How to repair an angle grinder at home

There can be many reasons.

Does not develop speed, or speed drops due to a breakdown of the speed control unit,

The problems with the grinder brushes are that they spark, there is a drop in speed and it does not develop power, the brushes can be replaced, sometimes you can do without replacement, just clean the brush assembly of the angle grinder (grinder grinder) from dust and dirt.

And you may have to replace the brush holder springs.

There are also more “banal” reasons, my angle grinder lost momentum due to the fact that the wire of the grinder was damaged, or from constant kinks, or somewhere it was touched by a cutting wheel.

The contact was not of good quality, it warmed up under load, and the speed dropped.

Turn off the angle grinder, “feel” the wire with your hands, and find the problem area.

Next, we cut the wire, strip the ends, twist it and insulate it with electrical tape.

But in any case, before you start looking for a problem and methods for eliminating it, you need to remember where the problems started, what preceded it.

The grinder, being the most popular tool in the house, is subjected to considerable loads and intensive use. Because of this, after some time it happens that when starting the engine, jerks, a burning smell and other malfunctions appear, suggesting that the angle grinder (angle grinder) has broken down. But you shouldn’t immediately take the device for repairs or buy a new one. Most malfunctions of this device can be resolved independently.

Do-it-yourself repair of grinder gearboxes

There are
two options to fix an angle grinder malfunction : use the services of a special service center or carry out the repair yourself. When making repairs yourself, you can save money , since the services of professionals are not cheap. If you have the funds and lack of skills, you should take a responsible approach to choosing a company that performs these repairs. It is important that the funds spent do not go to waste. Here, the section of the site “Ulch Grinder Repair” can help, where you can find information about companies repairing angle grinders in different cities of Russia. If the gearbox breaks down, you should think about repairing it yourself. For such repairs, no special tools or equipment are required . To press out the bearings, might you need pullers, which are usually available to a home craftsman? Spare parts can be easily found in specialized stores.

Stages of the lubrication process

Lubrication can be done in special workshops or independently. When performing lubrication on your own, you must remember that a lubricant that does not match the brand of the tool can cause tool failure. The process of processing with new lubricants implies the complete removal of the old lubricant layer. The parts and walls of the housing must not contain remnants of the old coating.

Stages of lubrication of an angle machine gearbox:

• disassemble the grinder;
• wash the sides and cavities of the gearbox with kerosene or a solution of kerosene and gasoline;
• dry the washed parts;
• mix new lubricant;
• coat bearings and cavities;
• assemble the tool.

When applying, the question arises: how much lubrication is required? Applying a large amount of lubricant will cause excess volume to leak out during operation. If the content is low, the operation of the gearbox will be difficult and will lead to rapid failure. Consequently, such a volume of material is placed in the housing that the gear teeth are hidden under the surface of the applied layer. The approximate coverage of angle grinder gearboxes is less than ½ the volume of the entire gearbox.

Device

The grinder gearbox is a mechanical part of an angle grinder power tool. It transmits the rotation of the electric motor rotor to the working tool. The source of energy for grinders is the power supply . The gearbox usually consists of a bevel gear pair with a reduction ratio in order to provide the required number of revolutions of the working tool.

The gearbox is broken, causes and common malfunctions

Increased vibration, the presence of an uncharacteristic sound during operation, strong heating of the case, jamming of the gearbox during operation of the angle grinder require immediate intervention to determine the causes of the appearance of these factors and eliminate them. As the practice of operating angle grinders shows, the most common gearbox malfunctions are caused by the following reasons:

Bearing wear (Lepse)

In the following video, the author completely disassembles a Lepse brand grinder made in Russia (electrical machine-building plant in Kirov) in order to determine the absence of spindle rotation with a normally operating electric motor. In this case, a complete analysis of all disassembled parts is performed. Even high-quality Soviet bearings after 10 years of operation have slight wear, determined manually by the amount of play. For a detailed description of actions in such cases, see the article at the link “Replacing bearings in an angle grinder gearbox.” In the case of the Lepse model grinder, play in the front rotor bearing requires replacing it. After replacing a defective bearing with a new one, it must be lubricated , just like all other bearings of the angle grinder.

