Causes of malfunction and characteristic symptoms
The main factors that affect stator failure are as follows:
- the supply network does not always guarantee a stable voltage, its surges are possible;
- during the operation of the power tool, any liquid, such as water, may enter the stator;
- when processing some materials (concrete, wood and others), a sick amount of dust is formed, from which it is difficult to protect itself from falling on the stator winding;
- long-term operation of the angle grinder under overload conditions, which causes overheating of the power tool;
- during operation, do not stop the angle grinder by pulling the cord out of the socket suddenly.
408-105 Stator for Hitachi G18SE3 and HAMMER angle grinders. Photo 220V
Typical signs of a stator malfunction are as follows:
- there is a persistent smell of burnt insulation of the winding wires;
- the temperature of the body parts rises significantly Angle grinder;
- the electric angle grinder hums more than under normal conditions;
- the appearance of smoke is quite real;
- the spindle starts to rotate more slowly, or even may stop completely;
- the opposite to the previous case is possible, the other extreme. the spindle starts to spontaneously work at increased speeds, it is peddling.
The stator of the angle grinder is a fixed structure in the form of a core made of sheet electrical steel. It has grooves in which the winding is placed, twisted in a certain way, its wires are located parallel to each other, to reduce eddy currents.
408-316 Stator for Bosch GWS6-100 / GWS6-115 HAMMER. Photo 220V
The winding is necessarily covered with an electrical insulating varnish in order to protect it from possible short circuits between the wires. In the grooves of the cores between the coils, insulation is made of electrical cardboard, glass tape and other similar materials. In the vast majority of models of the angle grinder, the stator is tightly fitted inside the housing made of high-strength plastic, which protects the entire electrical part of the angle grinder.
How to ring a stator angle grinder
408-317 Stator for Bosch GWS7-125 / GWS7-115 HAMMER. Photo 220V
The stator as an element of the electric drive of the angle grinder participates in the creation of an electromagnetic field in which the rotor rotates, which creates a torque on the spindle shaft. During operation, for a number of reasons, it fails. The user can independently diagnose damage and repair the stator.
- Causes of malfunction and characteristic symptoms
- Visual inspection for malfunction
- How to check the stator winding of an angle grinder at home in different ways
- Checking the armature / rotor and stator with a multimeter / tester
- On turn-to-turn circuit, indicator
- Makita, without instruments
- Multimeter. automatic: quickly and efficiently performs measurements
Makita, without instruments
In one of the Makita models in the following video, smoke emitted during operation, which is a sure sign of a burnt out rotor or stator. To determine the reasons, the author performed a complete disassembly of the angle grinder, which makes it possible to perform a good external examination of the angle grinder units suspected of malfunctioning. If there were no signs of smoke consequences on the rotor, then on the stator several places of burnt electrical insulating varnish were clearly visible.
How to check the stator winding of an angle grinder at home in different ways
There are a large number of different electrical devices with which you can diagnose the stator. However, at home, a limited number of technical means are used. Some are presented in the following videos.
On turn-to-turn circuit, indicator
The principle of operation of the device for determining the turn-to-turn closure is shown in the following video. The device in the tested winding induces a magnetic field. In the presence of short-circuited turns in the winding, the short-circuit current causes increased resistance to the electromagnetic field generated by the device. By adjusting the IKZ, a setting is performed, upon reaching which a light signal is triggered (the indicator lamp changes color from green to red) or a sound is heard. In addition to the main application, the author shows a way to determine the places of connection of the winding wires to the collector lamellas, in the absence of visually visible contacts.
Checking the armature / rotor and stator with a multimeter / tester
In the next video, a multimeter device, or as more commonly called a tester, is used as a tool for diagnosing the rotor and stator of an electric drive. It is used to measure various electrical parameters: resistance, current, voltage. To determine faults in the form of wire breakage, breakdown of the winding to the case, the “ohmmeter” mode is used, that is, a certain resistance value is set, which is comparable to that available in the tested circuit. In this case, with a limit of 200 ohms.
