How to check the anchor of an angle grinder at home

Checking the anchor of an angle grinder with a tester. possible diagnostic results

Among the most common causes of equipment failure, the most common is the turn-to-turn closure of the angle grinder armature. It can be detected. called. with a tester. A multimeter is an electrical measuring device that includes the functions of an ammeter, voltmeter and ohmmeter. They can not only check the presence of a turn-to-turn circuit in the winding of an angle grinder, but also measure the resistance between the lamellas. A simpler device is a tester. By checking the armature of the angle grinder with it, you can detect malfunctions caused by a short circuit.

how to check an angle grinder

The ancient Sufi wisdom says: “Smart is the person who is able to get out of a difficult situation with dignity. But he is wise who does not get into such a situation. ” Observing the rules for operating household appliances, avoiding overheating of the motor, you can avoid breakdowns and troubles in the operation of the angle grinder. and keeping the tool clean and dry will prevent its mechanisms from contamination and oxidation of current-carrying elements. Timely maintenance of the tool is guaranteed to save you from unpleasant surprises during work.

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How to troubleshoot an angle grinder correctly

Repair of the armature is possible only in one case. if during operation no vibrations are observed, since vibration disturbs the balance. In this case, the only way out is to completely replace the anchor. Otherwise, you can replace the winding and eliminate the short circuit.

Replacing the winding on the armature and stator with your own hands at home begins with cleaning the traces from the previous windings. Next, you need to carefully inspect the collector and, if necessary, clean the part from old, melted wires. The next stage is the installation of special sleeves that do not conduct current. Next, you need to rewind the coil. connect one end of the wire to the lamellas, check the performance of the part using a multimeter or indicator. At the end of the winding, we advise you to fix the turns with varnish.

Checking the anchor

Many inexperienced users of an angle grinder in the event of a tool breakage wonder how to check the anchor? First of all, an external inspection is performed to determine if there is a short circuit. If the winding of the wire is intact, not melted, this does not mean that there is no short circuit inside the device. To check this, you need to disassemble the angle grinder and check the serviceability of the anchor.

The movement of the armature must be free, not clamped. In the event of a short circuit, black spots and a fuel smell are present on the rotor parts, which indicates that the winding is melting. A short circuit is also indicated by crumpled turns and remnants of solder, traces of burnout on the lamellas, worn and burnt-out plates, the presence of graphite residues from the brushes between the lamellas.

They also check with tools and devices.

The resistance between all lamellas can be checked with a multimeter. To do this, set the value of 200 Ohm on the device, place the ends of the tester on two lamellas, which are adjacent. If the part is defective, the value will be less than one. If the device goes off scale, it means that the malfunctions of the angle grinder consist in the rupture of the winding turns.

If you don’t have the right tool at hand, you can use a conventional 12V 40W light bulb. You will also need two wires to check. On the side where there will be a minus, a break is made at the ends of the wire, the ends of the wire are applied to the collector. If, while scrolling the collector, on the plates of which the ends of the wire will be placed, the light will burn without interruption, there is no short circuit.

Before checking if there is a short circuit, you need to check the absence of openings with a tester. If the value is more than half, then there is a break. To check for a short circuit, you can use the short-circuited loop indicator. To do this, the indicator must be configured in such a way that one of the lamps shines red. Then you need to attach the tool to the winding and turn the rotor (armature). If there is a short circuit, the light will be on.

The turn-to-turn closure is also checked very simply using a choke. If the rotor of the angle grinder interacts with the throttle during operation, the plates will move, giving out vibration or a magnetic field, a short circuit is present.

Inspection of the stator of an angle grinder also begins with a visual inspection, for this the tool part must be disassembled. Dismantling the angle grinder begins with removing the brushes, gearbox, anchor. The next step is to carefully inspect the winding on the case to find out if there are any breaks.

You can also use a multimeter or short-circuit indicator to check for amperage, open or short circuit. The device is set to a value from 20 to 200 Ohm, two multimeter probes must be leaned in turn on the stator windings. Then we measure the resistance. If the resistance values ​​are the same, the tool is in good order, there is no short circuit of the turns.

