The corner grinder is cracking where the counts. corner grinder without a rear handle

Grinding Concrete with a 7 Grinder Wheel

The brushes of the engine of power tools are strongly sparkled

It is difficult to imagine an arsenal of a home master without such a popular power tool as an angular grinder angular grinder or corner grinder (folk name). The corner grinder gained its popularity due to universality, since this tool can be used for cutting, grinding, sawing, polishing, stripping, leaches and other works. And you can process absolutely any materials. During the operation of the tool, different breakdowns arise, and one of the most common is the sparking of brushes into corner grinders. Why do not many know the brushes on the corner grinder, so we will understand this issue, and also find out why they burn and how their replacement is performed.

Sparks, including on a good engine, appear due to the mechanical effect between the brushes and the collector. The brush, moving along the collector from one of its contact to another, alternately forms and breaks the connection with each of them. Now remember what happens if any working electrical appliance is pulled out of the outlet. usually at such a moment a spark slips between a fork and a socket. In the case of a brush engine, this is the same phenomenon.

Read also: What are the most energy.saving lamps

Therefore, a slight sparking even on a good electric motor is permissible, since the connection and gap here constantly arise.

Contact checking the brush-collection unit

The reason for the sparkling of the working parts of the block may be poor contact due to insufficient contact with the collector lamellas. During the operation of the vacuum cleaner, roughness forms on the surfaces of the switching parts of the engine, which prevent the necessary contact. To eliminate tubercles, grooves and scratches on the collector will help grinding with fine sandpaper. “nusy”.

Advice! If the brushes sparkle excessively, then they should be pressed tightly to the collector due to the springs. In this case, it is impossible to violate the free course of the elements of the block.


The gearbox of the corner grinder is a mechanical part of the power tool angular grind. He transfers rotation of the electric motor rotor to the working tool. The energy source for the Bulgarians is the power supply of the network. The gearbox usually consists of a conical pair of gears with a reducing gear ratio in order to ensure the required number of revolutions of the working tool.

The main malfunctions of the corner grinder and their causes

According to statistics, most cases of failure of the corner grinder are associated with the electric part of the device. Some breakdowns can be insignificant, which allows you to repair corner grinding grounds with your own hands. But, for example, when the engine windings are blocked, the repair of an angular grinding machine can only be carried out by a specialist.

Corner grinder does not turn on

The reasons that the corner grinder does not turn on can be as follows:

  • an electric fork is faulty;
  • faulty electric cable;
  • The launch button broke;
  • the contact between the power cable and the button is disturbed;
  • cliff of the contact wire of the electric shock;
  • severe wear of electric grinding;
  • The failure of the rotor or stator windings.
corner, grinder, rear, handle

Corner grinder does not develop momentum

The reasons that the corner grinder is not gaining momentum can be different.

  • Damage of the revolutionary control unit. To check this version, you need to connect the machine engine directly, bypassing the regulator and check the operation of the device.
  • Electric cable malfunction due to constant overcurrents or mechanical damage. Because of this, the damaged wire begins to warm up under load, and the engine speed is falling.
  • Dust pollution by dust. It is necessary to remove pollution with alcohol.
  • Problems with brushes. They can be worn out or have a short contact wire, as shown in the next photo.

The brush, although half.wiped, is quite efficient. In this case, a short contact wire prevents the spring with press the electrode to the collector. This situation can also be the reason why the corner grinder stopped working in normal mode.

The electric motor heats up

The reasons that the angular grinder is heated may be the following.

  • Incorrect operating mode of the device. As a result of overloads, the electric motor can be very hot, which often leads to blocking the windings.
  • Destruction of bearings located on anchor. As a result, the rotor clings to the stator, the engine operation is difficult, and the windings overheat. The problem is solved by the replacement of bearings.
  • Clogging of the ventilation ducts through which the air enters the engine cooling. It is necessary to clean the ventilation holes from dust.
  • Damage to the impeller, which serves to cool the engine. It is installed on the rotor, on the opposite to the collector side. If the impeller is broken, it must be replaced with a new.