Lack of gear clutch (Interskol), gearbox is noisy/clatters

When the Interskol model grinder is operating in the next video, there is a rattling noise , characteristic of a gear pair failure. The assumption was confirmed after opening the gearbox housing, where a breakdown of the drive small gear . Further disassembly of the angle grinder made it possible to determine the probable cause of the gear failure. Increased play in the front rotor bearing could cause increased forces in a pair of bevel gears, which led to failure of one of them.

Backlash (CROWN, Bosch)

Increased play not only of the rotor, but also of the spindle can cause an emergency.

The CROWN model grinder from the following video had increased spindle play . The author drew attention to the strong end runout of the working tool. Working in such conditions can lead to the destruction of , for example, a cutting wheel, which will create an unsafe situation for the person working with the angle grinder and the people around him. The author replaced the bearing using a puller.

In the next video, the spindle play is noticeably larger . This is due to the wear of both bearing units - the ball bearing located in the housing cover and the plain bearing located in the gear housing. Lack of lubrication - this is the conclusion the author draws by analyzing the defects. It should be noted the method by which the plain bearing is removed from the housing. A calibrated rod (in this case, a drill guide) creates pressure on the grease, which tightly fills the cavity of the inner diameter of the sliding sleeve. After loading, the lubricant penetrates into the gap between the bushing and the body and squeezes the bushing out of the seat.

By analogy with the previous two, in the next video there is spindle play in a Bosch model angle grinder . This shows that no special tool is required . to remove and replace rolling and sliding bearings without the use of pullers ; only available means are used, including a latch that matches the diameter.

Stator faults

Failure of the rotor bearing units may cause failure of the stator winding . Therefore, replacing the bearings will not solve the problem of the grinder’s performance. It is required to know how to rewind the stator winding . The video describes how to solve this problem yourself. The main thing is to successfully make a template and select a frame for winding copper wire (in the video this is an air freshener can).

The author once briefly mentioned the impregnation of the finished winding, naming only the impregnating material used - tsaponlak . It seems that there is a certain technology for this operation. However, it won’t be very difficult to fully understand some questions - the main thing is to adopt the basic principles of the technology for self-manufacturing the stator winding presented in the video.

It gets very hot, reasons and solutions

take up significant loads during operation . Therefore, during tooth contact, friction generates a significant amount of heat . Heat removal is ensured by the gear housing material, which has good thermal conductivity, by blowing through the impeller and part of the heat is removed by lubricant .

If the turns of the stator or rotor windings are shorted or the contacts in the brush assembly are broken, the circuit resistance increases, which affects the increase in heat generated. If the temperature of the gearbox housing exceeds the value indicated by the standards, then the reason should be sought in deviations from the normal operation of the above-mentioned components and parts of the angle grinder.

The following videos show the importance of using the lubricant material required by the technical documentation and the timely replacement of used lubricant. Over time, the lubricant becomes contaminated with abrasive materials due to gear wear and when working with materials that emit large amounts of abrasive dust (concrete, stone, ceramic tiles and others). If you use a lubricant that is not intended for use in gearboxes, the gears will quickly fail.

In the next video, the author proposes to remake the contact system of the brush assembly . The previous one included a spring in the electrical circuit, which heated up and quickly lost its electrical properties. The proposed contact system includes parts with a relatively large cross-section relative to the spring and avoids the generation of additional heat.

A set of problems emerged when disassembling the angle grinder in the video. The main source of increased heating here is a broken stator winding . In addition, during repairs, the broken bearing and brushes should be replaced.

