How to clean an anchor on an angle grinder. How to clean the armature collector

Power tool’s motor brushes are sparking too much The reason

It is difficult to imagine an arsenal of home without such a popular power tool, as an angle grinder angle grinder or angle grinder (popular name). The angle grinder has gained its popularity due to its versatility, because this tool can be used for cutting, grinding, sawing, polishing, deburring, grinding, and other work. Absolutely any material can be processed. During the operation of the tool there are different breakdowns, and one of the most common is the sparking of brushes on the angle grinder. Not many people know why the brushes on the angle grinder spark, so let’s look into this question, as well as why they burn out and how they are replaced.

Sparks, even on the working engine, appear because of the mechanical effect between the brushes and the collector. Brush, moving along the collector from one of its contacts to another, alternately forms and breaks the connection with each of them. And now remember what happens if you pull out of the socket any electric appliance, and usually at such moment there is a spark between the plug and the socket. In the case of a brush motor it is the same phenomenon.

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Therefore, a small amount of sparking, even on a functioning electric motor, is permissible because the connection and discontinuity here are constantly occurring.

Why the sparking of the brushes in the motor, what this phenomenon leads to and how you can eliminate it.

Subject: What to do if the brushes in an electric motor are sparking a lot.

So, initially I will say that the sparking itself during the work of collector electric machines. it is normal, but it should be very small, barely visible to the eye. It is not normal when an electric motor is running and sparks are flying straight off its brushes. that’s bad. The very same phenomenon of spark formation is associated with an intermittent electrical contact that occurs during the rotation of the armature, at the moment of the mechanical transition of the brush from one contact, on the collector, to another. At this time, the circuit is broken and the current flowing through the armature coils ends with a spark, a small arc discharge. Therefore, the greater the power and current in the circuit, the more noticeable the sparks. But in addition to this there are other factors that contribute to an increase in the spark.

You should also pay attention to the condition of the gaps between the contacts on the collector. It often happens that they are clogged with graphite dust, which is a conductor with a certain resistance

Naturally, if these gaps are contaminated, you need to clean them as well (using a pointed instrument). Don’t forget to check the state of the brushes, their development, the clamping force, the freedom of vertical movement. If you find problems with the brushes, be sure to fix them. Please note that when replacing graphite brushes you have to take into account that they come in different sizes. In this case, try to find exactly the same type as the old ones.

Check the armature in an alternating electromagnetic field. If there are shorted windings the armature will rattle in such a field as induced currents begin to form in it. For this purpose you can make a homemade device from a power transformer, having previously made a wedge-shaped cutout on its core, into which the armature should be inserted for testing.

Since this is important, I’ll say it again. increased spark formation during motor operation affects the longevity of the motor. This quickly creates a heavy fouling on the collector pins, which over time will break down the electrical equipment

It is better to eliminate the sparks at once, than afterwards to replace the whole armature on top of that.

What to do if there is wear

Make sure that the sparks are coming from the brush unit. To do this, you need to inspect the angle grinder housing. On some models the brushes are mounted on the outside, then to replace them you will not have to disassemble the housing. There are round plastic threaded plugs on such angle grinders.

To unscrew them, you will need a large slotted screwdriver, the working side of which is placed in the slot of the plug. The plugs are carefully unscrewed counterclockwise. Then remove the brushes with springs. New parts can be bought at building or electrical stores.

Since the original length of the brushes will be difficult to establish, you need to be guided by:

  • measure the distance from the surface of the manifold to the outside of the seat, taking into account the thickness of the compression spring and the brass contact plate;

If you can not set the model name of the angle grinder, it is better to take the angle grinder with you and pick up brushes in the store.

But to replace the carbon-graphite nickels on other models of cut-off machines, you will have to open the housing. To do this, you must unscrew the screws that can be located at the end. near the mains cable or on the side plates and the surfaces of the handle.

The plastic protectors can either be pulled down. through the cord. or apart.

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When disassembling the body, you need to be careful: often on the plastic elements of the handle is attached to the power button. Pulling too hard can tear out the wires.

Brushes on such models of lathes are hidden in the bracket on the collector. To remove the carbon pedals, you have to bend the brass plates or push them in and twist a little. Method of removal depends on the model.

clean, anchor, angle, grinder

Frequent Starter Malfunctions

The most common failure of the starter is a skewed rotor-anchor (the starter at start-up is as if “jammed”, the armature turns slowly and heavily, with a large load).

