of the design. Its purpose is to transfer the rotational energy from the rotating armature to the grinding disc, providing it rotary motion. The gearbox is responsible for the frequency and power of rotation of the working tool of the grinder.

The stator is a technically complex unit of the device design. The stator design includes windings, which, when interacting through magnetic field with armature windings set the latter in motion. The stator coils have a certain number of turns, calculated in accordance with the requirements of electrical engineering. If this unit fails, rewinding of the coils is required. This operation requires certain knowledge and skills. It is better to entrust the rewinding of the stator to a workshop specialist.

Schematic diagram of the grinder device

In the process of carrying out repairs, it is not enough to know the purpose of the main structural elements of the electrical circuit of the tool, you must also be able to read it. The electrical circuit of the angle grinder is not very complicated. However, even such a design in some cases during the repair can cause difficulties.

The electrical circuit of the grinder is arranged in a certain way. Two stator coils are connected in series through a cable to home network with a voltage of 220 V. These coils are not electrically connected to each other. The switching on and off of these windings is carried out mechanically using a switch. This switch is mechanically connected to the start button. Each of these windings is connected through a switch contact to a corresponding graphite brush.

Further, the electrical circuit with the help of two windings connected in parallel to the graphite brushes goes to the rotor coils. The circuit closes at the collector terminals. The armature winding includes a large number of separate small windings, but only two are connected to the graphite brushes.

Most often, the grinder fails precisely because of breakdowns of its electrical components and a break in the electrical circuit.

To diagnose and identify faults in the electrical circuit, a special device is used - a multimeter. This device may be required not only to test the performance of the grinder, but also any other electrical tool or device.

It is most convenient to start diagnosing from the electric current input section. The check is carried out in stages, checking and ringing each of the elements of the electrical circuit of the device.

Minor repair grinder

If, after pressing the start button, the tool does not start, it is likely that the cause of the breakdown is a small malfunction that can be fixed on your own. Diagnosis is best done in order from simple to complex. Most often, the place of a break in the electrical circuit is the section from the power supply to the graphite brushes. During the repair process, remove the casing and test the circuit in the area where the electric current is supplied to the start button. If there is no current supply to the button terminals, then the supply cable should be replaced.

If the electric current is supplied to the start button, but is not transported further, then the tool breakage consists in the failure of the start button. If the button fails, it must be replaced. For this purpose, carefully disassemble the trigger and replace the start button. When connecting, pay special attention to the terminals, as their incorrect connection can lead to burnout of the instrument windings.

Replacement of graphite brushes

The failure of graphite brushes is one of the most common breakdowns of an angle grinder.

The service life of this structural element of the tool is about 1.5-2 years. The process of replacing brushes is not particularly difficult. To replace these structural elements, you will need to open the tool case. After opening the case with a screwdriver, the brush holders, which are fixed on the collector, are lifted and shifted.

Brushes should be replaced only with branded ones purchased in special stores. When purchasing a new brush, it should be compared with the original, which is removed from the tool. The new brush should completely, in all respects, match the one removed from the grinder. After installing new brushes, you should check the smoothness of its movement.

After installing and checking the smooth movement of the brush, it is fixed with a brush holder. After fixing the brush holder, the tool body is closed.

Replacing brushes is the only operation that should be carried out on your own during the repair process; it is better to entrust other types of repairs to specialists.

(UShM), in the common people of Bulgarians, have a speed controller.

The speed controller is located on the angle grinder body

Consideration of various adjustments should begin with an analysis of the electrical circuit of the angle grinder.

the simplest representation of the electrical circuit of a grinder

More advanced models automatically maintain the rotation speed regardless of the load, but tools from a manual disk are more common. If a trigger-type regulator is used on a drill or an electric screwdriver, then such a regulation principle is not possible on an angle grinder. Firstly, the features of the tool suggest a different grip when working. Secondly, adjustment during operation is unacceptable, therefore, the speed value is set with the engine turned off.

Why regulate the speed of rotation of the grinder disk at all?

