Electric screwdriver then works, then not. Metabo

Repair of basic faults of electric screwdriver

An electric screwdriver is a multifunctional power tool to help with furniture assembly, minor repairs, or other tasks. But this device breaks down over time. If there is no money to repair or buy a new device, you can try to repair it with your own hands. For this, it is worth knowing what malfunctions are typical for tools of this type and understand how to properly eliminate them.

Screwdrivers can be cordless or cordless. Their main faults are virtually the same, and the differences are related to the type of power.

The mains electric screwdriver

If the unit does not turn on, first check the condition of the socket and then, if it is serviceable, inspect the plug. Often an electric screwdriver does not start, because the contacts are burned. If both units are intact, you should inspect the cable to make sure it is intact, not kinked or kinked. Also, a faulty trigger, worn brushes or burned-out motor winding are possible causes.

If the technique sparks, you need to look for a defect in the armature, electric brushes or motor collector.

Self-starting electric screwdriver reports a broken trigger.

If the chuck backlash is caused by damage of the gear shaft. If the chuck is jammed and it is impossible to extract the drill bit or bit, it means that the clamping jaws are jammed. If the cause is the absence of grease or damage of internal parts of the chuck. If this mechanism spins, it’s a gearbox malfunction.

If the ratchet is defective, inspect its locking paddles, spring and pins.

Cordless Electric Screwdriver

If the equipment doesn’t turn on, check the battery charger and condition of the battery. If it discharges quickly, its condition is diagnosed with a special tester.

Other malfunctions of the cordless electric screwdriver are similar to the mains technique.

The purpose of all parts and assemblies of the tool. what are they called

If the electric screwdriver broke, then before you repair it, you need to figure out exactly what part failed. To find out the malfunction yourself, you need to understand the purpose of each node and its design parameters.

This is interesting! If you encounter batteries that have a one-piece case design, it means that they are not designed for self-repair.

If the electric screwdriver broke, it is not difficult to repair it at home, if only to find the breakage. Among the frequent problems of faults of screwdrivers are failure of the batteries, the replacement of which can cause some difficulties. Let’s consider the mechanical and electrical faults, as well as the peculiarities of their elimination by your own forces.

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How to disassemble an electric screwdriver for repair

In order to disassemble the device, follow these steps:

Disassembled electric screwdriver

  • Carefully disconnect the start button from the housing without damaging the wires connecting it to the motor;
  • Remove the speed selector;
  • Disconnect the motor, gearbox, clutch and chuck by removing the 4 screws;
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To unscrew the chuck, unscrew the screw which can be seen inside the mechanism when the cams are unscrewed. The screw should be unscrewed clockwise because it has a left-hand thread. After that, the chuck must be unscrewed from the gear shaft by turning it to the left (right thread).

Faulty battery or cable of the electric screwdriver

Everyone understands that regardless of the “steepness” of the torque ratchet, without a power source, its operation is impossible. The first thing to do is to check the battery if you have a cordless screwdriver that is mobile and not dependent on a power source. The main cause of a malfunctioning battery is discharging it or using it for long periods of time. The second reason is eliminated by complete replacement of the battery, and the first reason is a simple recharging, using a rectifier, which is included in the set when selling the tool.

The battery of an electric screwdriver disassembled

As a rule, the same kit comes with two batteries: one is in use, that is, in operation, and the other on recharging. In the case of a failure of the battery charger is more rational to replace it with a new one, unless of course you are not an expert in electronics.

If you own a mains electric screwdriver. first of all, if there is no rotation of the motor, check the entire chain of electric drive: socket, cable plug and the cable itself. Believe me, it often happens that the socket fails (burn out contacts), the plug can refuse to work for the same reasons, and the cable itself can be damaged by rough handling.

How to choose a new cartridge correctly

Ideally, it should be the same as the old one. If you can’t find one, you must look for a model with the same parameters. shape, size, principle of work. All products are standardized, but even so, it is easier to combine parts from one manufacturer.

In the selection can be guided by other principles. If the tool is used frequently, you must decide what is more important. the convenience and speed of changing the working part or the reliability of the connection. In the first case, a quick-clamping cylinder will do, in the second. a cam, which is fixed with a key.

It is important not to make any errors. It is easiest to look for the right part when you have the tool and a sample of the old sleeve with you. How to change a chuck on an electric screwdriver, should be written in its manual. The thread on the housing and the shaft or the “Morse taper” is used for the connection.

