Angle grinders (angle grinders), popularly called angle grinders, are a popular and reliable tool. But everything breaks down sometime. It is not difficult to repair an angle grinder with your own hands if you have an instruction that tells you step by step order repair of the angle grinder. Below you will find answers to any questions about the repair of the gearbox, rotor, stator, carbon brushes of angle grinders.
Angle grinders among home craftsmen are very popular. The possibility of changing the working bodies allows cutting, grinding, polishing operations.
The presence of a soft starter makes the operation of the tool safe and convenient. Corner repair grinder simple and can be done independently. For those who dare to repair of angle grinder on your own, you will need a diagram of an angle grinder of the desired type, a tool, lubricants and this instruction.
Any do-it-yourself repair of an angle grinder begins with an investigation of emerging malfunctions. The grinder device is quite simple. The rotating rotor through a helical gear transmits torque to the shaft (spindle) of the working body. The necessary working tool is installed on the spindle, whether it is a cutting stone, a grinding or polishing wheel, and the necessary technological operation is performed.
By the way, about the shape of the tooth. On low-power angle grinders, spur gears are installed. Helical gears are used in grinders with a power of over 1000 watts.
Angle grinders, like any tool, break down over time. The causes of malfunctions of the angle grinder can be different. They appear not only from the improper use of the tool, but also from the untimely replacement of carbon brushes and lubricating fluids.
Regardless of the model of the angle grinder, malfunctions all appear in the same nodes. Malfunctions of angle grinders are conditionally divided into electrical ones. For novice repairmen, malfunctions are divided into simple and complex.
Mechanical failures of the angle grinder
The grinder is an angle grinder designed to perform cutting, grinding, polishing work. The grinder in the process of work is subjected to heavy loads, works in a dusty environment.
Excessive loads when using a grinder in the "Cutting" mode cause increased wear not only of the bearing, but also of the gear teeth of the gearbox.
The main malfunction of the grinder in terms of the mechanical part, wear or destruction of the plain bearing on the shaft of the large helical gear of the gearbox.
Troubleshooting an angle grinder is easy if you have its diagram, description and recommendations for implementation at hand. repair work.
Plain bearing repair
The weak point of any angle grinder is the bearings. And although there are few of them in the design, only three, it is they who most often lead to mechanical breakdowns. Bearings are affected by:
- high rotation speed;
- work at limit modes;
- insufficient amount of lubricant;
- ingress of dust or dirt;
- untimely replacement or destruction of carbon brushes.
The design of any angle grinder provides for a quick and easy replacement of any bearing.
Malfunctions of the angle grinder associated with wear or destruction of the plain bearing on the gearbox shaft are characterized by the appearance of an unpleasant extraneous sound.
The destruction of the plain bearing is detected by checking the play of the shaft of the installation of the working tool. It is determined by swinging in different directions of the shaft when installing the working tool.
At the next installation of the working tool, check the play of the shaft by shaking its end in different directions. Backlash should be absent or minimal.
The appearance of play indicates the need to replace the plain bearing.
Bearing repair consists in removing it from the housing and removing it from the gearbox shaft.
It is better to remove the bearing from the shaft with a puller. The inner race of a destroyed bearing is best removed using a tap of the desired diameter, previously screwed into the cage.
Bearings are removed from the rotor using a puller or in a folk way.
Keys or strips of metal are inserted into the vise, the bearings are placed on the keys and, using a soft metal tip and a hammer weighing at least 400 g, they are knocked out from the shaft axis.
Repair gearbox grinder
The degree of wear of the gears of the grinder gearbox is checked for a contact patch. Beforehand, the gearbox is completely cleaned of old grease. A special blue is applied to the small gear of the gearbox, the gearbox is rotated. Next, you need to remove the driven large helical gear and look through a magnifying glass at the contact patch. It should occupy a total of at least 50% of the tooth surface.
Otherwise, the gears must be replaced or the tooth profile corrected. described more than once on the pages of this site.