When cutting metal of different thicknesses, the quality of work is highly dependent on the speed of rotation of the disk.
When cutting hard and thick material, it is necessary to maintain the maximum rotation speed. When processing thin sheet metal or soft metal (for example, aluminum), high speeds will lead to edge melting or rapid blurring of the working surface of the disc;
Cutting and cutting stone and tiles at high speed can be dangerous.
In addition, a disc that spins at high speed knocks out small pieces from the material, making the cut surface chipped. And for different types stones are selected at different speeds. Some minerals are just processed at high speeds;
Grinding and polishing is basically impossible without speed control.
By setting the speed incorrectly, you can spoil the surface, especially if it is paintwork on a car or material with a low melting point;
The use of discs of different diameters automatically implies the mandatory presence of a regulator.
Changing the disk Ø115 mm to Ø230 mm, the rotation speed must be reduced by almost half. And it’s almost impossible to hold in your hands with a 230 mm disk rotating at a speed of 10,000 rpm;
Polishing of stone and concrete surfaces, depending on the type of crowns used, is carried out at different speeds. Moreover, when the rotation speed decreases, the torque should not decrease;
When using diamond discs, it is necessary to reduce the number of revolutions, since their surface quickly fails due to overheating.
Of course, if your angle grinder only works as a cutter for pipes, angles and profiles, a speed controller is not required. And with the universal and versatile use of angle grinders, it is vital.

Do-it-yourself repair of an angle grinder should be done with great care and without haste. The negative consequences of manipulations with the power and / or electronic unit can lead to the transformation of a minor breakdown into a complete rejection of the grinder, and then even a professional master will not save it.

Bulgarian - rules for working with electric grinding tools

corner grinder they call it “Bulgarian” only in the repair expanses of the former USSR for a prosaic reason - the Eltos-Bulgarian plant in Plovdiv was solely engaged in its production. The high-speed cutting wheel is an indispensable assistant in the processing of the most durable metal, in the arrangement siding on the ceiling, when cutting reinforcement, sheets, profiles and many other repair operations. The grinding capabilities of grinders are no less popular - they allow you to eliminate burrs, roughness from both metal and stone or marble.

Over the past 40 years, the range of angle grinders has grown tremendously, but the rules for handling this convenient and multifunctional tool didn't change much. Furthermore - repairs are often prevented by following simple operational guidelines:

Do not remove the guard over the abrasive wheel unless absolutely necessary. If this cannot be avoided, be sure to work in goggles and protect the tool from any side contact;
Do not process wood, chipboard, MDF and similar materials - saws and hacksaws are available for this;
Hold the grinder firmly and confidently - when the disc is jammed, the entire tool can be pulled out of your hands, it will be severely damaged and cause serious injury;
The work of any angle grinder is accompanied by the presence of characteristic sparks - beware of getting them on the electrical wiring, power cord and any other combustible materials;
Any workpiece - cut or grinded - must be securely fastened. Even if it is necessary to cut a reinforcing bar immured in concrete during construction strip foundation from corrugated board, you should make sure that the entire structure is strong before pressing the "Start" button on the grinder;
Do not press on the part to speed up the work. The principle of operation of abrasive wheels is to erase the material of the workpieces and does not need a large clamping force.. The accuracy of movements when working with a grinder is as useful as brute force is harmful.

Tool repair - rely on knowledge of its design and common sense

Any angle grinder consists of the following components and mechanisms, the location and condition of which should be confidently understood:

Anchor. The internal part of an electric motor that rotates when the tool is operated at a controlled angular speed. The higher the rotation speed of the armature, the greater the power of the grinder. Unlike the marine "brother", the anchor in the electrical equipment should not slow down under any circumstances;
The collector is a separate place (platform) at anchor, where the power and control windings are brought out. Already from the name it is clear - here the switching of signals to the engine and the control unit takes place. The collector is clearly visible after removing the case - the contact plates are polished and have significant dimensions;
Electric brushes - special variety conductors for supplying current from the power cable to the collector. In working condition, they sparkle weakly and evenly, their glow is visible through the ventilation holes in the grinder body;
The gearbox is a special mechanical device at the front of the grinder. Designed for transmission mechanical energy rotating armature to a rotating disk. In this case, both the speed of rotation of the working disk and the power developed by it are subject to adjustment;
The stator is the part of the electric motor of the angle grinder in which the armature (rotor) rotates. The most difficult part of the tool, due to the strict precision of the windings pressed into it. Rewinding the stator of a grinder with your own hands is an adventurous procedure, it is better to entrust it to a specialized workshop;
Handles, power cable with plug and housing with control and adjustment devices.

