Can I Install a Non-Diameter Diameter Disc on a Grinder?

You have long been using an expensive angle grinder of 1600 watts for a disk size of 230 mm. But disks have a nasty property to end. Not always at hand is just a large disk. And if the work is trifling? Do not buy healthy pancakes for 10 minutes of cuts. But it is full by 125 mm, 180 mm. Can I use them in our tool. We will talk about this in this article.

Bit of theory

All cutting wheels for this tool are designed for a very specific rotation speed. The closer to the spindle, the higher it is:

  • with a diameter of 115-125 mm. 10,000-11,000 rpm;
  • an increase in diameter to 150-180 mm lowers it to 8000-8500 rpm;
  • large diameters on powerful grinders operate at a speed of about 6000–6700 rpm.

Opportunities, dangers of working with inappropriate drives

It is tempting to set circles larger or smaller. Let’s try to predict the work of angle grinders and the difficulties that can be encountered.

  1. On a tool with the same spindle speed, you can install a pancake close in size, given that this is simple and the seat is the same. Instead of a 125 mm circle, 115 mm can be installed. This is normal. the spindle rotation is the same, the diameters are almost the same.
  2. Having tried to put a circle of 125 mm instead of a smaller one, we will encounter a mismatch in the height of the protective casing. The gap will remain, but will be too small. After this, you must either change the casing to a larger protection, or to remain without it. Rotational speeds are the same, the probability of spurious vibration is minimal, but no one has canceled the safety rules. There is a possibility of breakdown, and sparks hindering anywhere. Damn can pinch in the metal, bend strongly with an awkward movement. It will be able to fly apart due to poor workmanship. You can’t do this!
  3. Grinding wheels with a landing size of 150-180 mm can also be interchanged. For these models, the speed is already lower. up to 8500 rpm. Therefore, you can easily put a little smaller. But it will be difficult to do the opposite. protection will interfere. It remains to remove or put the appropriate diameter. The dangers of working without a casing were discussed above.
  4. Replace the circle on a very large grinder with a very tiny one. Theoretically, this is real, but the mass and dimensions of the tool will prevent accurate work. The disc size beyond the spindle diameters is also small. Small pancakes have a thickness of 2-3 times less, so the inconvenience of working threatens to break the circle. A high protective cover does not effectively protect against debris.

Video: Can I Install a Non-Diameter Diameter Disc on a Grinder?

It happens that on a small device you need to install a large circle. The nuances of this manipulation:

  • the casing will interfere and have to change to a larger one or work without it;
  • at speeds of 11,000 per minute, large loads are contraindicated. you can only gently cut off thin metal;
  • the size of the pancake is comparable to the size of the tool, which will complicate the work with fast cuts of thick metal and threatens to tear the apparatus out of the hands when the disk is jammed;
  • having an adjustment of revolutions, they can be reduced to 8000, but the problem of small leverage and tool weight will not go anywhere, and this threatens injury.

Note that you need to responsibly approach work and safety during its implementation. Therefore, do not place large circles on the small devices. they will not withstand the loads. It is required to use only discs for specified rotation parameters.

How to Lubricate a Bosch Angle Grinder Reducer

Angle grinders (angle grinder, angle grinder) under the German brand Bosch are of high quality, reliability and durability. The main competitive advantage of Bosch angle grinders lies in the widespread use of innovative technologies in the manufacture of the product.

But German quality cannot resist Russian negligence. Improper use of the tool, untimely replacement of grease, carbon brushes, bearings leads to failure of the tool.

In order to repair a Bosch angle grinder, you can go in two ways: give the angle grinder to a service center or repair the Bosch angle grinder with your own hands.

The first option is more expensive and not always high quality. The second option can be implemented only if the consumer has a great desire to figure everything out on his own.

A diagram of the Bosch angle grinder will help you repair yourself.

Bosch angle grinders are conventionally divided into low-power up to 1000 W, and powerful over 1000 W are marked GWS 7-125, GWS 20-230 or others.


The first number of 20 or more indicates a tool power of more than 1000 watts. The second number 230 confirms that this is the maximum diameter of the cutting wheel.

The first digit up to 20 indicates the power of the tool up to 1000 watts, and the second about the maximum diameter of the cutting wheel up to 125 mm.

Design Features of Bosch Angle Grinder

The design feature of the Bosch angle grinder is presented in the gearbox as a thrust bearing of a driven helical gear of a needle bearing. In Bosch rotary hammers, the driven gear is mounted on the spindle shaft by compression.

In Bosch angle grinders of low power, in which spur gears are placed in the gearboxes, the installation of shims is provided. This design allows you to restore the functionality of the contact gears, reducing the thickness of the gasket. Helical gears at high tool speeds wear out significantly less than spur gears.

How to Lubricate a Bosch Angle Grinder Reducer

The working environment of grinders is most often a dusty space. Dust is the main danger leading to failure of the power tool, an amorous and angle grinder.

Repair tool required

To repair a Bosch angle grinder, a tool is indispensable. We’ll make a reservation right away, if you have a screwdriver, this will significantly speed up the process of disassembling and assembling the tool.

But you can get by with a set of screwdrivers, preferably with a ratchet mechanism. You can not do without an open-end wrench, with which you will unscrew the nut securing the leading helical gear.

It is better to have a special puller for dismantling the bearings.

Diagnostics of the electrical part can be carried out using a tester or a short circuit detection device.

It is especially useful in that it allows you to determine the malfunction of the rotor or stator without removing the assembly.

The diagram of the Bosch angle grinder will help you carry out repairs yourself, and these instructions will help you adequately cope with any problem.

DIY disassembling Bosch angle grinder

For the owner of a power tool, knowledge of his device and the ability to disassemble is a must.

Knowing the disassembly procedure, the angle grinder allows you to independently perform such tasks as changing grease, changing bearings and carbon brushes.

To disconnect the gear housing pos. 821 from the stator housing pos. 888, it is necessary to disassemble (remove) the handle housing, angle grinder pos. 24.

This operation must be performed to remove the carbon brushes pos.810 holding the rotor manifold.

In the second stage, unscrew the 4 (four) screws pos. 61 that secure the gear housing and stator.

Having pulled out the rotor together with the gearbox, proceed to disassemble the gearbox.

Repair angle Bosch grinder begins with the disassembly of the gear pos.821. Dismantling of the gearbox starts with unscrewing 4 (four) screws pos. 60. As a rule, the screws are screwed into the sealant at the factory. Will have to make some efforts.

Just note! For Bosch low power grinders, the gearbox uses spur gears. For grinders with a power of more than 1000 watts, helical gears are used in the gearboxes.

How to remove the driven gear

After removing the gearbox cover, you can get the helical gear assembly pos. 26.

To remove the gear, you must use a press or puller. But the use of a puller is difficult, because it requires the use of special thin sponges.

Before removing the helical gear, check the gear backlash, tooth integrity, contact spot.

A bearing pos. 50 is pressed onto the spindle shaft, pos. 26. If the bearing has a large backlash, it is noisy when scrolling, the grease has dried, it is preferable to replace it.

To remove the bearing, it is necessary to remove the gear wheel, circlip and dismantle the bearing. If the bearing remains in the gear housing while removing the rotor shaft assembly, the bearing is removed using a hammer and a soft tip.