Breakdown of the stator to the housing is determined by applying indicator probes to its housing and one of the ends of the winding. The presence of any resistance value on the indicator indicates the presence of a defect in the form of a breakdown of the winding onto the case. When diagnosing a winding break, the indicator of the device will not show anything when combining the probes with the winding leads.
complex manipulations should be carried out when checking the rotor windings of the electric drive. A winding break can be in any connection with a separate collector lamella. Therefore, it is necessary to check the resistance between all lamellas of the collector, applying indicator probes to them one by one. In the absence of an open circuit, the resistance will have the same small value in all cases. Any deviation indicates a break. The breakdown of the winding on the case is checked with probes when they come into contact with the collector and “iron” from a set of sheets of electrical steel. The indicator scale should not react to this action.
However, it is impossible to determine the turn-to-turn circuit with a multimeter. Here, a device called the indicator of short-circuited loops (IKZ) is used. details about it in the information below.
Angle grinder device
Collector motor connection diagram.
It has three main nodes:
An anchor is a rotating part that has windings to create the required torque, which is transmitted to the motor gearbox. The stator has the same winding, which is divided into several parts. Electric current enters the winding through the carbon brush and flows to the armature. Then the current comes to the next brush and so on, until all sectors of the stator are involved.
An anchor is installed in this stator. This structural element of the angle grinder is considered the most difficult, since almost all windings are pressed into it.
The stator of the electric motor has the same appearance. The characteristic differences are:
- dimensions of the magnetic circuit;
- the number of turns of the wire;
- wire cross section.
When electricity runs through the armature windings, a magnetic field is created that constantly interacts with the same field of the stator. This interaction starts the electric motor. Sometimes permanent magnets are included in the stator. For example, an electric motor for a wiper of a passenger car has such parts. Each collector motor is capable of operating on any type of voltage. When changing its value, it is possible to adjust the required number of revolutions.
Typical stator faults are:
- break in the winding;
- turn-to-turn short circuit;
- burnt out winding;
- breakdown of an insulating surface.
When the chain is working properly, the armature starts to rotate and the disc starts to move with the help of the gears.
The gearbox maintains a certain speed and the required speed. Repair of an angle grinder is quite affordable in a domestic environment. You just need to first disassemble the device.
In order to move the cover, you need to unscrew the screw securing the plastic plate. All details will be visible, except for the gearbox, which hides a metal cap. It prevents the gearbox from getting too hot. To remove the gearbox, you need to unscrew the four screws. This will expose all the mechanical parts of the angle grinder.
When the device is plugged into an outlet and the disk accelerates at increased speeds, this means that the stator winding has received a turn circuit. The stator needs repair, most often it needs to be rewound.
It seems that rewinding the stator is a complicated job. There is an opinion that it is almost impossible to carry out such work at home. Indeed, sometimes even experienced electric motor wrappers refuse such work. However, with the appropriate experience and certain technical knowledge, an ordinary three-phase stator can be repaired in a few hours with all the preparatory work.
Before starting repairs and rewinding, the stator must be cleaned of dirt and the old winding removed from the slots. This work is done with steel brushes. In addition, damaged insulation is removed. To facilitate cleaning of the insulation, the stator is immersed in heated transformer oil, which softens the remaining insulation.
What may be required to repair the stator?
Tools required for work: round-nose pliers, ruler, vernier caliper, pliers, electric drill, steel brush, megger.
To carry out the work, the master will need:
CROWN angle grinder 650 watt
- round-nose pliers;
- steel hammer;
- wooden hammer;
- steel brush;
- electric drill;
After cleaning the stator from dirt, it is necessary to carry out the following sequence of actions:
- metal bags are checked;
- burrs are removed;
- the pins holding the core are pulled up;
- the insulation resistance is determined;
- pressure washers, edges of the core, varnished;
- insulation of grooves is done.
Stator rewind angle grinder: DIY repair
Wholesale production of hand sanders was started in the USSR in 1940. This device received the name “angle grinder” due to the fact that at first it was produced in a small angle grinder town Lovech, which had a patent for this invention.
Today, no production can do without this tool. However, any tool breaks at some point, but many parts can be repaired in a domestic environment.