An extremely desirable assistant in the repair will be layout and electrical diagrams, as well as detailed instructions specifically for the model of the angle grinder that needs to be repaired. Unfortunately, many manufacturers do not burden their devices with such excesses. In this case, you can get the necessary information from the know-it-all Internet and not repair the grinder with your own hands, counting on “maybe everything is simple there”, of course, if you don’t want to buy a new tool based on the results of the repair procedures ...

Do-it-yourself grinder repair - we eliminate typical malfunctions

The main principle in the repair of any electrical equipment is the postulate "move from simple to complex."

Whether it's a household electric cartridge or a turbine at a hydroelectric power plant, the repair sequence should exclude elementary faults in the first place. Electricity and electronics are called the "two sciences of contacts" for a reason. Typical malfunctions of angle grinders, coupled with methods for their elimination, are as follows:

The tool suddenly stopped showing signs of life. With a probability of 90%, we can conclude that the current from the socket does not reach the electric brushes. That is, the problem lies either in the power plug, or in the wire itself, or in the Start button mechanism. It is enough to disassemble the case and “ring” the cable with an ordinary tester for breaks - very often it is enough to replace the wire, and the angle grinder will work like new;
Are the wire and plug guaranteed to be intact, and the tool is still immobilized? It is necessary to disassemble the trigger, and it is desirable to mark the contacts to be removed - if they are subsequently connected incorrectly, the winding may burn out or the armature may jam. You can replace the start button with any similar one, the operating parameters are marked on it quite legibly;
The "Start" button and the power wire are in working condition, but the grinder does not want to work? It's time to work on the holders. Very often, it is enough to clean the contact plates on the collector, and a long-awaited spark and a smooth buzz of the mechanism appear. If not, then the brushes need to be replaced. The resource of these devices is usually limited to several years. A number of models of angle grinders are produced with a soldered connection of electric brushes, you need to solder and install new ones in the kit, their partial replacement is not allowed;
After replacing, carefully inspect the old electric brushes - if they have uneven wear, this is a clear sign of a shift in the center of gravity of the tool or its moving inside. It is better to contact a specialized company for the repair of complex electrical equipment - it is unlikely that you will be able to adjust the balance yourself without experience.

Brush replacement refers to the "top of the first level" in self-correction of faults in electric grinders. You can continue to paint repair recommendations, how to disassemble the grinder gearbox, rewind its winding or reconfigure the electronic filling. But serious breakdowns require a serious approach to work. If you have never seen this gearbox, how will you be able to fix it? The chance of turning on the grinder depends on your common sense - saving on professional repairs will result in the loss of the entire tool.

Schematic diagram of an angle grinder

Almost every craftsman who often works with metal knows the electrical circuit of an angle grinder. The grinder is a tool that is most often used for cutting metal. This tool is a source of increased danger, therefore, before each use, check the serviceability of the electrical and mechanical components of the structure.

Schematic diagram of an angle grinder.

The electrical component of the grinder design

For the entire period of its existence, the appearance of the instrument remained practically unchanged. The grinder has an elongated body in which an electric drive and a gearbox are mounted. A handle is fixed on the side surface of the tool to hold the tool in the working position; additionally, to protect the master, a protective cover is fixed on the tool body, covering the working element.

The device is an ordinary grinder.

The grinder, like any tool, can fail during operation. In most cases, to eliminate breakdowns, the simplest repair of working equipment, its electrical component, is required.

anchor;
collector;
electric brushes;
reducer;
stator;
start and lock button;
power cable with a plug for connecting to a household network.

Functions performed by the structural components of the angle grinder

Anchor grinder device.

Electric brushes in the design of the device are used to transmit electric current to the collector from the power cable. In the process of operation, if the brushes are in a normal technical condition, then through the ventilation openings of the housing, a uniform glow is visible. If the glow in the process of turning on the device is not observed or has a pulsating character, then this is a sign of problems with this electrical component of the device.