The corner grinder sparkles

If you notice a strong sparking when turning on an angle grinding machine in the place where the collector is located, then the reasons for this trouble may be the following.

  • Damage to the anchor winding: a break in one or more sections of the winding, an interval circuit. With such breakdowns, increased noise appears, engine speeds fall and brushes burn.
  • The contact between collector plates and winding was violated.
  • Weakly clamping brushes. With prolonged modes of corner grinding, the springs overheat and can “eat up”, while losing the elasticity.
  • Balance of the engine rotor.
  • Violation of the cylindrical surface of the collector. This sometimes happens after rewinding, if the anchor is not pulled on a lathe, but immediately installed in the device. In this case, you can also observe that the brushes sparkle excessively.
  • Between the collector’s lamels, insulation is impaired. There may also be clogging of the grooves of the proxy with graphite or breakdown between the lamellas.
  • Bearing wear that causes the rotor bearing also leads to the fact that brushes sincle greatly.
  • Violation of the geometry of the rampage shaft. This usually happens with an inaccurate disassembly of the electric motor when the shaft bends.
  • The graphite brushes are installed in the wrong brand. Brushes are selected based on the expected revolutions and stress.
  • Raising one or more lamellas leads to the fact that brushes are quickly burned. This happens due to overheating of the engine during prolonged operation. As a result of the glass mass, which serves as the basis of the collector, softens, and the lamella begins to rise. Due to the fact that the lamellas are raised, the brushes are erased very quickly.

Live wires

Electric motors for electric motors are made with a livestock wire. The wire of the brand of PSh is used. non.insulated, normal flexibility. The length of the live wire is measured from the most protruding part of the electric shock to the center of the hole in the tip or to the end of the wire without a tip.

The connection of the current.pissing wire with the material of the electric shock (seal) can be carried out by the methods of hemp (K), the collapse (p), the rations (P) and the pressing (h).

The length of the wire is set by GOST-12232-89, the required cross section of the wire is selected, depending on the current load, the ratio of these values ​​is given in the table

Nominal cross section of the wire, mm2 Permissible current load, and
0.16 3.90
0.30 6.00
0.50 9.00
0.75 12.00
1.00 15.00
1.50 19.00
2.50 26.00
4.00 38.00
6.00 50.00
10.00 75.00

The purpose of the brushes for corner grinding

Before you find out the causes of the sparkle of brushes on the corner grinding, you need to understand their purpose. Collector brushes are used not only in the design of angle grinding machines, but also in the device of all modern power tools. drills, peorators, electrolobsics and others. In the design of the corner grinder and other power tools, 2 brushes are used, which have a simple design. This design is based on the following elements:

  • The main part. has a rectangular shape, and is made of coal or graphite
  • Contact is the wires of the corresponding diameter through which the electric current occurs. Contact connects the wire to the graphite part
  • Spring. a mechanism that provides the clamp of the main part to the collector. There may not be a spring element, and this suggests that such a brush is intended for installation in a power tool where the brush holders have a clamping mechanism in the form of a curved plate

Devices are designed to transfer the electric current to the rotor of the power tool. The removed voltage from the stator is supplied to the rotor, which is reproduced using coal brushes and collector. The current supply to the collector provides its rotation. When rotating the rotor of the device, the device is in contact with the collector (copper lamellas. conclusions of the anchor winding), thereby ensuring the continuous flow of electric current.

In the process of applying devices, they are abrasion, therefore, they belong to the category of consumables. The service life of brushes depends not only on the working resource of the power tool, but also on the materials from which they are made. The wear of the brushes affects not only the mechanical effect due to the friction force, but also the thermal. Electric current when passing through the conductor causes its heating. The greater the current strength, the higher the heating temperature. When passing current through graphite brushes, they also heat up. The higher the load on the power tool, the higher the current, which means the temperature increases, which negatively affects the integrity of consumables.

