DeWALT angle grinder works a minute and then shuts off

Mechanical faults of the angle grinder

Angle grinder. it is an angle grinder, designed to perform cutting, grinding, polishing work. the angle grinder in the course of work is exposed to high loads, works in a dusty environment.

Excessive loads when using the angle grinder in cutting mode cause increased wear not only on the bearing but also on the gear teeth.

The main problem of angle grinder on the mechanical part, wear or destruction of the friction bearing on the shaft of the large helical gear reducer.

Troubleshoot the angle grinder is not difficult, if you have at hand its scheme, description and recommendations on how to perform repair work.

Friction Bearings Repair

The weak point of every angle grinder is the bearing. Although there are few in the design, only three, they are the most common causes of mechanical failure. The bearings are negatively affected by

  • high rotation speed;
  • operating at extreme speeds;
  • insufficient lubrication;
  • ingress of dust or dirt;
  • untimely replacement or destruction of carbon brushes.

Every angle grinder is designed for quick and easy replacement of any bearing.

Troubleshooting angle grinder associated with wear or destruction of friction bearings on the gearbox shaft is characterized by the appearance of unpleasant extraneous sound.

Failure of a plain bearing is indicated by checking the backlash of the work tool shaft. Determined by rocking in different directions of the shaft when installing the working tool.

When installing the working tool again check the shaft backlash by jiggling the end of the shaft in different directions. There should be no or minimal backlash.

If play appears, the plain bearing must be replaced.

angle, grinder, works, minute

Repair of bearing consists in taking it out of the housing and removing it from the gearbox shaft.

It is better to remove the bearing from the shaft by means of a puller. The inner ring of the destroyed bearing is best extracted by means of a tap of the required diameter, previously screwed into the cage.

Remove the bearings from the rotor with a puller or a people’s method.

Wrenches or metal strips are inserted into the vice, the bearings are placed on the wrenches and, using an arbor of soft metal and a hammer weighing at least 400 g, are knocked off the shaft.

Repair of angle grinder gearbox

Degree of wear of angle grinder gearbox gears is checked for contact patch. Clean old grease off the gearbox completely beforehand. On the small gear is applied a special blue, the gear is rotated. Next, you need to remove the large bevel pinion and look at the contact patch with a magnifying glass. It should occupy not less than 50% of the tooth surface in total.

Otherwise the gears need to be replaced or the tooth profile needs to be corrected. Correction of tooth profile is repeatedly described on the pages of this site.

But this fault can only be repaired by an experienced handyman. often than not, chipped, sheared or broken gears are replaced as a whole, and in pairs.

Diagnosis of the electrical part of the angle grinder

As mentioned above, most often the angle grinder refuses to work due to breakdowns in the electrical part of the unit. To properly diagnose the electrical circuits of the tool, electricians use a special device. a tester.

If you have pressed the button to start the machine, and it does not work, then in 90% of cases the cause of the breakdown is not so serious that you can not repair the angle grinder with your own hands.

Experts advise to adhere to the basic rule of power tool repair: move from simple to complex.

The first thing to do is to check the electric cable and the plug at its end. If it is collapsible, then unscrew it and check the reliability of contacts. Otherwise, you will have to disassemble the angle grinder (remove the hood of the machine) and “test” the cable with a tester, and make sure that the current approaches the contacts of the “Start” button. If the device shows a breakage, the cable should be replaced with a new one.

The situation when the current comes to the button, but does not pass further (when it is on), indicates the fault of the switch. Button cannot be repaired. It must be replaced by a new one, but first mark the removable pins so that you can connect them correctly in the future. If the contacts are not connected correctly, the motor winding may burn out.

If the test turned out that both the cable and the start button are serviceable, but the brushes do not receive current, it is necessary to make stripping of the contact plates of brush holders. If this procedure is ineffective, it is recommended that the brushes be replaced. Next, if the brushes are okay and are receiving current, check the rotor and stator for shorts and interruptions.

Checking the motor armature

The rotor of the electric motor can have the following faults: Inter-turn short circuits and broken wires on the lamellar contacts. Check the armature of the angle grinder can be checked with a multimeter: the device is set in the mode of changing resistance, set the value of 200 ohms, and using the styli measure the resistance between the two adjacent blades. So all pairs of blades need to be checked. If the resistivity is the same, there is no damage to the rotor winding. If during the test run, different resistance values are detected, and an open circuit is detected, there is a problem with the coil. Repair of the angle grinder armature will then be necessary.

