Do-it-yourself grinder anchor repair

In detail: do-it-yourself grinder anchor repair from a real master for the site my.housecope.com.

The grinder is used to perform many tasks on the farm. Regular use may damage the device. The most frequently broken element is the anchor. It is affected by a high thermal load, as well as mechanical and electromagnetic influences. As a result, many craftsmen have to think about repairing this part.

The grinder's armature consists of a winding that conducts current and a magnetic core. The magnetic core contains a torsion shaft. The design of the magnetic wire is formed by plates and grooves, which are isolated from each other by means of a varnish coating. A certain sequence of laying the conductors of the armature winding in the grooves has been developed. The conductors form a coil. Its ends are tied on lamellas. The layout of the beginning of the starting loop and the end of the last one is drawn up in such a way that they are closed on one lamella.

With constant overheating of the grinder motor, the armature melts. As a result of the high temperature, the contacts of the wires that connect the primary winding to the collector can fall off. All this leads to the fact that the current is not supplied.

There are criteria on the basis of which it can be concluded that an anchor repair is required:

the number of sparks emanating from the brushes on the engine manifold increases;
vibration appears at low speed;
the working shaft starts to move in different positions.

The presence of these signs indicates a breakdown of the anchor. Subsequent use can be dangerous.

The following damage to the anchor is known:

breakage of electric current conductors;
short circuit between turns;
violation of insulation, which leads to a short circuit of the winding on the metal surface of the rotor;
unsoldering the ends of the collector;
uneven collector abrasion.

Video (click to play).

As a result of these malfunctions, the engine gradually stops working. To find out the reason for the failure of the angle grinder, diagnostics should be carried out. It can be carried out visually or using appropriate instruments.

Standard diagnostics involve a visual analysis of the device. It is necessary to analyze the integrity of the wire and the supply of current to the motor manifold. With normal power supply, you should inspect the grinder from the inside. It is not difficult to disassemble the device. It is best to photograph the location of the main modules of the device when parsing. After disassembling, visually check the anchor for the following properties:

the anchor must be free;
the absence of black spots and odor, which can indicate the melting of the winding, the insulating varnish of which leaves traces;
the absence of crumpled turns and solder residues, which leads to a short circuit;
there should be no burnout on the lamella contacts, otherwise you should check the binding of the lamella cock and the winding shank;
lack of worn out or burnt-out plates;
the space between the lamellas should not contain graphite residues from the brushes.

If no shortcomings are revealed during visual inspection, then it is necessary to check with devices. The anchor on the grinder can be checked both with a tester and using a regular light bulb.

The multimeter is set to the ohmmeter position. The resistance is set to 200 ohms. The probes are connected to lamellas next to each other. If the value on the instrument is less than 1 ohm, then a short circuit is present. If the value is greater than the average, there may be a break in the turns.With a high resistance value or the absence of any value (in the case of using a digital device), one can also judge an open circuit.

There are situations when a break is not detected. Then a breakdown is made to mass. At maximum resistance, one of the probes is placed on the shaft, while the other moves along the plates. If the value is zero, then there is no damage. Then the rotor is checked in the same way with a multimeter. In this case, the probe moves along the lamellas. If it is impossible to perform the test with the tester, a light bulb is used.

In the absence of a device at hand, many are interested in the question of how to check the grinder for possible anchor breakdowns. The power supply wire breaks and a light bulb is placed where one wire breaks. Then the shaft rotates. By changing the brightness of the light bulb, one can judge about the short circuit between the turns. In the absence of combustion, the following conclusions are possible:

the location of the brushes does not correspond to the operating position, due to the actuation of the support spring;
rupture of the supply circuit;
short circuit or gap in the stator winding.

You can ring the indicator of short-circuited turns and an anchor checker. An experienced person can do this.

Repair of the grinder's armature cannot be performed if there is vibration, as the balance is disturbed. This situation requires replacement. It is possible to eliminate the short circuit and replace the winding.

First you need to disassemble the engine and remove the rotor. But before that, disconnect the power terminals and remove the brushes. The grinder rotor comes with a support bearing and an impeller for cooling.

