Makita Angle Grinder Stopped Working What Cause

Terms

Anchor. a rotating element of an electric motor containing windings.
The collector is a place at anchor to which all windings are brought. It looks like a series of plates isolated from each other.
A stator is a fixed part of an electric motor containing windings.
Brushes. carbon parallelepipeds supplying current to the collector.
A reducer is a mechanical device for transmitting rotation with changes in power and rotation speed.

The most popular tool in everyday life after a drill is an angle grinder or, as they call it more often, an angle grinder. angle grinder is used for cutting metals, wood, concrete, grinding various surfaces, cutting openings, doors, niches. If there is an angle grinder, then it can always be used and it is especially offensive when it ceases to function normally, jerking, twitching, burning smell.

the angle grinder is all arranged in the same way: an elongated housing in which the motor and gearbox are located, a handle and a protective casing are screwed on the side.

Makita Angle Grinder Stopped Working What Cause

On the body of the angle grinder is a sticker with the source data. Here you can find both the personal number of the angle grinder and the supply voltage. 230 V. Here we mean the maximum allowable voltage in the network. The current frequency in the network is 50 Hz. The consumption current is 5 A. The power consumed from the network is 1100 W, it is obtained as the product between the voltage (220 V) and current (5 A) multipliers. The frequency of rotation of the disk mounted on the angle grinder is 2800-11000 rpm. The anchor itself rotates at a faster speed than the disk itself. It is on this angle grinder that step-by-step regulation of the rotation speed is possible. The disk mounted on an angle grinder has an outer diameter of 125 mm, the mounting nut of the disk has an M14 thread.

A household tool designed for a phase voltage of 220 V has an armature winding and a stator winding. Energy is transferred from the network to the anchor using graphite brushes. The voltage from the network is supplied to the switch, which is mechanically connected to the power button of the angle grinder. The stator winding consists of two halves not electrically connected. An anchor winding consists of many windings, but at any moment in time, the brushes connect only two windings of the armature.

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When you turn on the angle grinder, current is supplied to the input of half of the stator winding, the output of the stator winding is connected to the brush holder into which the brush is inserted using a spring. The brush transfers current to half of the armature winding, on the other hand, the other brush receives current and through the brush holder transfers current to the other half of the stator winding. Current entered and exited the angle grinder. If the entire electrical circuit is operational, then the armature will begin to rotate.

Reverse, i.e. a change in the direction of rotation of the disk can be done if you swap the wires going to the brushes from the stator windings. Just disconnect the wires on the brushes and swap them.

At the end of the case, the angle grinder has a red wheel for stepwise regulation of the speed of rotation of the armature and a screw for removing the casing.

In this form, the angle grinder the brushes themselves are located inside the case and there is no access to them, but the developers simplified the replacement of the brushes when removing the casing. After unscrewing the screw, the plastic plate is removed and the outer casing is shifted towards the cord, exposing all the insides, including the brush holders.

The speed control mechanism is electronic. The whole circuit is filled with epoxy and only the speed wheel and the radiator are out. What is hidden inside. trade secret of the company. When the unit fails. speed ceases to be regulated, but remains at the maximum level. In any case, you should not despair, and in turn with the angle grinder you can turn on the most ordinary dimmer. dimmer. With it, you can adjust the speed of any AC alternator motor, the main thing is that the engine power does not exceed the power of the dimmer.

Video: Makita Angle Grinder Stopped Working What Cause


On both sides of the housing are steel brush holders with springs in the form of a curled strip of steel. A spring is needed to hold the brush pressed against the armature collector even with strong vibrations and heating of the armature itself.

The spring presses the brush and as the brush erases, the spring falls lower and lower into the steel brush holder. Brushes are erased and reduced. When their length becomes insufficient, the angle grinder stops working. In expensive models, there is a spring inside the brush that pushes the brush away from the armature collector. In cheap models, brushes are not equipped with a built-in spring.

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When choosing new brushes, it is better to contact the service centers of your manufacturer specifically for an angle grinder. The fact is that just as the graphic artist chooses twenty different simple pencils with different softness, the grinder manufacturers specially design brushes for a certain type of collector. If you use other brushes, for example, from a generator for a VAZ, then most likely the anchor will burn out soon, but for the first time, such brushes will fit.

The power button for the angle grinder is a plastic box with a mechanical linkage. The box is bulky enough to suggest that it commutes high switching currents and that the button goes not only to this equipment.

In the head of the angle grinder there is a gearbox that increases the speed of rotation of the disk to 11000 rpm. The gearbox rod on which the disk is worn contains a sheared washer that sits firmly on the shaft and has a support pad with a rubber ring for seating the disk.

Nearby is a foot with cuts, which fixes the protective casing. For greater safety, the guard can be moved and locked. The foot is pressed down to the angle grinder and the flap is moved to the desired level, after which the foot is released and it fixes the flap.

Nuts for mounting the disc are self-locking SDS and ordinary with key holes.

The gearbox is supported by four screws. If you untwist them and carefully tucking the screwdriver open the cover, then the gearbox parts will appear. The gear on the armature shaft has a left-hand thread and is threadedly connected to the armature shaft.

The gearbox uses rolling bearings, i.e. conventional bushings greased with grease. The teeth on the model with a power of 1100 W are straight, apparently this is quite enough for locksmithing, but in the 1500 W models, gears with curved teeth are used.

In order to remove the anchor, gently remove the brushes, remove the gearbox and pull the anchor out of the housing by the gear. At the other end of the anchor closest to the cord is a rolling bearing that is recessed into the housing plastic. To remove the anchor you need to pull hard and carefully.

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An anchor is a steel rod on which a steel cage is assembled from plates. In the grooves of the cell, turns of copper insulated wire are laid. At the rear end of the armature, called the collector, all ends of the windings are brought out. At the front end of the anchor is a gear for transmitting rotation.

To win in the force that needs to be applied to the disk for work, use gear. For a 2 kW angle grinder, the anchor gear has 10 teeth and the circle gear has 41 teeth. It turns out that at a speed of rotation of the circle of 8000 rpm, the armature rotates 8000X41 / 10 = 32800 rpm. If we take into account that the number of collector contact plates is 36, then 32800X36 / 60 = 19680 Hz. This is approximately the frequency that interferes with the network and to eliminate which ferrite rings are needed.

The gear wheel is located on the shaft. In production, the gear was heated, and the shaft was cooled. After that, the gear was put on the shaft. The resulting connection is cheap, simple and does not practically make it impossible to remove the gear without damaging the gear case. Heating the assembled part will cause expansion of both the shaft and the gear. The only way to remove the gear is the puller. At the same time, the grippers of the puller paws must be thin and strong enough to enter the small gap between the housing and the gear.

The gear shaft is mounted on the thread. Probably, the manufacturers calculated that the gear of the anchor flies more often than the gear of the gearbox. On this model, helical gears to increase the power output.

The gear has a RIGHT thread. For spinning gear, you need to wrap it with a rag so as not to break the teeth when unscrewing, hold it with a gas wrench and turn it AGAINST THE CLOCK HAND.

After removing the gear, it becomes clear that the thread is not made over the entire height of the gear, but only in its small area. The section without thread allows you to put on the gear exactly, without distortions.