How to remove pinion Bosch angle grinder

Leading gear pos. 27 is removed from the rotor shaft in the following sequence:

  • hold the rotor by hand and use the open-end wrench to unscrew the nut pos. 45 counterclockwise;
  • remove the washer pos. 59.;
  • pull out the helical gear, key 27.

Check visually the integrity of the gear teeth, contact spot.

If the gears are very worn (licked), there are chipped teeth, then they must be replaced. over, the replacement of gears is always done in pairs.

In low-power Bosch angle grinders, a needle bearing is used as a support bearing in the gearbox.

Do-it-yourself bosch angle grinder repair follow the strictly attached instructions. If you need to remove the needle bearing from the housing, quick thinking is indispensable. Its dismantling is carried out only at destruction.

To get the destroyed bearing race, you can use the proven method.

Video: How to Lubricate a Bosch Angle Grinder Reducer

A tap is selected with a diameter slightly larger than the inner diameter of the cage of the destroyed needle bearing. The tap is fixed in the screwdriver’s chuck and screwed carefully at low speeds into the clip. When the tap reaches the bottom of the gear housing, it will begin to raise the clip.

In addition to the spindle shaft needle bearing, Bosch angle grinders also use two more bearings mounted on the rotor shaft.

How to remove bearings from a rotor Bosch angle grinder

To remove the bearings from the rotor, pos. 803, Bosch angle grinders are recommended to use pullers.

The bearing pos.15 near the collector is easily removed, but to remove the bearing pos.14 from the impeller side, it is complicated by the fact that a number of preparatory operations are necessary.

The bearing pos.15 is closed by a soft rubber socket. A similar rubber protection pos.33 also covers the bearing pos.14.

To remove the bearing pos. 14, unscrew the nut pos. 45, remove the spur gear pos. 17 and the plastic protection pos. 33. Using a puller, you can easily remove the bearing from the rotor shaft.

And if there is no puller? A vice, two metal strips and a hammer with a soft metal extension will come to the rescue.

Dismantling Bosch angle grinder

Possible electrical problems

Faults in the electrical part of the Bosch angle grinder can be divided into simple and complex.

Simple electrical faults Bosch angle grinder

If you turned on the angle grinder and it refuses to work, start looking for a malfunction with a broken power supply wire. Most often, a wire break appears at the entrance to the angle grinder or to the fork. Avoid twisting; this will cause a short circuit in the tool.

To determine such a malfunction, it is necessary to open the handle covers of the angle grinder. In Bosch angle 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 secured with several screws.

Using the tester, ring the power circuits from the input plug, pos. 5, to the switch. With the whole circuit, proceed to check the operation of the switch. Bosch angle grinders use simple switches controlled by a switch lever.

But the electrical contacts of the switch burn up and become the cause of the failure of the angle grinder. It is impractical to restore the contacts of the plastic switch, it is necessary to replace it with a new one.

If the switch is intact, use a tester to check for the presence of a chain from each pin of the plug to each carbon brush. For whole chains, the angle grinder should turn on. If it does not rotate, then the malfunction is mechanical. Jamming of gears or destruction of bearings is possible.

Motor check

If your Bosch angle grinder is gaining momentum regardless of you, it starts to get very hot, spark, you need to pay attention to the integrity of the rotor windings, stator windings.

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

How to identify rotor failure

Rotor repair is a complex process available to foremen with straight arms.

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

Repair of the rotor is preferably carried out in special workshops. And you can rewind yourself, if you decide to repair the Bosch angle grinder yourself.

The 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 with a new rotor.

Stator Repair

Bosch angle grinder repair includes stator restoration. The main sign of stator failure is a spontaneous increase in the speed of the working angle grinder, which cannot be reduced by adjustments. A burned stator winding changes color, becomes darker. The stator core also darkens from high temperature.

The stator is easier to rewind, although here you must follow certain rules and sequence.

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

The length of the carbon brushes should not be less than 8 mm. By the way, in Bosch angle grinders, carbon brushes with a “shot” are used, a device that stops the operation of the angle grinder with a minimum length of the carbon brush.

The collector lamellas must not show any deposits or wear. Carbon deposits are easily removed with cotton wool soaked in alcohol.

Stator overheating and rotor short circuit

Speed ​​control malfunctions

In angle grinders of the Bosch series, 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 on one end screw.

The speed range of the controller can be set with a potentiometer hidden in the handle panel.

It is quite easy to remove a faulty regulator, since it is mounted only on the guide.

Repair of the speed controller angle grinder 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.

Red shows the jumper installed when the speed regulator fails.

Mechanical damage

Bosch angle grinder is designed for cutting, grinding, polishing work. The operation of the tool in dust at high loads is particularly detrimental to the durability of the gearbox, namely its gears.

In addition to wear and tear of gear teeth, mechanical failures include the destruction of bearings and the housing. Repair of the Bosch angle grinder in terms of replacing failed bearings and rebuilding the housing is not difficult if there is a desire and need.

Assembly angle grinder

The assembly of the angle grinder begins with the examination of all parts, assemblies, bearings, gears.

Pre-prepare the workplace with proper and good lighting, lay tools, lubricants, wipes.

What grease to use for a Bosch angle grinder

Repair to Bosch ears will not be of high quality if you do not change the grease during its execution. For high-quality lubrication of components, Bosch angle grinder is recommended to use those lubricants that are offered by the tool manufacturer. But their high price makes us look for another way, and there is one.

Domestic lubricant manufacturers have developed special lubricants for gearboxes and grinder assemblies.

In terms of quality, they are in no way inferior to foreign lubricants, but are much cheaper. The only negative, our lubricants require a more frequent change.

Rotor assembly

The assembly of the rotor consists in mounting bearings on it, installing the impeller. Lubricated bearings are pressed onto the shaft using a wooden extension. The bearing near the collector is closed with rubber protection. This is a general rotor shaft assembly algorithm.

In some models, the Bosch angle grinder has its own characteristics.

Gear assembly

The assembly of the gearbox begins with the installation of a rotor shaft in its housing. When the shaft is inserted into the housing, the drive gear, washer, and lock nut are put on the shaft. The gear housing with the inserted shaft must be placed in the stator housing.

When you insert the collector bearing into the socket, push the gear housing to the stator housing. Check the ease of rotation of the rotor in the bearings.

A spindle assembly with a mounted bearing and gear is mounted in the gear housing cover.

It remains to insert the cover into place and check the quality of rotation of the spindle shaft. If the shaft rotates easily by hand, it is fashionable to tighten the screws securing the rotor housing cover. The screws are pre-lubricated with sealant.

This is a general gearbox assembly algorithm. On some models, the repair of the gearbox Bosch angle grinder is slightly different.


  • Knowing the general scheme of Bosch grinders, you can safely take on the dismantling of a tool for lubrication;
  • The ability to repair a Bosch angle grinder with your own hands will extend the life of the tool, independently replace the grease, carbon brushes;
  • Observing the operating mode and technological maintenance of the tool, you will extend its trouble-free operation for many years.

Gear Lubricant Makita Angle Grinder

The long-life guarantee of any hand tool is its regular periodic maintenance. Of course, you can send for service and diagnostics to special service centers, but as they say, "If you want to do well, do it yourself." Therefore, it is worthwhile to figure out how to independently service such a tool popular among home masters as an angle grinder or angle grinder, in common people.