It is interesting!There are no differences between the brushes for the corresponding power tools (with the exception of the fixing method), since they are selected exclusively according to such a parameter as the dimensions of the main part.

Electric circuit

Knowledge of the appointment of the main parts will not give a 100% positive result in repair. It is also necessary to figure out and understand how the electrical circuit of the corner grinder is arranged and how the electric motor works. Two windings are involved in the diagram, which are sequentially connected through the power wire to the network with a voltage of 220 V and are not interconnected in the electrical circuit. The mechanically installed circuit breaker binds to the power button and disconnecting the grinder. Each of the windings is connected through contacts with graphite brushes. Through brushes, the windings are connected to the rotor collector.

corner, grinder, rear, handle

Mick The Grinder

It is also very important that the anchor has many windings, however, only two windings are connected to graphite brushes, and the failure most often occurs due to a rupture of the electric circuit. Diagnosis of the electrocope of the device is carried out by a special device. tester. A portable measuring device is used not only in the repair of corner grinders, but also to check other electrical tools and devices.

The correct check should be made from the input power cable with the transition to the sequential elements. When checking conductivity, the multimeter switch is set to the minimum voltage.

Malfunction of the electocepe of the collector motor

Most often, the breakdown in the electrical circuit of the corner grinder occurs for the following reasons:

  • Collector wear;
  • Breakdown button;
  • Wear of coal or graphite brushes;
  • Overheating and short circuit in the stator winding;
  • Overheating and burning of the rotor winding;
  • Damage to the power wire.

Such malfunctions are the most frequent, but there are other breakdowns associated with the break in the electric circuit.

corner, grinder, rear, handle

Diagnostics by the anchors checking device (throttle)

The anchor testing device determines the presence of an inter.flip circuit of the winding. The throttle is a transformer that has only the primary winding and the magnetic gap in the core is cut out.

When we put the rotor in this gap, its winding begins to work as a secondary winding of a transformer. Turn on the device and anchor the metal plate, for example, a metal ruler or a hacksaw canvas. If there is an interval circuit, the plate will vibrate or magnetize the anchor body from local oversaturation of the iron. Turn the anchor around the axis, moving the plate so that it lay on different turns. If there is no short circuit, then the plate will move freely along the rotor.

Reasons why brushes sparkle

Very often you can see how the brushes sparkle on the corner grinder. Signs of sparking through ventilation holes in the power tool case are found. Masters are interested in why the brushes on the corner grinder sparkle, even after their direct replacement. There are many reasons for this, and in order to understand this, you must have an idea of ​​the device of the power tool. If you know how the angle.grinding machine is arranged, then understand why the brushes skeve strongly, it will not be difficult.

The reasons for the strong sparkle of brushes on the grinds are the following factors:

  • Malfunctions of the anchor winding. If there is a violation of the insulation of the anchor winding, then in the end this contributes to the development of inter.flip circuit, as well as the closure on the core. In addition, a break in the winding may occur, which will eventually cause an increase in the load. A characteristic sign of a malfunction of the anchor winding is a reduction in revolutions, an increase in noise and a drop in power
  • The brushes are poorly pressed against the collector. A spring is responsible for the clamp of the main part, which over time of operation loses its original springy properties
  • The rotor winding broke off from the copper plate of the collector. this phenomenon is extremely rare, but when the power tool is overloaded, it may well occur
  • The centering of the anchor of the electric motor is violated, which ultimately contributes to a strong sincerity of the brush on the corner grinder
  • The form of the collector is broken. The collector, consisting of copper lamellas, has a cylindrical shape, which can be disturbed during the rewind of the rotor. With the slightest deformation of the shape of the collector, sparking of brushes will occur

Often masters, after they change the brushes on the corner grinder, observe the phenomenon of excessive spark. Based on the above factors, you can identify the cause, and eliminate it before the tool is out of order. The elements under consideration are inexpensive, however, due to their improper choice and application, the power tool may break. To find out what malfunction is the cause of severe sparking, you will need to disassemble the power tool, and make it inspection, as well as call the rotor winding.