Checking the motor windings, the presence of a short circuit, can also be checked using an electrical device that has a built-in light and sound alarm. The device can check for breakdowns of both the armature and the stator. For this, there is a special mode switch, with which you can easily switch from checking one part to another.

In what cases can you save an anchor and restore it yourself?

If the damage to the armature is established with guaranteed accuracy, the part must be removed from the electric motor. Disassembly of the motor must be done with special care, after removing the brushes and disconnecting the power terminals. The rotor is removed together with the support bearings and the impeller for cooling the motor, they form a single whole with it.

If most of the wiring in the armature is damaged and the balance is disturbed as a result of overheating, it is better to replace it entirely. An increase in vibration and an uneven hum during the operation of the mechanism indicate a violation of balancing.

How to rewind an anchor. step by step instructions

If the balance of the armature is not violated, and the problem is only in the damaged windings, then such an armature can be restored on its own by rewinding the coils. Rewinding a rotor at home requires a lot of patience and care.

The master must have skills in working with a soldering iron and devices for diagnosing electrical circuits. If you are unsure of your abilities, it is better to take the engine to a workshop for repair or replace the entire anchor yourself.

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To rewind the anchor yourself, you will need:

  • wire for a new winding. A copper conductor with a diameter that exactly matches the old conductor is used;
  • dielectric paper to isolate the winding from the core;
  • varnish for casting coils;
  • soldering iron with tin-lead solder and rosin.

Before rewinding, it is important to count the number of turns of wire in the winding and wind the same amount of new conductor on the coils.

The rewinding process consists of the following steps:

  • Dismantling of old windings. They must be carefully removed without damaging the metal body of the armature. If any burrs or damage are found on the housing, they must be smoothed out with a file or sanded with emery. Sometimes, to completely clean the body of slag, the craftsmen prefer to burn it with a burner.
  • Preparing the collector for connecting a new wire. There is no need to remove the manifold. It is necessary to inspect the lamellas and measure the resistance of the contacts with respect to the case with a megohmmeter or multimeter. It should be no more than 0.25 MOhm.
  • Removing the old wiring on the manifold. Carefully remove the remnants of the wires, cut the grooves in the part of the contacts. In the future, the ends of the wires of the coils will be inserted into the grooves.
  • Installing anchor sleeves. The sleeves are made of a 0.3 mm thick dielectric material such as electrical cardboard. Cut a certain number of sleeves and insert into the grooves of the cleaned anchor.
  • Rewinding reels. The end of the new conductor is soldered to the end of the lamella and wound in successive circular movements, counterclockwise. This is called “right-handed”. Winding Repeat for all spools. Near the collector, pull off the wires with a thick thread of cotton fabric (it is forbidden to use nylon, as it melts when heated).
  • Checking the quality of the winding. At the end of the laying of all windings, check with a multimeter that there are no interturn short circuits and possible breaks.
  • Finishing treatment. Finish the coil with varnish or epoxy to hold the winding together. At the factory, the impregnation is dried in special ovens. At home, this can be done in the oven. Alternatively, apply quick-drying varnishes for impregnation, applying a coating in several layers.

Is it possible to repair the anchor

Repair of the angle grinder armature cannot be performed if there is vibration as the balance is disturbed. This situation requires replacement. Short circuit elimination and winding replacement possible.

First you need to disassemble the engine and remove the rotor. But before that, disconnect the power terminals and remove the brushes. Angle grinder rotor is removed with support bearing and impeller for cooling.

Change anchor

Replacement of the armature on an angle grinder is carried out simultaneously with the replacement of the support bearings and the motor cooling impeller. To do this, you will need the following devices:

  • a new angle grinder anchor to suit your device;
  • screwdriver and wrench;
  • brush with soft bristles and cloth for wiping elements.
  • extraction of brushes;
  • unscrewing the gearbox;
  • removing the gear cover;
  • removing the ring that fixes the small gear to the anchor;
  • extraction of the armature together with the gear and bearing;
  • removal of the bearing with a special removable device;
  • removal of the gear and the fastening disk;
  • wiping the main elements with a napkin.