Gear Lubricant Makita Angle Grinder

The most susceptible to wear are the moving parts of an angle grinder. These are the bearings of the anchor, gears, as well as the gears themselves located in the gearbox. The lubricant (or lubricant) laid by the manufacturer ages over time, its properties are lost, all this leads to more wear of the gears in the gearbox and, as a consequence, to increased vibration and the appearance of extraneous noise during operation. Periodic maintenance and replacement of the lubricant in the gearbox angle grinder must be carried out at least once a year.

Characteristics and features of greases for grinders

When servicing any hand tools with moving parts, a lubricant is used that has the following characteristics and features:

  • There should not be solid particles in it that can cause chipping of the moving parts of the mechanism.
  • The temperature at which the lubricant becomes liquid should be more than 120 degrees.
  • The oil should not absorb moisture, should form a strong film that protects parts from corrosion.
  • And also, most importantly, the oil must be of such viscosity that it has the ability to stay on moving parts.

The consistency or viscosity of the lubricants is divided according to the NLGI (National Lubricating Grease Institute), and in certain cases it is necessary to use oil of a certain density. The viscosity of the oil is selected depending on the speed of the gearbox, the higher it is. the more liquid the oil should be. So, depending on the tool, the viscosity is selected:

  • Drills, punchers, jigsaws, where the gearbox has a low rotation speed. NLGI-2 grease which is soft.
  • Lightweight punchers and impact drills. Class NLGI-1, the consistency is very soft.
  • angle grinder, circular saws, lawn mowers. Class NLGI-0, semi-fluid in consistency.
  • Heavy punchers, jackhammers. Class NLGI-00, by consistency, is liquid.

Gear Lubrication Angle Grinder

Almost all world tool manufacturers require their recommended “own” lubricant sold under its brand. In principle, this is correct. The grease used for the gearbox angle grinder, in this case is tested at the factory, it gives a guarantee of long-term and correct operation of the angle grinder. However, there are drawbacks, which are in the high price of the lubricant from these brands.

Open Gear Lubrication Angle Grinder

In addition to the original oils, there are many lubricants on the market that are produced by third-party manufacturers, so the question of what exactly to lubricate the reducer with an angle grinder is not acute.

The products of Haskey, Castrol, Liqui Moly and others have shown themselves to be good for adding to an angle grinder.

Russian manufacturers also do not lag behind foreign ones and offer their products. So, the grease of a bevel gear reducer is an angle grinder from the company Nanotech. Of course, such a lubricant for the gearbox is not original and recommended by the manufacturer, therefore, if used, subsequent warranty repairs may simply be refused.

The correct lubricant filling process in angle grinders

After the choice of lubricant for the angle grinder is made, proceed directly to the maintenance of the tool. The correct maintenance process for an angle grinder consists of several steps. First you need to open the gearbox, then remove the old lubricant, apply a new one, check the correct application. Removing the old grease is necessary for the reason that when mixed with a new one, it will not allow it to work correctly and the entire maintenance procedure will not bring any result.

Video: Gear Lubricant Makita Angle Grinder

Correct lubricant filling in angle grinder

When to change grease in an angle grinder

The frequency of lubricant change depends on how often and under what loads the tool is operated. As a rule, this period is about a year. In the case of intensive operation with frequent overheating, the frequency of replacement is reduced to six months, sometimes more often.

For maintenance, you will need to disassemble the angle grinder gearbox by unscrewing 4 screws on its cover.

After removing the cover, you can see two bevel helical gears: a large and a small gear. The small gear is anchored and drives the large gear. The large one, in turn, is seated on the secondary shaft, to which a cutting or grinding disc is attached.

How to remove old grease in an angle grinder

The disassembled gear angular grinder must be well cleaned of the old lubricant. It no longer fulfills its functions, plus solid particles have already accumulated in it, resulting from wear of moving parts. When mixed with new, old lubricant also significantly degrades its performance. Therefore, the gearbox and gears must be thoroughly cleaned.

Removing old grease from the gearbox

Old grease is removed with a rag, paper towel or just a rag. Removed parts can also be washed in gasoline or thinner. The washed parts must be thoroughly dried before assembly. Residues of solvent or gasoline will mix with the new grease and change its consistency, which again worsens its performance.

Lubrication procedure for gearbox angle grinder

Before applying a new lubricant, it must be thoroughly mixed and monitored so that there are no lumps or foreign objects in it. A thin layer of lubricant is applied to the gears, making sure that it completely covers the teeth. It is more convenient to fill the grease inside the bearings with a syringe. Then the grease intended for the angle grinder is driven into the gear housing. This is necessary for the reason that during operation it can fly off the gears and with a small number of gears, the gears will work “dry”.

How much grease should be used when replacing the angle grinder in the gearbox

The amount of lubricant placed in the gearbox must be such that the oblique teeth of the gears are completely covered by it. Excess will cause it to squeeze out from under the cover, and an insufficient amount will not ensure the correct operation of the gearbox.

It is best to focus on the amount that was planted at the manufacturer of the angle grinder, but remember that the grease can dry out, while decreasing in volume.

In this regard, it is better to put a little more and check the correct distribution of the lubricant after turning on the angle grinder. In general, the amount of lubricant is usually approximately 30-50% of the full capacity of the gearbox.

Gearbox grease applied

Checking the correct application of lubricant to the gearbox angle grinder

The last step during the maintenance of the angle grinder is to check the correct application and distribution of the lubricant inside the gearbox. To do this, after the gear unit is assembled, the power tool is turned on without load for several minutes, while it should be ensured that there are no extraneous sounds, odors and other things. If they occur, you must immediately disconnect the angle grinder from the network. The heating of the gear unit is also checked. The lubricant must distribute the heat evenly and the temperature of the gear unit must not be very high.

After a short operation, unscrew 4 screws, then remove the cover from the gearbox. Visually inspect helical gears for grease. If it is absent, it means that too little lubricant has been incorporated and should be reported. If in the process of work it is squeezed out of the cracks, then it means it was laid too much and the excess should be removed. After making any changes, the operation of the angle grinder without load is again checked.

Grease overview for angle grinder

Earlier it was said that there are many types of lubricants both from a foreign manufacturer and from a domestic one. Good lubricant for power tool gearboxes is available from Bosh. It is called “Grease for gearboxes” and is packaged in tubes of 65 grams. One such tube is enough for a few maintenance angular grinder.

Lubricant for gearbox angle grinder of various brands

From the lubricants intended for the reducer to the angle grinder manufactured by the domestic manufacturer, one can recommend the products of the company Nanotek. It is called "Nanotek MetalPlak Electra" and is designed for tools that work with intense load. SHRUS or Tsiatim-221 are also widely used from domestic lubricants, however, they require preliminary preparation and, in fact, are a home-made lubricant.

DIY Grease Angle Grinder

DIY grease for gears angle grinder consists of a base and thinner. The basis for homemade lubrication is usually SHRUS with molybdenum disulfide or Tsiatim-221. They have a second viscosity according to NLGI, therefore, for use in the reducer of an angle grinder, the base must be diluted. As a diluent, it is best to use a simple mineral industrial oil, which, for example, is I-20 oil. To obtain an NLGI 0 viscosity, approximately 70 percent base and 30 percent diluent will need to be mixed. The resulting mixture is thoroughly mixed and ready to be applied to the gears and bearings of an angle grinder.

DIY grease making

Timely maintenance of any electric tool is the key to long-term and trouble-free operation. A properly working tool is also a guarantee of safety for the person using it. Using the tips given above, everyone can correctly choose the lubricant for the gearbox angle grinder and replace it without resorting to the help of expensive service centers for servicing power tools.

