Rewinding an electric motor with your own hands at home

In all the time I’ve been using the power tool, this is the first time I’ve “burned” it myself. During prolonged work, my Makita 9555HN angle grinder began to smoke a lot. This happened due to haste and at the same time due to oversight. The totality of all my actions and events resulted in a very strong overheating of the instrument. Overheating was not noticed in a timely manner due to the fact that the work was carried out in welding goggles. Since they are leather, it is safer to work in them, since they will not get wound up, unlike rag or knitted ones. And since the leggings are designed to protect against temperature, the work was carried out as if nothing had happened.

In addition to just long work, which lasted about an hour and a half, there was another aggravating point: the tool used somewhat heavy equipment in the form of a thick, six-millimeter grinding wheel and a metal brush in the form of a cup.

The operating time of this angle grinder is small, therefore, we will repair it.

Let's disassemble the tool. The process is quite simple: unscrew the screw securing the black plastic casing and route it along the power cable. Next, lift the spring-loaded brush clamps and remove the brushes (there are two of them, located on different sides).

Let's move on to analyzing the front part of the angle grinder. Unscrew the four screws securing the gearbox and remove it. Next, remove the electric motor rotor. To do this you need to use a screwdriver. We install it in the technological groove and carefully turn it, controlling the process. The rotor is pulled out easily, without any excessive force (the main thing is not to forget to remove the brushes before doing this).

We blow the rotor with compressed air and inspect it. Externally there is absolutely nothing to complain about - it is perfect. The enamel on visible areas of the wires has not darkened and has retained its integrity. Unfortunately, there is nothing to test it for interturn short circuit yet. We put it aside and disassemble it further.

Now you need to get to the stator. After we removed the rotor, we had access to the plastic stator protection fasteners. Unscrew the two long screws and pull it out. Before you begin to remove the stator, you need to disconnect its windings and straighten the wires. You can use a rubber hammer to remove the stator. The process is as follows: with a hammer we apply light blows to the front end of the angle grinder body, and due to the sufficiently large mass, the stator will begin to come out of the seat. When removing the stator, you must ensure that its wires pass through the technological windows freely and do not cling to anything.

An inspection of the stator revealed the presence of burnt conductors in its windings. The enamel on them has darkened significantly and damage has appeared. The stator needs to be replaced.

We still have an open question with the rotor. I remember that some large retail outlets that sell spare parts for power tools can suggest and check some parts. We take the stator and rotor and go in search of spare parts.

But before going to the store, the rotor will have to be disassembled a little. We need to remove the plate and bearing from the front. Otherwise, there may be difficulties when checking it. To remove the plate you need to unscrew the M6 ​​nut. The bevel helical gear is installed without a key, the fit is free. After removing the gear, carefully tighten the bearing together with the plate.

As expected, checking and purchasing the parts needed for replacement was not difficult. All you had to do was get to the right, specialized store selling those same spare parts. Here we checked the rotor, which in turn was also “sintered,” and bought new parts.

We will begin the assembly by preparing all the parts and components of the angle grinder. First you need to blow off the dusty elements with compressed air. Next, rinse the gearbox parts in gasoline. After this, we will lay out all the components of the angle grinder and begin assembly.

The stator is installed first.

It snaps into place without any difficulty or special tools. Just hand effort is enough. The main thing in this process is to correctly route the four wires that connect to the terminals. It is also worth paying attention to the red wire - the jumper (the one that connects the two windings). When installing the stator, this wire tends to take a position directly opposite the mounting hole of the plastic protection. If this is not taken into account, then during further assembly, when screwing in one of the screws, the wire will be guaranteed to be broken.

After the stator has taken its place, we install its protection.

Next, you need to prepare a new rotor for installation.

Here you need to install the previously removed plate, bearing, gear with nut and don’t forget to move the rubber ring from the old rotor to the rear bearing. In the diagram it is indicated as number 3 and is called a labyrinth rubber ring.

After completing the above work, we place the assembled rotor in place. Next, use four screws to fasten the gearbox housing. The screws must be tightened evenly crosswise.

Now the rotor is fixed and the brushes can be installed. We place them in special brush holder channels, fix them and connect flexible contacts.

Next, install the protective casing and try to start the electric motor. In our case, everything worked without any complaints, the engine ran smoothly, there were no sparks on the brushes.

The final part of the work will be lubrication and assembly of the gearbox. Having sufficiently filled the cavity inside the gearbox, we installed the last element of this device and securely fixed it.

Having started the angle grinder, it became clear that there was so much lubrication in the gearbox that the first start was even somewhat difficult. During subsequent launches this effect was no longer present. But then it was revealed that after about 30-40 seconds the gear housing begins to heat up. This effect had not been observed previously. You will have to disassemble the gearbox again and remove some of the lubricant.

Clearly there is a lot of lubrication.

But the gear is “dry”. Centripetal acceleration removes all lubricant.

Excess lubricant has been removed.

But two questions remain: what is the lubrication rate for an angle grinder gearbox? And what type of lubricant should be used?

Repairing an angle grinder with your own hands is a completely solvable task. The main thing is not to rush, understand the design, remember all the circumstances under which it broke, determine what could have worn out during operation, make diagnostics and begin repairing it.

Bulgarian and its operation

An angle grinder is called an angle grinder. The name of the instrument is due to the fact that it was produced in Plovdiv. It is intended for performing work on grinding or trimming hard material:

Does a good job of sharpening tools.

A grinder is a very necessary tool these days, so almost everyone has one.

There are grinding machines of different power: from 500 W to 2500, depending on the thickness of the wheel - from 115 mm to 230 mm. The most popular ones in use are angle grinders with a power of 1.2 W, and the most used disc is 125 mm thick.