The installation of a new part for the grinder is carried out in the reverse order:

  • installation of the clamping disc on the shaft;
  • bearing pressing;
  • installing a small gear and securing it with a retaining ring;
  • placing the armature in the gearbox with the docking of the holes;
  • fixing the gearbox in the housing of the angle grinder;
  • installation of brushes;
  • device check.

Thus, repairing an anchor with your own hands can be done quickly and easily. But in order to prevent such cases, you need to use the device with care and not subject it to prolonged high loads. the tool in a dry place and the necessary care will extend its service life.

How to remove

For high-quality diagnostics and possible repairs, the anchor should be completely removed from the angle grinder. If necessary, for work, you can use the information on the link “How to remove the anchor from the angle grinder“.


Before proceeding with the repair, you should diagnose the failed angle grinder. This will allow you to determine the true cause of the interruptions in the operation of the power tool, and make it repaired at minimal cost. The electrical part of the angle grinder, which includes the rotor, is diagnosed according to certain rules using available devices. Information on how to check the rotor for serviceability can be obtained from the link “Do-it-yourself check, continuity of the angle grinder armature”.

12 grooves and 24 slats

check, anchor, angle, grinder, home

Rotor for Interskol angle grinder-2300M, HAMMER. Photo 220V

The rotor winding with such design parameters is performed as follows.

  • Sets the winding direction (usually clockwise when viewed from the collector side).
  • Insulation made of electrical cardboard and other similar material is installed in the cleaned grooves. The winding wire is soldered to the lamellae according to the old laying pattern.
  • The wire is laid in the groove opposite the lamella indicated by the first number and, according to the winding step, is guided into the groove, returning back. The number of such stacks corresponds to the size of the winding turns.
  • A circuit with 12 grooves and 24 lamellas is built after soldering the middle of the winding to the lamella and continuing the winding of the winding wire in the same groove. The required number of turns is maintained and the lamella is soldered to the lamella.This is how the first complete coil is obtained.
  • Further, the winding is carried out in the grooves and with the soldering of the middle of the winding to the lamella and the end of the winding to the lamella
  • By winding the coils in the above way, the last of which ends on the lamellas, all 12 grooves and 24 lamellas will be used in the stacking scheme.

Required tools

To rewind the rotor windings, the following basic materials, tools and fixtures are required.

Rewinding can be done in two ways:

  • completely in manual mode without the use of any equipment;
  • productivity is greatly increased with the use of the simplest devices.

The user must know how to handle an electric soldering iron.

The presence of a winding wire, the diameter of which must correspond to the failed wire.

Insulating cardboard or similar material.

Sandpaper, textolite plates, softwood and other materials for auxiliary work.

Epoxy or other impregnating varnish.

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Other locksmith tools: hammers, a set of screwdrivers, hacksaw blades, sharp objects such as a well-sharpened knife, chisels and other tools.

DIY angle grinder rewind

Serviceable rotor for Bosch angle grinder GWS6-100 / GWS 850 MAX. Photo 220V

The rotor is one of the most complex structural elements of an angle grinder. At the same time, it is in a constant rotating state, which creates additional problems in maintaining normal operating conditions. Therefore, the cause of the malfunction of the angle grinder may be an armature breakage. However, you should not throw away such an angle grinder, actually do the repair yourself. Rewinding broken coils is not such a difficult task and many can do it quite well.

Laying diagram, winding Interskol 230, Makita 9558HN or 9558BN and other models

The order of winding of the rotor windings depends on the number of slots in the rotor core and collector lamellas. The parameters that determine the location of the winding wire on the rotor include the direction and pitch of the winding. The rotation of the spindle shaft (right or left) is just connected with the choice of which side the wire is laid in. When repairing the rotor, it is necessary to record the above data of the burned out winding.