The electrical part often burns out. This may be due to:
- strong heating from high overloads;
- power surge;
- water caught on conductive surfaces;
- abruptly pulled out plug from the socket;
- blow on the switch and so on.
The most common fault that you can try to repair is a broken stator coil. This is mainly due to large overloads. Do-it-yourself stator rewinding of an angle grinder is quite possible today. However, such work requires certain experience and relevant knowledge.
Most often, an electric motor fails for a number of characteristic reasons:
- broken winding;
- the magnetic circuit is torn;
- malfunctioning of the anchor collector.
Signs of a Broken Stator
Schematic diagram of the speed regulator angle grinder.
When the voltage rises, the strength of the spark increases in leaps and bounds. over, most often only one brush is exposed to this phenomenon. As a result, the insulation of the wire wound on the stator coil breaks through.
When the collector sparks a lot, it means that the armature is poorly balanced. When checking the collector, the voltage is increased, the sound of the engine must increase slowly and smoothly, while no vibration should occur.
When resonance appears, we can talk about poorly done balancing. Repair of the electric motor is required.
Electric motor stator repair angle grinder
Reversible rotation of the collector motor.
First, the frontal remnants of the winding are cut off. Then a new winding is made. It is made using a template fixed to an axis that holds two large plates. It is very important in such work to get the right number of turns. Wire of a certain diameter should have maximum compaction. Two coils are inserted into the stator body. Conclusions are made from the winding wire, which are insulated with flexible plastic tubes, cambric.
Before the start of laying the winding, according to the technological process, the symmetry of the groove boxes is checked. If they do not cover the winding, then to prevent their damage when the coil wires are laid, temporary inserts are installed.
The coil, which will need to be laid, is mounted directly above the surface of the groove located at the bottom of the bore. With the help of a special plate, the coil conductors are mounted.
To avoid crossing the wires that are located in the groove, they are laid in exactly the same sequence as the winding on the template. The arrangement of the conductors must be strictly parallel.
In the next step, the stator housing rotates one notch. The other coils from the initial coil group are laid in the groove. After that, interlayer gaskets are installed in the grooves. The conclusions of the reel group are screwed with twine to the outer contour of the reels. These ends should be parallel to the coil leads. The lower side of the coils of the next coil group is mounted in a similar way. This operation continues until all the slots of the coils that enter this step are completely filled.
After the end of winding, the stator coils are sleeve. The sleeves must have certain dimensions, depending on the dimensions of the stator. The thickness of the material for the sleeve is taken as 0.2 mm. In this case, the length of the sleeve must exceed the dimensions of the stator. The excess is almost always 1.5 mm.
The liner material is a special electrical cardboard. A heat-resistant film is wound on top of it. The resulting structure is wrapped in sticky tape. Then, sealed coils are mounted in the stator grooves, the free movement of the armature is checked.
A fully formed coil is tied with keeper tape, then varnished. The completion of all work is complete drying, after which the stator will be completely ready for operation.
Rewinding spools using a template
It is not always possible to find the right template
In the next video, the author warns those doing rewinding with their own hands about the difficulties with choosing a template. It is not always possible to choose the right one right away. Guaranteed high-quality rewinding gives a much more laborious, but reliable method directly on the “hardware”.
Rewinding windings directly on the core
The following video details the technology for repairing the stator angle grinder. The author shows all the stages of work and argues his choice of winding rewinding directly on the “iron”. This model has wide slots, and the finished coil will be difficult to fit snugly into them. As a guiding device, the author uses a plate, which he folds along the height of the corresponding extreme point of laying the winding in the grooves. The surface of the plate is covered with electrical tape to protect the insulation from damage to the wire and is fixed to the core with the same electrical tape. The process of such rewinding is quite laborious. With a large number of turns, you should record your actions, for example, by appropriate notes on paper. This will help you avoid mistakes.
After winding is completed and the guide plate is removed, the coil can weaken its packing due to residual stresses, individual turns can fall out of the total mass. In this case, strapping with a thread made of natural material (synthetics cannot be used) will preserve the winding density. The spool can be tightly fitted into the grooves, allowing the use of various wedge-shaped objects. However, the author does not welcome their use, since this negatively affects the quality of impregnation.
