With modern finishing works various construction tools. Grinding machines are no exception.

Any tool can become damaged due to frequent use. And in order to repair a grinder with your own hands, you need to have an idea of ​​its components and possible reasons breakdowns. Since the angle grinder is the most popular, subsequent repairs will be considered using its example.

In terms of design and external characteristics, such a machine is an angle grinder, as it consists of the same parts.

The grinder consists of:

• protective casing;
• ventilation hole;
• push-button switch;
• side handle;
• spindle lock.

Repairing a grinder should be done carefully and slowly, since the consequences of repairing power and electronic units can turn a minor breakdown into the unusability of the device.

You won't need many tools to repair a sander:

• soldering iron;
• tester;
• screwdriver.

Components of the device mechanism

Bearing caked with grease - common reason grinder breakdowns.

The machine has internal components and mechanisms, the structure of which also needs to be understood;

1. Anchor. This is one of the internal elements of the electric motor that makes rotational movements during operation of a device whose speed is controlled. The power parameters of the tool determine the rotation speed of the armature; the higher it is, the more powerful the device. During normal operation, the armature should rotate easily and freely, nothing should interfere with its rotation;
2. Collector. This element has the appearance of a separate armature platform and the power and control windings are output to it. The collector performs the function of sending signals to the engine and control unit. To see it, you need to remove the case; it looks like polished contact plates with significant dimensions;
3. Electric brushes. Plays the role of a conductor for conducting current from the power cable to the collector. If this element functions normally, then weak and uniform sparks will occur; they can be observed through the ventilation holes in the device body;
4. Gearbox. It is a mechanical device located in the front of the machine. Its purpose is to transmit the mechanical energy of a rotating armature to a rotating disk. In this case, both the revolutions of the rotating disk and their speed development are subject to adjustment;
5. Stator. This is the element of the electric motor in which the armature moves. He is the most complex element, since the windings in it must be pressed in with strict precision. It is not recommended to rewind the stator yourself; it is better to entrust this work to a specialist.

When making repairs, it is recommended to rely on the layout and electrical diagrams, have on hand the instructions that came with this particular model of grinder. But many models do not come with such instructions; in this case, it is wiser not to carry out repairs yourself, but to seek help from a service center.

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When repairing any equipment, consistency must be observed. Simple faults are:

1. The device suddenly stopped working.

The first thing to check is the electric brushes, since there is a possibility that they are not receiving current from the power supply.

To replace the bearing, the horseshoe retainer must be removed.

Specifically, the problem may lie in the power plug or in the wire itself, and the “Start” button may not work. To fix the problem, the housing is disassembled and the wiring is tested using a break tester. In frequent cases, the problem is in the wiring, and after replacing it, the grinder will start working again;

1. After checking, the wires and plug are intact, but the device does not show any working signs. In this case, the starting unit is disassembled, and the elements being removed are marked, since if they are connected incorrectly during assembly, this may lead to the winding burning out or the armature may jam. The button is replaced with a similar model;
2. Start button and power cable work, but the machine refuses to work. In this case, it is recommended to examine the brush holder. Most often, the problem is the contact plates of the collector, which, after cleaning, will begin to produce a spark and a smooth hum. If these signs do not appear, then the brushes must be replaced, since their service life is limited. If many models are produced with soldered connection of brushes, then in this case it is necessary to desolder and replace them as a set, since partial replacement is not performed;
3. After changing electric brushes, they should be carefully inspected if the wear is uneven - this is a sign of a shift in the center of gravity or internal moving parts. If such a problem occurs, it is recommended to contact a specialized service department, since it is impossible to adjust the balance with your own hands.

Repairing brushes is a minor repair when troubleshooting, but more serious damage is best left to specialists.

This additional condition, so that you feel more comfortable when contacting us. If something doesn’t suit you during or after the repair, just call our dispatch center 24/7 and I will return all your money to the last penny! By the way, in 2018 we received only 9 requests for a refund (out of 38,990 requests!).

🔧 After the warranty you will receive LIFETIME SERVICE

There is no need to worry about what will happen to your equipment after the warranty. I give every client a lifetime service in Lenremont. This means that if this technique breaks down again after the warranty period, repairs will cost 2 times less! So you get 25% discount on post-warranty repairs.