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The number of turns and the diameter of the wire is fixed after removing the frontal part of the failed winding, which will allow you to accurately get the complete bundle of wire located in the groove.

Most of the operated grinders, regardless of the model (Interskol, Makita and others), are structurally made with 24 lamellas and a core with 12 grooves. The winding step is chosen equal to 6.

How to rewind an angle grinder at home, detailed instructions, video

The following video describes the repair of a Makita model angle grinder with increased sparking in the brush-collector assembly. To determine the causes of the defect, a complete diagnostics of the electrical part of the angle grinder was carried out.

The reason for the increased spark was a break in one of the armature windings of the angle grinder. The author eliminates the defect by rewinding the broken winding. After determining the necessary parameters for laying the old coils and then removing them, a new winding is wound. It is produced using a special device.

After the end of winding, the coils are fixed in the grooves using wedges made of wood or other soft material. The author connects the wires of the windings and the terminals of the collector lamellas (“cockerels”) by welding. Be sure to check the electrical circuit of the coils after this operation with a multimeter and a short circuit indicator.

If no breaks, breakdowns and turn-to-turn short-circuits are found, the operation of impregnating the winding with epoxy resin is performed. To create conditions for high-quality impregnation, the rotor is preheated. The author describes in sufficient detail the technological methods that contribute to the better flow of the resin into the coils.

Since the rotor rotates at high speeds, it is important to ensure that it is well balanced to reduce the loads on the bearing units. The author of the video only indicates the presence of this technological operation, more detailed information is not provided. After balancing, the manifold is machined in the working position, that is, based on bearing assemblies. When performing the specified processing, mechanical particles may get into the winding, therefore, devices should be checked for breaks and short circuits.

One and the same author repairs grinders of different models: in the first video the model “SKIL” is being repaired, and in the second video the model “Bosch” is being repaired. Therefore, the repair methodology in both cases is the same.

It is important to correctly determine the parameters and the winding scheme of the failed rotors on both models. Here, in addition to visual inspection, the author uses a tester, which shows the minimum resistance in the presence of such a connection, to determine the location of a closed electrical circuit for a wire from the groove of the core with the corresponding pin of the lamella. The author recommends performing a graphic representation of the installation scheme with the indication of the required parameters.

Unlike the previous video, in this the author specifically demonstrates his actions when working on a lathe during the removal of the old winding, freeing the grooves from the remaining bundles of wires and the actions when winding the wire. The author is professionally engaged in the repair of power tools, therefore, in the arsenal he has a special device for winding.

After the end of the winding, the ends are fixed according to the scheme by bending the bends of the “cockerels” of the lamellas. Additionally, the wire of the frontal part of the armature is bandaged using natural heat-resistant threads (synthetics cannot be used categorically). Next, the ends of the wires are welded with the bent ends of the lamellas and the control is carried out for the presence of breaks and short circuits with the appropriate devices.

After heating the rotor to about 100 ° C (pyrometer readings), the winding is impregnated with epoxy resin.

In the next video, the winding of the armature winding is done without the use of a device, purely by hand. Hand winding has its own peculiarities related to wire fastening. In the video, it is looped onto the rotor shaft just behind the manifold. The author fixes the ends of the windings to the lamellas without the use of soldering and welding technologies. Lamella hooks are upset at the wire connection points using special attachments in a shock manner.

Several videos are devoted to the repair of the anchor of the “Metabo” model angle grinder. One of them touches upon the issue of reworking the surfaces of the rotor after impregnation. This information supplements the information previously presented. During this technological operation, resin may get on some working surfaces. The video shows how to clean them.

How to ring an anchor with a multimeter?

To complete this procedure, you will need the measuring instrument itself and tools to disassemble the device. How to ring an anchor with a multimeter. instructions:

  • Prepare your work surface. There should be enough space to accommodate the necessary tools and parts removed from the device.
  • Disassemble the angle grinder and remove the anchor.
  • Clean the part from dirt and dust.
  • Using the recommendations in the presented video, you can independently ring the anchor with a multimeter.

