How to check the armature of an angle grinder at home

The device for checking the armatures and stators of electric machines

Another device with which you can verify the stator of an angle grinder is a device for verifying the armatures and stators of electric machines PUNS 5. The device has a light and sound alarm and makes it possible to detect winding short circuits, open circuits, measure the insulation resistance of the coils.

The device works in two modes. “armature” and “stator”. The mode is changed with a switch. The device is equipped with a handy tool for mounting and securing the motor to be checked. It consists of two feet attached to the shaft. The legs move freely along the shaft, allowing the distance between them to be varied, so that different sized motors can be checked. The inspection is carried out with two feeler gauges. Open or short circuits in the stator windings are indicated by special red LEDs and an acoustic signal. The check procedure is described in more detail in the instruction to the device.

The angle grinder can malfunction due to

Most often, the tool will stop working when the armature (rotor) is damaged. If you open the housing, you can see that the brushes are burned or worn unevenly. Indirect signs of such a breakdown are heating of the tool and vibration during work.

check, armature, angle, grinder

Electrical breakdowns are more difficult to detect. These include:

Also quite common causes of tool failure can be:

  • breakage of wires in the power cable and failure of the switch. the angle grinder does not turn on;
  • A short circuit in the rotor windings and a fault in the electronics cause the tool to run only at low speeds;
  • sparking due to worn carbon brushes or heavy wear on the motor manifold;
  • Smoke can be caused by short circuits in the stator or rotor windings, or by excessive use (when air cooling ducts are clogged with dust).

As you can see, many breakdowns are caused by faults in the electrical part of the tool. Therefore, you need to be able to detect them before you decide to send the tool to a repair shop.

Repair, replacement, rewinding

After carrying out diagnostics and determining the types of rotor faults, the decision about the repair methods follows. It is possible to make repairs with your own hands, which will be associated with independent rewinding of the armature. If this option seems time-consuming and complicated, you can follow a simplified scheme and replace the burnt rotor with a new one, corresponding to the model of the angle grinder. The easiest but also the most expensive option is to contact a special service.

In deciding to repair the armature with their own hands to help information that is available in the links “How to remove the armature of the angle grinder”, “Replacing and repairing the armature of the angle grinder”, “Rewinding armature grinder with their own hands.

Sections: Grinder repair with their own hands, Anchors grinders

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Motor construction

To quickly learn how to check the electric motor, you need to clearly understand the structure of the main parts. All motors are based on two construction parts: a rotor and a stator. The first component always rotates under the action of the electromagnetic field, the second is stationary and just creates this vortex. To understand how to check the electric motor, you will need at least once to disassemble it with your own hands. The design differs from manufacturer to manufacturer, but the principle of diagnosing the electrical part is still the same. Between the rotor and stator is a gap in which small metal chips can accumulate during depressurization of the housing.

Bearings can give high currents if they wear out, causing the protector to blow. Dealing with the question of how to check the electric motor, you should not forget about mechanical damage to moving parts and borono, where the contacts are.

Step by step instruction: how to rewind the motor at home

If the problem does not concern the starter, gear, but you found the problem in the winding, then here you have to buy copper and enlist the help of a collector puller. To begin with a tester, a multimeter will help you to test the circuits, and in order to check the performance of the machine, use a short-range transformer. So you can pick up the necessary actions and tools to subdue the angle grinder.

The process itself consists of the following steps:

  • Fixing the old winding. It must be carefully removed without damaging the metal body of the armature itself. If you find scratches or burrs, you need to smooth them out with a burr or soldering iron. Sometimes, in order for the body to be completely stripped use a torch.
  • Preparing to connect the new wires. There is no need to remove the manifold itself. It is necessary and examine the lamella and measure the resistance of the existing contacts in relation to the body with a multimeter. The value should be approximately 0.25 megohms.
  • Removal of old wires. Carefully remove the remnants and cut the slots in the contacts. You will need them later in order to insert the coil wires.
  • Mounting the sleeves. The shells are created from cardboard of the electrical type, it is a material with a thickness of no more than 3 mm. Cut the necessary amount and insert it into the grooves of the armature.
  • Rewinding. The end of the wire must be soldered to the end of the lamella and wound in a counterclockwise circle. The same action is repeated in relation to all the caddles.
  • Quality check. After all windings are made, use a multimeter to check for shorts or breaks.
  • Finishing. The finished coil is treated with epoxy or varnish. At home, the finished work is dried in the oven. You can use a varnish, which dries faster.

It may seem like a complicated job. We can assure you that no, but time and effort on this will have to spend, not a few.