Usually wire breaks occur at the connection to the winding. Examine the places where the coils are connected to the lamellae to make sure that the contacts are securely soldered.

If you do not have a measuring device, you can check the rotor, using a 12 V light bulb and a battery for this purpose. The power should be between 30-40W. Checking is done as follows: apply voltage of 12 V from the battery to the plug of angle grinder, connect a light bulb in the gap of one wire, start rotating the spindle angle grinder. If the winding is intact, the light bulb will light evenly, without flickering. When there is an intercircuit, the degree of incandescence of the bulb’s coil will change. In this case, the repair of the angle grinder armature with your own hands will be difficult, because the winding circuit of the armature is quite complicated, and the process itself requires special equipment and knowledge. It is therefore recommended that this operation be entrusted to specialists. But the best way out of the situation will be to replace the armature on the angle grinder with a new one.

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If the light bulb does not light up when testing the rotor, this indicates a breakdown in the stator or a short circuit in its windings, as well as problems with the electric brushes.

Checking a Motor Stator

To check the stator of an angle grinder, use a multimeter like the one above. The values should be set to 20-200 ohms and do the following. Touch the stator winding contact with one probe and the housing with the other probe. If the device shows resistance, it means that there was a breakdown on the housing. Touch the probe to the contacts of one winding and then to the contacts of the other. If the resistance is the same, it means that the coils are in order. If one winding shows an open circuit, the stator needs to be rewound or the part needs to be replaced with a new one.

To rewind the stator at home without any special knowledge, skills or equipment would be problematic. It’s best to call in a professional motor rewinder.

The main faults of angle grinder

2016-08-16 Repair 5 Комментарии и мнения владельцев

Angle grinder, or commonly known as an angle grinder is an indispensable helper for home craftsmen. There is always a use for it in the household. And the more often you work with the tool, the greater the probability of its failure. Since all angle grinders are arranged similarly, the diagnosis of basic problems for different models will be similar.

To begin with, let’s understand the main nodes of the angle grinder. For all models of angle grinders, regardless of the model, is characterized by the presence:

  • Anchor. the rotating part of the electric motor.
  • Collector: the part of the armature to which all the windings are wound. Is a series of insulated copper plates, the so-called lamellae.
  • Stator. the fixed part of the electric motor.
  • Brushes. carbon or graphite brushes that carry current to the collector lamellae.
  • Gearbox. a mechanical device for transmitting rotation from the armature to the cutting or grinding wheel.

What repair of angle grinder with their own hands can the user

Although the angle grinder and is not a tool of particular complexity, to perform repairs the user can not all nodes.

In addition to simple replacement of bearings or gears, there are problems that cannot be solved without special equipment or tools.

  • A press is needed to press out the idler pinion. To rewind the rotor without tools is not possible.
  • Such malfunctions include breakage of the rotor. For the average user, such a malfunction ends up at the service center.
  • Advanced users can revive a burnt-out rotor with certain skills and concepts. But sometimes it is easier to buy a new one than to rewind.

For most users, the repair of angle grinder with their own hands is limited to a certain range of faults.

Systematization of faults in the electrical part of the angle grinder

  • The easiest problem that can cause an angle grinder not to start is a broken power lead. Most often there is a break in the power cord near the plug or in the power inlet of the tool. The problem can easily be solved by replacing the power cord or removing a broken piece of wire.
  • Increased heating in the carbon brushes area. This most frequently occurs because the carbon brushes are shorter than the nominal size. The carbon brushes must be at least 8 mm long.
  • The trigger of the angle grinder is stuck. Failure is due to burnout of internal contacts in the button. Fixes by completely replacing the switch with a new one.
  • Some angle grinder models have a device that enables infinitely variable speed adjustment of the angle grinder. The angle grinder‘s speed regulator improves the angle grinder’s smoothness of operation and prevents the grinding tool from jamming. Repair of the angle grinder’s speed regulator is to replace it completely.

Failure grouping by mechanics angle grinder

  • Unusual noise in the gearbox of the angle grinder, gearbox heating. Failure is associated with destruction of the bearing, wear of gear teeth, drying out of lubricant. Remedied by replacing gears when tooth is worn excessively. If the gear teeth are slightly worn, you can try to fix it. Tooth profile may be repaired by hand, filing with a round drift file and drill. Grease is replaced with new grease each time the gearbox is repaired. New grease is applied to carefully washed components.
  • The bearing needs to be replaced when it breaks down or has a large amount of play. Some models have an interference fit of the bearing on the spindle. Replacing requires special equipment, such as a press. Parts must be cooled or heated.
  • replacement of bearings on the rotor is required when there is a large run-out. The presence of excessive runout can be easily seen on the rotor manifold and by the wear of the carbon brushes.