Or, alternatively, too fast, “frantic” rotation of the armature after the traction relay is actuated and the engine crankshaft does not turn. In the first case, there are symptoms of wear and failure of bronze-graphite bushings, used in starters as plain bearings, and, as a consequence, skewed rotor shaft at startup.

clean, anchor, angle, grinder

In the second one you can be sure that the “bendix”. the starter motor drive with the driving gear, which meshes with the gear of the engine flywheel. has told “to die for a long time”. To replace both sliding bushings and bendix is not possible without removing and disassembling the starter.

And as this process is rather labor-intensive, it is recommended for preventive purposes to make at the same time a visual inspection, minor repairs, and, if necessary, the replacement of all worn parts.

Diagnostics with an armature checker (choke)

An armature test tool to detect the presence of a winding short circuit. The choke is a transformer that only has a primary winding and a magnetic gap cut out in the core.

When we put the rotor in this gap, its winding begins to work as a secondary winding of the transformer. Turn the device on and place a metal plate, such as a metal ruler or a hacksaw blade, on the armature. If there is an inter-turn fault, local iron oversaturation will cause the plate to vibrate or become magnetized to the armature body. Rotate the anchor around its axis, moving the plate so that it lies on different coils. If there is no short circuit, the plate will move freely around the rotor.

How to know if the brushes need to be replaced

Many people change the brushes only after they discover severe sparking of the tool, as well as the appearance of a burning smell. Many craftsmen do not stop even these signs, and they continue to operate the tool until it ceases to turn on. When is it necessary to change the carbon brushes, so as not to damage the device of the power tool. There are the following signs for this:

  • Strong sparking. if there are signs of strong sparking, it is necessary to disassemble the tool, and inspect the consumable elements. Sparking is the first sign that consumables need to be replaced
  • If you can smell carbon buildup, it is recommended to disassemble the angle grinder and replace the graphite brushes
  • If the main part is worn more than 30%-40%. However, it is almost impossible to determine their initial length, unless you measure it before installing the elements
  • When signs such as jerking and “growling” of power tools appear

Are still subject to replacement devices, if they have uneven wear and tear, as well as not of the same quality.

This is interesting! At home angle grinder is not recommended to buy copper-plated brushes, as they will quickly fail the armature collector due to the high copper content in the composition. Copper-plated elements can be used on grinders, which have a special coating on the manifold plates.

Checking and repairing the angle grinder armature

What does the diligent homeowner want to see in his “luggage” of power tools? To this question everyone, without even thinking for a moment will answer. the drill. And immediately add. and, of course, an angle grinder! After all, it is she who will help cut metal, ceramic, brick, concrete, asphalt, stone or wood; perform work on the arrangement of niches, arched and doorways. With this power tool, you can grind surfaces from rust, scab and build-up; get rid of welds or simply polish the metal to a shine. Angle grinder will become an indispensable assistant in other types of home repair.

Whatever the angle grinder (angle grinder) has a reliable design, during operation, some nodes and parts fail. Failure of the armature, which works in rather harsh conditions, is often the reason for the lack of normal functioning of the electric drive. In this article, the master plumber will consider how to repair or replace the anchor of the angle grinder.

clean, anchor, angle, grinder

Anchor motor of angle grinder is a current-conducting coil and a magnetic wire, in which a shaft of rotation is pressed. It has a pinion at one end and a collector with lamellae at the other. The magnet wire consists of grooves and soft plates coated with varnish to isolate it from each other.

Two conductors of the anchor winding are placed in the grooves according to a special scheme. Each conductor is half a coil, the ends of which are connected in pairs on the lamellae. The beginning of the first coil and the end of the last coil are in the same groove, so they are shorted to one lamella.

When you buy a power tool, few people think about the fact that someday it will fail. Breakdowns can occur with any electric tool, regardless of the price or the manufacturer.

  • Breakage of conductors.
  • Inter-scroll fault.
  • Ground fault is a short circuit of the winding to the metal body of the rotor. Is caused by insulation failure.
  • Collector leads soldering.
  • Uneven wear of the collector.

The main causes of breakdowns of bolsters, including their anchors, can be considered:

Angle grinder repair

  • Mechanical wear. most often the brushes suffer.
  • Failure to follow the operational “passport” mode of operation. armature and stator.
  • Overloads and power surges. stator and rotor.
  • Failure of small parts. bearings, clamps, nuts, washers, etc.
  • Dropping, shocks and other careless attitude to the angle grinder. breakage of the housing.
  • Lack of preventive cleaning. Geareducer malfunction or breakage of the on/off button./off.

