Do-it-yourself troubleshooting and repair of the grinder

Choosing a smooth start angle grinder: highlights

Before buying a power tool, it is recommended to clearly determine what scope of work will be performed with its help:

In the first case, you should pay attention to the models for professional use: these are powerful (more than 2-2.5 kW) and ergonomic angle grinders with a smooth start, a speed controller. But the cost of such grinders will be high.

For periodic work, it is enough to purchase an average power machine - about 2 kW. If the work will be performed with thin or soft metals and alloys, then 1.5 kW will be enough.

For use at home, in the garage or in the country, it is better to get a small 900-1000 W angle grinder. This is enough for most jobs: car repairs or small metal structures.

You should also pay attention to the power source - if you often have to work with a tool without access to the mains, then it is advisable to purchase a rechargeable angle grinder and a pair of spare batteries.

Before buying a power tool, it is recommended that you pay attention to important little things.

• Cord length - Power cables that are too short will make your work uncomfortable. Even with a portable extension cord at hand.
• Handle - for long-term operation, it is better to choose an angle grinder with a vibration-absorbing handle. This will reduce fatigue during work.
• Model type (for right-handers or left-handers) - a number of manufacturers produce grinders that can be convenient specifically for left-handers - with a non-standard position of the handles.

• Protection fastening - the casing is fastened either by bolts to the body, or by latches, which allows you to quickly change its position. The rigid mount will force you to unscrew and tighten the screws every time.
• Type of brushes - carbon elements can pass through the body, then they are changed without removing the plastic parts of the angle grinder, in 2 minutes. If the brushes are inside the grinder, you will have to disassemble the tool.
• Clamping nut - there are ordinary ones, which are wrapped with a pin wrench, and there are quick-clamping nuts - they are tightened by hand.

You should also pay attention to whether there is a manufacturer's service center near the place of residence

This is important if you buy a professional tool, it may eventually require replacement of parts.

Expert opinion
Kulikov Vladimir Sergeevich

When buying, you need to clarify information about the warranty period, according to statistics, malfunctions appear in the following sequence.

With proper maintenance and careful handling, angle grinders will last much longer. The table shows the statistics of service workshops

Grinder repair

To remove the rotor, it must be freed from the gearbox pos. This is fraught with overheating of the disc, its deformation and destruction.

Features of the design of the Makita grinder The grinder is an angle grinder, which received this name only in the vastness of the former USSR.

Nuts for fastening the disc are self-locking SDS and conventional with wrench holes.

The higher the speed of its rotation, the more power the grinder has

The reason is just one careless movement, namely, deliberate or accidental pressing of the button when the disc is spinning. If there is no current supply to the button terminals, then the supply electric cable should be replaced.

The principle of operation of Makita grinders is based on the conversion of electrical energy into mechanical energy.

Appointment

The anchor needs to be repaired or replaced. The most convenient way to start diagnostics is from the electric current injection site.

Insert the pre-lubricated LLB bearing into the bearing housing. Before you start repairing a grinder with your own hands, it is best to have in front of you a layout and electrical diagram and detailed instructions that correspond to a specific model.

The electrical component of the grinder design

Practical experience of ordering and arranging ... Knitting. The machine itself has an axle lock button. Diagnostics of the operation of the angle grinder rotor Interturn closure, as a rule, occurs when the tool overheats during operation. At the front end of the armature is a gear for transmitting rotation.

To install discs, a special wrench is attached to the angle grinder, which fixes the nut for clamping the disc. If this element fails, then it is unlikely that an inexperienced worker will be able to restore the winding. How to read a wiring diagram In order to properly repair a grinder or carry out maintenance, you must first of all learn how to read the diagrams of a power tool, including an electric one. Technical indicators The power consumed by the power tool is W.
Diagnostics of the grinder Stopped turning on How to find a breakage Repair of a tool

Mechanical malfunctions of the Interskol grinder

Of the mechanical malfunctions of the Interskol grinders, the gearbox remains a weak point. The gears used in the gearbox wear out over time, the teeth are destroyed, and backlash appears in the joints.

Repair of the gearbox of the grinder Interskol LBM 125

In order to repair the gearbox of the Interskol grinder, it is necessary to establish the nature of the malfunction. Most mechanical gearbox failures are detected visually or by ear. Large runout of the spindle shaft, jamming or turning of the gears of the gearbox are determined by a simple inspection of the condition of the spindle shaft. And the increased noise during the operation of the gearbox, uncharacteristic sounds, overheating can be determined by ear or by touching the body with a hand.