But such a malfunction is eliminated only by an experienced craftsman. Most often, licked, cut or destroyed gears are changed entirely, and in pairs.
How to properly disassemble the grinder gearbox
When repairing a gearbox of any angle grinder, the most difficult task is to remove the gears and press out the thrust bearing.
The disassembly of the gearbox begins with the removal of the gearbox cover pos.1 and the detachment of the stator housing and the release of the rotor pos.2. The freed rotor is clamped in a vice and the fastening nut (pos. 3) of the drive pinion is unscrewed.
The spindle bearing is pressed into the gearbox cover. To get the bearing, in some angle grinders, remove the retaining ring that secures the thrust bearing and remove the bearing.
The destroyed bearing pos.1 in the gearbox housing pos.2 is easiest to get by prying it with a screwdriver.
In other models, a retaining ring fixes the gear in the spindle.
The driven large gear on the spindle is attached in several ways:
- The gear is pressed onto the spindle.
- The gear is attached with a key.
The leading small gear is either screwed onto the shaft along the left-hand thread (in some Sparky models, the thread is right-handed), or fixed with a keyway and clamped with a nut.
How to remove gears
In angle grinders up to 1000 W, spur gears are used, and in angle grinders, helical gears are used.
Gear repair consists in replacing them, and only in pairs.
Continuous and trouble-free operation of the gearbox depends on availability.
Spindle lock button repair
The spindle lock button is for fast withdrawal working tool. The button breaks when you press it while the disk is rotating. The repair of the grinder consists in the complete replacement of the button.
The button should only be pressed when the grinder is at a complete stop.
Electrical malfunctions of the grinder
The electrical circuit of the main part of the grinders is almost the same. Rotor transmits torque through the gearbox to the working tool. The rotor rotates in the stator field. The control circuits consist of a button that regulates the speed and performs a soft start of the tool, carbon brushes that provide the transfer of alternating voltage to the collector lamellas. Power is supplied to the instrument via the connecting cable.
The main malfunctions of the angle grinder in the electrical part include:
- breakage of the power cable at the input to the tool;
- destruction or wear of carbon brushes;
- failure of the power button;
- breakage or short circuit of the stator;
- breakage or short circuit of the rotor;
- exfoliation or development of collector lamellae.
Malfunctions of the grinder in the electrical part are best determined with a tester or other device. Suitable for these purposes and homemade device popularly called "arkashka" .
The scheme of the angle grinder is quite simple and does not require special knowledge. It is only necessary to observe caution and safety precautions when performing repair work and to know electrical engineering in the volume of high school.
Finding a break in the power wire
One of the common breakdowns of the grinder is the inability to turn on the tool or spontaneous stop during operation. The cause of malfunctions of this kind is a break in the power cable poz.27 at the entry point. The malfunction is eliminated by replacing the cable or throwing out the failed section. The fault is easily found with a tester.
If there is no tester at hand, but there is a screwdriver with a neon indicator light, then the malfunction can be found by connecting the power wires to the phase one by one.
Carbon brush failures
The reliable operation of any power tool depends to a large extent on the integrity and correct operation carbon brushes. High-quality fit of carbon brushes, their correct location relative to the collector lamellas affects the performance of the rotor collector.
Remember! The length of the carbon electric brush cannot be less than 8 mm.
Timely replacement of carbon brushes avoids most faults.
The degree of wear of carbon brushes is characterized by the types of sparking at the collector site. Sparking should be uniform over the entire contact patch of the carbon brush and lamellas and should not exceed a length of more than 8 mm. Circular sparking indicates a malfunction in the rotor circuits.
Repair of the power button and speed controller
Power button malfunctions most often manifest themselves in difficult and unreliable turning on of the tool at start-up. Such a malfunction spontaneously appears and disappears.
It is unacceptable to work as a grinder with a faulty power button. This malfunction leads to jamming of the cutting discs during operation and their destruction with unpredictable consequences.