At the initial stage of diagnostics, the value of the measuring device is set at 200 kOhm. If your multimeter does not have such a scale, then you can limit yourself to 20 kΩ. To ring the armature, one probe of the measuring device is applied to the ground, and the second is touched to each of the plates. If no indicators appear on the scale of an analog multimeter or a digital screen, most likely there is an interturn short circuit in the armature winding. You can accurately diagnose the problem using a special device that is available from professional locksmiths.

Checking the anchor of an angle grinder with a tester. possible diagnostic results

Among the most common causes of equipment failure, the most common is the turn-to-turn closure of the angle grinder armature. It can be detected. called. with a tester. A multimeter is an electrical measuring device that includes the functions of an ammeter, voltmeter and ohmmeter. They can not only check the presence of a turn-to-turn circuit in the winding of an angle grinder, but also measure the resistance between the lamellas. A simpler device is a tester. By checking the armature of the angle grinder with it, you can detect malfunctions caused by a short circuit.

Features of checking the anchor of an angle grinder with a tester

The diagnostic procedure will help pinpoint the problem of the motor part. The device, which is in the arsenal of tools of many amateur electricians, will allow you to check the anchor of an angle grinder with a tester. With the help of the tester, you can check not only the anchors of the grinders, but also the stator windings of other electric motors. In the video below, you can see one of these homemade measuring instruments in action.

When the tester is connected to the network, the indicator lights up. A red light without the attachment of a technical device to the anchor means that the device is ready to be checked. The working active surface of the measuring device has two points of contact with the investigated one. One of them is the generator coil, the second is the coil of communication curls. When checking the armature of an angle grinder with a tester, it is necessary to substitute this surface to the groove under investigation. Make sure that the sensors do not extend beyond the armature plates on both sides at the same time.

If the electrical part is in good order or rewound, then during its check with the tester opposite each of the grooves, the indicator will glow green. If there is a malfunction in the armature of the angle grinder, in particular, a turn-to-turn circuit, a red light will be indicated on the indicator of the device in the place of its localization. Use care during the diagnostic procedure to ensure proper surface contact when checking the angle grinder armature with the tester. Mechanical damage should not be excluded from the reasons for the failure of the angle grinder, which can be noticed visually without ringing with a multimeter. They can be both significant and small. You may notice a breakage on inspection by disassembling the angle grinder. It is necessary to diagnose such malfunctions before checking the armature for interturn closure.

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If you do not have experience in disassembling a power tool or preparing to work with measuring instruments for ringing the armature with a multimeter and are not confident in your own strengths, you should not interfere with the design of the angle grinder. Do not experiment to avoid damaging the angle grinder. In this case, in order to find the cause of the breakdown of the power tool and check the anchor of the angle grinder with a tester, it is better to contact a service center or qualified locksmiths who specialize in repairing equipment.

What problems in the operation of the device can be detected when checking the anchor of an angle grinder with a tester

If you have sufficient knowledge to perform the correct disassembly of the power tool, then in some cases you will be able to diagnose the cause of the device breakdown with your own hands. Checking the anchor of the angle grinder with a tester for inter-turn closure will allow you to determine further actions regarding the detection of faults or the repair of equipment. If the part is intact but the tool still does not work, seek qualified assistance. Did you check the anchor of the angle grinder with a tester to pinpoint the cause of the equipment failure? If you have the necessary tools, you can repair equipment yourself in such cases:

  • If the winding is damaged in the upper visible layers, you can try to solder it. Such an anchor will last some more time. After sealing, it must be checked or ringed with a multimeter;
  • in case of turn-to-turn closure, winding rewinding or armature replacement is required.

Breakdown diagnostics and repairs of the angle grinder can be performed while energized. For the sake of your own safety, entrust this work to professionals.

Light bulb

In the absence of a multimeter, you can ring the rotor’s electrical circuit using a 12 V light bulb. First, connect two wires to the bulb itself. The power source is an ordinary battery, to the ends of which the ends of the break of one of the wires connected to the light bulb should be connected. Such an amateur “device” is used instead of a multimeter, where the ends of the wires are applied to the lamellas without touching each other. Carefully rotate the anchor to monitor the brightness of the light bulb. If it burns constantly without blinking, then there are no breaks in the winding.