To disassemble the gearbox, unscrew (4) four screws M4 × 14, pos. 11, remove the spring washers DU-1000ER, pos. 12, pull out the gearbox cover, pos. 13. The mounted spindle, pos. 10, will remain in it. The spindle is mounted in the bearing, pos. 14. Bearing size 6201-2RZ. Russian analogue 180201.

Use a press to press the spindle out of the bearing housing. But you can gently knock out with a hammer. The main thing is not to damage the cover of the gearbox housing.

The bevel gear wheel pos. 16 is held on the keyed connection and is fixed with a retaining ring pos. 17. A ball with a diameter of 3 mm is used as a key in the Interskol UShM 125/900 grinder. If you remove the retaining ring, then it is not difficult to remove the gearwheel. In other models of grinders Interskol UHM 125, a key is used.

Remove the gears and inspect for teeth licking, crushing or biting, or play in the keyed connection.

Repair of the gearbox of the grinder Interskol LBM 230

To disassemble the gearbox LBM 230, it is necessary to remove the cover pos. 6 by unscrewing 4 (four) screws. The spindle, pos. 8, is held in the bearing, pos. 9, pressed into the cover body, pos. 6. Bearing size 6203zz. Russian analogue 180203.

The gear wheel pos. 11 is pressed onto the spindle with an interference fit. To remove it, you need a press. Craftsmen manage to remove with a hammer, preheating the gear.

Remove the gears and inspect them for licking teeth, their destruction.

Repair of the grinder Interskol LBM 230

Video:

Possible electrical faults

Malfunctions of the electrical part of the Bosch grinder can be conditionally divided into simple and complex.

Simple malfunctions of the electrical part of the Bosch grinder

If you turned on the grinder, and it refuses to work, start looking for a malfunction with a break in the power supply wire. Often a broken wire appears in the place entrance to the grinder or plug. Do not twist, this will cause a short circuit in the tool.

To determine such a malfunction, you must open the grinder handle covers. In Bosch grinders up to 1000 W, the cover is fastened with one screw at the end. For Bosch grinders over 1000 W, the handle cover is fastened with several screws.

Using a tester, ring the power circuit from the input plug pos. 5 to the switch. With a complete circuit, proceed to test the operation of the switch. Bosch grinders use simple switches controlled by the on-lever.

But the electrical contacts of the switch burn out and cause the grinder to fail. It is impractical to restore the contacts of the plastic switch; it is necessary to change it to a new one.

If the switch is intact, use a tester to check the presence of a circuit from each pin of the plug to each carbon brush. With whole circuits, the grinder should turn on. If it does not rotate, then mechanical failure... Gear jamming or bearing destruction is possible.

Checking the electric motor

If your Bosch grinder is gaining momentum regardless of you, it starts to get very hot, sparkle, you need to pay attention to the integrity of the rotor and stator windings. An involuntary set of revolutions of the LBM indicates a malfunction of the stator windings. The integrity of the windings is checked with a tester, and the short circuit between the turns is checked with a special device.

An involuntary set of revolutions of the LBM indicates a malfunction of the stator windings. The integrity of the windings is checked with a tester, and the short circuit between the turns is checked with a special device.

How to identify a rotor malfunction

Rotor repair is a complex technological process available to straight-handed craftsmen.

A rotor malfunction is indicated by a drop in engine speed, the appearance of a long sparkling trace at one of the brushes. This is the first sign of a short circuit in the turns of the armature winding.

It is preferable to repair the rotor in a specialized workshop. Or you can rewind yourself if you decide to repair the Bosch grinder yourself.

Dark color of the rotor winding and burnt collector lamellas indicate a short circuit in the rotor circuits. The malfunction is eliminated only by replacing it with a new rotor.

Stator repair

The repair of a bosch angle grinder also includes the restoration of the stator. The main symptom of a stator failure is a spontaneous increase in the speed of a working grinder, which cannot be reduced by adjustments. A burnt-out stator winding changes color and becomes darker. The stator core also darkens from high temperatures.

It is easier to rewind the stator, although certain rules and sequence must be followed here.

If you have removed the stator housing cover, carefully inspect the condition of the carbon brushes and rotor manifold fins.

The length of the carbon brushes should not be less than 8 mm. By the way, Bosch grinders use carbon brushes with a "shot", a device that stops the grinder's operation at the minimum length of the carbon brush.