The gearbox is one of the most important components of the design. Its purpose is to transfer the rotational energy from the rotating armature to the grinding disc, ensuring its rotational movement. The gearbox is responsible for the frequency and power of rotation of the working tool of the grinder.

The stator is a technically complex unit of the device design. The stator design includes windings, which, when interacting with the armature windings through a magnetic field, set the latter in motion. The stator coils have a certain number of turns, calculated in accordance with the requirements of electrical engineering. If this unit fails, rewinding of the coils is required. This operation requires certain knowledge and skills. It is better to entrust the rewinding of the stator to a workshop specialist.

Schematic diagram of the grinder device

The internal structure of the grinder.

The electrical circuit of the grinder is arranged in a certain way. Two stator coils are connected in series through a cable to a household network with a voltage of 220 V. These coils are not electrically connected to each other. The switching on and off of these windings is carried out mechanically using a switch. This switch is mechanically connected to the start button. Each of these windings is connected through a switch contact to a corresponding graphite brush.

Most often, the grinder fails precisely because of breakdowns of its electrical components and a break in the electrical circuit.

Minor repair grinder

Causes of a malfunction of the grinder.

Replacement of graphite brushes

The failure of graphite brushes is one of the most common breakdowns of an angle grinder.

After installing and checking the smooth movement of the brush, it is fixed with a brush holder. After fixing the brush holder, the tool body is closed.

Replacing brushes is the only operation that should be carried out on your own during the repair process; it is better to entrust other types of repairs to specialists.

Do-it-yourself grinder repair

As you know, nothing lasts forever and even the tools of branded manufacturers break, not to mention the so-called "consumer goods". And the grinder (angle grinder) is no exception. By the way, they began to call the angle grinder "Bulgarian" during the time of the Union, because then this tool was produced in Bulgaria and the first models were supplied from there. The grinder, as a tool, has become very widespread due to its versatility and ease of use. There are also many varieties and models of angle grinders, however, the principle of operation and the device are not fundamentally different. Therefore, having considered the device of the tool, possible malfunctions and repair methods, they can be applied to any model of the grinder.

The case is made of strong impact-resistant plastic. Depending on the power, there are various dimensions and shape of the tool. Some models have an angular speed regulator, which is designed to optimally select the speed for various types of work.
Another component can be a reducer. The gearbox is designed to create optimal conditions for the transfer of rotation from the rotor of the electric motor to the cutting or grinding wheel. This reduces the number of revolutions on the output shaft of the gearbox. Properly selected rotation speed and circle diameter is the key to the most efficient operation of the tool.

The button for replacing the working disk, when pressed, locks the disk in a certain position, preventing it from scrolling when removed.

Typical malfunctions of angle grinders and diagnostic and repair methods

Bulgarian suddenly stopped working .
The first thing to do - disconnect physically from the network and manually rotate the disk. If the disk does not spin or spins very tightly, immediately disassemble the tool for visual inspection. If it spins easily, then the most likely thing is that electricity does not reach the brushes of the electric motor. That is, the problem lies either in the power plug, or in the wire itself, or in the Start button mechanism. It is enough to disassemble the case and “ring out” the cable with a conventional tester, or in some other way, for a break. After eliminating the break or replacing the wire, the grinder will work.

More serious malfunctions follow, respectively, and repair requires certain knowledge and skills.

- breakage or licking of gear teeth of the gearbox;
- jamming of bearings;
- failure of the armature or stator;
- failure of the control electronics;
- failure of the collector;
- deformation of the hull;

Bearings.
Another sore spot for angle grinders (as well as other twisting power tools). Few machines stand out for their strong immunities against dust, and the high speed implies rapid wear. In general, bearings are not the worst failure, they are easy to change. However, it is important to replace it on time, otherwise there is a high probability of a more serious breakdown, the repair of which is comparable to the purchase

Rules for using the angle grinder and preventive maintenance

After working at low speeds, do not immediately turn off the power tool. To prevent local overheating, it is necessary that it work for some time (more than 1 min.).

It is important to strictly observe the terms for replacing (adding) lubricant and its quantity indicated in the operating instructions.

With increased noise during the operation of the grinder or with a deterioration in its performance, it is necessary to carry out a prof. service.