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Every year the choice for this construction power tool becomes wider, but the operating rules remain almost unchanged. And even if you always adhere to them, sooner or later malfunctions arise in the mechanism, which you can try to fix yourself by collecting everything you need to repair the angle grinder.

The main causes of grinder malfunctions and their elimination

Below are the most common problems and how to fix them.

Commutator brushes burn (spark)

Sparking in the commutator is most often observed in cases when it is time to replace the carbon brushes. This usually happens after several years of using an angle grinder.

Standard brushes are designed for 7,000 hours of operation, after which they are washed.

Grinders have a simplified system for replacing brushes, so repairs are quite easy and quick:

1. Using a flat-head screwdriver, unscrew the two plastic caps on both sides of the casing.
2. Remove old brushes from their nests.
3. Wipe the collector with an alcohol swab, as there is carbon residue on the lamellas from the work of old brushes. You can also use tweezers with cotton wool or rags soaked in cologne.
4. Install new brushes into the sockets.
5. Screw on the plastic caps.
6. Check the angle grinder in operation.

Video: replacing grinder brushes will help eliminate sparking

Grinder won't turn on

To determine the exact cause of this malfunction, it is necessary to examine the electrical circuit of the device. It is advisable to start from the outlet and end with testing the electric motor. After the location of the circuit break has been found, the flow of electric current in the tool should be restored. Most often, the cause of a break is dust or oxidation of the terminals or contacts of the start button.

Broken spindle lock button

The defect is purely mechanical in nature. This happens when the circle jams or when the rod cavity is severely clogged. In this case, replacing the disk will help to produce a special flange wrench, which, as a rule, is always included in the kit of the sold tool. You can keep the shaft from turning using an open-end wrench. At the base of the flange mounting there is a specially machined turnkey plane.

Video: repairing the spindle lock at home

The engine has stopped working

If voltage is supplied to the motor, but it does not rotate, you need to check the condition of the brushes and bearings. Brushes may stick, bearings may jam.

1. If the brushes are sunk, they must be thoroughly cleaned and then the nests in which they are located must be blown out. Additionally, you should check the rubber seals on the covers covering the brush sockets. After all, the insulation of brushes and commutator from dust depends on them.
2. If the reason for the engine stopping is in the bearings, they must be removed from the rotor shaft, repaired or replaced. Sometimes flushing and lubrication is enough to ensure that the old bearing continues to function.

The angle grinder works in fits and starts and does not develop full power

The angle grinder motor operates jerkily if an interturn short circuit occurs in the rotor coils. The most common reason is irregular use of the tool, which results in overheating of the motor. Rewinding armature coils is a rather complicated and painstaking task, doomed to failure without certain skills. Therefore, if the armature fails, it is recommended to replace the entire part, along with the bearings. The value of the spare part must exactly match the value of the original.

The grinder gets very hot

Most often, the body of an angle grinder gets very hot due to improper operation of the device. Since the angle grinder is equipped with an asynchronous electric motor, an increase in the workload on it does not affect the rotation speed in any way. This can be misleading for an inexperienced user, as a result of which he continues to work without interruption for an unlimited time. But this cannot be done. The passport of each tool indicates the optimal operating time of an angle grinder under load, usually it is 5–7 minutes. After this, it is recommended to take a break of 1 minute or let the grinder idle.

When working with a tool, it is important to follow the correct order of stopping the grinder. After turning off the start button, you need to wait until the engine stops completely. If the rotating angle grinder is placed on the ground or a dusty floor, small particles of sand will be sucked through the ventilation holes. They will get inside the engine and will erase the protective insulating layer.

Bulgarian is not gaining momentum

If the tool is equipped with an electronic shaft speed control unit, a malfunction may cause the shaft speed to “float” under load. Most likely, there is a short circuit on the board; the control unit should be replaced.

Gearbox failure

The gearbox gears play an important role in supplying rotational motion from the electric motor to the working tool. In addition, there is a decrease in speed and, accordingly, an increase in power. Grinders with power up to 1100 W use spur gears. If the engine power exceeds this figure, helical gears are used, which have greater fracture strength.

If you hear a crunching or grinding sound from the gearbox when you turn on the motor, the grinder must be turned off immediately. It is impossible to work with such a gearbox; this will lead to complete cutting off of the remaining gear teeth. After stopping the engine completely, you need to remove the gearbox cover to establish an accurate “diagnosis”.

If the cause of extraneous sounds is chipped teeth, the damaged gears must be replaced. In this case, the cavity of their rotation should be thoroughly cleaned of grease and metal fragments that formed from the previous mechanism. After replacing parts, you need to completely renew the lubricant inside the gearbox.

Video: how to repair and adjust the gearbox

If the grinder smokes during operation

When you are engrossed in stone processing or metal grinding, it is easy to not notice how the tool has overheated. If the work is not stopped, very soon acrid, stinking smoke will begin to emerge from under the casing. This is the armature windings burning, in which, unable to withstand the thermal load, the insulating layer melts. If you do not interrupt the work, the grinder may burn out.

If you notice an unpleasant odor, you should immediately turn off the angle grinder and unplug the power cord from the outlet.

You can begin disassembling the instrument only after the housing has completely cooled down and the emission of caustic fumes has stopped.

Excessive sparking at the manifold

A fan of sparks flying out from under the commutator brushes usually indicates a violation of the insulation on the armature or a short circuit between the wires in the windings. In this case, you should stop working and turn off the angle grinder from the network. Next, you need to disassemble the body and examine the angle grinder’s anchor in detail. The simplest repair option is a complete replacement of the anchor.