The collector lamellae must be free of carbon deposits or wear. Carbon deposits are easily removed with cotton wool dipped in alcohol.

Overheating of the stator and short circuit of the rotor

Malfunctions of speed regulators

In the Bosch series grinders, especially of low power, speed controllers are installed.Access to the speed controller is carried out by opening the handle of the stator housing, which is held by one end screw.

The speed range of the regulator can be set with a potentiometer hidden in the knob panel.

Removing a faulty regulator is easy enough, since it is attached only to the rail.

Repair of the LDM speed regulator is a complex process, the implementation of which requires not only special knowledge, but tools and equipment.

If the speed controller is out of order, but there is no new one, then disconnect the supply wires and install a jumper.

A jumper is shown in red, which is installed when the speed regulator fails.

Bulgarian and its operation

Angle grinder (angle grinder) is called a grinder. The name of the instrument is due to the fact that it was produced by the Eltos-Bolgarka plant in Plovdiv. It is designed to perform work on grinding or trimming hard material:

• metal;
• concrete;
• stone.

Performs well sharpening of the tool.

The grinder in our time is a very necessary tool, so almost everyone has it.

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

Every year the choice for this construction power tool is becoming wider, but the operating rules hardly change. And even if you always adhere to them, sooner or later malfunctions arise in the mechanism that you can try to fix with your own hands, collecting everything you need to repair the grinder.

Features of operation and repair

If you follow all the requirements of the operating instructions for this device, this will extend its service life.

The most frequent breakdowns of grinders result from several reasons:

worn out parts (brushes most often suffer);
malfunctions of the armature and stator occur due to non-observance of the operating mode recommended by the operating instructions;
overload in the power supply network, voltage surges lead to breakdowns of the stator and rotor;
worn or damaged fasteners (nuts, washers, etc.)

and bearings;
careless and careless handling of the device leads to damage and destruction of the case;
non-observance of the mode of preventive procedures (cleaning and lubrication) is fraught with malfunctions in the gearbox, as well as the "on" button of the device.

If there is no reaction to pressing the power button, feeling a burning smell or uneven operation of the grinder, check the device yourself. The wear of the brushes, their displacement, and the breakdown of the power button itself can lead to such malfunctions. Turn off the unit and try to turn the circle (disk) with your own hands.

If the disc does not spin or moves only when a lot of force is applied, then the cause of the malfunction lies in the gearbox. If the dial is easy to turn, check the power circuits. If you do not find the above faults, test the brushes and the motor. If there is a breakdown in the button, then it must be changed.

If the angle grinder sparks during operation or it slowly builds up speed, there is a breakdown in the anchor. You can try to remove and rewind it on your own, and also entrust this matter to the master. But heed the advice of professionals - this is only a temporary measure. After rewinding, the anchor will work no longer than a month, so it is more profitable to buy a new device, especially since the prices for these devices are quite affordable.

Repair of an angle grinder - do it yourself

Chipped gear teeth. It is best to contact a specialized workshop for stator rewinding.

Tool required for repair

During the repair process, remove the casing and test the circuit at the section where the electric current is supplied to the start button. For the same purposes, for repair and maintenance, we need to know the grinder device, which is inextricably linked with the disassembly process. The control circuits consist of a button that regulates the speed and performs a smooth start of the tool, carbon brushes, which ensure the transfer of alternating voltage to the collector lamellas. Makita grinder models are available for discs with diameters of mm, mm, mm, mm and m.

The shaft gear is threaded. Brushes During the work of the grinder, the graphite brushes are gradually erased. This smoothes the push, and at the same time reduces vibration, ensures the smoothness of the working body. Installing the rotor in the gearbox housing The repaired or new rotor with the bearings fitted is inserted into the gearbox housing, put on, according to the drawing, all the parts, put on the drive gear and fix it with a nut. In production, the gear was heated and the shaft was cooled.

For this, a flat disc surface is used. If your grinder, after assembly, works without extraneous noise, without jerking, you can be congratulated. The gear wheel on the armature shaft has a left-hand thread and is threaded to the armature shaft. Repair of the collector and rotor lamellas Removing the rotor is not particularly difficult.
Do-it-yourself grinder repair

LBM device

Any grinder consists of the following parts:

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

All these details can be divided into two parts:

• electric;
• mechanical.