Anchor construction

The angle grinder’s anchor consists of a current-carrying winding and a magnetic core. In the magnetic wire there is a shaft that performs torsion. The magnetic wire construction is formed by plates and slots, which are insulated between each other by a coating of varnish. Developed a certain sequence of laying the conductors of the anchor winding in the grooves. The conductors form a coil. Its ends are tied on lamellae. The layout of the beginning of the start coil and the end of the last coil is made in such a way that they are shorted to one lamella.

If the angle grinder motor is constantly overheating, the armature will melt. The contacts of the wires that connect the primary winding to the collector may fall off as a result of the high temperature. All this leads to no current being supplied.

Visual inspection of the tool

Very often it happens that the tool is still working, but not in the way it should be. And in 30% of cases the fault is burnt out armature. You can detect it visually, before you open the case.

Indirect signs of a “tired” electric motor armature are such malfunctions:

  • Very strong arcing can be seen on the collector when the motor is running.
  • When you try to start the angle grinder (or drill, circular saw, etc.), you can observe a.When trying to start the angle grinder (power drill, circular saw, etc.), a rapid voltage drop is observed (lights flash).
  • The electric motor start-up is accompanied by a sharp jerk.
  • There is a characteristic smell of burnt wiring coming from the housing.
  • The tool does not produce the same power.

Note that more than half of these signs may also indicate trivial wear of motor brushes. If it is worn or chipped, it is probably not the anchor that is at fault. Replace with new ones, clean the collector from graphite deposits, and continue to work quietly. If the brushes look intact and the above symptoms are present, there is an 80% chance that the problem is with the motor armature.

If the power tool shows no signs of life at all, there may be more reasons than just checking the anchor.

Disassembly of the angle grinder

How to check the stator of an angle grinder (angle grinder)? Begin with the disassembly of the device. To perform the work you will need a screwdriver.

  • Remove all unnecessary parts from the surface that will be disassembled angle grinder.
  • Remove the work disk.
  • Remove the screw that secures the cover.
  • Remove the screws securing the plate.
  • Slide the hood in the direction of the cord.

The stator is on the outside of the motor, on top of the rotor. To get the stator you must first remove the brushes, then remove the gearbox and only after that pull the armature from the angle grinder body. Remove the rotor from the stator before checking. It is recommended to perform the inspection in bright light. The first thing to do is to carefully inspect the winding and make sure that there are no visible breaks. If examination does not reveal the cause of malfunction of the stator, then you need a special device for testing.

How to check the armature on the angle grinder?

Rules for Visual Inspection

Standard diagnostics involve a visual analysis of the device. Analyze the continuity of the wire and the current flow to the collector of the motor. If the power supply is normal, the angle grinder should be inspected from the inside. It is not difficult to disassemble the unit. The best way to disassemble the unit is to photograph the location of the main modules. After disassembly, make a visual check of the armature for such features:

  • The armature should run freely;
  • The absence of black spots and odor, which may indicate the melting of the winding, the insulating varnish which leaves traces;
  • No crumpled coils or solder residue, which leads to short circuits;
  • there must be no burnout on the lamella contacts, otherwise check the binding of the lamella cock and the winding busbar;
  • Absence of worn or burned out plates;
  • The space between the lamellae must be kept free of graphite residues from the brushes.

If the visual inspection does not reveal any defects, it is necessary to check with an instrument. The angle grinder’s armature can be checked with both a tester and an ordinary light bulb.

Inspection with a tester

The multimeter should be in the ohmmeter position. Set the resistance to 200 ohms. probes are connected to the lamellae next to each other. If the value on the meter is less than 1 ohm, there is a short circuit. At a value greater than the average it is possible that the turns breakage is present. If the resistance value is high or if there is no resistance value (when using a digital device), an open circuit can also be detected.

There are situations where no breakage is detected. Then the ground fault is detected. At maximum resistance, one of the probes is placed on the shaft and the other is moved across the plates. If the value is zero then there is no breakage. Then the rotor is checked with a multimeter in the same way. In this case the probe moves over the slats. If the test cannot be done with a tester, a light bulb is used.

Inspection with a light bulb

In the absence of a handheld device, many people wonder how to check an angle grinder for possible armature failures. The power supply cable is broken, and a light bulb is placed at the point where one of the wires is broken. Then the shaft is rotated. A short between the coils can be judged by the change in brightness of the light bulb. In the case of the absence of combustion, it is possible to draw such conclusions:

  • the location of the brushes does not correspond to the working position, due to the triggering of the retaining spring;
  • The power circuit is broken;
  • Short circuit or rupture in the stator winding.

How to Check the Armature good or damaged.(Tagalog)

Can be tested with a short-circuit indicator and an armature tester. This can be done by an experienced person.