Simple problems and how to diagnose and repair them yourself

If your angle grinder does not start when you press the start button, start by inspecting the power cord where it enters the tool.

Unscrew the cover of the angle grinder and check the continuity of the power cord with a tester or phase. Strictly obey the safety rules.

If the power cord is intact and the angle grinder does not start, replace the start button.

If the angle grinder does not work when you install a new button, check the quality of the carbon brushes attachment and their tight fit to the rotor manifold.

Complex malfunctions and repair angle grinder with their own hands

The following types of breakdowns require some knowledge and skills to fix them:

  • Jammed or destroyed bearings.
  • Licking or destruction of gears gear teeth.
  • Breakage or short circuit in the rotor or stator.
  • Failure of control circuit parts.
  • Breakage of the gear housing.

Peculiarities of repair angle grinder (angle grinder) with their own hands

Angle grinder (angle grinders), in common parlance called angle grinders, are considered an extremely reliable and popular tool. However, every thing breaks sooner or later and needs to be repaired. To repair the angle grinder yourself is not so difficult, if you have on hand the instruction, which indicated the order of action. Below you can find answers to questions related to the repair of the stator, rotor, gearbox and carbon brushes angle grinder.

Angle grinders are extremely common among many craftsmen at home. Ability to interchange work pieces enables polishing, grinding and cutting applications. And the presence of a soft starter significantly increases the convenience and safety of work. Fixing the angle grinder. it’s easy work, with which you can cope and their own forces. Those who have decided to do it, will need a diagram of the angle grinder required type, materials for lubrication, the tool itself and a step by step guide.

Any repair of angle grinder by your own forces should begin with the identification of faults. angle grinder is characterized by an uncomplicated device. When rotating the rotor through a helical gear torque is transmitted to the spindle (shaft) of the working element. There is a polishing or grinding wheel or stone on the shaft.

The shape of the cog should also be noted. On the angle grinder small power, as a rule, are installed gears with straight teeth. Helical designs are used in devices, the power of which starts from 1000 watts.

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The angle grinder, like any tool, is subject to all kinds of failures over time, the causes of which can be very different. They can occur not only from improper use of the device, but also from untimely/incorrect change of carbon brushes and lubrication materials.

Regardless of the model and brand of angle grinder, all have almost the same problems. They can be divided into electrical and mechanical. For repairmen-beginners who do not know how to disassemble the angle grinder, breakdowns can be divided into complex and simple.

Where to Buy

Employees of companies that sell power tools and accessories for it, offer buttons for grinders of different types and brands.

So, there is a situation: yesterday, all of a sudden the button fell out on the angle grinder (grinding machine Zubr, 1100W, 125 disk). I think the tool is under warranty (it is not even one year old yet). but I do not need it for service so I disassembled it on my own Bottom line. the plastic thing in the tool body, that holds the main button (plastic, letter “G”) broke. There is no such machine available anywhere in the city. even in the service center What to do, how can it be replaced?? Or what to do now?

Angle grinder stator repair

The cause of the failure of the stator of the grinder can be determined. For this, pay attention to intermittent faults. The rotor may develop revolutions in excess of the allowable, which will indicate an inter-turn short circuit in the winding. Many breakdowns can only be repaired in a service center, but to ensure trouble-free operation, timely cleaning, lubrication, replacement of brushes and bearings can be performed.

Failure of the stator of a Makita angle grinder is rare, and constant overheating of the angle grinder can be the cause. In this case, the housing gets very hot, and there is a smell of burning in the ventilation ducts. In the winding of the stator can be a short circuit or a breakage, so without special tools to determine the fault and repair the device is difficult. To repair the angle grinder with your own hands or to replace the stator, you need to carry out the following actions:

  • Dismantling the gearbox of the angle grinder;
  • Disassembling the rotor after removing the mounting bar;
  • Removing the stator guard;
  • Unscrewing the screws fixing the stator in the housing;
  • Removing the handle cover and disconnecting the power wires;
  • Removing the stator.

A real constructor from Dewalt. Dewalt angle grinder repair!

The stator is tightly seated in the housing, so the extraction process can be accompanied by light blows on the housing with a mallet. Most often the stator must be replaced, but sometimes amateurs can do the rewinding themselves.

Drilling part stuck in the chuck

Sometimes you don’t have to disassemble the stator to figure out why it doesn’t kick. The core bit can get jammed in the chuck.