The malfunction is eliminated by completely replacing the button with a new one.
AT modern models Bulgarians have a built-in soft starter with a speed controller. It cannot be repaired, but will require complete replacement. No, advanced left-handed masters, of course, will be able to repair such a knot.
Stator repair
The failure of the stator is indicated by the spontaneous spin-up of the machine shaft, the angle grinder begins to gain maximum speed. Such a malfunction indicates the appearance of an interturn short circuit in the stator winding.
Some malfunctions can only be repaired by specialists. Extension uninterrupted operation the stator can only be cleaned, lubricated and replaced with carbon brushes and bearings.
Usually the stator fails quite rarely. This leads to frequent overheating of the tool during operation. The malfunction is manifested by a strong heating of the body of the grinder and the appearance of a smell of burnt insulation.
The stator can have both an open and a short circuit. Without disassembling the stator, these faults are easy to find using the IK-32 device.
Faults are eliminated by replacing the stator. For those who like to make their own hands, we can recommend. There is nothing difficult in this.
The stator is removed easily, but in different models USM in its own way.
Stator removal procedure:
- remove the grinder gearbox;
- remove the rotor, after removing the fastening bar;
- remove the plastic protection of the stator;
- unscrew the screws securing the stator in the housing;
- remove the handle cover and disconnect the power wires to the stator;
- remove the stator by tapping on the housing wooden mallet or a bar.
Repair of the angle grinder rotor
The failure of the rotor in the angle grinder is caused by improper use of the tool, frequent overheating, untimely replacement of carbon brushes, ingress of abrasive particles and dust on the collector lamellas.
First, the length of the spark on the collector increases, then the smell of burning appears and, on last step, smoke. The operation of a faulty gearbox is accompanied by a knock and a hum.
The destruction of even a pair of teeth leads to incorrect operation of the tool.
You can extend the life of the rotor by preventing dust from entering the tool, preventing the tool from overheating, changing carbon brushes and lubricants in a timely manner, using only those working tools and diameters recommended by the power tool manufacturer.
The rotor is a complex assembly that requires repair in service centers. But lovers of DIY can.
Repair of the collector and rotor lamellas
Dismantling the rotor is not particularly difficult.
To remove the rotor from the angle grinder:
- remove the cover of the grinder handle;
- release and remove the carbon brushes;
- unscrew the screws securing the gearbox housing to the main body;
- remove the gearbox housing;
- remove the rotor.
The removed rotor should be carefully examined. If large grooves are rubbed on the lamellas, they should be removed by turning the collector in a lathe.
With minor grooves, the defect is eliminated by grinding. The rotor is clamped into the chuck of an electric drill and the wear is removed with the help of a file and sanding paper. The process is easy.
The drill is clamped in a vise or securely fastened to flat surface. The end of the rotor on which the lamella is placed is inserted into the drill chuck and securely clamped. Bearings are pre-removed from the rotor.
The second end of the rotor must be supported with a set of wooden blocks. The drill turns on and a small number of revolutions is set. At the first stage, use coarse sanding paper No. 40..80, on final stage smaller №120..200.
After grinding, it is necessary to mill the grooves between the lamellae. This is best done hacksaw blade, specially sharpened. After milling the collector grooves, the edges of the lamellas must be deburred using a diamond file. Properly sanded lamellas should be free of burrs.
Detailed photo report on the replacement of the input shaft bearing of the gearbox of the 800W belt grinder.
During the operation of the grinder, without extraneous sounds, the engine speed increased sharply and the belt stopped.
To determine the malfunction, unscrew the three screws of the drive belt cover.
After dismantling the cover, the following picture was discovered:
The drive belt melted instantly due to a malfunction of the grinder gearbox. The primary shaft of the gearbox (with a large pulley) rotated easily by hand, but sometimes braked sharply.
To disassemble the grinder gearbox, unscrew the screw in the center of the large pulley. We hold the pulley with round-nose pliers.