How to remove the gearbox

Some designs of angle grinders, where the front rotor bearing is fixed with a flat washer secured to the body with screws, create problems when disconnecting the rotor from the gearbox . The author of the following video suggests making a technological hole in the impeller and unscrewing the screws of the flat washer securing the bearing through it. Problems in removing the gearbox can be eliminated in this way.

How to change

The presented video describes the complete technological process of disassembling , identifying defective parts, replacing them and subsequent assembly of the Makita model angle grinder. This technology contains general repair principles for angle grinders of any model. damage to the housing was discovered , making normal operation impossible. The gearbox was repaired by replacing it with a new housing with an installed fixing mechanism. In addition, worn brushes were replaced.

Should the gearbox of a new angle grinder heat up?

Grinder gearboxes operate under increased loads, so the housing of even new gearboxes heats up . However, in the presence of high-quality lubrication and the absence of technical malfunctions, the body temperature should not exceed the standard values ​​​​presented in the technical documentation attached to the angle grinder. Usually it should be around 40°C.

What to lubricate: CV joint and other options

The best option for lubricating the gearbox is a brand from the manufacturer of the grinder itself . This lubricant is tested on the manufacturer's models, so it is best suited for use. The main disadvantage is its high cost.

Lubricant for Makita angle grinder gearbox, 30 grams. Photo VseInstruments.ru

Users of grinders find options based on domestic oils, which are somewhat worse than branded ones, but much cheaper. CV joint lubricant has good adhesion . If we take it as a basis and add MS-20 liquid oil to obtain the desired consistency, then the use of such a lubricant in an angle grinder is fully consistent with the operating conditions of a bevel gear pair. More information about lubrication of grinder gearboxes can be found in the article at the link.

Getting high-quality lubricant with your own hands

If you want to use a good lubricant composition for an angle grinder gearbox, but there is no possibility of purchasing it, then you should make it yourself using lubricant for CV joints. Do not forget that the material used must have good adhesion.

The composition must adhere firmly to the rubbing elements. The composition for CV joints is characterized by increased adhesion and the ability to work at high temperature loads.

To prepare the mixture, a composition for the CV joint and MS-20 oil are taken to enhance the required viscosity and density. Using a homemade mixer, the composition is mixed with a small supply of oil (drop by drop).

You can also obtain material from a mixture of lubricants Tsiatim-221 and TAD-17. The main component is Tsiatim.

Prevention, maintenance, diagnostics

Carrying out preventive maintenance for angle grinders significantly reduces the likelihood of sudden failure of a power tool . Ultimately, the costs of repair work are reduced, and the grinder’s resource indicators increase. to carry out the following maintenance work regularly, approximately once a year (depending on the intensity of use of the grinder)

1.Perform disassembly.

2. Clean all internal and external surfaces.

3. Check the wear of the graphite brushes . If necessary, replace them following the following procedure:

The brush assembly located on the body of the Makita GA9020 angle grinder provides convenient replacement of brushes. Photo VseInstruments.ru

4. Determination of gearbox defects.

5. Inspection of rotor parts.

6. Inspect the wiring for insulation damage. Check the status of the contacts.

7. Reassemble in reverse order.

8. Check for a few minutes at idle speed.

Maintenance work on the angle grinder will not take much time; timely preventative maintenance will delay costly repairs.

Why does the grinder spark strongly in the area of ​​the brushes?

During normal operation, a small, uniform spark is observed inside the housing. If it is too strong, the brushes must be replaced. The problem occurs in the following situations:

• Damage to the armature winding - an interturn short circuit has occurred or a section of the winding has broken.
• Loss of contact between the winding and the collector plates.
• Violation of insulation between the collector lamellas.
• Severely worn “grinder” bearings , which provoke the beating of the angle grinder’s armature, causing the brushes to spark and burn strongly.
• Using brushes whose characteristics do not correspond to the speed and voltage in the network.
• Motor overheating due to continuous operation for too long.