Anchors for angle grinders can be rewound at home. To do this, you need to have certain skills when working with a soldering iron. To rewind the anchor with your own hands, you will need:

a wire with a copper core that matches the previous conductor;
dielectric paper to insulate the winding;
varnish for casting coils;
soldering iron.

It is important, before starting winding the armature, to count the number of turns in the old winding and perform the same number on the new coil.

removing the previous windings - try not to spoil the surface of the case. If damage occurs, grind with an emery or a file;
inspection of the collector - the value of the resistance of the lamella contacts in comparison with the shell should not exceed 0.25 Mohm;
cleaning the collector from old wires - developing grooves for inserting the ends of new wires;
setting of sleeves - they are made of a material that does not conduct current, for example, electrical cardboard. Their size is 0.3 mm;
rewinding coils - the end of the new wire is attached to the end of the lamella. Rewind counterclockwise. Secure the wires with cotton thread near the collector;
control for the absence of short circuits - measure the resistance with a tester;
applying varnish or epoxy to secure the winding - dry it in the oven or use products that dry quickly.

If you cannot perform such actions, then you can replace the grinder's anchor.

The replacement of the armature on the 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:

new anchor for the grinder, suitable for your device;
screwdriver and wrench;
a brush with soft bristles and a cloth for wiping the elements.

Disassembly stages:

extraction of brushes;
unscrewing the gearbox;
removing the gearbox cover;
removing the ring that fixes the small gear to the anchor;
removing 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 a grinding machine 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 grinder body;
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. Keeping the instrument dry and properly cared for will extend its useful life.

Grinder repair: do-it-yourself anchor, video, how to check with a tester, rewind the electric motor at home

Grinder repair: 4 main components for repair

In order to repair the grinder, it is enough to study the basics of technology and know the design features of the device. There is no doubt that every electric tool may stop working sooner or later. Most often this happens due to the fact that the operating conditions were not observed. The grinder is not included in the list of exceptions. If suddenly you have such a nuisance, you can not immediately contact the workshop, but try to figure it out on your own, especially since most of the problems are easily solved.

Repairing a grinder is not an easy task, you need to know all the subtleties and reasons why the device may fail. For example, repairing an induction motor or a sparking collector is not always within the power of an ordinary person. And then you have to contact the master. In order to understand what the grinder's device is, you need to know how this technique works. With the help of electricity, the engine runs, which transmits rotation to the shaft thanks to the gear. At the end of the shaft there is a cutting or grinding wheel.

The quality of the grinder's work depends on the number of revolutions per minute. A professional tool is capable of developing a speed of 1000 rpm.

The first thing to do in the event of a breakdown is to disassemble the device and clean it, in most cases the grinder starts working.

The grinder body is made of durable plastic. Its main task is to keep all components in place and transfer the physical strength of a person at the time of work.

If this did not happen, you need to understand exactly where the breakdown occurred. The composition of the grinder may differ depending on the model, but the main parts are the same.

When parsing, we can see 4 components:

The body, which consists of 2 parts;
Engine;
Reducer;
Electrical component.

The motor drives the gear, which in turn drives the cutting element.

Oddly enough, in most cases, the breakdown of the grinders occurs due to the accumulation of dust and as a result of the release of the power button. Therefore, first you need to determine the integrity of the electric drill, its slats and the battery. All this is not so difficult, it is enough to know how the device works. If you have once studied the structure of a vacuum cleaner or washing machine, then it will seem like a trifle to you, and a special video can help.

If you are sure that the armature is broken, then you will need to get the electric motor.

Disassembly of the motor must be carried out as carefully as possible. Disconnect all brushes and terminals from power.

Do not forget that before changing the winding, no matter what kind of power tool Bosch, Sparky, Makita, Interskol, you need to manually establish the reasons for the breakdown of the grinder. To do this, you will be helped by the winding and reducer diagram, as well as a special indicator. We take out the rotor, and with it the support bearings and the cooling impeller. All this is a single whole subject. If you notice that most of the wiring is damaged and the balance is out of balance, then it is best to replace this component completely. The fact that the balance is disturbed can be indicated by the appearance of a rumble and vibration in the mechanism.