✅ 2 years warranty on repairs

Yes! I am so confident in the skill of my masters that I boldly give you 2 years warranty for repairs. This is the biggest guarantee in all of Russia.

And one more surprise - you will receive 4 months warranty on all spare parts, since Lenremont orders parts from a direct supplier.

This guarantee means that, if suddenly Your equipment will break again, a technician will come and repair it for free her. Even if the technician who repaired your equipment gets sick or no longer works for us, you do not need to worry that you will be left without warranty repairs: we have more than 100 technicians for each type of equipment on our staff. We take full responsibility for ensuring that you, our dear client, are satisfied.

While creating another creation, I needed a sander. Having brought her into the light of day, it turned out that she was not half-dead. We take on the task of repairing it at home.

So, we have what looks like a Chinese grinder. Even though I got it cheap, it’s still a pity to throw it away. Due to intensive use, the following symptoms appeared: when turned on, the noise increased, some uncharacteristic rattling appeared, the power decreased, and then jamming began.

Let's start to sort it out. Unscrew all the screws from the cover,

And from the sanding pad.

We rent the site.

We remove the casing.

Apparently, the engine seat was broken due to work. And when voltage is applied, the rotor warps and jams.

We shoot from seat sizes.

We cut out gaskets from pressed steel. We place it on one side of the casing.

Note the position of the bushings. This is very important, otherwise you will suffer during assembly.

Carefully, so as not to damage the brushes, remove the engine.

Insert the gasket symmetrically. We carefully put everything back together. Make sure that the bushings fit into the grooves. We put on the casing. We tighten it with screws. Let's check.

Changes can already be felt in better side. The motor rotates the shaft without any problems. No jamming is observed. We assemble and attach the sanding pad.

We check again - excellent! Now you can continue creating!

Angle grinders (angle grinders), popularly called grinders, are a popular and reliable tool. But everything breaks down someday. Repairing an angle grinder with your own hands is not difficult if you have instructions in front of you that tell step by step order performing angle grinder repairs. Below you will find answers to any questions about repairing the gearbox, rotor, stator, and carbon brushes of angle grinders.

Angle grinders are especially popular among home craftsmen. The ability to replace the working parts allows for cutting, grinding, and polishing operations.

Availability of device soft start makes the tool safe and convenient to operate. Corner repair grinding machine simple and can be done independently. For those who decide to implement angle grinder repair yourself, you will need a diagram of an angle grinder the right type, tools, lubricants and this manual.

Any repair of an angle grinder with your own hands begins with an investigation of emerging faults. The device of the grinder is quite simple. The rotating rotor transmits torque through a helical gear to the shaft (spindle) of the working body. The required working tool is installed on the spindle, be it a cutting stone, a grinding or polishing wheel, and the required technological operation is performed.

By the way, about the shape of the tooth. On low-power grinders, spur gears are installed. Helical gears are used in grinders with a power of over 1000 W.

Angle grinders, like any tool, break over time. The reasons for malfunctions of the angle grinder can be different. They appear not only from improper use of the tool, but also from untimely replacement of carbon brushes and lubricants.

Regardless of the angle grinder model, faults appear in the same units for all. Malfunctions of grinders are conventionally divided into electrical ones. For novice repairmen, faults are divided into simple and complex.

Mechanical malfunctions of angle grinders

An angle grinder is an angle grinder designed to perform cutting, grinding, and polishing work. The grinder is subjected to heavy loads during operation and works in a dusty environment.

Excessive loads when using an angle grinder in the “Cutting” mode cause increased wear not only of the bearing, but also of the gear teeth of the gearbox.

The main mechanical malfunction of the angle grinder is wear or destruction of the sliding bearing on the shaft of the large helical gear of the gearbox.

Troubleshooting an angle grinder is not difficult if you have its diagram, description and recommendations for implementation at hand repair work.

Repair of plain bearings

The weak point of any angle grinder is the bearings. And although there are few of them in the design, only three, they are the ones that most often lead to mechanical failures. Bearings are negatively affected by:

• high rotation speed;
• work at extreme conditions;
• insufficient amount of lubricant;
• ingress of dust or dirt;
• untimely replacement or destruction of carbon brushes.

The design of any angle grinder allows for quick and easy replacement of any bearing.