The grinder does not gain momentum and gets warm

The protection indicator indicates engine overload and battery overheating.

During operation, all components of the angle grinder heat up and if no measures are taken to protect the angle grinder from overheating, the tool may simply fail. What happens when overheating, that is, when the operating temperature of the angle grinder exceeds? Of course, all parts will be subject to linear expansion, the lubricant will lose its viscosity and simply leak out, thus increasing the friction force between the parts of the angle grinder. Not to mention the fact that it will be impossible to hold the instrument in your hands, and this can lead to sudden injury.

In most cases, the electric motor is prone to overheating, which can be protected in different ways. Modern designs of angle grinders provide an indicator that lights up when the temperature reaches 130 ºС; when the temperature rises to 160 ºС, the engine slows down, but when this value reaches 200 ºС, the power supply to the tool is turned off. There are models where temperature control is limited only by an overheating indicator. What is interesting is that some owners of grinders are dissatisfied with such automation and spontaneous stopping of work due to overheating. But it’s better to take an extra “smoke break” than to have the electric motor repaired.

Gearbox housing for grinder MAKITA GA5030

The most common cause of overheating is the gearbox housing of the angle grinder, inside which the gears rotate. Of course, the lubrication and ventilation of the gearbox itself removes a certain amount of heat generated as a result of friction of the parts. But the housing material from which the gearbox is made also plays an important role.

Angler impeller MAKITA 9565

Now they are increasingly making it from metal instead of plastic, and metal, as you know, removes heat better. Although it leads to a heavier overall weight of the tool, compared to the effect of heat removal, this can be tolerated. It should be noted that the term “metal” means a durable aluminum alloy, which has high thermal conductivity.

The impeller may also be involved in cooling the electric motor, the teeth of which are not made at right angles to the axis of rotation, but are inclined - which improves heat dissipation.

I bought a Fag-180/1300 “Dachnik” angle grinder for one-time work. I am not a supporter of such tools, but I chose based on the price, since I considered it irrational to buy an expensive angle grinder “for a one-time use”, and I was unable to rent an angle grinder. While the angle grinder was not in use, I already tried it at idle and discovered an interesting fact: after 1-2 minutes of operation, the gearbox gets very hot (it’s difficult to hold your hand on it). Hence the question: is this a normal phenomenon for such cheap angle grinders or is there a defect that will subsequently turn into a breakdown? I opened the gearbox: there is a lot of green grease in it.

Why does the grinder heat up?

The electric motor overheats in the following cases:

• Incorrect operating mode. As a result of too high loads, the motor windings burn out.
• Destruction of armature bearings. The result is difficulty in operating the engine and, as a result, overheating.
• Clogged ventilation ducts through which air flows to the electric motor, acting as a cooler.
• Closing the turns of the stator and rotor windings.

The angle grinder gearbox overheats due to lack of lubrication or its poor quality.

Design and electrical circuit of the grinder

Over the many years of existence of such a tool as an angle grinder, its appearance, as well as its internal structure, have remained virtually unchanged. To repair an angle grinder with your own hands, you need to know the structure of its mechanical part, as well as its electrical part.

If you look at the figure below, you can see what parts the angle grinder consists of.

The figure below shows the electrical circuit of the angle grinder.

The electrical part of the angle grinder has the following elements:

The following figure shows the connection diagram for the angle grinder, namely its engine.

All components of an electric motor perform specific functions.

The main malfunctions of an angle grinder and their causes

According to statistics, most cases of angle grinder failure are associated with the electrical part of the device. Some damage may be minor, which allows you to repair the angle grinder yourself. But, for example, if the motor windings burn out, only a specialist can repair an angle grinder.

Grinder won't turn on

The reasons that the angle grinder does not turn on may be the following:

The angle grinder does not develop speed

The reasons why the angle grinder does not gain momentum can be different.