Attention! The screw has a left-hand thread!
After unscrewing the screw, unscrew the pulley, holding the shaft by the dust removal fan. The pulley has a conventional right hand thread.
Remove the aluminum fan cover, fan impeller and lower part plastic fan case.
The fan housing is removed with some interference, as it is immediately the top cover of the grinder gearbox. It houses the seat of the upper bearing of the input shaft of the gearbox. The upper bearing of the input shaft was without damage and backlash. To access the lower bearing it is necessary to remove the gear of the secondary shaft of the gearbox. To do this, remove the retaining ring and gear.
After these operations, we remove the input shaft from the lower bearing. In my case, only fragments of the separator remained in the lower bearing, the balls strayed to one side. All that's left of the bearing.
Since the grinder is more than five years old, it was decided to check and lubricate all bearings.
To do this, you need to disassemble the tape drive platform. From the secondary shaft, it is necessary to pull out the gear fixing pin.
Unscrew the three platform mounting screws and the tape position adjustment screw (located on the other side).
Using a wide screwdriver, we shift the platform along the guides of the case. Remove the retaining ring and take out the shaft of the driven roller of the tape. The tape drive roller is removed from the platform body with some effort together with the bearing. Protective anthers are removed on bearings with a sharply sharpened awl. Bearings are checked for play and smoothness of rotation and filled with grease. I greased all the bearings with Litol-24.
Assembly is carried out in reverse order.
Don't forget before complete installation platform in place - insert the spring of the screw for adjusting the position of the tape!
The dismantling of the outer race of the failed bearing was carried out using narrow nose pliers with curved ends.
A new bearing was installed in place of the extracted cage.
After installing the belt drive platform, the gear fixing pin and the gear of the gearbox output shaft were inserted into the secondary shaft of the gearbox. The gear is fixed with a retaining ring.
After that, the input shaft of the gearbox was installed and grease was added.
After these operations, it remains to close the gearbox and assemble the dust removal fan.
Creating another creation, I needed a grinder. Having taken her into the light of day, it turned out that she was not half dead. We take care of repairs at home.
So, we have a Chinese grinder. I got it, though cheap, but still a pity to throw it away. Due to intensive use, the following symptoms appeared: when turned on, noise increased, some uncharacteristic rattling appeared, power decreased, and then jamming began.
We start to disassemble. Remove all screws from the cover
And from the grinder.
We're filming the site.
We remove the cover.
Apparently, the engine seat was smashed from work. And when voltage is applied, the rotor warps and wedges.
We shoot from seat sizes.
We cut out the gaskets from the pressboard. We place on one side of the casing.
Note the position of the bushings. This is very important, otherwise you will suffer during assembly.
Carefully, so as not to damage the brushes, we take out the engine.
Insert the gasket symmetrically. We carefully collect everything back. Pay attention that the bushings sit in the grooves. We put on a jacket. Tighten with screws. We check.
Changes are already being felt in better side. The motor rotates the shaft without problems. No jamming is observed. We assemble and fix the sanding pad.
Check again - great! Now you can keep creating!
This is an additional condition for you to feel more comfortable when contacting us. If something does not suit you during or after the repair, just call our dispatch center by 24/7, and I will refund all your money down to the last penny! By the way, in 2018 we received only 9 requests for a refund (out of 38,990 requests!).
🔧 After the warranty, you will receive LIFETIME SERVICE
No need to worry about what will happen to your equipment after the warranty. I give every client a lifetime service maintenance in Lenremont. This means that if the technique breaks again after warranty period, repairs will cost 2 times cheaper! Thus, you get 25% discount on post-warranty repairs.
✅ 2 year repair warranty
Yes! I am so confident in the skill of my masters that I boldly give you 2 years warranty for repairs. This is the biggest guarantee in all of Russia.
And one more surprise - you will receive 4 months warranty for all parts, since Lenremont orders parts from a direct supplier.