Bearings broke

If there is something wrong with the bearings, the angle grinder vibrates and makes noise under load; the sound is dominated by a low-frequency hum. This is due to the fact that the damaged bearing begins to hum during operation. Vibration occurs from the appearance of additional play on the bushings securing the rotating shaft. This malfunction can be eliminated by replacing the bearings. To do this you need to do the following:

1. Remove the brushes from the brush holders.
2. Remove the plastic housing by unscrewing the fastening screws.
3. Remove the gearbox cover and disconnect the drive gear.
4. Remove the armature shaft along with the cooling impeller and bearings.
5. Using a puller, separate the bearings from the shaft axis.
6. Reassemble the structure in reverse order.

Video: how to change a bearing on an angle grinder

If the grinder hums but does not rotate

If the angle grinder shaft does not rotate, there are two most likely reasons, both related to the mechanical part of the tool.

1. The gearbox is jammed.
2. The bearings are jammed.

To check the versions, turn off the grinder and try to turn the tool disk manually. If the spindle does not rotate or rotates slowly, the reason does not lie in the electrical part; you need to disassemble the gearbox and look for the reason there.

If the soft start does not work

If the soft start does not work, the reason lies in a malfunction of the electronic control unit. The solution to the problem is to replace the entire block. Only a specialist with the appropriate knowledge and diagnostic equipment can disassemble the unit and look for the cause of the problem.

Angle grinder device

Any grinder consists of the following parts:

• rotor - part of the electric motor that rotates during operation and is controlled in speed, also called an armature;
• collector - the place on the rotor where the control winding wires are located;
• brushes - parts that serve as current conductors from the cable to the commutator winding;
• gearbox - a mechanism that acts as a drive from a rotating rotor to a spinning disk, consists of a spindle, a bearing, and two gears (a large gear and a shaft gear);
• stator – part of the electric motor in which the rotor operates;
• grinder cooling impeller;
• start button;
• electrically driven network cable;
• protection casing;
• grinder body;
• additional handle.

All these details can be divided into two parts:

What is angle grinder used for and how is it designed?

The angle grinder (angle grinder), or “grinder”, has firmly entered the everyday and industrial life of not only the craftsman, but also the common man who likes to comfortably solve plumbing and carpentry tasks. The popularity of this power tool is due to its simplicity, versatility and multifunctionality of use.

With the help of various additional attachments, the grinder can cut metal, grind various surfaces, and clean them of rust or old paintwork. The angle grinder's arsenal includes such functions as sharpening cutting tools, chipping concrete walls, cutting ceramic tiles or stone.

The device of the grinder

Structurally, the grinder is an electric motor with a power of 500 to 2000 W, which converts the power of electric current into rotational motion. A planetary gearbox, consisting of two main gears with a straight or bevel gear, serves the same purpose. The rotation of the spindle of the working shaft is carried out in direct transmission mode, the speed is determined by the ratio of the number of gear teeth. Some angle grinders are equipped with an electronic engine soft start unit and rotation speed control.

Professional angle grinder with engine speed control

Electric motor type: asynchronous, single-phase. Electromotive force arises when the rotor winding interacts with the magnetic field of the stator, which is fixedly fixed in the housing. Thanks to the angular transmission of torque, the level of safety during operation is significantly increased. If the disk jams in a viscous material, the tool body does not rotate reactively, which prevents possible injury to the operator.

Many have experienced in their own practice the phenomenon of reactivity when operating an electric drill. When a drill bit jams, for example, in hard wood, the body of the device begins to forcefully rotate in the opposite direction, is torn out of the hands and can lead to injury or even disfigurement.

How to disassemble an angle grinder

How to disassemble an angle grinder? It's not such a complicated process. This does not require special knowledge, but everything must be done carefully and with caution. Every owner needs to know how to disassemble any working tool, because periodically it needs internal cleaning from dirt and dust, and its service life depends on this.

Nowadays on the market you can choose different types of grinders, which differ in operating parameters, size, and quality. Manufacturers are also different. Whatever model of grinding machine you buy, they all have the same model for assembling parts.

Disassembling the angle grinder will require few tools; you just need a regular screwdriver or a reversible one with a ratchet mechanism.

Having prepared the screwdriver, you can start disassembling:

1. We unscrew the screws from the body and remove one side of the product.
2. Remove the nut that holds the disk in place and unscrew the bolts securing the protective casing.
3. Remove the brushes.
4. Disconnect the wires from the engine.
5. We unscrew the bolts that secure the gearbox inside and very carefully remove it; the rotor is also removed with it.
6. We unscrew the bolts that hold the stator and remove it.
7. We assemble the angle grinder back, put everything in place one by one in reverse order and screw it on.

When disassembling an angle grinder, it is important to remember the order in which parts are removed in order to assemble it correctly.

Types of breakdowns in grinders

Typical minor damage

In the event of a malfunction, it is first necessary to eliminate elementary breakdowns:

1. The grinder does not turn on. The angle grinder suddenly became faulty - it stopped turning on. In this case, you need to check the serviceability of the socket, then the plug and the power cord; perhaps the drive simply does not work due to the fact that no current flows into the product.
2. The cable and plug are intact, but the drive does not work. You need to check the start button. It is easier to repair an angle grinder switch by purchasing a new button and replacing it. Since it is rarely repairable - mainly, the plastic switch rod inside breaks. If you want to experiment, you can disassemble it, numbering the contacts, and put everything back in its place so that after assembly there is no short circuit.
3. The above parts are unharmed, but the angle grinder does not want to work - which means it’s time to check the brushes. Perhaps it's time to change them in the grinder. Brushes constantly heat up from work, so they wear out quickly and need to be replaced more often than other parts, and in pairs.

Major faults

Having ruled out all minor damage, you need to figure out why the tool does not want to turn on and how to repair it. Most likely, the malfunctions are serious and require additional knowledge. This happens if:

• the body is deformed;
• one of the bearings is jammed;
• the armature or stator does not work;
• the gear teeth of the gearbox are broken or worn out;
• the collector has failed;
• The control electronics sensor shows no signs of life.