Why brushes burn on the corner grinder

In addition to sparking, often the owners of the power tool are faced with the fact that the brushes on the corner grinder are burning. This phenomenon differs from sparking in that the rapid wear of the main part of the element occurs. Immediately after the installation of new elements, they are worn out immediately with the first use of the power tool. It is necessary to figure out why brushes on a corner grinder are burning.

The main reason is not hidden in the brushes themselves, but in the collector. If lamellas fall on the collectors or abrasion, then this leads to an increase in the load. This load is experienced by graphite elements, which, when the angular grinder is turned on, begin to wear out quickly. this process of accelerated wear is called combustion. Elements literally burn due to a large current passage. Many call this process abrasion, but in reality the brush can quickly erase from mechanical exposure. The cause of combustion is severe sparking, as a result of which graphite is literally burning.

The reasons why the brushes on the corner grinder burn are as follows:

  • LASTING or wear of the Copper Lambels of the collector. What the wear of the collector lamella looks like, shown in the video. The material also shows how to try to eliminate such a malfunction
  • Interpretation close between lamellas or winding windings contributes to an increase in current from which the brushes heat up and begin to burn. To identify the cause, you will need to call the anchor
  • With strong overload of the power tool-if we operate the corner grinder for a long time without breaks, then the result of this application will manifest itself in the form of combustion of brushes in 5-10 seconds

There is also such a thing as a circular fire. This phenomenon arises with large shocks of the anchor current, for example, during overloads, short circuits, as well as with a decrease in the network voltage. Circular fire manifests itself with re.ignition of the arc. Increasing the load and even short circuit occurs when using a corner grinder for sawing wood. When processing wood, a cutting of the cutting disk occurs, thereby the current increases 15-25 times from the value. Most often, the causes of combustion of elements are a collector, so if 2-3 pairs of brushes have to be changed in a month, then it is time to diagnose the power tool.

Prevention angular grinder

Prevention of corner grinder includes compliance with passport requirements during its operation, performing periodic maintenance and scheduled repairs. First of all, it is necessary to strictly observe the ratio of work cycles and breaks recommended by the manufacturer. It is also necessary to periodically clean the internal space of the corner of the corner grinder from dust, timely change the brushes and make the reducer lubrication. If the corner grinder occurs during the operation of stable vibrations and uncharacteristic sounds, an internal examination of the mechanical part should be immediately carried out and the necessary repair should be carried out.

Unlike the usual fast.packed nut of corner grinder, is a rather expensive device. And how long it can last and whether its repair is possible in case of failure? If someone knows the answer to this question, please share information in the Комментарии и мнения владельцев.

Prevention of angular grinder breakdown

The service life of a grinding machine directly depends on the departure of the owner for it. Each tool needs good care, then it will work regularly for a long time.

Any corner grinder will heat up during work, but in order to postpone the corner grinder for a long time, it is necessary to adhere to some rules in the work:

corner, grinder, rear, handle
  • Do not overload the tool to avoid overheating and smoke.
  • Do not put pressure on it during work.
  • Clean and lubricate the necessary parts inside the case in time.
  • With noticeable improper work, stop the operation and conduct an inspection for the presence of problems.
  • Replace fast.intelligent parts in a timely manner.
  • If the corner grinder smokes, urgently stop working and no longer turn on.
  • Do not use the tool when processing wood.type material.
  • Hold the corner grinder tightly in the process of work, so as not to drop and not damage.

Adhering to the listed simple recommendations and rules in working with a tool called an angular grinder, it is possible to extend its period of work longer than a warranty period.