Although the brush is half worn out, it is still fully functional. In this case, a short contact wire prevents the spring from pressing the electrode to the collector. This situation may also be the reason why the angle grinder stopped working normally.

The electric motor is heating up

The reasons why the angle grinder is heating up may be the following.

Bulgarian sparkles

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

Damage to the armature winding: break of one or more sections of the winding, interturn short circuit. With such breakdowns, increased noise appears, engine speed drops and brushes burn.

Why won't the grinder turn on?

Most angle grinder problems are related to the electrical part. The tool may not turn on for the following reasons:

It is advisable to solve problems with an electric motor in a specialized workshop that employs qualified specialists and has modern diagnostic equipment and repair tools.

Types of breakdowns in grinders

Typical minor damage

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

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:

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.

Reasons for strong vibrations of the grinder

The source of this problem may be:

• Poor quality of the cutting or grinding wheel, their uneven wear.
• Contamination of mechanisms or severe wear of the mechanical part - bearings, shaft seat.
• Brushes are dirty.

If your grinder stops working, if it makes noise, vibrates a lot or overheats, it is recommended to contact a service center, which will not only fix the current problem, but also diagnose all components of the tool.

Diagnostics of the electrical part of an angle grinder

As mentioned above, most often an angle grinder refuses to work due to breakdowns of the electrical part of the unit. To correctly diagnose the electrical circuits of a tool, electrical equipment repair technicians use a special device - a tester.

If you press 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 angle grinder yourself.

Experts advise adhering to the basic rule of repairing power tools: moving from simple to complex.

The first step is to check the electrical cable and the 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 angle grinder (remove the casing of the device) and “ring” the cable with a tester, and also make sure that the current is suitable for the contacts of the “Start” button. If the device shows a break, the cable should be replaced with a new one.

How to disassemble an angle grinder for diagnostics

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

1. Using a wrench, remove the disk or other attachment from the spindle of the unit.

2. Unscrew the handle.

3. Remove the protective cover.

4. Open the special windows located on the sides of the angle grinder casing and remove the electric brushes, having first disconnected the terminals.

5. Unscrew the gear housing from the angle grinder motor housing.

6. Pull the gear housing lightly and remove it from the housing. In this case, the gear unit will be removed along with the rotor.

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

• To disassemble the gearbox, unscrew the screws holding the cover. After removing the cover, you will see the gears of the gearbox.

• To remove the anchor from the angle 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 may be damaged.

Mechanical breakdowns and their elimination

Mechanical failures of angle grinders include the following.

Mechanical faults can also include a broken shaft lock. In order to replace the retainer, you will need to disassemble the gearbox and remove the large gear.

Industrial gearboxes are one of the most commonly used equipment. However, their active use can lead to wear of parts and subsequently disrupt the technical characteristics of the unit. The main signs of problems with the gearbox are extraneous noise, vibration, oil leakage, heating or freezing of the housing. How to fix all problems with minimal costs?

Rice. 1 — Main problems of industrial gearboxes

If, when inspecting the gearbox, we noticed that oil is leaking from it, the input shaft does not rotate, and it itself makes sounds that are unusual for it - this is a clear sign of problems. We identify the 6 most common root causes of gearbox problems and offer methods to combat them.

Why does the gearbox get hot?

You can accurately determine the heating of the gearbox using a special thermal imaging ; if you do not have one, then the heating can be determined by touch.

Rice. 2 — Checking the gearbox with a thermal imager

The root causes of gearbox heating may be:

Problem:

Solution:

Gearbox surfaces must be clean

Why does the gearbox howl?

If you hear a loud noise or a sharp knock coming from the gearbox, the root cause may be the following:

Problem:

Solution:

— bearings are not adjusted or damaged

adjustment and replacement of the worm pair

Rice. 3 - Damaged worm gear teeth

Why is the gearbox humming?