If it is determined that the malfunction has occurred in the mechanical part of the angle grinder, then you need to pay attention to the condition of the large gear located on the shaft and the bushings. If the teeth are partially worn out or the shafts become wobbly, they must be replaced immediately.

The most common breakdowns

Grinder malfunctions happen quite often. Everyone who works with this tool knows about this. What goes wrong most often?

The spindle lock button is broken.

Just one awkward press on the spindle lock button while the disk is rotating leads to its breakdown. Sometimes it can be broken if it is used to remove a jammed disk. To prevent this from happening, you need to use an open-end wrench inserted into special holes near the place where the disk is attached.

Broken gear teeth

It mainly occurs when jamming occurs. If you hear a rumble in the gearbox, this is a sign of just such a malfunction. When more than one tooth of a gear is broken, the grinder will not be able to cut the required material.

In order for the tool to continue working, it is necessary to change the gears, all of them, and even the bevel wheel. Before going to the store for spare parts, remember the manufacturer, model and power of the product.

The electric motor does not work.

This type of breakdown occurs with angle grinders that work in places where there is a lot of dust, and when they are given a rest, they are left on the ground. Dust that gets inside spoils the winding. Large loads, especially for a small power angle grinder, result in motor failure.

If the grinder is used for cutting materials that create a lot of dust, then it is recommended to cover the ventilation holes with something.

Bearing fell out

The weakest link, and not only among grinders, are the bearings. High rotation speeds quickly wear out the mechanism. The good news is that changing the bearing is easy. Replacing a worn out bearing on an angle grinder must be done on time to avoid a breakdown that cannot be fixed.

Stator fault

This breakdown is easy to determine when the angle grinder is turned on, but the disk speed is too intense and differs from normal operation - this means that there is a turn short circuit in the stator on the winding. Stator failure is considered the most serious; special skills are required to eliminate it. When you have doubts about your abilities, it is better to turn to professionals so that you don’t have to buy a new tool later.

If the decision to repair it yourself is made, it begins with cutting off the frontal parts of the winding, all remnants are removed. The next step is to make a new winding according to the template. It should be identical in the number of turns, with the same density and from wire of the same thickness as the previous one.

Gearbox

Angler grinders with power less than 1100 W are usually equipped with spur gears. They are located on the stator. Grinders with higher power have helical gears. Each of the options has a cone-shaped shape; the gearbox rod of the angle grinder intersects with the stator shaft at an angle.

Repair of an angle grinder gearbox mainly consists of replacing gears. If a disc gear breaks, it is difficult to replace it because it is very firmly fixed. It is easy to disassemble the gearbox:

• you need to unscrew the nut on its side;
• carefully take the rotor housing in a vice and knock out the gearbox housing with light blows;
• change the position of the clamped rotor and knock out the bearing through a wooden board;
• Unscrew the gear from the shaft.

That's it - the gearbox is disassembled.

Speed ​​controller

Not all models of angle grinders have a speed controller. When an angle grinder is used for cutting, it is, in principle, not needed, but if grinding is carried out, it is simply necessary. If it suddenly stops working, then most likely the board has burned out, which needs to be removed and bought the same one at a power tools store for further replacement.

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Repairing an angle grinder yourself is not always possible. If suddenly something does not work out or everything is not clear, it is better to contact the service center.

Checking the stator with a multimeter

The electrostator is located on the outer portion of the electric motor, on top of the rotor. Before checking the stator, you need to dismantle it and remove the brushes, and then remove the gearbox. First, carefully inspect the winding and make sure that there are no visible breaks or other defects on its surface.

Possible causes and signs of a non-working angle grinder stator:

• A sharp increase in voltage;
• penetration of moisture into the engine;
• overload of power tools and created internal overheating of components;
• abruptly removing the cord from the outlet while the tool is running;
• the appearance of a smell of burnt rubber or plastic;
• case overheating;
• the appearance of smoke from the electric motor during its operation;
• slow rotation of the shaft or its complete absence;
• The grinder sharply picks up speed.

Important! When the protective coating on the winding wires overheats, the varnish melts, releasing a pungent odor, and the winding insulation is damaged. Short circuit of even one winding completely removes the tool from working condition.

The multimeter allows you to check for a break in the stator windings; to do this, you must perform the following steps:

1. The meter is set to R mode to a maximum of 200 Ohms.
2. They begin checking the error of the multimeter, to do this they touch the probes together, the tester arrows should point to “0”.
3. Touch the probes to the terminals on the windings, if the instrument scale shows “infinity”, the winding is not working and rewinding is necessary.
4. Check for the presence of a short circuit on the housing. A very dangerous condition of a power tool that not only causes a loss of power, but is also a potential source of electric shock to the user.
5. Includes resistance measurement.
6. The red probe is installed on the winding terminal, the black one is fixed on the stator housing.
7. When the stator winding short-circuits to the housing, R on the display is less than on the working winding. This failure can only be eliminated by rewinding the windings.
8. To measure an interturn short circuit in an electrostator, R is measured on a separate winding.
9. Determine the “0” point of the windings by measuring R of each. The least resistance will indicate a faulty one.

A multimeter allows you to quite accurately determine malfunctions in the armature and stator of an angle grinder motor. A detected malfunction can be eliminated by rewinding the electric motor or replacing it from the repair kit. Currently, there are enough such sets in the retail chain for most popular models of angle grinders.

Important! When replacing faulty engine components, it is imperative to replace new brushes, especially since they are completely inexpensive.

After repairing the stator or rotor, the tool is reassembled using the saved disassembly photographs. Check the functionality of the tool. If everything is done correctly, the grinder will serve its owner for many more years.

Characteristic symptoms of malfunctions

Before it completely breaks down, the angle grinder gives signals about the beginning of problems.