Do not take on the repair of a grinder if you do not have basic knowledge of working with a soldering iron. In such a situation, it is better to take the device to a workshop and contact a professional.

If the balance of the anchor is not disturbed, and the problem lies only in the reeling, then the anchor must be restored. The work will be to rewind the coil yourself, everything should be done carefully with patience and accuracy. If the balancing of the angle machine works intermittently, then first you need to check it with a tester. In the event that the groove shows different data, it will not be possible to repair the electric motor itself. But a replacement will help to restore it.

In order to replace the rewind in the anchor, you will need:

New wires for winding should be copper conductors, the diameter of which will correspond to the previous wires;
Dielectric paper for winding insulation;
Varnish to fill the coils;
Soldering iron with solder and rosin.

Before rewinding, you need to count the turns of the wire and apply the same amount in the new winding.

If the problem does not concern the starter, gear, but you find a problem in the winding, then here you will have to purchase copper and enlist the help of a collector puller. To begin with, a continuity tester is carried out, a multimeter will help you to ring, and in order to check the operation of the device, use a short-acting transformer. So you can find the right actions and tools to subdue the grinder.

The rewinding process is painstaking and will require patience and skill.

The process itself consists of the following steps:

Elimination of the old winding. It must be carefully removed and will not damage the metal case of the anchor itself. If you find any scratches or burrs, they should be ironed out with sandpaper or a soldering iron. Sometimes, in order for the body to be completely cleaned, a burner is used.
Preparing to connect new wires. It is not necessary to remove the collector itself. It will be necessary to inspect the lamella and measure the resistance of the existing contacts in relation to the case with a multimeter. The indicator should be approximately 0.25 Mohm.
Elimination of old wires. The remains must be carefully removed and grooves cut in the contacts. Later they will be needed to insert the coil wires.
Installation of sleeves. The sleeves are made of electrical type cardboard; this is a material whose thickness is no more than 3 mm. The required amount is cut and inserted into the anchor grooves.
Rewind. The end of the wiring must be soldered to the end of the lamella and wound counterclockwise in a circle. The same action is repeated for all tubs.
Quality checking. After all the windings are made, use a multimeter to check for short circuits or breaks.
Final treatments. The finished coil is treated with epoxy resin or varnish. At home, finished work is dried in the oven. You can use a varnish that dries faster.

It may seem like the job is difficult. We hasten to assure you that there is no, however, you will have to spend a lot of time and effort on this.

The anchor is the part on which a large amount of dirt most often accumulates. If the grinder has malfunctions, they can be identified by independently using a multimeter or, in other words, an ammeter.

The check begins with finding the faulty component. If your device is completely out of order, this may be evidence of crumbling brushes or a destroyed layer of dielectric that is between the plates. If you observe sparking inside, it means that the current collectors are damaged in the grinder.

Checking the stator for turn-to-turn closure with a multimeter does not take much time

Regardless of what result you get during the examination, you need to check the resistance. It should be the same for each of the measurements.

If the indicators show a deviation, this indicates a violation of the connection of the coils and a poor fit of the brushes.

Pay attention to the brushes, their wear should be the same, and if there are scratches, they must be replaced with new ones. If you did not find any malfunctions, then you need to measure the resistance at the lamella and the coil.

As you could find out from our article, angle grinder is not a complex structure, because it includes only 4 parts. But it is rather difficult to identify the true cause of the breakdown, and as it turned out, most often this is a careless attitude to the tool. To prevent this from happening, take care of your instrument, but if the device is out of order, take the time and follow our instructions to bring it into working order.The grinder, being the most demanded tool in the house, is subject to considerable stress and intensive use. Because of this, after some time, it happens that when the engine is started, jerks, a burning smell and other malfunctions appear, suggesting that the angle grinder (angle grinder) has broken down. But do not immediately carry the device for repair or buy a new one. Most faults in this device can be rectified by yourself.Over the long years of the existence of such a tool as angle grinder, its appearance, as well as its internal structure, have practically not changed. To repair a grinder with your own hands, you need to know the structure of its mechanical part, as well as electrical.If you look at the figure below, you can see what parts the angle grinder consists of.