Do-it-yourself grinder repair. Bulgarian device

After a certain period of use, the grinder is characterized by such breakdowns as the wear of graphite brushes, the burnout of the stator windings, and so on. Of course, the wear itself takes place in terms of mechanics. For a complete introduction to the topic: “How to repair a grinder,” consider the electrical circuit of a collector motor alternating current, since just such an electric motor is installed in the grinder.

AC commutator motor circuit

The diagram (Fig. 1) shows electrical connections stator windings, rotor and graphite brushes. Graphite brushes in the electric motor are installed in brush holders. The brushes are in contact with the collector lamellas. One ends of the stator windings are connected to an external power source. The other ends of the stator windings are connected to graphite brushes, the electrical circuit is closed on the rotor windings.

The speed controller of the grinder is connected by wires to the circuit collector electric motor sequentially. The connection diagram of the speed controller should be indicated on the body of the controller itself, or in the manual for the grinder.

Bulgarian device

According to the arrangement of the grinder, everything is indicated in the figure and no explanation is required. With the help of the driven and driving bevel gears, rotation is transmitted from the electric motor to the gearbox shaft.

Collector motor malfunctions

Possible causes of breakdown of the electric motor of the angle grinder are as follows:

rotor collector wear;
wear of graphite brushes;
burnout of the stator windings;
burnout of the rotor windings;
lack of contact connection of the ends of the stator windings with graphite brushes;
mechanical damage to the cable wire at the base of the plug;
mechanical damage to the wire along the length of the cable;
capacitor failure,

as well as other possible causes associated with any break in the electrical circuit.

Checking the collector motor

The cause of a malfunction of the collector motor is detected by a measuring device, using the example of such devices as:

If out of stock measuring device, any gap can be determined with an indicator screwdriver.

So let's say that the burnout of the stator windings (Fig. 3) is usually caused as a result of a general overheating of the electric motor. In this case, the insulation of the wires in the stator winding is broken and the winding itself can close to the frame housing. To establish such a possible cause of the malfunction, one probe tip of the device is connected to the output end of the stator winding wire, the second probe tip is connected to the stator frame housing.

To check the rotor winding, the probes of the device must be connected to the lamellas (plates) of the collector (Fig. 4).

That's all for now. Follow the rubric.

tell me, please, the cross section of the wire of the stator winding of the angle grinder Kolner 580 wt. Number of turns 167

08/09/2014 at 13:38

Hello Damir. Here, in general, it is not necessary to carry out settlement calculations. You need to take a piece of wire from the stator winding of the grinder and measure the cross section copper wire with a caliper \ lathe measuring tool \ or with this piece of wire, contact the seller consultant when purchasing the wire. It is desirable that the rewinding of the stator of the electric motor is carried out by an appropriate specialist, since the resistance of the winding is also taken into account here.

06/14/2015 at 18:00

Hello fellow electricians!
Tell me, please, why the electric motor of the angle grinder can warm up when idling for 2-3 minutes after turning it on to a cold one after replacing the rotor.
Initially, when working with a diamond disc on a new angle grinder, they overheated it by stopping the disc at full rotation of the rotor. Dismantled, checked the rotor — open circuit on the collector (two black lamellae). No other items were checked. They put a new rotor - it began to warm up without load.

06/15/2015 at 06:26

Hello Pavel. I believe that with this malfunction, you will also need to inspect and check for resistance the stator winding of the grinder's electric motor. A possible reason for the rapid heating of the electric motor is the cause of an interturn short circuit in the winding, that is, the insulation is broken (covering the wires with varnish). When the rotor stops abruptly, a current is created in the electric motor circuit that exceeds nominal value several times. This is just my personal opinion and I would also like to know the opinion of my friends, participants in the correspondence.
Victor.

01/17/2016 at 00:33

Hello!
Please tell me - after replacing such an anchor of the perforator http://rotorua.com.ua/product/jakor-perforatora-einhell-858/, the perforator barrel began to rotate in the opposite direction. What could be the reasons? Defective anchor or some kind of discrepancy? thanks for the answer.

01/18/2016 at 05:32

Hello. Maybe you need to reverse? If, when switching the reverse, the barrel of the perforator continues to rotate in the other direction, try changing the wires going to the brush holders.

Comments are closed.