Makita 125 Angle Grinder Variable Speed

Angle grinder, which is popularly called the angle grinder, is a universal tool with which you can perform a list of works: cutting, grinding, cleaning metal, wood, stone and other materials. This tool has found its application in industry. It is ideal for both professional repair work and household chores.

Makita 125 Angle Grinder Variable Speed

Now on the market there are a large number of different models of angle grinders designed for home or professional use. The latest angle grinder with speed control is equipped with special nozzles of any size, characterized by the presence of descent safety locks and additional functions. With all the variety of models and sizes, an angle grinder has a common task, which is to facilitate the person’s workflow as much as possible and save time.

Which angle grinder to choose? Household and professional tools

When buying an angle grinder, you should take into account such indicators as rotation speed, power, the presence of additional functions and disk sizes.

Indispensable in everyday life are angle grinders. This is a conventional angle grinder, which are compact in size and demanding on the operating mode. After 10-15 minutes of operation, the owner of a conventional grinding machine is forced to take a mandatory break to prevent its overheating. The household angle grinder is not designed for daily use. Their technical indicators are much lower than that of professional devices that can be used for a long time without fear of overheating. In addition, professional angle grinders are equipped with brass inserts and a metal housing. This is due to the fact that they have to be used in extreme conditions: laying pipelines, earthwork, etc. For such an environment requires a tool that is as much as possible protected from dust and moisture.

Universal angle grinders

Universal are considered an angle grinder with speed control. These machines are ideal for jobs such as cutting, grinding and polishing any materials.

angle grinder with speed control and soft start are mainly used in those cases when it is necessary to polish stone or wooden surfaces. This is due to the structural features of these materials, the processing of which at high speeds is undesirable, as it leads to the destruction of the surface and rapid wear of the nozzles.

The best manufacturers of grinders

Angle grinders are produced by domestic and foreign companies. High results were achieved by the German manufacturer Bosch, Japanese Hitachi and Makita. Mostly they produce models for professional use: an angle grinder with speed control, power exceeding 1200 W, and various disk diameters. Angle grinders make it possible to carry out any kind of complex work. Using special diamond blades, it is possible to cut concrete and stone, to cook walls under wire. The presence of an additional side handle provides control over a powerful power tool during its operation.

Bosch: Model GWS 850 CE

The Bosch angle grinder with speed control and an output of 850 watts is ideal for grinding with diamond cups in natural and artificial stone. This angle grinder is one of the most popular electronic tools in the work of professional stonecutters, who every day are faced with the need to polish in places where granite or marble are cut. This angle grinder is lightweight, which greatly facilitates operation: the master can hold it with one hand.

The Bosch GWS 850 CE angle grinder with speed control is warranted for one year of professional use.

You can adjust the grinding speed using six positions. The rotation speed range of grinding nozzles and discs is from 2,800 to 11,000 rpm.

The quality of polishing directly depends on the speed of rotation of the nozzles. The smaller it is, the higher the quality of work. This requirement applies to granite, marble, glass and other surfaces that can be operated with a grinding tool equipped with an adjustment function. To work with marble surfaces, experts recommend a choice of speed at which the grinder produces 2800 revolutions. Wooden surfaces can be treated with special nozzles at the highest speeds. The maximum speed for this angle grinder is 11,000 revolutions.

Video: Makita 125 Angle Grinder Variable Speed

Bosch GWS 850 CE comes with a key, handle and two mounting washers for discs and nozzles.

Nozzles for polishing work

The quality of polishing work depends on the adjustable speed and correctly selected nozzles. For grinding marble and granite surfaces by experienced engravers who work with stone professionally, flexible diamond blades are recommended. For wood, an emery petal circle is suitable. For polishing metal products and surfaces, it is best to use circles containing felt or felt, which is attached to the nozzles with a special Velcro. Felt nozzles are also suitable for polishing glass. But in this case, you need to purchase a special diamond paste. Painted or varnished surfaces must be treated with lamb wool tips.

Household Makita GA5030 angle grinder

Makita angle grinder with speed control is considered one of the best models of household angle grinders. Its price is 2500 rubles. The Makita GA5030 has a low weight that does not exceed 1.8 kg, which is an advantage of this tool compared to other similar models in this price category.

Professional Angle Grinder Makita 9565Cv

Angle grinder Makita angle grinder 125 mm speed control provides the implementation of any kind of work at speeds from 2800 to 11000 rpm. Makita 9565Cv requires a 125 mm diameter drive and 220 volt power. Power Consumption Angle Grinder. 1400 watts. 125 mm angle grinder with speed control 9565Cv is a professional power tool, the design of which contains:

  • adjustment of rotation speed, which makes it possible to optimize the operating mode. The spindle receives a certain speed necessary for a specific task: cutting, grinding or grinding;
  • power button lock. This is important to ensure safety during operation, especially in cases of unplanned power outages (turning off the light, pulling the plug out of the socket). Thanks to the secondary start-up fuse, the owner of the Makita 9565Cv is protected against arbitrary switching on the angle grinder and does not risk injury;
  • double isolation;
  • speed stabilization system, which, due to changes in disk loads, facilitates the process of working with massive labor-intensive parts;
  • two-position side handle, which ensures reliable holding of the power tool during operation. A convenient version of the handle performs an anti-vibration function.

9565Cv angle grinder is an angle grinder "Makita" 125 with speed control and smooth descent, due to which the power tool is protected from critical overloads when turned on. A soft start protects the angle grinder system and the numerous parts contained in it (disk, winding, engine brushes) from a strong power surge. Turnovers are typed smoothly, the angle grinder does not tremble in the hands.

How to choose the required disk size?

For angle grinders, discs with a diameter of 115 to 230 mm are intended. Working is the part that extends beyond the apparatus. Nozzles tend to wear off during use. Disks with a diameter of 115 mm quickly wear out and are suitable for cutting products with a thickness of not more than 3 cm. over, this diameter is unsuitable for working in hard-to-reach places. For such operations, 180-230 mm discs are better suited.

Metabo WEV 10-125 Quick

This is another angle grinder with speed control. 125 mm is considered the optimum disk size for the Metabo WEV 10-125 Quick. Among all the well-known 125-mm angle grinders, this model is considered the best in terms of power. It features a wide range of adjustment of spindle speeds and a constant speed under the influence of a variable load. This is ensured by built-in electronics, which protects the engine from the overload grinder and produces a smooth start of the system. The angle grinder has an automatic safety clutch and corner brushes that turn off if voltage suddenly drops. This is important for safety during operation of a powerful angle grinder.

Hitachi G13SS

The ergonomic shape of the model, the presence of a removable handle in its design, which allows it to be installed on either side, the ease of replacing carbon brushes are advantages for Hitachi G13SS that many users have already appreciated.

What to consider when buying?

If you want to purchase an angle grinder, you need to get acquainted with the technical indicators of the model you like. Best of all, if there is a soft start. This will protect the owner of the angle grinder from possible jerks when turning on the power tool and from knocking out fuses. The problem of increasing the load on the system of an angle grinder can occur when the speed is reduced. In such cases, overheating occurs. It is desirable that the angle grinder be equipped with modern sensors that regulate the speed of revolutions during overload and overheating. The more complex the model system, the higher its class and the more expensive it is. At the same time, more and the amount of work that can be done using expensive power tools.