If the armature is faulty, the motor overheats, the winding insulation melts and the turns are short-circuited. Solder off the contacts that connect the armature winding to the collector plates. Current stops flowing and motor stops working.

The extent of repair work can be determined by expert diagnostics of the rotor damage. The specifics of the formation of defects, which most appear when the angle grinder overheats during prolonged work at high loads, allows you to determine them visually.

Standard diagnostics involves a visual analysis of the device. It is necessary to analyze the integrity of the wire and the power supply to the collector of the motor. Inspect the angle grinder from the inside if the power supply is normal. It is very easy to disassemble the machine. The best way to disassemble it is to take pictures of the location of the main modules of the device. After disassembly, conduct a visual inspection of the armature for such properties:

How to determine the problem of angle grinder armature

Signs of angle grinder armature failure are: increased sparking of brushes on the motor collector, vibration of the motor at low speeds, rotation of the working shaft in different directions. If these symptoms are present, you should stop working with the tool. it is dangerous. Suspicions can be easily checked with simple tests.

Visual inspection from outside

Troubleshooting should begin with a visual inspection of the angle grinder:

  • Carry out a general inspection of the tool.
  • Pay attention to the integrity of the power cord, the presence of voltage in the socket.
  • Using a voltage gauge, make sure that current is flowing to the motor collector and start button.

Inspection of the device from the inside

If everything is okay with the power supply, but the angle grinder doesn’t work, you’ll have to open the housing to get access to the motor. Disassembly is usually straightforward. But it is necessary to adhere to simple rules that will avoid trouble during reassembly:

  • Be sure to unplug the unit before disassembly.
  • Remove the blade and protective cover from the spindle.
  • Open the enclosure in a well-lit area, on a clean tabletop.
  • Be sure to note the location of all the parts and assemblies before disassembling. It is recommended to draw or photograph the internal structure of the device.
  • Keep screws and fastening screws in a separate location so that they do not get lost.

It is best to inspect the motor under bright light, so that all the small details are clearly visible. Anchor should rotate freely around its axis, properly functioning bearings should not make a sound during operation. There should be no traces of melted wiring on the armature, and the circuit windings should be intact, with no breaks. You can smell the rotor. If there is a short circuit between the cores, the insulating varnish gets burnt and gives off a persistent, specific smell. But this diagnosis requires a certain amount of experience.

Carrying out a continuity check with a tester

If visual inspection does not yield obvious results, it is advisable to continue the examination with a multimeter. Having set the tumbler of switching modes in position of ohmmeter (range 200 Ohm), it is necessary to “probe” two neighboring lamellae of an armature with two probes. If the resistance on all turns is the same, it means that the windings are serviceable. If the tester shows different resistance or open circuit on some pairs, there is a problem with the coil.

A wire break can occur between the winding and the core. The connection points between the coils and the collector flanges at the bottom of the armature should be carefully inspected and the solder pins visually inspected.

Repair: Fix the insulation breakdown

If the breakdown of the insulation was small and you found it, you need to clean the place of fouling and check the resistance. If its value is normal, insulate the wires with asbestos. Dab some quick drying glue like Supermoment on top. It will seep through the asbestos and insulate the wire well.

If you still can’t find the place of the insulation breakdown, then try carefully soaking the winding with impregnating electrical insulation varnish. Punctured and non-punctured insulation will soak in the varnish and become stronger. Dry the armature in a gas oven at about 150 degrees. If that doesn’t work, try rewinding or replacing the armature.

Brazing the collector plates

The blades are mounted on a plastic base. They can be wiped down to the base. Only the edges are left where the brushes can’t reach.

Such a collector can be repaired by soldering.

  • From a copper tube or plate, cut the necessary number of lamellae to size.
  • After stripping the anchor of any copper residue, solder with ordinary tin and soldering acid.
  • When all the lamellas are soldered, grind and polish. If you don’t have a lathe, use a drill or screwdriver. Insert the armature shaft into the chuck. Grind first with a file. Then polish with zero-grit sandpaper. Don’t forget to clean the slots between the fins and measure the resistance.
  • There are lamellae that are not completely damaged. To rebuild them, you need to do more preparation. Lightly grind the manifold to clean the plates.