Pay attention to the work of your assistant: you should be wary if:

• the brushes began to spark excessively;
• The grinder gets hot during operation;
• the motor hums inside the housing when the tool is turned on;
• body vibration has become significantly greater during work;
• the grinder gearbox is cracking inside;
• the sound of bearings squeaking when spinning up or periodic wedging is heard when the rotor shaft rotates;
• The angle grinder is smoking, or there is an uncharacteristic smell of burning coming from it.

In order not to buy a new grinder, you need to be careful about the operation of the tool. In case of any deviations from the usual operation, begin troubleshooting, determine the cause and repair the power tool.

Prevention of breakage of an angle grinder

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

Any angle grinder will get warm during operation, but in order to postpone angle grinder repair for a long time, you must adhere to some rules in work:

1. Do not overload the tool to avoid overheating and smoke.
2. Do not forcefully press on it while working.
3. Clean and lubricate the necessary parts inside the housing in a timely manner.
4. If abnormal operation is noticeable, stop operation and inspect for problems.
5. Replace wearing parts in a timely manner.
6. If the grinder smokes, immediately stop working and do not turn it on again.
7. Do not use the tool when processing wood-type materials.
8. Hold the grinder firmly during operation so as not to drop or damage it.

By adhering to the listed simple recommendations and rules when working with a tool called an angle grinder, you can extend its service life longer than the warranty period.

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

Angle grinders are especially popular among home craftsmen. The possibility of changing the working parts allows for cutting, grinding, and polishing operations.

The presence of a soft start device makes the operation of the tool safe and convenient. Repairing an angle grinder is simple and can be done independently. For those who decide to repair angle grinders on their own, you will need a diagram of an angle grinder of the required type, tools, lubricants and these instructions.

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

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

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

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

Rewinding the armature

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 armature 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 filling coils;
• soldering iron

Before starting to wind the armature, it is important to count the number of turns in the old winding and do the same number on the new coil.

Rewind scheme:

• removing previous windings - try not to damage the surface of the housing. If damage occurs, sand with sandpaper or a file;
• inspection of the collector - the resistance value 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;
• placement of sleeves - they are made of non-conducting material, for example, electrical cardboard. Their size is 0.3 mm;
• rewinding the coils - the end of the new wire is attached to the end of the lamella. Rewind in a counterclockwise direction. Secure the wires near the collector with cotton thread;
• 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 it is not possible to perform such actions, then you can replace the angle grinder’s anchor.

Mechanical malfunctions of angle grinders

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

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

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

It is not difficult to troubleshoot an angle grinder if you have its diagram, description and recommendations for performing repair work at hand.

Repair of plain bearings

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

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

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

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

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

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

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

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

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

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

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

Grinder gearbox repair

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

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

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

Armature fault

There are criteria on the basis of which we can conclude that the anchor requires repair:

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

The presence of these signs indicates a broken anchor. Subsequent use may be dangerous.

The following damage to the anchor is known:

• breakage of electrical conductors;
• short circuit between turns;
• insulation failure, which leads to a short circuit of the winding to the metal surface of the rotor;
• soldering the ends of the collector;
• Uneven commutator wear.

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.

How to properly disassemble an angle grinder gearbox

When repairing the gearbox of any angle grinder, the most difficult task is removing the gears and pressing out the support bearing.

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

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

The destroyed bearing, pos. 1, in the gearbox housing, pos. 2, is easiest to get out by prying it off with a screwdriver.

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

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

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

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

Read also: DIY liquid fuel burner

How to remove gears

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

Gears are attached differently in different angle grinders. The drive gear is mounted on the rotor shaft with a keyed connection or mounted on a thread. The driven gear is secured to the spindle shaft by an interference fit or a keyed connection. Details on how to remove gears and bearings from the shaft.

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

Long-term and uninterrupted operation of the gearbox depends on the presence of a sufficient amount of lubricant and its timely replacement.

Spindle lock button repair

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

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

Checking and repairing the angle grinder's anchor with your own hands 1

Almost all electrical appliances used in everyday life use an asynchronous electric motor. An important advantage of this type of motor is that when the load on it changes, the speed does not change.

This means that if, for example, you cut stone for a long time and without stopping with a household grinder, there will be no noticeable external signs of engine overload. The disk rotation speed will be constant, the sound will be monophonic.

Only the temperature will change, but this may not be noticed if your hands are wearing gloves.

The induction motor commutator is sensitive to overheating

If you are not careful, an advantage can turn into a disadvantage. Asynchronous motors are very sensitive to overheating; a significant increase in operating temperature entails melting of the insulation on the rotor windings.

At first, the motor will work intermittently, and then - when an interturn short circuit occurs - the motor will stop completely. If you overheat the grinder's engine several times, it is most likely that the anchor will melt.

In addition, the high temperature causes the contacts connecting the wires of the primary winding to the collector to become unsoldered, which leads to an interruption in the supply of electric current.

How to determine if an angle grinder's armature is faulty

Signs of a broken armature angle grinder are: increased sparking of the brushes on the motor commutator, vibration of the motor at low speeds, rotation of the working shaft in different directions. If such symptoms are present, you should stop using the tool - this is dangerous. Suspicions can be easily verified using simple tests.

Visual inspection from outside

Troubleshooting should begin with a visual inspection of the angle grinder:

1. Carry out a general inspection of the instrument.
2. Pay attention to the integrity of the power cord and the presence of voltage in the outlet.
3. Using a voltage indicator, make sure that current is flowing to the motor commutator and the start button.

The indicator checks the integrity of the electrical circuit

Inspection of the device from the inside

If everything is in order with the power supply, but the angle grinder does not work, you will have to open the case to gain access to the motor. As a rule, disassembly is not difficult. But you need to follow simple rules that will help you avoid troubles during reassembly:

1. Be sure to disconnect the device from the mains before disassembling.
2. Remove the working disk and protective cover from the spindle.
3. Open the case in a well-lit place, on a clean table surface.
4. Remember the location of all parts and assemblies before disassembling. It is recommended to sketch or photograph the internal structure of the device.
5. Place screws and fastening screws in a separate place so that they do not get lost.