Work Protection With Angle Grinder

Work Protection With Angle Grinder

Any cutting device has high security requirements. Especially when it comes to cutting metal and other hard materials.

An angle grinder, or an angle grinder (angle grinder), is the most dangerous power tool, and when working with it, safety precautions must never be neglected. Even experienced professionals sometimes get injured using an angle grinder in violation of the instructions.

Safety precautions

There are several types of protective equipment required for the operation of this device.

Personal protective equipment

Guaranteed eye safety when using an angle grinder are safety glasses. They have several varieties:

  1. Open glasses. They resemble ordinary glasses for vision correction or protection from the sun, but have a denser structure and increased thickness of the plastic. These glasses protect your eyes from sparks and small fragments. Their disadvantage is exposure to dust. When working with ceramics and stone, dust is formed that can cause eye irritation. In this case, the following type of glasses will do.
  2. Closed glasses. They fit tightly on the contour of the face and do not allow dust to penetrate the eyes. Also protect eyes from shards and sparks. Some models have a ventilation system that prevents fogging on the inside of the lens. This version of the glasses will cost a little more, but it has more advantages.

Glasses must be worn regardless of the nature of the material being cut or ground.

Face mask

Another safety feature when working with an angle grinder is a face shield. It can be reinforced with a special mesh, which makes it stronger. Such a mask is much better than glasses, because it protects not only the eyes, but also the rest of the face.

The main cause of injury is a saw blade split. Its fragments flying with great speed can injure not only a person working with an angle grinder, but also people nearby.

Principles of Safe Operation

Video: Work Protection With Angle Grinder

The presence of personal protective equipment undoubtedly reduces the risk of personal injury when using the angle grinder. But it is worth remembering also other safety requirements.

  • Protective cover. This device must always be on the angle grinder. Some negligent operators remove protection in order to wear a larger diameter wheel that is not designed to work with this angle grinder. Sometimes the casing is removed in cases where it is necessary to use an angle grinder at an uncomfortable angle. Such actions are not allowed. Of course, the protective casing does not provide absolute safety, but in most cases it will protect you from getting injured. Recently, a protective modification for the angle grinder has appeared a useful modification. It is called dust extraction. The name is clear. this device helps to direct dust particles in the opposite direction from the operator, which greatly simplifies the work.
  • Hand protection. To prevent sparks and hot metal particles from getting on the skin of the hands, it is recommended to use special welding gaiters. Small sparks, getting on the skin, do not bring obvious pain. But when a large burning particle gets in, it causes severe pain. At this moment, the hand may flinch, thereby creating a traumatic situation. Gaiters help to avoid getting hot metal on your hands.
  • The choice of abrasive wheel. To work with an angle grinder, you should use an exclusively suitable circle for it. If you use a circle with a diameter larger than the specified, then it can split, even without touching
  • with the cut object. The fact is that different models of angle grinder have different speeds, and abrasive wheels have different revolving resistance.
  • You should also not use circles with visible external defects such as chips, deep scratches or cracks.
  • It is forbidden to install a disk for sawing wooden products on an angle grinder. Firstly, it is dangerous. the saw blade can meet with a knot, because of which the tool can be pulled out of the hands. Secondly, the disk will soon become unusable, because it is not adapted to such a load. The speed of the circular saw is much lower than that of the angle grinder.
  • Sawing object. If the workpiece is small, you need to fix it with something. The best option for this would be to use a vise. Never cut the product with one hand while holding it with the other. In this case, the sawing element may be pulled out of the hands.

If the product is large and installed motionless, the bite of the abrasive disc must be prevented. General rules:

  1. Always unplug the angle grinder when replacing a disc. This is to prevent accidental startup.
  2. When choosing an abrasive disc, give preference to a trusted manufacturer.
  3. When working, make sure that the power cord is away from the cutting circle.
  4. When using an angle grinder, eliminate the possibility of winding hair and clothing onto a rotating disc.

The correct location of the power tool in your hands is the key to safe use. Do not neglect the instructions for working with the angle grinder, this tool is capable of causing severe injuries when neglected.

Angle Grinder Status 125 Variable Speed

Engine power angle grinder is 1250 W

Set the optimal settings for specific tasks. With speed control on any material, an even cut is obtained.

Disc diameter 125 mm

The most popular disk size for household and repair work.

  • Angle Grinder Status 125 Variable Speed
  • 3 year warranty
  • 14 days to return
  • Official Manufacturer’s Warranty




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The Dnipro-M brand is well known to the Ukrainian consumer due to the ratio of reliability, comfort and reasonable price. He deservedly takes a leading position and receives in return the respect and trust of customers.

Video: Angle Grinder Status 125 Variable Speed

Internal characteristics. an important aspect when choosing an angle grinder. Consider in advance what tasks the tool will perform and, in accordance with this, choose an angle grinder. Let us consider in more detail the main indicators of the GL-125S model. The 1250 W engine produces up to 11,000 rpm. For this model, a circle with a diameter of 125 mm is suitable, which is quite enough to perform basic household tasks. Such a size can make a shallow cut of corners, pipes, tiles and other materials. However, remember! To remove a protective casing and establish circles of the wrong diameter or disks for circular saws are forbidden!

Among the advantages of the GL-125S model it is worth noting:

External parameters are equally important when choosing a power tool. The compact design weighs only 2.2 kg, which allows it to be transported, stored and carried out in small rooms and even at height without any problems.

If you still have questions regarding the tool or its purchase, fill out the callback form below.
We will contact you within a few minutes (during business hours).

Guard For Working With Angle Grinder

It is not permissible to install larger circles on the angle grinder than those for which it is intended. Getting to work with an angle grinder, you need to be extremely assembled. A protective casing and glasses are prerequisites for safe operation.

The screen is a semicircular plate with two ribbons, frontooccipital and parietal. Their adjustment can be smooth or step to fit in size and securely lock the protection during operation. A plastic visor may be provided to protect not only the face, but also the frontal part of the head.

With helmet mount. the screen is attached to the safety helmet with a lifting and fixing device that moves it up / down. From a metal mesh. such protective shields are a fine-mesh strong mesh and protect against large solid particles.

And breakaway particles can cause eye injury. Therefore, do not neglect the goggles for the angle grinder. Eyes are the most important organ of the human body, they must be protected and taken care of their safety when performing various work operations.

First of all, these are construction glasses. special devices that protect the eyes from the smallest particles of the processed material and exposure to radiation hazardous to the organs of vision.

Guard For Working With Angle Grinder

They partially or completely close the organs of vision and are offered with different types of glasses: mineral, organic or made from various modern polymeric materials. They are indispensable when performing welding operations, working with lasers, and bright light sources. Used in the glass and metallurgical industries.

The most convenient and modern welding masks are chameleon masks. Working with an angle grinder is associated with sparks and fragments that are inevitable when cutting material, so protection from them will not be superfluous. A respirator is required when cutting concrete or slate and is desirable when working with metal, especially indoors. Glasses and a shield protect only from small particles, however large a splinter flying off directly, they will not stop!

Video: Guard For Working With Angle Grinder

Buy safety glasses for angle grinder

The diameter of the circle must not exceed the diameter of the standard protective casing. An angle grinder, it is an angle grinder, is a very traumatic tool. If the angle grinder were not so indispensable for many types of work, it would probably be worth introducing a restriction on the use of this tool. In general, it is very important to know how to work the angle grinder.