Malfunctions of the angle grinder associated with wear or destruction of the sliding bearing on the gearbox shaft are characterized by the appearance of an unpleasant extraneous sound.

Destruction of the sliding bearing is detected by checking the play of the working tool installation shaft. Determined by rocking in different sides shaft when installing the working tool.

When installing the working tool again, check the shaft play by rocking its end in different directions. There should be no or minimal play.

The appearance of play indicates the need to replace the plain bearing.

Bearing repair involves removing it from the housing and removing it from the gearbox shaft.

It is better to remove the bearing from the shaft using a puller. It is best to remove the inner race of a damaged bearing using a tap required diameter, previously screwed into the holder.

The bearings are removed from the rotor using a puller or the traditional method.

Keys or strips of metal are inserted into the vice, the bearings are placed on the keys and, using a soft metal attachment and a hammer weighing at least 400 g, are knocked out from the shaft axis.

Grinder gearbox repair

The degree of wear of the grinder gears is checked for the contact patch. The gearbox is first completely cleaned of old grease. A special blue is applied to the small gear of the gearbox, and the gearbox rotates. Next you need to remove the driven large helical gear and look through a magnifying glass at the contact patch. It should occupy a total of at least 50% of the tooth surface.

Otherwise, the gears must be replaced or the tooth profile adjusted. has been described more than once on the pages of this site.

But such a malfunction can only be eliminated by an experienced technician. Most often, licked, cut or destroyed gears are replaced entirely, and in pairs.

How to properly disassemble an angle grinder gearbox

When repairing the gearbox of any angle grinder itself challenging task is to remove the gears and press out the support bearing.

Disassembling the gearbox begins with removing the gearbox cover pos. 1 and disconnecting the stator housing and freeing the rotor pos. 2. The freed rotor is clamped in a vice and the fastening nut pos. 3 of the drive small gear is unscrewed.

The spindle bearing is pressed into the gearbox cover. To remove the bearing, in some angle grinders you must remove the retaining ring that secures the support bearing and remove the bearing.

The destroyed bearing pos. 1 in the gearbox housing pos. 2 is most easily removed by prying it off with a screwdriver.

In other models, a locking ring secures the gear in the spindle.

The driven large gear is mounted on the spindle in several ways:

1. The gear is pressed onto the spindle.
2. The gear is secured with a key.

The driving small gear is either screwed onto the shaft along the left-hand thread (in some Sparky models, the thread is right-handed), or is fixed with a key connection and clamped with a nut.

How to remove gears

Grinders up to 1000 W use spur gears, while angle grinders use helical gears.

Gear repair consists of replacing them, and only in pairs.

Long-term and uninterrupted operation of the gearbox depends on availability.

Spindle lock button repair

The spindle lock button is designed to quickly remove the working tool. The button breaks when you press it while the disk is rotating. Repairing an angle grinder involves completely replacing the button.

The button should be pressed only when the grinder is completely stopped.

Electrical malfunctions of the angle grinder

The electrical circuit of the main part of the grinders is almost the same. The rotor transmits torque through a gearbox to the working tool. The rotor rotates in the stator field. The control circuits consist of a button that regulates the speed and ensures a smooth start of the tool, carbon brushes that ensure transmission AC voltage on the collector lamellas. Power is supplied to the instrument via the connecting cable.

The main electrical malfunctions of an angle grinder include:

• break of the power cable at the entrance to the instrument;
• destruction or wear of carbon brushes;
• failure of the power button;
• stator break or short circuit;
• rotor break or short circuit;
• peeling or deterioration of collector lamellas.

Electrical malfunctions of an angle grinder are best determined with a tester or other device. Suitable for these purposes and homemade device popularly called "arkashka" .

The grinder scheme is quite simple and does not require special knowledge. You just need to be careful and safe when performing repair work and have a high school level knowledge of electrical engineering.

Finding a broken power wire

One of the most common breakdowns of an angle grinder is the inability to turn on the tool or spontaneous stopping during operation. The cause of malfunctions of this kind is a break in the power cable pos. 27 at the entry point. The malfunction is eliminated by replacing the cable or discarding the failed section. The fault can be easily found using a tester.

If you don’t have a tester at hand, but have a screwdriver with a neon indicator light, then the fault can be found by connecting the power wires to the phase one by one.