Wheel for adjusting the spindle speed of the unit.

An electric motor consisting of a rotor and a stator.

Start button. Sometimes a soft start system is connected to it.

High impact plastic housing.

Spindle lock button (used when changing tools).

Safety clutch. Protects the motor from overload when the tool is jammed.

Protective cover. Covers the tool and protects the user from escaping particles of the processed material, and also prevents injury to a person when a tool is destroyed, such as an abrasive disc.

Tool clamping nut. It can be unscrewed using a special key that comes with the power tool. There are also quick-locking nuts that can be unscrewed without a wrench.

The gearbox housing and the gearbox itself. Consists of a block of gears that transmit rotational movements from the rotor to the spindle with the tool.

The picture below shows electric diagram of the grinder.The electrical part of the angle grinder has the following elements:

an electric cable with a plug for connecting to the mains;

start button;

stator;

electric brushes (carbon or graphite);

collector;

anchor (rotor).

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The following figure shows grinder connection diagram, namely its engine.All components of an electric motor perform specific functions.

Rotor - this is the shaft on which the coils and the collector are located. The rotor, rotating in the magnetic field of the stator, transmits the rotational motion to the angle grinder.

Collector... It is the part of the rotor to which all control cables are connected. Electrical signals from the control unit to the engine pass through the manifold. It is to the collector that the electric brushes are connected.

Electric brushes. Their main task is to transfer electric current from the power cable to the collector.

Stator. It is a coil with a certain number of turns. The task of the stator is to create a magnetic field, which, interacting with the armature, sets the latter in motion.

According to statistics, most cases of failure of angle grinders are associated with the electrical part of the apparatus. Some breakdowns may be minor, which allows you to repair the grinder yourself.But, for example, if the motor windings burn out, only a specialist can repair the angle grinder.The reasons that the angle grinder does not turn on may be the following:

defective electrical plug;

defective electrical cable;

the start button has broken;

broken contact between the power cable and the button;

breakage of the contact wire of the electric brush;

strong wear of the electric brushes;

failure of the rotor or stator windings.

There may be different reasons for the angle grinder not picking up speed.

Breakage of the speed control unit... To test this version, it is necessary to connect the engine of the device directly, bypassing the regulator, and check the operation of the device.

Faulty electrical cable due to constant bending or mechanical damage. Because of this, the damaged wire begins to warm up under load, and the engine speed drops.

Dust contamination of the collector... Remove contamination with alcohol.

Brush problems... They may wear out or have a short contact wire, as shown in the following photo.

The brush, although half worn out, is quite functional. In this case, the short contact wire prevents the spring from pressing the electrode against the collector. This situation can also be the reason why the angle grinder stopped working in normal mode.The reasons why the grinder is heating may be as follows.

Incorrect mode of operation of the device... As a result of overloads, the electric motor can become very hot, which often leads to burnout of the windings.

Bearing failurelocated at anchor. As a result, the rotor clings to the stator, the motor becomes difficult to operate, and the windings overheat. The problem is solved by replacing the bearings.

Clogged ventilation ductsthrough which air enters to cool the engine. It is necessary to clean the ventilation openings from dust.

Impeller breakage, which serves to cool the engine. It is installed on the rotor, on the side opposite to the collector. If the impeller is broken, it must be replaced with a new one.

Image - Do-it-yourself grinder anchor repair

Turn-to-turn closures stator and rotor windings. You will need to rewind the coils or replace these parts with new ones.

If you notice strong sparking when turning on the angle grinder in the place where the collector is located, then the reasons for this trouble may be as follows.

To diagnose the electrical part of the angle grinder, as well as eliminate mechanical damage to the device, you will need to disassemble it. Disassembly is carried out according to the following algorithm.

Unscrew the handle.

Remove the protective cover.

Open the special windows located on the sides of the angle grinder casing and remove the electric brushes after disconnecting the terminals.

Unscrew the gearbox housing from the LBM motor housing.

Pull lightly on the gear housing and detach it from the housing. In this case, the gear unit will be removed together with the rotor.