Glasses or their replacement mask must be closed. Sparks and splinters fly along a complex path and are able to fly behind glasses or a mask if they are open from the side. The protective cover is the first barrier between the operator and the circle rotating at great speed.

Many who use the angle grinder more or less regularly, at least once, but have come across it. Most often, the destruction of the circle occurs when it is clamped (jammed) in the slot. The protective cover is installed so that sparks and debris are not ejected towards the operator. As it would not be inconvenient in some cases to work with the casing, its removal from the tool is unacceptable.

Hands are in close proximity to the rotating circle and must be protected from sparks, abrasive particles and metal fragments. Clothing should not be wide and well dressed. Each type of work (type of processed material) has its own abrasive tool. Circles of large diameters (both new and used and reduced in diameter) may not withstand high speeds and collapse.

You can also not use damaged circles: with cracks, chips and potholes, having deviations from roundness or flatness. This can lead to a back strike and the final destruction of the circle with the creation of a traumatic situation.

Bosch 850 Angle Grinder Adjustable

The presence of an angle grinder in the household makes it easy to solve the problems of processing solid-state surfaces in the repair process. In addition, this equipment, also known as the “angle grinder,” may be needed in locksmith events, as well as when removing unwanted raids. Today there are many models of angle grinders from different manufacturers, but the choice is recommended to make in favor of reputable companies. These include the Bosch GWS 850 CE Professional, which comes in a wide configuration, is characterized by build quality and reliability. Despite positioning as a professional unit, the angle grinder is quite suitable for private needs. The tool is not difficult to handle, but a set of useful options and high performance will not be superfluous. However, this model should not be overestimated either, as competing grinders also have something to offer.

Model Overview

Bosch 850 Angle Grinder Adjustable

The device is presented in the line of professional equipment, which is designed for a wide range of operations. In particular, the Bosch GWS 850 CE angle grinder handles the processing of metal materials, stone and wood. The operator will be able to perform cutting, grinding, painting, and also remove traces of paintwork and rust. High power helps the instrument to perform the listed actions qualitatively. However, this does not affect the dimensions and ergonomics of the device. The user can easily manage all the capabilities of the unit without outside help. of course, basic training and knowledge of the handling of an angle grinder will still be required.

In addition to compactness and maneuverability, the device will please the owner with electronic filling. Actually, the introduction of control systems with a hint of intelligence has long been practiced by other manufacturers, but this concept is implemented most successfully and without serious errors in the Bosch GWS 850 CE angle grinder.


Not only advanced electronic systems, but also the basic technical potential speak of the accessory of this unit to professional models. So, the German angle grinder has the following characteristics:

  • The power potential is 850 watts.
  • The number of revolutions. a range from 2 800 to 11 000 with the possibility of adjustment.
  • The size of the grinding wheel in diameter is 12.5 cm.
  • Grinding spindle thread. M14.
  • The length of the spindle thread is 2.2 cm.
  • The mass of the device in full is 2.6 kg.
  • The mass of one tool is 1.6 kg.

The main thing that the tool pays attention to is a high level of power and an extensive speed range. Thanks to these characteristics, the Bosch GWS 850 CE angle grinder shows its effectiveness even when working with stone surfaces.

Features and benefits of the model

The user controls the instrument using an electronic settings system. Compared with the adjustment in traditional models, this innovation allows you to set the machine optimal parameters for working with a specific material. In addition, the Bosch GWS 850 CE is equipped with a soft starter. This means that a sharp start of processing is excluded, as a result of which the largest number of errors are made. The user of this angle grinder will start work quietly, slowly and accurately. To ensure stable processing in the future, the device is also equipped with a current limiter, which will eliminate the negative effects of voltage drops.

Video: Bosch 850 Angle Grinder Adjustable

So that the operator can easily and quickly change the components of the machine, a fixed spindle is provided in its design. Facilitates maintenance operations and the location of carbon brushes with direct access. To increase the overall structural strength, the Bosch GWS 850 CE angle grinder was provided with reinforced plastic and armored winding. On the one hand, protective barriers protect the user himself, on the other hand, they increase the tool wear resistance.


The manufacturer strongly recommends keeping the tool clean and in good condition. For this, it is necessary to use work elements that correspond to the characteristics of the material and processing conditions. It is also necessary to regularly check all slots and ventilation openings of the device, since their contamination can lead to breakage directly during the operation. In case Bosch GWS 850 CE spare parts or accessories are required, the manufacturer’s service department provides original components upon request. In addition, the user can get a wiring diagram of the device. then, in accordance with it, independently determine the malfunction and eliminate it. However, without appropriate preparation, such actions are not recommended.

Operation Nuances

You can start work if several conditions are met. Firstly, the tool must be in good condition, and all its components and functional parts must be correctly selected from the point of view of the upcoming processing. Secondly, the workpiece must be securely locked. During operation, the Bosch GWS 850 CE angle grinder must not be subjected to excessive pressure. Even coarse abrasive work should be carried out with moderate tension, correctly grasping the handle of the tool. After the operation is completed, it is not necessary to turn off the machine immediately. You should leave it idling for a few minutes. This must be done, as sudden changes in voltage in the mechanical elements adversely affect the durability of the device.

Each material has its own processing characteristics. For example, in the process of cutting metal should lead the working body against rotation. This will bring the Bosch GWS 850 CE to the end of the intended section without leaving the laid line. In the case of stone, another nuance is important. The dust generated is dangerous for breathing, therefore, an effective suction of dirt should be provided, and work must be done in a respirator.

Almost all Bosch angle grinders are renowned for sophisticated ergonomics in every way. And the adjusting capabilities, and the device handles with protective coatings cause only positive feedback. Despite its high performance, the power tool can be operated even with one hand. this is evidenced by user experience. In terms of the direct function of the processing machine, the Bosch GWS 850 CE also shows its best. Opportunities for working with stone and metal are implemented in accordance with advanced German standards.

Price issue

Professional equipment is not cheap. The difference with a budget power tool can be several thousand rubles. However, in the case of the Bosch GWS 850 CE, the price is quite acceptable and averages from four and a half to five thousand rubles. Given the high level of the manufacturer, the considerable power of the device and acceptable functionality, the price really looks attractive. But, with a detailed analysis, the angle grinder all falls into place. In addition to electronic adjustments and a really high-quality housing, the German company does not offer anything special. Therefore, the price justifies the purchase, but no more.


If you need a modern functional tool for periodically solving simple problems at home, then the modification of Bosch GWS 850 CE Professional may be one of the best options. The tool is easy to use, convenient and safe. In addition, the ability to process metal and stone makes it almost universal in terms of operation. However, if you plan to purchase an angle grinder for permanent work at construction sites, you will have to think about it. If we talk about the purely professional qualities of the device, it will not please anyone with anything special. Sufficient power, functionality at an average level. these same qualities are provided by less famous models of the segment. Ergonomics can be called the only trump card of this angle grinder, so if a short cable does not bother you, then you should consider this option.

Angle Grinder Vityaz 125 Variable Speed

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Angle Grinder Vityaz 125 Variable Speed

power 2400W, disk 230mm

Power 850 W, disc 125 mm, speed control

800W, 125mm drive, 1.9kg weight, no speed adjustment

circle diameter 125 mm, power 1500 W, weight. 2.4 kg, speed control 2200-7500 rpm

230 mm angle grinder, power 2600 W, soft start

disk diameter 125mm, 840W, 11000 rpm., weight 2.1 kg angle grinder

Voltage 230 V, power 1150 W, number of revolutions 11000 rpm, disk diameter 125 mm.