It is best to inspect the engine under bright lighting so that all small parts are clearly visible. The armature should rotate freely around its axis; properly functioning bearings should not make any sound during operation.

There should be no traces of melted wiring on the armature, the circuit windings should be intact, without breaks. You can smell the rotor. When there is an interturn short circuit, the insulating varnish burns and emits a persistent specific odor.

But such a diagnosis requires some experience.

Continuity testing of circuits with a tester

If a visual inspection does not give clear results, it is recommended to continue the examination using a multimeter.

Having set the mode switch to the ohmmeter position (200 Ohm range), you need to “ring” two adjacent armature lamellas with two probes. If the resistance on all turns is the same, this means that the windings are working properly.

If on some pairs the tester shows a different resistance or an open circuit, there is a malfunction in this coil.

Using a multimeter in resistance measurement mode, check the integrity of the coils

A wire break can occur between the winding and the core. You should carefully examine the junction of the coils with the collector lamellas in the lower part of the armature, and visually check the soldering of the contacts.

Checking contacts with a light bulb

If you don’t have a tester, you can get out of the situation using a simple 12-volt light bulb. The power can be any, optimally 30–40 W.

The voltage from the 12 volt battery must be applied to the plug of the angle grinder by inserting a light bulb into the gap in one wire. If the armature is working properly, if you rotate the spindle by hand, the light should light without changing brightness.

If the heat changes, this is a sure sign of an interturn short circuit.

If the light does not light, this may indicate the following:

1. The brushes may become stuck in the non-working position. The retaining spring has worked.
2. There has been a break in the supply circuit.
3. There is a short circuit or break in the stator winding.

There are other diagnostic methods, but they require more sophisticated equipment, which is not usually used at home. An experienced technician will determine the breakdown with a high degree of accuracy using a “punch” or a simple transformer with a cut toroidal core and one primary winding.

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

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

Diagram of an angle grinder's anchor device

If most of the wiring in the armature is damaged and the balancing is disrupted as a result of overheating, it is better to replace it entirely. An imbalance is indicated by increased vibration and an uneven hum when the mechanism operates.

How to rewind an anchor - step-by-step instructions

If the balancing of the armature is not disturbed, and the problem is only in damaged windings, then such an armature can be restored independently by rewinding the coils. Rewinding a rotor at home requires a lot of patience and accuracy.

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

To rewind the anchor yourself you will need:

• wire for a new winding. A copper core with a diameter exactly matching the old conductor is used;
• dielectric paper for insulating the winding from the core;
• varnish for filling 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 onto the coils.

The rewinding process consists of the following steps:

1. Dismantling old windings. They must be carefully removed without damaging the metal body of the armature. If any burrs or damage are found on the body, they must be smoothed out with a file or sanded with emery. Sometimes, to completely clean the body of slag, craftsmen prefer to burn it with a torch.
2. Preparing the collector for connecting a new wire. There is no need to remove the manifold. You should inspect the lamellas and measure the resistance of the contacts in relation to the housing with a megger or multimeter. It should be no more than 0.25 MOhm.
3. Removing old wiring on the manifold. Carefully remove the remaining wires and cut grooves in the contacts. In the future, the ends of the coil wires will be inserted into the grooves.
4. Installation of sleeves for anchors. The sleeves are made of dielectric material 0.3 mm thick, for example, electrical cardboard. Cut a certain number of sleeves and insert them into the grooves of the cleaned anchor.
5. Rewinding reels. The end of the new conductor is soldered to the end of the lamella and wound in successive circular movements, counterclockwise. This laying is called “laying to the right.” Winding Repeat for all coils. Near the collector, tie the wires together with a thick thread of cotton fabric (it is prohibited to use nylon, as it melts when heated).
6. Checking the winding quality. After laying all the windings, check with a multimeter for the absence of interturn short circuits and possible breaks.
7. Finishing processing. Treat the finished coil with varnish or epoxy resin to secure the winding. In factory conditions, the impregnation is dried in special ovens. You can do this at home in the oven. As an option, use quick-drying varnishes for impregnation, applying the coating in several layers.

Replacing the anchor yourself at home

Practice shows that if you decide to replace the armature of an angle grinder, then it is best to change it together with the support bearings and the engine cooling impeller.

To replace you will need:

1. New angle grinder anchor. Must match your model. Interchange with other models is not permitted.
2. Screwdrivers, wrenches.
3. A soft brush and cloth for wiping the mechanism.

How to remove an anchor

Replacing the anchor begins with disassembling the angle grinder. The following steps are performed:

1. Use a screwdriver to unscrew the brush units on both sides. The brushes are removed. To remove, you will need a wide flat-head screwdriver
2. Unscrew the 4 screws securing the gearbox housing. Remove the housing carefully
3. Carefully open and remove the gearbox cover to gain access to the inside of the gear mechanism. To disassemble the gearbox you will need a puller
4. The retaining ring securing the small gear to the armature is removed.
5. The armature retainer is released from its fastening and the armature is removed along with the small gear and bearing.
6. The gear, bearing and armature fixing disk are removed and wiped with a rag. The bearing is removed with a special puller. The puller is activated by rotating the thrust screw

How to put an anchor in place

To install a new angle grinder anchor in place, you should take a new part, and then assemble the tool in the reverse order. The sequence of actions is as follows:

1. A fixation disk is installed on the armature shaft.
2. The bearing is installed using the pressing method.
3. The small gear is fitted and secured with a retaining ring.
4. The anchor is inserted into the gearbox housing, and the docking holes are aligned.
5. The gearbox mounting bolts are tightened.
6. The anchor with the gearbox is inserted into the body of the angle grinder and fixed.
7. The brushes are deposited in their places and closed with lids.