After removing the armature, the motor stator will remain in the casing, which is also easily removed for diagnostics after unscrewing the fasteners.

To disassemble the gearbox, unscrew the screws holding the cover. Removing the cover reveals the gears of the reducer.

To remove the anchor from the grinder, you will need to unscrew the nut located inside the gearbox.

In order to remove the bearing from the armature, it is recommended to use a special puller. Otherwise, the shaft could be damaged.

As mentioned above, most often the angle grinder refuses to work due to breakdowns in the electrical part of the unit. For the correct diagnosis of the electrical circuits of the instrument, the repairmen of electrical equipment use a special device - tester.

If you pressed the start button of the unit and it does not work, then in 90% of cases the cause of the breakdown is not so serious that you cannot repair the grinder yourself.

Experts advise adhering to the basic rule of repairing a power tool: move from simple to complex.

The first step is to checking electrical cable and plug at its end. If it is collapsible, then unscrew it and check the reliability of the contacts. Otherwise, you will have to disassemble the grinder (remove the cover of the device) and “ring” the cable with a tester, and also make sure that the current goes to the contacts of the “Start” button. If the device shows a break, then the cable should be replaced with a new one.

The situation when the current flows to the button, but does not pass further (when the position is on), indicates switch malfunctions... The button cannot be repaired. It must be replaced with a new one, but first mark the removed contacts in order to connect them correctly in the future. If the contacts are incorrectly connected, the motor winding may burn out.

If during the check it turned out that both the cable and the start button are in good order, but no current flows to the brushes, then it is necessary to make cleaning the contact plates of the brush holders... If this procedure is ineffective, it is recommended to replace the brushes. Further, if everything is fine with the brushes, and the current flows to them, the rotor and stator should be checked for shorts and breaks.

The rotor of the electric motor may have the following malfunctions: interturn short circuit and wire breakage at the contacts of the lamellas. You can check the grinder's anchor with a multimeter: the device is switched to the resistance change mode, the value is set to 200 Ohm, and the resistance between two adjacent lamellas is measured with the help of probes. Thus, it is required to check all pairs of lamellas. If the resistance values are the same, then the rotor winding is not damaged. The detection of other resistance values during the “ringing out”, as well as the detection of an open circuit, indicates a malfunction in this coil. In this case, the grinder's anchor will need to be repaired.

Usually, the rupture of conductors occurs at the junction with the winding. Inspect the places where the coils are connected to the lamellas, make sure that the soldering of the contacts is secure.

If you do not have a measuring device, then you can check the rotor by using 12 V light bulb and battery... The power should be between 30-40 watts. The check is done as follows: apply a voltage of 12 V from the battery to the plug of the angle grinder, connect a light bulb to the break of one wire, start rotating the spindle of the angle grinder. If the winding is in good condition, the light will burn evenly, without blinking. With an inter-turn closure, the degree of incandescence of the spiral of the light bulb will change. In this case, repairing the grinder's anchor with your own hands will be difficult, since the anchor winding scheme is quite complicated, and the process itself requires special equipment and knowledge. Therefore, it is recommended to entrust this operation to specialists. But the best way out of the situation would be to replace the anchor on the grinder with a new one.

If the light does not light up when testing the rotor, this indicates the presence of an open in the stator or a short circuit in its windings, as well as problems with the electric brushes.

To check the stator of the grinder, use, as in the previous case, a multimeter. The values you need set to 20-200 Ohm and do the following. Touch one probe to the contact of the stator winding, and the second to the body of the part. If the device shows resistance, it means that there has been a breakdown to the case. Touch the probes to the contacts of one winding, and then to the contacts of the other. If the resistance is the same, then the coils are serviceable. If the device shows an open circuit on one winding, it means that you will need to rewind the stator or replace the part with a new one.

It will be problematic to rewind the stator at home without special knowledge, skills and equipment. It is better to contact a specialist who is professionally engaged in motor rewinding.

Mechanical breakdowns of angle grinders include the following.Mechanical failures include breakage of the shaft retainer. In order to replace the retainer, you will need to disassemble the gearbox and remove the large gear.