  • The drill bit was not greased on the shank when it was inserted in the chuck. It is necessary to carefully move the sealing rubber on the cartridge and add WD-40 to the joint.
  • The shank broke;. Pulling out the stator. In this case you should first inject WD-40, and only then try to remove the drill. If it is not possible, it is necessary to dismantle the chuck and knock out the core bit.
  • Drill bit with adapter takes the place of the chuck. Here also first of all treat the connection place with WD-40. After a few minutes, you can start to tap the chuck lightly with a hammer while slowly loosening the drill bit with the other hand. The chuck jaws must then be loosened.

Drill bit comes out of the chuck

When during the work under load, the drilling mechanism falls out of the chuck, the reason is in the exhaustion or breakage of the latter. Remove and disassemble the chuck to find the source of the problem.

Important! Further work with such an electric electric screwdriver is not possible, in addition, the falling out drill bit can cause injury.

Chuck falls out

If the chuck comes off the chuck, the cause is a failed retaining ring on the place where the chuck is attached to the bushing of the raster. The way out is simple. replace the ring.

Repair of angle grinder with your own hands

As you know, nothing is everlasting and even tools from brand manufacturers break down, not to mention the so-called “consumer products”. And angle grinder (angle grinder). is not an exception. By the way, to call the angle grinder “angle grinder” have become in the Soviet Union, because then this tool was produced in Bulgaria, and there were delivered the first model. Angle grinder as a tool has become very popular due to its versatility and convenience in operation. Also, there are many varieties and models of angle grinders, but the principle of operation and design is not fundamentally different. Therefore, having considered the device of the tool, possible malfunctions and repair methods, they can be applied to any model of angle grinder.

The device of the angle grinder is relatively simple. The basis of the tool is its body, inside which is an electric motor, starting device and gear drive to the spindle, to which various attachments.

The housing is made of impact-resistant plastic. tool in various sizes and shapes depending on its power. Some models have an adjustable rpm controller for choosing the best rpm for different applications.Another component can be a gearbox. The gearbox is designed to ensure optimal transmission of the rotation from the rotor of the electric motor to the cutting or grinding wheel. This reduces the number of revolutions on the gearbox output shaft. Correctly set the speed and diameter of the wheel. key to the most efficient operation of the tool.

Replaceable disc button, which locks the disc in a certain position, preventing it from spinning when removing it.

A safety clutch serves as a limiter in case of sudden reactive torque. Otherwise, if the disc jams in the material, the angle grinder itself starts to rotate sharply, which can cause injury to the worker. This coupling prevents it from spinning.

The electric motor normally comprises a stator and a rotor. The stator sits in the guide flanges of the plastic housing of the angle grinder. There is a special device on the back of the stator called a brush mechanism. It houses the carbon-copper brushes. Brushes are needed to transfer the voltage to the rotor via the collector unit.

The rotor is located inside the stator and is mounted in the housing in bearing units that are inserted directly into the tool housing. The front bearing unit is usually made of a metal plate, or, alternatively, this plate can be made of aluminum alloy.

The gear case of the angle grinder is almost always made of aluminum alloy and has several threaded holes for attaching an additional handle. By screwing the handle into different holes, you can change the plane of the work.

The gearbox is two gears that change the direction of the output shaft by 90 degrees and reduce the rotation speed. The ratio of the number of teeth of the primary gears to the number of teeth of the secondary gears is called the gear ratio.

Typical malfunctions of bolsters and methods of diagnosis and repair

the angle grinder suddenly stops working.The first thing to do. Physically disconnect the machine from the mains and turn the disc manually. If the disc does not spin or spins very slowly. immediately disassemble the tool for visual inspection. If it spins easily, the most likely possibility is. Electricity does not reach the brushes of the electric motor. In other words, the problem is in the power plug or in the wire itself, or in the mechanism of the “Start” button. It is enough to disassemble the housing and “ring” the cable with an ordinary tester, or in any other way, to check for breaks. After eliminating a wire break or replacement, the angle grinder will work.

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Wire and plug are undamaged but tool still does not work. It is necessary to disassemble the starting mechanism, and it is desirable to mark the removable contacts. if you later connect them incorrectly, it can burn out the winding or jam the armature. It’s not often that a starter can be repaired. It is easier and safer to replace the starter button with any similar one of the same capacity. Such a button isn’t expensive and you can buy it at any store of the corresponding profile.