How to rewind at home, stages of work
The repair begins with the removal of the broken old winding. Using pliers (pliers, round-nose pliers), the stator slots are freed from the old winding.
Next, the stator coils are rewound. It can be carried out on a specially manufactured template or directly into the grooves of the stator core. It depends on the depth and width of the wire space.
The wound coil is installed in the stator with the obligatory positioning of the beginning and the end of the winding wire, as described above in the text. The winding is fixed in the stator while maintaining all gaps (fixing options will be discussed further in the videos below). The stator is heated in the furnace to about 80 ° C. 110 ° C. Using a brush, apply varnish or pre-prepared epoxy resin with hardener. When applying, it is important to achieve the deepest possible penetration of the impregnation.
Practical tips for rewinding stator windings are given in the following videos.
The main stator faults are as follows:
- wire breakage of the winding;
- breakdown of the winding wire to the body;
- interturn short circuit of wires inside the winding.
Winding diagram, how to choose the thickness of the wire
The stators of an angle grinder have a very similar design and differ in the size of the parts in which the magnetic flux is formed, the number of turns in the windings and the diameter of the wire. The standard connection diagram for the angle grinder is shown in the following figure.
Here L1 and L2 denote the stator coils.
The burned-out winding is removed, while it is necessary to collect information about the old coils: determine the number of turns, the wire diameter, the beginning, end of the winding and the required direction during rewinding work. The number of turns is determined by direct counting of the wires after cutting the failed coils.
The wire diameter should correspond as closely as possible to the replaced windings. Therefore, a micrometer with a measurement accuracy of up to 0.01 mm is most suitable as a measuring tool. Measurement should be carried out on the surface of the wire of the burnt coil, stripped of the insulating coating.
How to call
For high-quality diagnostics of the stator of an angle grinder, a complete disassembly of the power tool should be performed in order to eliminate all other structural elements, including the rotor, in order to provide free access to all its parts. At the initial stage, it is necessary to perform a visual inspection. For a more complete picture, it is imperative to check for defects using electrical devices. What devices and how to ring the stator of the angle grinder is described in detail under the link “How to ring the stator of the angle grinder”.
Rewinding the stator do-it-yourself angle grinder
408-317 Stator for Bosch GWS7-125 / GWS7-115 HAMMER. Photo 220V
An asynchronous collector motor is used as an electric drive in angle grinders. One of the main components of its design is the stator. which always works in tandem with the rotor and creates a magnetic field with which it rotates. In the event of a malfunction of the stator, the angle grinder fails and must be repaired. There are two main ways to repair the stator. either replace the defective stator with a new one, or rewind the burned-out winding to a new one. Such repairs, when done independently, require certain knowledge and skills. The article describes tips for those who want to learn how to do it yourself.
- Angle grinder and stator device
- Causes of breakdowns
- Major malfunctions
- How to call
- Winding diagram, how to choose the thickness of the wire
- Required tools
- How to rewind at home, stages of work
- Rewinding spools using a template
- Rewinding windings directly on the core
- It is not always possible to find the right template
- Repair technology with a detailed description of varnish impregnation after rewinding
Graphite or carbon brushes. how to check
The first sign of a bad brush is an irregular ring of light around the collector with periodic flashes. Remember, we said above that by the glow you can understand whether the brushes of the angle grinder are in good working order or not. It only requires replacement of brushes with exactly the same.
Mechanical breakage angle grinder
These breakdowns are in such assemblies as a gearbox, a spindle retainer (locking button), flange fasteners, bearing part.
Most often, bearings fail. They can wear out and can be damaged if the tool is used incorrectly. For example, an angle grinder was used as a chaser, but the model was on ball bearings. they would simply fail very quickly. For gating, you need a tool with any other type of bearings, for example, roller bearings.
If the bearings fail, they can pull the gearbox itself along with them, simply breaking the teeth of the gears. Everything is quite simple here. replace the failed parts with new ones and your angle grinder will be in service again.