Step-by-step diagnostics of an electrician with a multimeter or a light bulb

Power failure diagnostics

Perhaps the most common malfunction of a grinder's electrical equipment is a break in the power wires inside the sheath of the power cable. To diagnose and repair such damage, it is enough to disassemble the rear handle of the grinder and check the voltage at the terminals in front of the switch. Another way is to disconnect the cable terminals and use a multimeter to check the resistance of each wire for an open.

Checking carbon brushes

In the process, the carbon brushes are erased and must be replaced when the minimum size is reached. The first sign of a problem with the brushes is an irregular spark ring around the manifold with bursts. Some models have round holes with screw caps for replacement and inspection of brushes. But for most grinders, in order to change them, you have to completely disassemble the body or the rear handle, as in a repair.

How to disassemble angle grinder

How to disassemble a grinder? Not such a complicated process

This does not require special knowledge, but everything must be done carefully and carefully. Each owner needs to know how to disassemble any working tool, because from time to time it needs to be cleaned internally from dirt and dust, and its durability depends on it.

At the present time on the market, you can choose for yourself a different type of grinder, which differ in performance, size, quality. Manufacturers are also different. Whichever model of grinder you buy, everyone has the same assembly model.

Having prepared a screwdriver, you can start disassembling:

We unscrew the screws from the body and remove one side of the product.
Remove the nut that holds the disc, unscrew the bolts securing the protective casing.
We remove the brushes.
Disconnect the wires from the engine.
We unscrew the bolts that fasten the gearbox inside, and very carefully remove it, and the rotor is removed with it.
We unscrew the bolts that hold the stator and remove it.
We put the grinder back, put everything in place in the reverse order and fasten it.

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

What is the angle grinder used for and how it works

The angle grinder (angle grinder), or "grinder", has firmly entered the everyday and industrial life of not only a craftsman, but also a common man in the street who likes to comfortably solve locksmith and joinery tasks. The popularity of this power tool is due to its simplicity, versatility and versatility.

With the help of various additional attachments, the grinder can cut metal, grind various surfaces, clean them from rust or old paint and varnish coatings. In the arsenal of angle grinders there are functions such as sharpening cutting tools, chipping concrete walls, cutting ceramic tiles or stone.

Grinder device

Structurally, the grinder is an electric motor with a power of 500 to 2000 W, which converts the strength of an electric current into a rotational motion. The same purpose is served by a planetary gearbox consisting of two main gears with a direct or bevel gear drive. 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 grinders are equipped with an electronic soft start engine and speed control.

Professional angle grinder with engine speed control

Electric motor type - asynchronous, single-phase. The electromotive force arises from the interaction of the rotor winding in the magnetic field of the stator, which is motionlessly fixed in the housing. Thanks to the angular transmission of torque, the level of safety during work is significantly increased. If the disc gets stuck in a viscous material, there is no reactive rotation of the tool body, which prevents possible injury to the operator.

Preventive maintenance of the angle grinder

Unexpected breakage can be avoided by regularly performing not only visual inspection but also maintenance of the tool. The manufacturer usually indicates the prevention regulations in the passport. In order for the grinder to serve for a long time and without "surprises", you should:

• timely carry out maintenance of the tool;
• comply with the norms of operation and storage;
• avoid long-term operation of the tool under load at reduced speeds;
• do not allow the working part of the tool to be pinched;
• monitor mechanisms and timely change worn parts.

Preventive disassembly, cleaning and lubrication of mechanical parts will increase the service life of the tool by several times. Such uncomplicated maintenance will avoid costly repairs.

The optimal storage conditions for an angle grinder are dry rooms, protected from sudden changes in air temperature. When preserving the instrument for a long time, it is preferable to pack it in a plastic bag in a cardboard box.

All repairs to the power tool must comply with safety regulations. Under no circumstances should the case be disassembled when the device is plugged in. Containers with combustible and flammable materials should not be located near the place of disassembly.

How to remove the bearing from the grinder anchor?

