How to Pull Anchor Out of Angle Grinder

How to Pull Anchor Out of Angle Grinder

angle grinder successfully solve problems for processing a large number of types of materials. The difference in the modes of their processing, work in conditions of increased dust formation from abrasive particles contributes to the failure of components and parts Angle Grinder. Often enough rotor malfunctions, as one of the main elements of the electric drive. The rotor is repaired after complete disassembly of the angle grinder, where it is a separate unit not connected with other elements. Information on how this disassembly is performed in this article.

The principle of operation of the engine angle grinder

An angle grinder integrated into the construction is used as a converter of electrical network energy into mechanical energy. induction motor. It is distinguished by the presence brush collector assembly, where the stator brushes are in contact with the collector lamellas and supply current to the rotor windings connected to them. Further on the conductor (rotor) located in the electromagnetic field formed by the stator, forces act in accordance with the laws of this field, which actually make it rotate.

Work scheme angle grinder. Source here

Anchor device

The rotor is a assembly in the form of a shaft with bearings on bearing assemblies. Placed on the shaft round core, in the grooves of which are wound coils of copper, coated with insulation wire. At one end of the shaft collector, on another. pinion gear, which transfers the torque to the working spindle angle grinder.

How to determine the fault of the angle grinder

Serviceable rotor for Makita UShM 9069 MAX. Photo 220V

One of the operational advantages of induction motor motors is preservation of spindle revolutions when changing load. Therefore, according to external signs (frequency of rotation, tonality of sound during operation), it is almost impossible to determine the operation of an angle grinder with overload. The main factor here will be angle grinder temperature, the increase of which is not immediately noticeable when working with gloves.

It is high temperature that is the reason why fusion of insulation on the rotor windings. Engine will start work intermittently and eventually stop. During overheating, the angle grinder can solder the contacts of the rotor windings with the collector, which leads to to an open circuit. The presence of inter-turn winding closure makes it possible to rotate the shaft in different directions.

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In the presence of increased sparking (as a cause of interturn circuit of the rotor windings or its poor contact with the collector) in the brush-collector assembly, checking the operation of the electrical part angle grinder.

Diagnostics starts with a visual inspection all elements angle grinder. Sequential analysis allows you to fully examine all structural elements from all sides. Shot from an angle grinder anchor must be inspected under bright light. Melted wires with traces of burning, wire breaks, violation at the joints of the windings. the presence of such defects requires repair of the rotor or its replacement. You can also pay attention specific odor from burnt insulation.

If the external inspection does not give results, the search for the causes of the malfunctions continues with the help of the continuity of the electrical circuits with devices (multimeter, short circuit indicator and others).

How to remove the rotor from the gearbox angle grinder, step-by-step instructions, necessary tools, video

To remove the rotor, use public locksmith tools and accessories: hammers, screwdrivers, wrenches, pullers, brushes with soft bristles, wipes for cleaning parts and others. The operation procedure is the same for all models, differences arise due to the design of individual units and parts. It is performed as follows:

Video: How to Pull Anchor Out of Angle Grinder


  • brushes are removed from the holders of the holders in order to maintain their integrity;
  • the gearbox is separated from the casing of the electrical part;
  • the gearbox cover is removed;
  • a nut is unscrewed or a retaining ring is removed that fixes the driving small gear on the rotor shaft;
  • the anchor is removed along with the gear and bearing (options without bearing and gear are possible);
  • bearings are removed by a puller in the presence of a large backlash and the need for replacement;
  • all parts and assemblies are wiped with a brush with soft bristles and napkins.

The following video shows complete disassembly angle grinder model Bosch. It just shows the general disassembly procedure without detailing individual operations.

Detailed repair Makita model angle grinder with the replacement of a failed rotor, the author describes in the next video. The rotor defect is clearly visible during visual inspection. In the model Makita angle grinder removing the rotor and assembling the angle grinder after replacing it made technologically simple without the use of special devices.

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In the next video spindle stuck onto the angle grinder of the DVT model. The cause of the defect is rotor bearing crumbled, located in the gear housing. When removing the rotor from the gearbox, the pinion gear is released by loosening the locking nut. The author shows with concrete examples what consequences for the rotor and other parts an angle grinder can lead to work on faulty bearing supports.

In the review, the Spark model angle grinder in the next video is made complete disassembly of all components of the angle grinder. The author, who has extensive experience in repairing grinders of various models, gives brief characteristics of the design features of some assembly units and parts. So celebrated easy removal by hand of the rotor angle grinder from the gear case.

However not all models manage to remove the rotor from the gearbox without problems. In the following video on the Interskol model angle grinder, some users perform this operation with targeted damage to some parts, for example, the impeller. The author describes another option without sacrificing design for details angle grinder, based on knowledge of the laws of physics. The difference in the inertial properties of elements with different masses is the basis for the method described in the video. A heavier rotor, using the force of inertia, leaves the seat of the lower bearing race.

Repair of the angle grinder of the Electric appliance model is described by the author in the next video. Here the reason for the wear of the steel brushes failed rotor bearings. To replace them rotor was removed from an angle grinder. The process of removing from the gearbox in the video is missing. The author in the comments claims that pressed the bearing out of the gearbox. However, designs where the bearing is fixed in the support using plates screwed to the gear housing, this method is not suitable. Here apply the method described earlier using the inertial properties of massive parts or by making a technological hole in the impeller through which the fixing plate fasteners are unscrewed.

The following video describes gearbox repair with replacement of worn gears, why it is necessary to remove the rotor. This operation performed with a hammer (necessarily wooden or rubber!). Light impacts on gear housing pressing out rotor bearing. Important: with a tight fit, it is possible to damage some parts of the bearing housing.

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Difficulties

At home pullers cannot always be found, which are specially designed to press out bearings or other parts of a certain size. In some designs of bearing assemblies, the use of pullers is not provided at all, there are completely different approaches to solving the problem of removing the anchor.

How to remove bearings at home

This approach, for example, is used when removing the rotor from the gearbox in the next video, during repair angle grinder model Stern. Fixing plate does not allow to remove the bearing by direct extrusion. The method was previously mentioned in the text. unscrew plate fasteners through technological holes in the impeller. The author of this video uses this method.

The lack of “regular” pullers can be compensated by similar devices used in other areas of technology. In the next video, this puller taken from the automotive industry, where it is used to remove ball bearings.

In the absence of any removable devices, you can try to remove the gear housing from the bearing by impact. The author of the following video, when repairing one of the Makita models, did it.

Bearing replacement

During troubleshooting, a common defect is increased clearance of rotor bearings. To avoid big trouble should be replaced.

When replacing rotor bearings to the DVT angle grinder at home in the next video any means at hand are used. Rotor extruded using a metal rod screwdriver and wrench supported by the tide inside the gear housing. Performing this action is not very convenient, but in the end it reaches its goal.

In the next video further developed way untwisting the fasteners of the fixing plate to the housing of the bearing reducer through the technological holes in the impeller. Since the impeller is plastic, it’s effective burn holes heated rod, for example, a nail. To maintain balance, it is recommended make two holes at once.

Collector replacement

Replacing only one collector will not solve the problem. Completely soaked anchor when removing the collector will damage the windings remaining on the rotor. The new collector is practically impossible to adapt to the old terminals of the windings. Therefore, it is better to rewind new windings at the same time when replacing the collector. The most technically simple option (much more expensive) is to completely replace the rotor.