If, in operating condition, the gearbox makes sounds similar to a hum while vibrating, the problem may lie in increasing the permissible vibration level. a vibrometer - will help you accurately determine the vibration indicator .

Rice. 4 — Determining the vibration level with a vibrometer

Causes of increased vibration levels and their solutions:

Problem:

Solution:

— misalignment of gear and unit shafts

tighten foundation bolts

Why does the gearbox freeze?

The gearbox freezes if you fill it with oil that is not intended for low ambient temperatures. To solve this problem, it is necessary to fill in a special oil, which is universal and suitable for both the summer and winter seasons (for example, TRANSOL-200A oil).

Why is oil leaking?

If you find traces of oil on or around the gearbox, we advise you to immediately inspect the gearbox and take all necessary actions. Oil can flow through the seals and along the plane of contact of the bearing caps to the housing or through the seals. To solve the problem you will need:

Solution:

— the drainage vent is clogged with debris

replace the faulty cuff

Why does the gearbox output shaft not rotate when the engine is turned on?

The output shafts of the gearbox must always rotate freely. If this does not happen, then the reason lies in the following:

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Why does the gearbox get hot?

You can accurately determine the heating of the gearbox using a special thermal imager; if you don’t have one, you can determine the heating by touch.

The root causes of gearbox heating may be:

READ Table for cutting metal with an angle grinder

Gearbox surfaces must be clean

Why is oil leaking?

If you find traces of oil on or around the gearbox, we advise you to immediately inspect the gearbox and take all necessary actions. Oil can flow through the seals and along the plane of contact of the bearing caps to the housing or through the seals. To solve the problem you will need:

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:

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.

Main malfunctions of angle grinders

An angle grinder (“grinder”, angle grinder) is an electric tool necessary for manual cutting, cleaning and grinding of various materials. Depending on the type of wheel used, it is used to work with metal, stone, and concrete. There are models for domestic and professional use. The range of circle diameters is 115-230 mm. Like other tools, “grinders” do not work, get very hot or make noise for various reasons - due to non-compliance with operating rules, too intense loads, and natural wear of parts of components.

How to extend the service life of an angle grinder

If you follow all the rules and recommendations when working with an angle grinder, you can be sure that such a power tool will last much longer than its warranty period.

During the Soviet era, angle grinders were made in Bulgaria. Therefore, the angle grinder began to be called the grinder. Currently, there are many companies producing angle grinders of various models. But the basic elements are the same. After familiarizing yourself with the device, possible breakdowns and diagnostics of the tool, you can repair an angle grinder of any modification with your own hands.

Do-it-yourself repair of grinder gearboxes

There are two options to fix an angle grinder malfunction : use the services of a special service center or carry out the repair yourself. When making repairs yourself, you can save money , since the services of professionals are not cheap. If you have the funds and lack of skills, you should take a responsible approach to choosing a company that performs these repairs. It is important that the funds spent do not go to waste. Here, the section of the site “Ulch Grinder Repair” can help, where you can find information about companies repairing angle grinders in different cities of Russia. If the gearbox breaks down, you should think about repairing it yourself. For such repairs, no special tools or equipment are required . To press out bearings, might you need pullers, which are usually available to a home craftsman? Spare parts can be easily found in specialized stores.

How to disassemble an angle grinder gearbox correctly, video

There are many companies specializing in the production of angle grinders. The basic design principles of angle grinders for all companies are practically the same. However, there are some features that should be taken into account when repairing angle grinders of a certain brand. The experience of such repairs is presented by craftsmen in video formats, it is presented below.

Hitachi

The following video describes in detail the process of disassembling the gearbox spindle of an angle grinder of one of the Hitachi models. This is caused by replacing a stuck bearing located in the gear housing cover. In order to get to it, you must remove the driven gear pressed onto the shaft. Due to the small distance between the gear and the gearbox cover, the puller jaws are modified by grinding their surface to the required thickness in order to fit into this gap. Important: before pressing out the gear, you must remove the retaining ring that secures it.