After completing these steps, the grinder is ready for work. The anchor has been replaced.

: how to check an angle grinder

An ancient Sufi wisdom says: “A smart person is one who is able to come out of a difficult situation with dignity. But the one who does not find himself in such a situation is wise.

» By following the rules for operating household appliances and preventing the motor from overheating, 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 eliminate unpleasant surprises during operation.

Source: https://100uslug.com/proverka-i-remont-yakorya-bolgarki-svoimi-rukami/

Electrical malfunctions of the angle grinder

The electrical circuit of the main part of the grinders is almost the same. The rotor transmits torque through a gearbox to the working tool. The rotor rotates in the stator field. The control circuits consist of a button that regulates speed and smoothly starts the tool, and carbon brushes that transmit alternating voltage to the commutator lamellas. Power is supplied to the instrument via the connecting cable.

The main electrical malfunctions of an angle grinder include:

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

Electrical malfunctions of an angle grinder are best determined with a tester or other device. A homemade device, popularly called an “arkashka” .

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

Finding a broken power wire

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

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

Carbon brush malfunctions

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

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

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

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

In grinders, it is recommended to use carbon brushes only from tool manufacturers. Homemade carbon brushes can be installed, but only for a short period and immediately replaced as soon as possible.

Repair of the power button and speed controller

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

It is unacceptable to operate an angle grinder with a faulty power button. This malfunction leads to cutting discs jamming during operation and their destruction with unpredictable consequences.

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

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

Stator repair

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

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

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

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

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

The stator is easy to remove, but different models of angle grinders have their own way.

Stator removal procedure:

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

Angle grinder rotor repair

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

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

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

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

The rotor is a complex assembly that requires repair at service centers. But DIY enthusiasts can repair the rotor themselves.

Repair of commutator and rotor lamellas

Removing the rotor is not particularly difficult.

The procedure for removing the rotor from an angle grinder:

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

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

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

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

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

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

In addition to general malfunctions in models of angle grinders from different manufacturers, there are also specific breakdowns that are characteristic only of the tool of a given manufacturer. But more on that in another article.

Replacing the Anchor on the Bulgarian

Checking, repairing, not replacing the angle grinder's anchor on your own

The angle grinder's anchor is subjected to temperature, mechanical and non-electromagnetic loads than all other components. Therefore, it is a common cause of tool failure, but as a result, it often needs repair. How to check an anchor

You can’t fix the element at home to determine its functionality – in our article.

Angler anchor device

The armature of an angle grinder motor is a conductive winding, not a magnetic circuit, into which the rotation shaft is pressed. It has a drive gear at one end and a commutator with lamellas at the other. The magnetic core consists of grooves of soft plates coated with varnish to insulate each other.

Two conductors of the armature winding are laid in the grooves according to a special pattern. Replacing a burnt armature on an Interskol 125/900 grinder, the rear armature bearing and brushes. The conductor makes up half of the turn, the ends of which are connected in pairs on lamellas. The beginning of the first turn and the end of the last are in the same groove, so they are closed to one lamella.

How to check the angle grinder's anchor for serviceability

Types of armature faults:

• An insulation breakdown to ground is a short circuit of the winding to the metal rotor body. Occurs due to destruction of insulation.
• Wiring of collector terminals.
• Uneven wear of the commutator.

If the armature is faulty, the motor overheats, the winding insulation melts, and the turns become short-circuited. The contacts connecting the armature winding to the collector plates are unsoldered. The current supply stops and the motor stops working.

Types of armature diagnostics:

• visually;
• multimeter;
• light bulb;
• special devices.

Standard diagnostics

While you take the diagnostic device, inspect the anchor. There will be damage here. If the wiring is melted, the burnt insulating varnish will leave black marks, or, in other words, a specific smell.

There are bent, not crumpled turns or conductive particles, nettles, and solder residues. These particles cause short circuits between turns.

The lamellas have curved edges, called cockerels, to connect to the winding.

Due to disruption of these contacts, the lamellas burn out.

Other commutator damage: raised, worn or burnt plates. Graphite from the brushes may accumulate between the lamellas, which also indicates a short circuit.

How to check with a multimeter

• Set the resistance to two hundred ohms. Connect the probes of the device with two adjacent lamellas. If the resistance is the same between all adjacent plates, then the winding is working. If the resistance is less than one ohm and is not very close to absent, a short circuit between the turns occurs. If the resistance is no more than two times higher than the average, then there is a break in the winding turns. When there is a break, the resistance is so high that the device goes off scale. On an analog multimeter, the arrow will go all the way to the right. But digital won’t show anything.

: how is the verification carried out?

If you don't have a tester, use a twelve-volt light bulb with a power of up to forty watts.

How to check the rotor of an angle grinder using a light bulb

• Take two wires and connect them to the lamp.
• Make a break on the negative wire.
• Apply voltage to the wires. Place the ends of the break against the collector plates and do not rotate it. If the light bulb lights up without changing brightness, then there is no short circuit.
• Perform a short circuit test to the iron. Connect one wire to the lamellas and the other to the rotor iron. Then with the shaft. Replacing the anchor on an angle grinder Interskol 125/900. If the light is on, it means there is a ground fault. The winding closes to the rotor body, or the shaft.

This procedure is similar to diagnostics with a multimeter.

Checking with a short-circuited turns indicator (SCI)

There are anchors in which you do not see the wires connected to the collector due to the filling with an opaque compound or because of the bandage. Therefore, it is difficult to determine the commutation on the commutator relative to the slots. An indicator of short-circuited turns will help in this matter.

This device is small in size and not easy to use.