To understand that the bearings are about to break, the noise they make during operation will help. The tool must be switched off and completely de-energized. After disassembling you get to the bearing assembly, shake it in different directions. If everything is in order, it will not play, and if there is wear, then it will be noticeable right away. the bearing will simply go shaking. To replace it, use a puller, remove the clip itself with a tap. just screw it into it and take it out. We do not recommend using folk methods to replace bearings such as hammers and vices.
Checking the power cut
The most common problem is damage to the power cable. The break occurs inside the insulating shell and is not visible externally. If the internal insulation is damaged, a short circuit can occur. In order to check if everything is in order with the wire. disassemble the case of the angle grinder and check if there is voltage at the terminals that go to the switch from the side of the power cable. If you disconnect them, you can check each core with a tester. Although this is unnecessary work. if there is no voltage, then the wire must be changed entirely.
The start button of the angle grinder often breaks. This happens due to the banal ingress of dust and small debris. It is easy to find out whether it works or not. see if there is a voltage at its output contact with an indicator screwdriver, a light bulb or a tester. In case of malfunction, nothing needs to be repaired. just replace the button with a new one and that’s it.
It is even easier to check the rotation regulator. it will either change the number of revolutions or not. In case of malfunction. replace with a new one.
Manifold angle grinder
In order not to get injured, it is necessary not only to properly operate the tool, but also to disassemble and repair it.
It is unacceptable to carry out any repair work if the device is plugged in or the battery is not removed from it.
Before you start removing the bearing. take good care of a good stop.
In order to knock out some part, it is allowed to use drifts made of soft materials.
It is strictly forbidden to hit with a hammer or other tool directly on the bearing when pressing it in. The blows are applied strictly along the tube, which pushes the bearing into place.
After dismantling the bearings, they must be thoroughly cleaned by removing the old grease and rinsing in alcohol or acetone.
After pressing in the bearings, it is necessary to check them for backlash by swinging.
Any of the nodes in which a malfunction is found should be changed, and not tried to be repaired on your own. Since without qualifying experience, you can easily turn a minor malfunction into a huge problem before buying a new tool.
To check the smooth turn-on, you need to take a regular ammeter and look at the current surges with and without connection. Although usually, in case of problems with this unit, it is enough just to see how the angle grinder functions in different modes.
How to fix minor breakdowns
If your angle grinder refused to turn on, then when the problem is small, you can do the repair yourself without going to the workshops. Just do not forget at the same time, if your device is under warranty, then you cannot open the angle grinder yourself. this will deprive yourself of warranty repairs. Here you immediately need to contact the specialized service center.
In order to find out why the grinding machine does not work, you need to go from simpler to complex. First, check if there is light in the room in principle. If so, switch the instrument to a different outlet and preferably in a different room, removing the extension cord, if any. If it does not help, carefully examine the power cord. It could be damaged during operation. outwardly you did not notice anything, proceed to disassembling the angle grinder case. The wire needs to be checked with a tester, then you will know for sure whether it is damaged or not. If so, just replace it with a new one. If, after replacing the cable, the tool does not work or it turns out to be intact, then you need to go further.
Examine the power button. Carefully disassemble it, be sure to mark the wires and terminals, or take photos on the phone in the process, so that later you do not confuse anything during the reassembly process. If you connect the contacts incorrectly, you will cause a short circuit, which will lead to very serious problems.
If the button is faulty, then it is worth replacing it.
If everything is in order with the button, inspect (if any) the speed controller. After that, if the malfunction is still not found, go to the brushes. They can be heavily littered and cannot be repaired, but require a complete replacement. It is not difficult to do it.
Usually, graphite brushes or carbon brushes for an angle grinder, with intensive use of the tool, last about one and a half to two years. They wear out quickly and need to be replaced. Do not forget to de-energize the angle grinder when replacing the brushes and remove the residual voltage from them with a screwdriver with an insulated handle.
Usually the brushes are simply screwed on and you need to unscrew the fasteners and replace them with new ones. There are models of an angle grinder where the brushes can be replaced without disassembling the case. there are special plugs installed, which are simply removed for the period of repair.
It is worth noting that the brushes must be changed to exactly the same ones and no others will suit your unit. After that, turn on the angle grinder for 10-15 minutes at idle speed to “rub in” new brushes.