The gearbox is broken, causes and common malfunctions

Increased vibration, the presence of an uncharacteristic sound during operation, strong heating of the case, jamming of the gearbox during operation of the angle grinder require immediate intervention to determine the causes of the appearance of these factors and eliminate them. As the practice of operating angle grinders shows, the most common gearbox malfunctions are caused by the following reasons:

Bearing wear (Lepse)

In the following video, the author completely disassembles a Lepse brand grinder made in Russia (electrical machine-building plant in Kirov) in order to determine the absence of spindle rotation with a normally operating electric motor. In this case, a complete analysis of all disassembled parts is performed. Even high-quality Soviet bearings after 10 years of operation have slight wear, determined manually by the amount of play. For a detailed description of actions in such cases, see the article at the link “Replacing bearings in an angle grinder gearbox.” In the case of the Lepse model grinder, play in the front rotor bearing requires replacing it. After replacing a defective bearing with a new one, it must be lubricated , just like all other bearings of the angle grinder.

Lack of gear clutch (Interskol), gearbox is noisy/clatters

When the Interskol model grinder is operating in the next video, there is a rattling noise , characteristic of a gear pair failure. The assumption was confirmed after opening the gearbox housing, where a breakdown of the drive small gear . Further disassembly of the angle grinder made it possible to determine the probable cause of the gear failure. Increased play in the front rotor bearing could cause increased forces in a pair of bevel gears, which led to failure of one of them.

Backlash (CROWN, Bosch)

Increased play not only of the rotor, but also of the spindle can cause an emergency.

The CROWN model grinder from the following video had increased spindle play . The author drew attention to the strong end runout of the working tool. Working in such conditions can lead to the destruction of , for example, a cutting wheel, which will create an unsafe situation for the person working with the angle grinder and the people around him. The author replaced the bearing using a puller.

In the next video, the spindle play is noticeably larger . This is due to the wear of both bearing units - the ball bearing located in the housing cover and the plain bearing located in the gear housing. Lack of lubrication - this is the conclusion the author draws by analyzing the defects. It should be noted the method by which the plain bearing is removed from the housing. A calibrated rod (in this case, a drill guide) creates pressure on the grease, which tightly fills the cavity of the inner diameter of the sliding sleeve. After loading, the lubricant penetrates into the gap between the bushing and the body and squeezes the bushing out of the seat.

Popular brands of lubricants

gearbox lubricants are much more expensive than domestic ones. The Bosch brand is widely known among foreign brands. It is used to lubricate tools of the same brand, as well as other models of grinders. The coating has good performance qualities.

Among domestic manufacturers, products called “Metal Plaque Electra” are known. Lubricants of this brand are used for many components of electric tools.

READ Interskol Ushm 125 900 How to Disassemble

Operating an angle grinder without a lubricant coating will first lead to minor operational problems and then to failure of the tool. Lubricated gearboxes will extend the life of the tool and increase productivity. The master himself decides which lubricant is suitable for the existing device.

Prevention, maintenance, diagnostics

Carrying out preventive maintenance for angle grinders significantly reduces the likelihood of sudden failure of a power tool . Ultimately, the costs of repair work are reduced, and the grinder’s resource indicators increase. to carry out the following maintenance work regularly, approximately once a year (depending on the intensity of use of the grinder)

1.Perform disassembly.

2. Clean all internal and external surfaces.

3. Check the wear of the graphite brushes . If necessary, replace them following the following procedure:

The brush assembly located on the body of the Makita GA9020 angle grinder provides convenient replacement of brushes. Photo VseInstruments.ru

4. Determination of gearbox defects.

5. Inspection of rotor parts.

6. Inspect the wiring for insulation damage. Check the status of the contacts.

7. Reassemble in reverse order.

8. Check for a few minutes at idle speed.

Maintenance work on the angle grinder will not take much time; timely preventative maintenance will delay costly repairs.