Do-it-yourself grinder repair

An angle grinder (grinder) is very popular in everyday life when carrying out various repair and construction work, so the device is often subjected to overloads and harsh operating conditions, which invariably leads to wear in the mechanism. Repair grinder in most cases, you can do it yourself.

What is produced in Bulgarian

In the grinder device, almost every component is subjected to loads, which for various reasons can lead to a general failure of the device:

The rotor is the most loaded part of the grinder, because. it is subjected to both electromagnetic and mechanical influences at the same time:

Numerous windings of the armature (an integral part of the rotor) have a fairly thin wire with a protective varnish color, which is destroyed when the shaft is overheated or jammed. The wire burns out or a short circuit occurs between the turns. In such a situation, do-it-yourself repair of the grinder is carried out only by replacing the rotor.
The collector on the rotor is a powerful group of contacts that are produced mechanically due to the friction of the brushes and burn due to sparking.
Bearings are located on the rotor shaft, which are heavily loaded, which causes wear to the extent of their destruction. Therefore, if extraneous noise occurs during operation, do-it-yourself repair of the grinder with the replacement of bearings must be carried out immediately. At the same time, there is a transfer groove on the rotor shaft, which is also produced with a decrease or destruction of the “tooth” shape. Elimination of breakdown is carried out only by replacing the node.

The stator has several powerful electrical windings that are very rarely damaged.
The mechanical transmission requires periodic cleaning and lubrication, and if increased gaps are found in the pair, it is necessary to replace them.
Electric brushes are made from graphite-based materials, which causes them to wear out faster. Replacing brushes is a fairly easy undertaking, and individual models of angle grinders can be repaired without disassembly, because. have direct access to the brushes.

Simple do-it-yourself repair

Do-it-yourself grinder repair to avoid defeat electric shock it is imperative to carry out in accordance with the rules of electrical safety, therefore, in the absence of such knowledge, skills and abilities, it is recommended to contact professional craftsmen. Troubleshooting and repair should be carried out in a certain sequence:

The tool does not turn on, while buzzing, as from a transformer, does not occur - indicates a malfunction in electrical circuit: the speed control button is corny burned out, there is no contact in the brushes due to their development, or one of the conductors is broken. Do-it-yourself grinder repair is carried out in a consistent check of all electrical elements to detect a break: wire, button, contacts on brushes, motor windings.
When you try to turn it on, the tool makes buzzing sounds without rotating the shaft - there are serious violations in the mechanical and electrical parts. It is necessary to check the free rotation of the shaft when the device is turned off, because it can be partially wedged, which does not allow the spinning of the rotor. If the motor shaft rotates easily by hand, and when turned on it does not spin, then the device has short circuit. Do-it-yourself repair of an angle grinder comes down to complete disassembly and replacement of the rotor with brushes.
High sparking in the area of the brushes with the impossibility of bringing the motor shaft to full speed - increased production of brushes with weak contact. Immediate repair is needed, because. sparking causes increased heating of the device, and the resulting arc is able to pierce the electrical part of the grinder, which is unsafe.
Detection of crunches, knocks, any strong vibrational manifestation with a properly working electric motor of the device indicates the development of a transmission mechanism or bearings. Breakage requires immediate total disassembly of the tool with a strict rejection of all worked out parts. Ignoring the urgency of repair leads to a complete failure of the grinder.

Rules for self-repair grinder

For safety reasons and the possibility of repairing the grinder with your own hands, you must adhere to a number of rules:

Disassembly and assembly are carried out in the exact reverse order, and very often the identification of serious damage can make it impossible to quickly assemble the tool, so the sequence of operations and the location of all components must be recorded on paper or a photo.
Disassembly of the tool is carried out only when completely disconnected from the mains. Experiments with connecting a disassembled device to a 220 V network are unacceptable, because. this can cause a short circuit with a striking arc.
The basis of repairing an angle grinder with your own hands is the timely replacement of failing parts with similar ones. at the same time, "Kulibinsky" improvements are unacceptable.
Bearings are replaced only with similar ones due to special removable and mounting devices that do not allow breaking working parts.
The laying of a new lubricant must be standardized and using a suitable technical specifications lubricant. Excessive lubrication or the use of inappropriate lubrication leads to increased load with overheating.

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