If your switch is out of order, it is forbidden to turn on the angle grinder directly. This will cause the disc to jam and fly apart, causing serious injury to the operator. If the speed regulator is faulty, it must be completely replaced, since it is almost never repairable.
How to remove, get it
The culture of production when performing repair work is shown by the author of the following video. The technology of work on removing the stator from the housing of the angle grinder has been worked out with the use of an auxiliary tool (just a wooden block of a certain size), which does not require the use of large forces.
Ringing and rewinding
If the burned-out stator becomes the cause of the breakdown of the angle grinder, a dial tone will reveal in more detail which part of it is involved. If there are defects in the coil windings, some users rewind new ones on their own. A detailed description of the production of such work on the links “How to ring the stator angle grinder” and “Rewinding the stator angle grinder with your own hands”.
For the DWT model angle grinder, in the next video, a new stator was purchased to replace the burnt one. The new stator was positioned as a unit precisely from the angle grinder of this model. The process of disassembling the angle grinder before removing the faulty stator from the housing is described in detail. When examining the appearance of the purchased new and old stators, some difference was observed. However, after assembly and testing for performance, it turned out that they practically do not affect the operation of the angle grinder.
DIY stator repair angle grinder
Almost any structural element of an angle grinder can fail. Operating experience says that stator breakdown is not such a rare occurrence, which means that you should have effective methods of repairing it. The presence of service centers with qualified specialists greatly facilitates the solution of the issue of stator restoration. However, such repairs can be done by yourself. For which the owner of the angle grinder must have some experience in electromechanical repair work. It is possible to eliminate most of the defects in the stator without the use of special tools. This article is to help users who repair the stator do-it-yourself angle grinder.
In the next video, the author repairs a Bosch angle grinder. Working in a highly dusty atmosphere, of course, can cause severe wear of the collector lamellas, but it should not be taken as an unambiguous reason for the failure of the stator windings. Other operating conditions should also be considered here (overload, operating time, and others).
The author’s diagnosis is in the nature of fortune-telling on the coffee grounds. A sharp change from a burnt-out rotor, which turned out to be still fully operational, to a burnt-out insulation on a stator, which really failed, indicates the absence of a systematic approach to repair work.
During disassembly of the angle grinder, the stator is released from the housing by strong hammer blows. Although it is wooden, strong enough blows can damage the protruding parts of the case.
Why not immediately make the output ends of the stator of normal length remains a mystery. The author twice does the same, very laborious work without really explaining the reasons.
Burnt out, rewind
The varnishing described in the repair should not be copied one by one. Because ordinary carpentry varnish does not have the required electrical insulating properties. If it is difficult to choose an impregnation agent, it is better to use a material based on epoxy resin, which is easy to find. The quality of the impregnation will improve if the stator is heated, rather than waiting for the varnish to stop penetrating into the winding.
Repair, preparation for work, necessary tools
Multimeter Bison. Photo 220V
Before carrying out repair work, diagnostics are carried out in order to determine the parts and assemblies due to which the angle grinder cannot function normally. The electrical part of the angle grinder is inspected visually for traces of surface burning in places of short circuit. If, after inspection, there are no obvious signs of malfunctions, the electrical part is checked by ringing with the help of special devices (multimeter, short-circuit indicator, and others). After finding and analyzing the damage, a method is adopted for its elimination.
There are two main ways to repair a stator with your own hands:
General rules for repairs
Basic safety requirements for repair work with an angle grinder.
- The angle grinder, like any power tool, has a cable for connecting to the mains. When carrying out repair work, disconnect the power plug from the outlet to prevent electric shock.
- The tool used for repairs must be in good condition. The working surfaces should not have any breakages, they should be securely fastened in the devices for holding the tool in the hands. The devices themselves should not create inconvenience to the user performing the repair work.
- Some parts of the angle grinder may have sharp edges, burrs. To prevent the possibility of injury, work in gloves that protect hands from direct contact with potentially traumatic parts will help.
- During the impregnation of the stator windings, fire safety requirements must be observed, since the varnishes used belong to the category of flammable liquids. The use of open fire (smoking and others) is not allowed. It is better to carry out work in a separate isolated room with a fire extinguisher.