Today, home and professional craftsmen use several methods to solve this problem.If it becomes necessary to remove the bearing from the anchor of a grinder or other tool, this can be done using the following devices:

1. Strippers. These are special devices that allow you to easily and safely remove bearings of different sizes from the anchor of the grinder. The use of pullers practically does not require the use of physical force, even if the bearing is tightly seated. The centering mechanism ensures the simultaneous installation of the device's grippers. It can be used in any position. Before removing the bearing, you need to clean the grinder armature shaft from old grease, shavings, sand so that nothing interferes with removing the part. The centering mechanism allows the puller to position itself precisely. If the bearing is intact, and the dismantling process is carried out for inspection, it should be pulled out by the inner ring so as not to damage it. For large anchor shafts, grinders use a massive puller with three or four gripping paws, and for small ones, devices with replaceable plates or strips are suitable.
2. Hammers, chisels, wrenches and other tools at hand. In this case, in order to remove the bearing from the anchor of the grinder, it is heated with gas, squeezed in a vice, grinded, chopped and performed many other operations. These methods, of course, can be effective, but there is a great risk that the seat of the part will be mechanically damaged. And often the bearing itself after such manipulations without a puller will be unsuitable for further use. In addition, the performer may be injured if pieces of the clip hit the face, eyes or head, which fly apart after impacts.

As practice shows, pullers are more effective in this situation. They allow you to quickly, easily and without much risk remove the bearing from the armature of the power tool and inspect or replace parts. If you have to periodically carry out such operations, you should acquire such a useful device. The use of improvised devices is permissible only if you have experience in repairing power tools and an urgent replacement of a part is required.

A few words about the lubrication of the Interskol grinder

Before assembling the mechanical units of the Interskol grinder, without fail, lubricate the parts with the recommended lubricant. Lubricants of foreign and Russian manufacturers are widely represented on the Russian lubricant market. Today you can buy high-quality lubricants from a domestic manufacturer. They are in no way inferior in quality to foreign counterparts, but they are several times cheaper.

A special grease has been developed for the grinder gearboxes with high adhesion. Adhesion is the property of a substance to adhere to a lubricated surface.

Conclusions:

• Choosing a grinder, opt for a Russian angle grinder from Interskol;
• You will get a reliable, durable, ergonomic, cheap tool;
• Give preference to Interskol grinders of the UHM 125 class;
• In the household, they are more in demand and safer.

I wish you success!

Care and proper operation of the grinder

To make the grinder work for a long time, follow the rules:

1. Watch the integrity of the insulation of the wire, plug. Do not remove protection.

2. Lubricate and clean the entire tool.

3. Regularly check the wear of the brushes and the contamination of the brush holders.
4. Do not overheat the instrument.
5. Don't quit.

6. After turning off the grinder, wait until the circle stops rotating, then put it on the ground. When the engine stops, the tool sucks in particles of earth and other hard particles through the air vents, which hit the winding of the motor. The result is an open or short circuit.

   

   

   

   

   

   

   

   

   

   

7. Try not to use the grinder outdoors in winter. The engine heats up while you are running. The air is icy.As a result, condensation forms. Moisture is harmful to the engine.
8. Always use the circles recommended by the tool manufacturer. If the grinder is 180 mm, do not put more than 200 mm there. The larger the circle, the lower the rpm should be. You will have to remove the protection, and the turnover will be exceeded. Oscillation and vibration will increase. As a result, the circle will fly apart. This is fraught with not only serious injuries. The bearing of the reducer is broken, the gears are erased.

If you actively use a grinder, then you are a good master. It will not be difficult for you to understand the structure of the tool and fix it with your own hands. First, find the problem and determine which parts to check

Repair the grinder carefully, without haste, so that minor damage does not turn into a major one.

Features of the device. Differences between models

The grinder (angle grinder) appeared in the middle of the 20th century and quickly became an important tool for manual metalworking. Its advantages:

• Versatility: the tool allows you to cut, clean and polish.
• The increase in processing speed compared to hand tools and machine tools - this applies to small amounts of work.

• Ease of maintenance - no adjustment of angle grinder is required, and its care consists in periodic cleaning, blowing from dust.
• The small size allows you to carry the grinder around the work area.

But there are also negative aspects:

The angle grinder is an electric motor that transmits torque to the main shaft with fixing nuts through a gearbox. Circles are clamped in them: cutting, cleaning, polishing.

Expert opinion
Kulikov Vladimir Sergeevich

Grinders from each other mainly differ in size, engine speed and electric motor power

You should also pay attention to the size of the discs with which the grinder can be used.

Standard sizes:

Wheels for cleaning work, as well as for processing stone and other materials, may be different.

It is recommended to purchase models with a soft start - this option increases the resource of the motor. After pressing the button, the engine does not immediately reach operating speed, but with a slight delay - that is, it unwinds smoothly.

Adjusting the speed of the electric motor expands the field of application of angle grinders - the tool can be used for grinding and polishing surfaces. These operations are carried out at reduced revolutions.