Carbon brush malfunctions

The reliable operation of any power tool depends to a large extent on the integrity and proper operation carbon brushes. High-quality fit of carbon brushes, their correct location relative to the commutator lamellas affects the performance of the rotor commutator.

Remember! The length of the carbon electric brush cannot be less than 8 mm.

Timely replacement of carbon brushes allows you to avoid most malfunctions.

The degree of wear of carbon brushes is characterized by the types of sparking at the commutator site. The sparking should be uniform across the entire contact patch of the carbon brush and lamellas and not exceed a length of more than 8 mm. Circular sparking indicates a malfunction in the rotor circuits.

Repair of the power button and speed controller

Malfunctions of the power button most often manifest themselves in difficult and unreliable turning on of the tool when starting. This malfunction appears and disappears spontaneously.

It is unacceptable to operate an angle grinder with a faulty power button. This malfunction leads to jamming cutting discs in the process of work and their destruction with unpredictable consequences.

The malfunction is eliminated by completely replacing the button with a new one.

IN modern models grinders have a built-in soft start device with a speed controller. It cannot be repaired, but will require complete replacement. No, advanced left-handed craftsmen, of course, will be able to repair such a unit.

Stator repair

The failure of the stator is indicated by spontaneous spinning of the machine shaft; the angle grinder begins to gain maximum speed. Such a malfunction indicates the appearance of an interturn short circuit in the stator winding.

Some faults can only be fixed by specialists. Extending the uninterrupted operation of the stator can only be done by timely cleaning, lubrication and replacement of carbon brushes and bearings.

Typically, the stator fails quite rarely. This is caused by frequent overheating of the tool during operation. The malfunction is manifested by strong heating of the grinder body and the appearance of a smell of burnt insulation.

There can be either an open circuit or a short circuit in the stator. Without disassembling the stator, these faults can be easily found using the IK-32 device.

Malfunctions are eliminated by replacing the stator. For those who like to make things with their own hands, we can recommend it. There is nothing complicated about it.

The stator can be easily removed, but different models Angle grinder in its own way.

Stator removal procedure:

• remove the grinder gearbox;
• remove the rotor, having first removed the fastening bar;
• remove the plastic stator protection;
• Unscrew the screws securing the stator in the housing;
• remove the handle cover and disconnect the power wires to the stator;
• remove the stator by tapping the housing with a wooden hammer or block.

Angle grinder rotor repair

Failure of the rotor in an angle grinder is caused by improper use of the tool, frequent overheating, untimely replacement of carbon brushes, and abrasive particles and dust getting on the collector slats.

First, the length of the spark at the collector increases, then a burning smell appears and, at the last stage, smoke. The operation of a faulty gearbox is accompanied by knocking and humming.

The destruction of even a couple of teeth leads to improper operation of the tool.

You can extend the life of the rotor by preventing dust from getting inside the tool, preventing overheating of the tool, timely changing carbon brushes and lubricants, using only those working tools and diameters recommended by the power tool manufacturer.

The rotor is a complex assembly that requires repairs service centers. But those who like to make things with their own hands can do it.

Repair of commutator and rotor lamellas

Removing the rotor is not particularly difficult.

The procedure for removing the rotor from an angle grinder:

• remove the cover of the grinder handle;
• release and remove the carbon brushes;
• Unscrew the screws securing the gearbox housing to the main body;
• remove the gearbox housing;
• remove the rotor.

The removed rotor must be carefully inspected. If large grooves are rubbed into the lamellas, they should be removed by turning the commutators in a lathe.

For minor grooves, the defect is eliminated by grinding. The rotor is clamped into the chuck of an electric drill and the wear is removed using a file and sanding paper. The process is simple.

The drill is clamped in a vice or securely mounted on flat surface. The end of the rotor on which the lamella is located is inserted into the drill chuck and clamped securely. The bearings have been previously removed from the rotor.

The second end of the rotor must be supported with a set of wooden blocks. The drill is turned on and a small number of revolutions is set. In the first step use sanding paper coarse grain No. 40..80, on final stage smaller one No. 120..200.

After grinding, you need to mill the grooves between the lamellas. This is best done hacksaw blade, specially sharpened. After milling the collector grooves, the edges of the lamellas must be cleaned of burrs using a diamond file. Properly ground lamellas should not have burrs.