Start button and power cord are in good working order, angle grinder does not work. Check brushes and brush holders. Brushes may be broken or completely worn out. The life of these devices is usually limited to several years, of course, depending on the intensity of use. Repair breakage or replace brushes.

Then come more serious malfunctions, respectively, and repair requires certain knowledge and skills.

In determining the mechanical defects of the angle grinder you should pay more attention to the condition of the plane (big gear), the shank (the gear on the shaft) and bushings. Uneven wear of the gears or misalignment of the shafts indicates the immediate replacement of worn parts.

Break out of spindle locking button.The cause is just one careless movement, namely pressing (intentionally or accidentally) the button while the disc is spinning. Sometimes the damage is due to trying to remove a jammed disc using a button. Many grinders have special slots on the spindle, where the disk is mounted specifically for the usual wrench, look at his angled grinder, most likely you have this. Well, you’d better use them and a wrench than a jig locking button.

Chipped gear teeth.Usually occur as a result of jamming (in such a situation, tool breakage is not the worst thing that can happen). A sign of malfunction is a rattle in the gearbox. If the pinion loses two or three teeth, then the tool can’t cut. You must change the gears in pairs and change the pinion and bevel wheel. When you go to the store for gears, don’t forget to write down the name of your angle grinder and its power.

Motor failure.It often happens with tools that are operated in dust and made to rest in the sand or on the ground: the dust that is sucked in causes the winding to wear down. However, you can ruin the motor without dust. because of severe overload, especially if the tool is low-powered. That’s why small grinders often burn out not only the armature, but also the stator. Small grinders sometimes have a defective electronic speed control unit. If you use an angle grinder to cut strongly dusty materials, particularly slate, well helps to protect the tool put a stocking on the places of ventilation slots in the body.

Bearings.Another sore spot of grinders (as well as other twisting power tools). Few machines are strong immune to dust, and high frequency of rotation implies rapid wear and tear. In general, bearings are not the most terrible breakage, they are easy to change. However, it is important to make the replacement in time, otherwise there is a high probability of a more serious failure, the repair of which is comparable with the purchase

StatorIf the disc starts to gain speed and accelerates too much when turned on, there is definitely a short circuit in the stator winding. Repair of stator belongs to the most serious breakdowns, requires appropriate skills. If you are not confident in your abilities, it is more expedient to entrust this to professionals or use the services of a repair shop.

Repair of stator of angle grinder begins with cutting off the frontal parts of coil, the remnants of which are removed. Next, make a new winding using a template clamped between two large plates on an axis that can be inserted into an electric drill. The main thing is to achieve an identical number of turns, made with the proper density and maintain the thickness of the wire. Insert two coils in the stator body, we make conclusions from the same winding wire, insulated with flexible tubes of appropriate diameter.

Gearbox In models with power up to 1100 W, spur gears mounted on the armature are usually used, but angle grinders with higher power, such as 1500 W, require helical spur gears. Both are tapered, because the axis of the reducer rod intersects with the armature shaft, and transmission is possible only by angular meshing of the teeth. As a rule, the repair of the gearbox of an angle grinder consists only of replacing the gears. If the disc gear breaks, it will be very difficult to remove it for replacement, in the gearbox this unit is best fixed.

Speed regulatorAre almost all modern models of drills, jigsaws, screwdrivers have a speed regulator. But not all angle grinders (grinders) are equipped with such a mechanism. For cutting metal with a cutting stone regulator is in principle not needed, but for grinding it is simply irreplaceable. The proposed scheme of self-made regulator is very simple and reliable. Parts are few and not expensive. If you already have an angle grinder without built-in speed regulator, you can easily upgrade it.

You can assemble and separately in a box with a socket and use it as a carrier with a power regulator. Or you can immediately assemble the regulator in the body of the angle grinder and derive the handle of the resistor.

Angle grinder usage rules and preventive maintenance

The power tool must not be allowed to run under load for a long time at a significantly reduced RPM (this can be determined by ear) compared to idle RPM, and even less should the tool be jammed (blocked), otherwise it will burn out in a matter of seconds.

Do not turn the power tool off immediately after working at low speed. In order to prevent local overheating it is necessary to let it run for some time (more than 1 min) to avoid overheating.).

It is important to clearly observe the dates of replacement (addition) of grease and its amount specified in the instruction manual.

Prophylaxis consists in complete or partial disassembly of the tool, cleaning, greasing and replacement (if necessary) of some parts.Timely replacement of relatively inexpensive parts that wear out quickly will save more expensive components in the long run, which in the end leads to savings in tool use, eliminates premature repairs and greatly extends the life of the tool.

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