Video: Angle Grinder Vityaz 125 Variable Speed

circle diameter 125 mm, power 850 W, weight. 1.9 kg, speed control 2800-11000 rpm

Mains voltage, V, 220. Current frequency, Hz, 50. Disk diameter, mm, 115. Spindle thread, M14. The number of revolutions, rpm, 11000.

electronic current limiting system, interlock system

angle grinder 125 mm, power 1100W, with speed adjustment

circle diameter 125 mm, power 1100 W, weight. 2.0 kg

230mm, soft start, model DISCONTINUED from production

Electromash angle grinder 180-2000 Voltage / frequency: 230 V / 50 Hz Power: 1800 W Number of revolutions: 8000 rpm Disk diameter: 180 mm&

angle grinder Kress 1400 WSXE / 1 220 V Frequency. 50 Hz Type of grinder. angular power. 1400 W, Revs. 6500-12000 rpm Circle diameter. 125 mm spindle

Voltage / frequency: 230 V / 50 Hz Power: 1100 W Number of revolutions: 3000. 7500 rpm Disk diameter: 125 mm Angle grinder Vityaz MShU-125 / 1100Е

electronic stabilization of revolutions, aluminum gear housing, soft start

How to Insert Brushes into an Angle Grinder

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

The device and purpose of the angle grinder

angle grinder is designed for grinding and cutting various materials.

How to Insert Brushes into an Angle Grinder

The main elements of the angle grinder

The angle grinder consists of the following elements:

  1. The aluminum alloy flat gear housing dissipates heat better.
  2. Carbon brushes.
  3. Grip mount
  4. Electronic soft start system. Prevents jerking when turned on and reduces starting loads on the engine.
  5. Quick detachable guard.
  6. Ball bearings.
  7. Electric motor
  8. Switch angle grinder.

A wide selection of bearing products is offered by the Thermopolis company.

Main malfunctions, their causes and diagnostics

The main breakdowns and causes:

  1. Burns, sparks and twitches. Reasons: violation of the insulation of the armature winding, wear of the brushes, collector, clogging of the brush holders. Even after replacing the brushes, the angle grinder sparkles and twitches if the brush holders are clogged.
  2. Clapping sound. Brushes or interturn circuit of any of the windings.
  3. Crispy sound. The reason is in the bearings.
  4. Mechanical rumble and heavy tapping. Gearbox malfunction.
  5. angle grinder has stopped working, does not turn on. If the disk is manually spinning tightly or not spinning, the cause is the gearbox. If it turns easily, check the electrical circuits. If chains work, check motor and brushes.
  6. The spindle lock button has broken. The reason is clicking on it during rotation of the disc or jamming of the disc.
  7. angle grinder works in fits and starts. Check engine for interturn short circuit.
  8. Vibrates. The reason is in mechanics. Check bearings, rotor shaft and gearbox.
  9. Heats up. If it heats up in the engine area, the cause is worn out brushes or a short circuit in the turns of the windings. If the gear case is warming, then the grease has dried or the gears have worn out.
  10. It does not gain momentum or power drops. The reason is in the electronics or engine. Check soft starter control board and speed controller, brushes and collector.
  11. Smokes. The reason is overheating of the tool. Check motor windings for insulation melting.
  12. Humming and not spinning. Check motor bearings and gearbox.

How to disassemble and assemble an angle grinder

To troubleshoot the angle grinder must be disassembled.

    Remove the nut that holds the working disk.

Turn off bolts of fastening of a protective casing.

Remove the housing bolts from the angle grinder and those that secure the housing to the gearbox.

Remove the top of the rear housing. Turn off bolts of fastening of a cord. Remove the wires and button from your grooves. In some models, for example, in DWT, the rear case is not disassembled into parts, but is removed entirely.

  • Disconnect the motor wires.
  • Remove the brushes.
  • Disconnect the gear housing from the body of the angle grinder. Together with it, the engine anchor is removed.
  • Remove the gearbox bolts located around the casing mount.

    To disconnect the anchor from the aluminum housing, unscrew the nut located in the gear housing.

    Reassemble the tool in the reverse order.

    The clamping nut is not untwisted

    During operation, the disk can tighten so tightly with a nut that it begins to crumble. It is not possible to unscrew the nut with a wrench. And you do not need to do this, since you can break the angle grinder. First, break the disc all the way to the nut. Then find the metal plate a little thinner than the working disk. Use it to drain off the rest of the disc under the nut. It can be easily unscrewed with a key or hands. In order not to bring the tool to this problem, put the washer under the nut.

    How to remove a tightened nut

    The casing cannot be removed

    In some grinders, for example, Bosh, the casing is not bolted, but latched. To remove it, you need to turn the cutout of the casing perpendicular to the angle grinder. To dress, turn until it clicks.

    Stator check

    The stator is checked with a multimeter.

    1. Inter-turn closure. Set the resistance mode to 200 ohms. Connect the test leads to the ends of one winding. A unity means an open, and zero means a short circuit between the turns. If it shows a resistance of more than 1.5 ohms, then check the second winding. Both windings should have approximately the same resistance.
    2. Breakdown on the mass or shorting of the winding with the metal housing of the stator. In the multimeter, set the maximum resistance mode. Connect one probe to the end of the winding, the other probe to the metal housing of the stator. The unit indicates the absence of breakdown.

    Anchor Check

    First visually inspect the collector and winding. There may be visible damage: black marks, bent turns of the winding, raised, worn or burnt collector plates. After inspection, proceed with the tester.

    1. Set the resistance to 200 ohms. Connect the test leads to two adjacent collector plates. If the resistance is the same between all adjacent plates, then the winding is working. If the resistance is less than 1 ohm and very close to zero, there is a short circuit between the turns. If the resistance is above the average two or more times, then there is a break in the turns of the winding.

    The determination of the breakdown to mass is done in the absence of a winding break. Put the maximum resistance on the scale of the device. Depending on the tester, it can be from 2 MΩ to 200 MΩ. Connect one probe to the shaft, and the other to each plate in turn. In the absence of faults, the resistance should be zero. Do the same with the rotor. Connect one probe to the iron body of the rotor, and move the other along the plates.

    Checking the power button

    Put the tester in dialing mode.

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

    Click the button. A sound signal indicates the health of this part of the button.

    Do the same with the other input and output of the button.

    How to ring the start button

    Video: How to Insert Brushes into an Angle Grinder

    Power cord check

    Connect one probe to the plug pin, the other to the button inputs. In one of two positions there should be a sound signal. Do the same with the other pin of the plug.

    Check soft start and speed control

    If the power button and power cord are working but the engine does not turn on, check the softstart control board. Remove the screw that secures the control board. Remove it carefully. Call all items. If there is a speed regulator in the angle grinder, then it can be connected in series with the power button and have one board with soft start. But may have a separate fee. It is checked similarly to soft start.

    Precautions before starting repairs

    1. Read the instructions. Read the description and assembly diagram of the angle grinder.
    2. Unplug the tool.
    3. Prepare a workplace on a table with good lighting.
    4. Fix on paper or in the photo the order of disassembling the tool in order to properly assemble it after repair.

    DIY troubleshooting

    If you are unsure of your abilities, it is better to take the tool to the workshop.