How to disassemble a gearbox

When repairing the mechanical part of the corner grinder, first of all, it is necessary to separate the gearbox from the drive, unscrewing the four bolts and licking the leading and driven gears. For its internal inspection and repair of components, it is necessary to remove the lower part of the gearbox, which is also attached to the main body with bolts. Next, the gearbox is disassembled in separate parts, sequentially separating bearings, gear and flange from the shaft.

How to remove gear gears

The lead gear of the angular grinder gearbox is usually attached to the shaft of the vest and pressed by a nut, and the driven is fixed using a key and a split washer. The video below shows the procedure for the repair of the reducer, removing the upper bearing and replacing the driven gear. A video in English, but everything is extremely clear there, so you can watch without a sound.

Repair. how to remove and connect the INTERSKOL angular grinder button

The following scheme will help to understand the device of the angular grinder button:

  • The start button directly is at position 41, which is built into the case (pos.47).
  • The voltage from the power cable is supplied to the launch button (pos.53).
  • To control the start button (pos.41) The corner grinder is equipped with a lever (pos.46).
  • Also connected to it are electricity (pos.55) and special brush holders (pos.44).
  • Even in the electric part, the corner grinder, which includes the power button, includes the rotor (pos. 31) and stator (pos.42).

It becomes clear from the circuit that you can get to the start button only by removing the handle in the rear of the case angular grinder.

To repair the Launch button of the INTERSKOL corner grinder, we will need:

  • We unscrew the screws on both sides of the handle with a cross.shaped screwdriver and remove it;
  • Remove the site for adjusting the revolutions, with a flat screwdriver, tidying its latch;
  • Using a crucible screwdriver, disconnect the contacts of the network wire from the power button, after removing the clamp;
  • Disconnect four wires from the start button, which go from the engine and capacitor to its contacts;
  • We extract a broken button from the case.

To make sure that the contacts have burned out in it, it is enough to remove the collapsible cover.

  • We attach the removed engine and capacitor wiring to the button contacts. they must be located in the same sequence as on the old button;
  • Insert the button back into the housing;
  • We fix the site of the revolution regulator back;
  • We fasten the contacts of the network wire and clamp;
  • Check the work of the corner grinding of idle;
  • Scour the handle lid with screws.
  • Corner grinder is collected, and the button works properly.

Replacing the Makita Corner Grinding button

Simple replacement of the button with the angular grinder Makita

How to change

Maintenance of the corner grinder with the replacement of the sequins of the electric motor is easy.

Remove the back cover of the case and you will get access to the brush-collection node. We show in the video the example of the Model “Interskol 115/900” (suitable for 125/900).

In some models, the corner grinder is enough to turn out the plastic plugs of the corners on the sides of the case, and the brushes assembled with springs, currently and contacts will fall out themselves.

The brush node located on the case of the corner grinder Makita GA9020 provides a convenient replacement of brushes. Photos all tools.RU

Replace the brushes when their wear and tear reaches one third of the original height.

When cleaning and flushing the collector and brush holders, use only gasoline or white spirit.

It is convenient to blow and dry the insides of the machine using a car compressor. You can use a household vacuum cleaner.

Some manufacturers produce brushes with a pre.established working surface. Such brushes do not require running.

Brushes with a flat end operate (run) at idle in a corner grinder, without load. After running in, it is advisable to blow the brush nodes and a collector for removing coal dust.

Where could I buy

It is important to replace the worn part of the same new, made by the same manufacturer from the same material with all the necessary properties.

No need to go shopping with a brush removed in your hands and select a very similar product, it can only be similar.

You can find the manufacturer’s catalog on the network, select the modification of your angular grinder, determine the number (code) of the desired part. Then go to the Internet posts of the supplier company. Then persuade her to send you not a box, but only one couple of original brushes.

We need to go into a separate section of our site, which collected companies whose qualified specialists will help to get the original part in proprietary packaging, in the agreed time, at the address you specified for a pleasant price.