First check the anchor for breaks. Otherwise, the indicator will not be able to detect a short circuit

. For this purpose, use a tester to measure the resistance between two adjacent lamellas. If the resistance exceeds the average by at least twice, it means there is a break. If there is no break, proceed to the next step.

#29 Issue: How to remove an anchor from an angle grinder without breaking anything | Lifehack

Having watched a lot of videos on the topic of removing the anchor

With
the grinder
, I came to the conclusion that no one knows how to remove it.

The resistance regulator allows you to select the sensitivity of the device. It has two light bulbs: red and green. Replacing an anchor on an angle grinder

makita ga9020/repair. Adjust the regulator so that the red light starts to light.

On the indicator body there are two sensors in the form of white dots, located three centimeters far from their native edge. Attach the indicator with the sensors to the winding. Rotate the anchor slowly.

If the red light comes on, it means there is a short circuit.

Diagnostics with an armature testing device (throttle)

The armature testing device determines the presence of an interturn short circuit in the winding. A choke is a transformer that only has a primary winding without a magnetic gap cut out in the core.

When we place the rotor in such a gap, its winding begins to work like the secondary winding of a transformer. Turn on the device, do not anchor a metal plate, a nettle, a metal ruler, or a hacksaw blade.

If there is an interturn short circuit, the plate will vibrate or be magnetized towards the armature body due to local oversaturation of iron. Rotate the anchor around its axis, moving the plate so that it lies on different turns like oil.

Tips on how to remove a bearing from an armature; timely replacement of carbon brushes on an angle grinder. If there is no short circuit, the plate will move freely along the rotor.

How to repair an anchor at home

A third of screwdriver failures occur due to the anchor. With everyday intensive operation, malfunctions arise already in the first six months, nettles, when brushes are not replaced in a timely manner. With gentle use, the screwdriver will last no more than a year.

The anchor can be saved if the balance is not disturbed. If during operation of the device you hear an intermittent hum or there is strong vibration, then this is an imbalance. This anchor must be replaced. But you can repair the winding, not the collector. Small short circuits are eliminated.

If a significant part of the winding is damaged, of course, rewind it. Grind worn, not very damaged lamellas, build them up, or solder them. In addition, you should not undertake anchor repairs if you are unsure of your abilities. Replacing brushes on a makita ga5030 grinder do the brushes on the grinder spark? How to fix it.

It is better to replace it, in other words, take it to a workshop.

Collector groove

After some time, wear from the brushes forms on the commutator. To get rid of it, you need to:

Grind the commutator using cutters for longitudinal grinding, then, of course, through cutters.

Don't forget to clear the rotor of chips to prevent a short circuit.

How to rewind an anchor

Before disassembling the armature, write down or sketch the direction of the winding. It may be left or right. To determine it correctly, look at the end of the armature of an unfamiliar commutator.

Put on gloves, take sharp wire cutters or a hacksaw. Remove the winding end parts. The collector needs to be cleaned, but it is not necessary to remove it.

Carefully, without damaging the slot insulators, knock out the rods of the remaining parts of the winding using a hammer or a metal chisel.

: Remove the winding

Using a needle file, without damaging the insulator film, remove the remaining impregnation. Count the conductors in the slot. Calculate the number of turns in the section, do not measure the diameter of the wire. Draw a diagram. Cut cardboard sleeves for insulation and insert them into the grooves.

: Winding left not right

After winding, weld the section leads to the collector cocks. Now check the winding with a tester not a short circuit indicator. Proceed with impregnation.

Instructions for impregnation (taking into account the speed controller)

• Once you are sure there are no problems, send the armature to the electric oven to warm up for better flow of the epoxy resin.
• After warming up, place the anchor on the table at an angle for better spreading over the wires. Apply resin to the frontal part and slowly turn the anchor. Drip adhesive in anticipation on the opposite frontal part.

At the bottom of the process, lightly grind the commutator. Balance the anchor if you have dynamic balancing without an angle grinder. Now make the final grind on the bearing. It is necessary to clean the grooves between the lamellas; do not polish the collector. Excessive sparking on the armature commutator, replacing the armature on an angle grinder

. Replacement.

Make a final check for opens and shorts.

The peculiarity of the winding for angle grinders with adjustable speed is that the rotor is wound with a power reserve. Current density affects the number of revolutions. Replacing bearings on an angle grinder and the reason is a short circuit on the stator or armature winding. The wire cross-section is too high and the number of turns is too low.

Repair: Elimination of insulation breakdown

If the insulation breakdown was small and you did not find it, you need to clean this place from carbon deposits and check the resistance. If its value is normal, insulate the wires with asbestos. Apply quick-drying “Super Moment” type glue on top. It will seep through the asbestos and will not insulate the wire well.

If you still haven’t found the location of the insulation breakdown, then try carefully soaking the winding with impregnating electrical insulating varnish. Punched or unpierced insulation will be saturated with this varnish and will not become stronger. Dry the anchor in a gas oven at a temperature of about one hundred and fifty degrees. If all this does not help, try rewinding the winding or changing the armature.

Soldering the collector plates

The slats are mounted on a plastic base. They will be erased to the very foundation. Only the edges remain that the brushes cannot reach.

There is an option to restore such a collector by soldering.

• Cut the required number of lamellas to size from a copper pipe or plate.
• If you have stripped the armature of copper residues, solder it with regular tin and soldering acid.
• When all that remains for our client to do is solder the lamellas, do grinding not polishing. If you don’t have a lathe, use a drill or, in other words, a screwdriver. Insert the armature shaft into the chuck. First, sand with a file. Then polish with zero-grade sandpaper. Don't forget to clean the grooves between the slats and measure the resistance.
• There are lamellas that are not completely damaged. To restore them, more thorough preparation is necessary. Lightly grind the commutator to clean the plates.

Source: https://vdiweb.ru/zamena-jakorja-na-bolgarke/