    Power cord and power button

    Damaged cord and button must be replaced. On the button, unscrew the bolts securing the incoming and outgoing wires. Disconnect it from the chain and install a new one.

    Soft start and speed control

    If only the triac is out of order in the control board, then a new one must be put in its place. Pre-grease the metal part of the element with thermal grease. If other elements of the board burn out, replace it completely.


    Brushes must be checked periodically. When one is worn by 40%, change both. And also clean the brush holders.

    • To remove the brushes, you must either remove the rear housing or remove the plugs in the housing.
    • Clean brush holders of dust and carbon deposits. Wrap a cloth around the screwdriver and moisten with alcohol. Nagar is cleaned off with a file. The brush should walk easily in the brush holder, then it will be well pressed by the spring.
    • Insert new brushes.

    Brush holder cleaning

    Stator Rewind

    For high-quality winding coils, you will need an enamel wire and an electric cardboard.

    Remove the winding and old insulation from the housing. Carefully consider the grooves. When the coils burn, insulation is burned and a short to the case occurs. Deposits remain on it, which must be removed with a file or a diamond bur. Deposits will interfere with the new winding. She may tear.

    The winding is saturated with varnish. To disconnect the wires and count them, you need to strip out the insulation. Preheat the winding with an industrial hairdryer or any burner.

    Burn matches or lighters with any fire to make the enamel completely burnt out. Take a micrometer and measure the thickness. Record the diameter of the wire and the number of turns.

    Take any wire and make a loop out of it so that it fits in the grooves of the stator. Under the diameter of this loop, select a cylinder for winding coils. For example, spray can. If its diameter is not enough, then wrap the can with paper.

    Wrap both windings from the enamel wire. Fasten the frontal parts with glass tape or thick thread. The thread should not break and melt. At the loose ends, put on shrink cambric.

    Make sleeves from the electric cardboard and insert them into the grooves. Place the windings in them.

    Check the resistance in the windings of the tester. If everything is fine, continue.

    So that during operation the wires do not vibrate and do not rub against each other, they must be impregnated with any oil-based varnish. Put the starter preheated in the oven vertically and squeeze the varnish onto the winding with a syringe. When the varnish starts to leak from below, turn the stator over and soak on the other side.

    When the varnish is dry, proceed to connect the windings. Connect the two ends of the different windings to each other and connect to the nearest brush. Connect the other two connected ends to the start button. Connect the wire from the second brush to the button.

    Rewind stator on video

    Anchor Repair

    If the balance is disturbed, the anchor must be replaced. The winding and collector are subject to repair. Small short circuits are eliminated. If a significant part of the winding is damaged, it can be rewound.

    A not very developed collector is corrected by a groove. But if the plates are erased to a plastic base or partially burnt out, then the restoration is carried out by soldering or galvanic building.

    Badly damaged collector

    If the collector was completely worn out, then after soldering it will be enough for no more than a month of active use. And not completely damaged plates after such a repair can withstand several brush changes and do not evaporate. You will need to cut the copper plates in size and solder them with a lot of solder. Strain excessively with a file and polish.

    With galvanic build-up, reduced copper is very solid. The life of the collector is like new.

    Completely restored collector

    By galvanic build-up, it is possible to restore both a completely wiped collector and partially damaged plates. The restored collector must be grooved and the plates divided with a drill or hacksaw blade.

    In order to rewind the anchor correctly, you need to correctly disassemble it and remove the parameters for the template:

    1. Winding direction.
    2. How many grooves and slats.
    3. The number of conductors in the groove.
    4. The winding pitch, i.e. how many grooves between the grooves of one section. For example, if the conductors exit the first groove and enter the sixth, then step = 5.
    5. How many conductors are in one groove, so many coils in one section.
    6. Wire thickness.

    For example, 80 conductors in a groove, 12 lamellas and 24 grooves. 12 sections of 2 coils. The winding passes in two circles, so we divide 80 conductors in the groove by 2, and another 2, since there are 2 coils. We get 20 turns of one coil.

    Anchor winding pattern

    1. We solder the beginning of the wire to the lamella 1 and pass it through the first and sixth groove. We make 20 turns. The first coil of the first section is ready.
    2. We solder the wire on the lamellas 2 and repeat the winding through the same grooves. The second coil of the first section is ready.
    3. We solder the wire on the lamellas 3. Pass the coil through the second and seventh groove. We wind the first coil of the second section and solder the wire to the lamellas 4.
    4. The second coil of the second section is fixed on the slats 5.

    How to remove the old and rewind a new winding:

    Use a hacksaw or wire cutter to remove the frontal parts of the winding.

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

    Use a file to remove any remaining impregnation. Count the conductors in the groove and measure the diameter of the wire. Draw a diagram. Cut the insulation sleeves from the cardboard and insert them into the grooves.

    After winding, weld the conclusions of the sections with the collector plates. Check the winding with a tester.

    Soak the winding with epoxy.

    Anchor Bearings

    Bearings crumble or jam over time. They need to be changed.

    • Disassemble the angle grinder, remove the anchor from the stator.
    • An anchor is inserted into the gear housing by a bearing. If the housing cannot be removed, fasten the rotor in a vice and tap the gear case with a wooden block.

    Gearbox disassembly and repair

    The gearbox must be disassembled not only for repair, but also for preventive cleaning and lubrication.

      Remove the bolts and disassemble the gear housing. You will see dirty grease that needs to be removed.

    old grease will spill out of it. Clean parts with a rag or toilet paper. Flush the housing and parts with kerosene.

    Apply new grease recommended by the manufacturer in the tool manual.

    Spindle lock button

    If the button has flown out, then such an angle grinder cannot be operated.

    Spindle lock button

    Since the spindle can spontaneously lower to the gear and block it during operation.

    Spindle Lock

    The locking unit consists of a spindle with a rubber ring, a spring and a plastic button.

    1. To replace the button, disassemble the gearbox.
    2. Remove the spindle from the housing.
    3. Put the spring on the button on the inside.
    4. Insert the spindle into the gear case from the inside, and the button from the outside. Press until it clicks.
    5. Assemble the gearbox.

    Spindle lock button replacement and gearbox repair

    Care and proper operation of the angle grinder

    For the angle grinder to work for a long time, follow the rules:

      Watch integrity of isolation of a wire, plug. Do not remove protection.

    Lubricate and clean the entire tool.

    After turning off the angle grinder, wait until the rotation of the circle stops, then lay it on the ground. When the engine stops, the tool through the ventilation holes sucks together with the air stream particles of earth and other hard fractions that hit the motor windings. As a result, an open or short circuit occurs.

  • Try not to use the angle grinder in the winter on the street. While you are running, the engine heats up. The air is icy. As a result, condensation forms. Moisture for the engine is fatal.
  • Always place the circles recommended by the tool manufacturer. If the angle grinder is 180 mm, do not put more than 200 mm there. The larger the circle, the less speed should be. You will have to remove the protection, and the speed will be exceeded. Oscillations and vibrations will increase. As a result, the circle will fly apart. This is not only fraught with serious injuries. The bearing of the gearbox is broken, the gears are erased.
  • If you are actively using an angle grinder, then you are a good master. It’s not difficult for you to understand the device’s device and repair it with your own hands. First, find the fault and determine which nodes should be checked. Repair the angle grinder carefully, without haste, so that a minor breakdown does not turn into a major one.

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