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Remove the transmission bolts located around the body mount.

To disconnect the armature from the aluminum housing, unscrew the nut located in the gearbox housing.

Reassemble the tool in reverse order.

The clamping nut does not loosen

During operation, the disc may be tightened so tightly with the nut that it begins to crumble. You cannot unscrew a nut with a wrench. And you don't need it because you might break the grinder. First, completely break the disc in the nut. Next, find a metal plate that is slightly thinner than the drive plate. Use it to drain the rest of the disc under the nut. It can be easily unscrewed with a wrench or by hand. To prevent the tool from causing this problem, place a washer under the nut.

How to remove a tightly tightened nut

The casing cannot be removed

Some sanders, such as Bosh, have latches on the body instead of bolts. To remove it, you need to turn the cutout of the housing perpendicular to the coffee grinder. To get dressed, turn until you hear a click.

Stator check

The stator is checked with a multimeter.

Anchor check

First, visually inspect the commutator and winding. Damage may be visible: black marks, bent windings, lifted, worn or burnt commutator plates. After inspection, proceed to the tester.

Determination of breakdown by mass is carried out in the absence of a winding break. Set the maximum resistance on the device scale. Depending on the tester, it can range from 2 MO to 200 mm. Connect one probe to the shaft and the other. To each plate in turn. If there are no faults, the resistance should be zero. Do the same with the rotor. Connect one probe to the iron rotor body and move the other along the plates.

Checking the power button

Put the tester into dialing mode.

Insert one probe into the output of the button and the other into the opposite input.

READ Is it necessary to lubricate the grinder gearbox?

Press the button. A beep indicates the status of that part of the button.

Do the same with the other input and output buttons.

How to ring the start button

Checking the power cord

Connect one probe to the plug and the other. To push-button inputs. There should be a beep in one of the two positions. Do the same with the other plug of the plug.

Checking soft start and speed controller

If the power button and power cord work but the engine does not turn on, check the software control board. Remove the screw that secures the control panel. Remove it carefully. Name all the items. If the grinder has a speed control, it can be wired in series with the power button and have one soft start board. But there may be a separate fee. This is checked in the same way as a soft start.

Source

How to reduce the heating of an angle grinder gearbox / needle instead of a bushing

Due to the work being performed, when the appearance of stone, wood and iron dust is inevitable, as well as its entry into the body of the angle grinder and settling on the moving mechanical parts of the gearbox, the angle grinder needs repeated preventive inspection and boils down to the following actions:

• Removing dust and larger pieces of debris from the gearbox housing;
• Checking the presence of grease in the bearings on the gears, in addition to the integrity of the graphite brushes and changing them as needed.

Based on the circumstances that an angle grinder is a resourceful, massive piece of equipment that gets very hot during operation, the question of what kind of lubricant to use for the angle grinder gearbox is very important. We would like to immediately highlight the types of lubricants, the use of which for the gearbox (bearings and gears) of an angle grinder is not recommended by specialists. This:

Silicone, pigment and lithium lubricants and derivative materials based on them, produced in Russia and imported, have proven themselves to be excellent.

When choosing which lubricant to lubricate the gearbox of an angle grinder, it is worth listening to the worldview of experts in their repair, or simply called long-time users of this tool. Although their ideas will be far from unambiguous.

Thus, CV joint lubricants, widely known among car owners, are equally strongly both recommended and rejected by specialists. At the same time, both states give quite convincing reasons for and against the introduction of CV joints.

We can definitely say that the lubricant for the gearbox of an angle grinder must meet the following requirements:

• Be heat-resistant and not even leak from the gearbox during its heating;
• Increase gliding;
• Reduce the friction force between contacting and moving elements of parts;
• Moderately redistribute the thermal load, immediately performing cooling functions;
• Protect iron parts from corrosion, dirt and dust from penetrating into the mechanism.