This warranty means that, if suddenly Your technique will break again the master will come and repair for free her. Even if the master who repaired your equipment falls ill or no longer works for us, you do not need to worry that you will be left without a warranty repair: we have more than 100 masters for each type of equipment in our staff. We take full responsibility for making you, our dear customer, satisfied.
With modern finishing work various construction tools. Grinding machines are no exception.
Due to frequent use, any tool can fail. And in order to repair the grinder with your own hands, you need to have an idea about its components and possible reasons breakdowns. Since the angle grinder is the most in demand, subsequent repairs will be considered on its example.
By constructive and external characteristics such a machine is a grinder, as it consists of the same parts.
The grinder consists of:
- protective cover;
- ventilation hole;
- push button switch;
- side handle;
- spindle lock.
Repair of the grinder should be done carefully and slowly, since the consequences of repairing power and electronic components can turn a minor breakdown into unsuitability of the device.
It will take not so many tools to repair the grinder:
- soldering iron;
- tester;
- screwdriver.
Components of the device mechanism
A grease-caked bearing is a common cause of grinder breakdowns.
The machine has internal components and mechanisms, the device of which also needs to be sorted out;
- Anchor. This is one of internal elements an electric motor that performs rotational movements during the operation of the device, the speed of which is adjustable. The power parameters of the tool determine the speed of rotation of the armature, the higher it is, the more powerful device. At normal operation the anchor should rotate easily and freely, nothing should prevent its rotation;
- Collector. This element looks like separate site armatures and power and control windings are output to it. The collector performs the function of supplying signals to the engine and control unit. To see it, you need to remove the case, it looks like polished contact plates with significant dimensions;
- Electric brushes. Plays the role of a conductor for conducting current from the power cable to the collector. If this element is functioning normally, then sparks will be weak and uniform, they can be observed through the ventilation holes in the device case;
- Reducer. It is a mechanical device located in front of the machine. Its purpose is to transfer the mechanical energy of a rotating armature to a rotating disk. In this setting, both the revolutions of the rotating disk and their development of speed are subjected;
- Stator. This is an element of the electric motor in which the armature comes into motion. It is the most difficult element, since the windings in it must be pressed strictly in accuracy. It is not recommended to rewind the stator on your own, it is better to entrust this work to the master.
When repairing, it is recommended to rely on the layout and electrical circuits, have at hand the instructions that were attached to this particular model of the grinder. But many models do not fit similar instructions, in this case, it is most reasonable not to carry out repairs on your own, but to seek help from the service.
Back to index
When repairing any equipment, the sequence must be followed. Simple faults are:
- The device suddenly stopped working.
First of all, the electric brushes are checked, since there is a possibility that they are not getting current from the power supply.
To replace the bearing, you need to remove the horseshoe retainer.
Specifically, the problem may be in the power plug or in the wire itself, and the Start button may also not work. To fix the problem, the case is disassembled and the wiring is called using a break tester. In frequent cases, the problem is in the wiring, and after replacing it, the grinder will work again;
- After checking, the wires and the plug are intact, and the device does not show any working signs. In this case, the starting block is disassembled, and the elements to be removed are marked, since if they are incorrectly connected during assembly, this may lead to the winding burning or the armature may jam. The button is replaced with a similar model;
- start button and power cable work, but the machine refuses to work. In this case, it is recommended to examine the brush holder. The most common problem is the contact plates of the collector, which, after stripping, will begin to spark and even buzz. If these signs are not given, then the brushes must be replaced, since their service life is limited. If many models are made with a soldered connection of the brushes, then in this case it is necessary to solder and change as a set, since a partial replacement is not made;
- After changing the electric brushes, they should be carefully examined if the wear is uneven - this is a sign of a shift in the center of gravity or internal moving parts. If such a problem occurs, it is recommended to contact a specialized service, since it is impossible to adjust the balance yourself.
Brush repair is minor repairs when troubleshooting, but more serious breakdowns are best left to specialists.