Breakdown of the winding onto the core body is checked by connecting one of the ends to the collector, and the other to the core or shaft. If the light comes on, then there is a breakdown of the winding on the case.

Tester, multimeter

A multimeter device or its other name, a tester for measuring electrical parameters: current, voltage, resistance. can be used to search for wire breaks of windings or their breakdown to the core body.

In the next video, the author offers a diagnostic option from simple to complex. With the help of a multimeter, the stator is called first. It is much easier to check it than the rotor. If there are no breaks and breakdowns of the winding to the case on the stator, then we can conclude that the armature is faulty. Further, it should be diagnosed in more detail with the definition of the exact type of defect and the determination of the method of elimination. Continuity is carried out with a multimeter in the “resistance test” mode with a set minimum measurement scale (up to 200 Ohm).

In this video, as in another, the process of determining winding breaks is shown, which is really quite laborious, since measurements are taken between each pair of lamellas along the entire circuit of the collector. In this case, on an armature that does not have breaks in the windings, all readings of the multimeter should not differ from each other within 0.1 ohm. It is much easier to check the breakdown of the windings on the body by placing one probe on the core body, and the other on the collector plates. The scale of the multimeter should not respond with any reading.

It is impossible to determine the turn-to-turn short circuit with a multimeter. Other devices are used here.

Checking, dialing the anchor of the angle grinder with your own hands

Rotor for Interskol angle grinder-2300M, HAMMER. Photo 220V

Electric motor chek. How to test if field coil is damage.

If the angle grinder fails, diagnostics are performed to identify the causes. One of them may be a breakdown of the armature (rotor) of the electric drive. You can check the functionality / failure of this rotating unit yourself. It is necessary to have in the arsenal only simple devices for carrying out the continuity of the electrical circuit.


For a competent diagnosis of anchor malfunctions, it is important to know the device and how it works. The main elements of the armature are a round core, consisting of a set of electrical steel plates and a winding wound into its grooves in a certain way. Two anchor windings are placed in each of the grooves according to a special scheme. The first and last turn of one of the windings are in one groove and are closed on one lamella.

Rotor for Makita angle grinder 9069 MAX. Photo 220V

The core is pressed onto the rotor, rotating under the action of forces arising in the electromagnetic field formed by the armature windings and the stator coils working with it in pair. In grinders, an anchor is an assembly unit, with a drive gear located at one end of the shaft, and a collector unit at the opposite end.


The presence of a turn-to-turn short circuit in the rotor can be determined using an armature tester. It is a transformer with one primary winding, in fact it is a wire wound on a ferromagnetic core. In this case, a triangle cutout is made in it, in which the tested rotor can be stably positioned. Its winding starts to work as a secondary coil of a transformer.

In the presence of turn-to-turn closure, the parameters of the rotor magnetic field have a higher intensity, the metal strip placed on the core surface will vibrate and magnetized will be attracted to the core body. The plate will move freely on the body of the rotor core if it has normal windings without defects.

Turn-to-turn closure indicator

In the next video, the author is testing a self-made device for determining the turn-to-turn closure (IMZ). The principle of its operation is based on the interaction of electromagnetic fields created by the coils of the IMZ device and the armature or stator windings. In the presence of a turn-to-turn short circuit, the parameters of the magnetic field of the device change, which is fixed by the light indication. the red light comes on, in the absence of a short circuit, the green light is on.

Carbonized traces and the presence of a specific odor are the cause of burnt insulation and ultimately damage to the winding wires. Attention should be paid to crumpled or swollen turns, which may authorize the presence of breaks in this place. Solder particles may be present on the windings, which are source of short circuits.

Violations of the contacts of the windings with the collector can be detected by the burnt out lamellas. Damage to the collector itself is visually diagnosed. raised, worn or burnt plates.