For detailed instructions on how to disassemble an electric screwdriver, see the video.

Threaded connection

A 10-mm L-shaped hexagon is needed for the operation. It is inserted in the cams, tightly clamped and rotated. It is more convenient to fix the hexagon in your hand or on a support and start the motor at a low speed. It only needs to work for a fraction of a second. This is usually sufficient to loosen the connection and remove the sleeve without hindrance. If the method does not work, the tool should be disassembled to approach the connection from the other side.

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Typical malfunctions of cordless screwdrivers

Chuck run-out. If you encounter such a fault, it means that for some reason your gearbox spindle is bent or its bearing is damaged. The bearing in the different screwdriver models can be a ball-type device or a bush made of bronze. In any of these cases, it is necessary to change the entire gearbox of an electric screwdriver.

A whistling or creaking noise from the motor. In this case, the electric screwdriver motor is running, but it makes an abnormal sound. This can be caused by one of the motor magnets separating from the housing and sticking to the rotor body. A clogging of the rotor bearing can also cause the appearance of unusual noise. If the design of the electric screwdriver allows disassembly of the motor, the fallen off magnet can be put back in place (if it has not been damaged) and secured with a suitable adhesive. You can solve the hissing noise problem by greasing both sides of the slide bearing with a liquid grease spray, e.g. WD-40. It is also a good idea to thoroughly lubricate the rotor shaft itself. It should be noted that rapid clogging of the bearings and the subsequent appearance of whistling sounds when rotating signals that they are already seriously worn. The right thing to do is not to wait for a more serious breakdown, but to replace the entire electric motor assembly.

The electric screwdriver keeps turning after releasing the start button. In a fault-free electric screwdriver, after releasing the start button, the brake device must work to stop the gear rotation. The problem is caused by a defective thyristor in the control circuit. It is possible, of course, to find a semiconductor device with suitable parameters, but it would be wiser to replace the whole power unit.

Button for reversing the direction of rotation does not work. Almost all screwdriver models use a microswitch to change the direction of rotation of the chuck, which is mounted in the power unit of the device. Failure of the switch would necessitate the replacement of the entire power unit of an electric screwdriver.

Slipping of the gear steering clutch. The rotational speed of the electric screwdriver chuck is regulated by a special clutch, which can be represented in the form of a toothed washer. The teeth of the coupling wear out over time and the coupling slips. It looks as if the electric screwdriver cannot tighten the fasteners with the necessary torque.

The electric screwdriver does not turn on. There are several possible causes for this

  • Failure of the switching unit. The problem can be solved by replacing the unit with a functioning unit.
  • Broken contact wires. Replace faulty wires and solder broken contacts.
  • Electric motor burns out. Replace a burnt-out motor with a new one.
  • Critical wear of the graphite brushes. Carbon brushes are a consumable item (on models with a collapsible motor), a spare set of which must be supplied with the electric screwdriver.
  • Discharge or failure of the battery. The battery must be charged or replaced with a new one.

Replace a defective chuck. There is a left-hand thread locking screw inside the chuck. Before unscrewing a screw, it is recommended to spray its thread with a liquid grease spray and lightly tap the screwdriver on its head. After removing the screw, clamp the L-shaped wrench in the chuck, fasten the body of the electric screwdriver and, turning the wrench counterclockwise, unscrew the chuck from its axis. Before you start unscrewing the chuck, you must set the electric screwdriver to drilling mode at first speed.

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How an electric screwdriver works

Before repairing any device, you need to know how it is built, the logic of its operation, the interaction of nodes and parts with each other.

All screwdrivers have a basic design that varies little from one another. This device consists of:

  • the housing in which all the other components of the device are installed. This part is made of metal or plastic. Bosch GSR 10,8-2-LI, BlackDecker BDCDD12B and others. There are models in which these two materials are used simultaneously.
  • Single-phase collector motor with electronic control. rotation direction and speed regulation, choice of operating mode. screwdriving, unscrewing, drilling. The motor consists of a collector and a stator. The power is supplied to the collector by spring-loaded copper or graphite brushes.
  • Planetary gearbox with torque limiting capability. Gearbox is mounted on the electric motor shaft. Depending on the model of the electric screwdriver, this assembly is made of plastic or metal. The second version is characteristic for professional applications.
  • Chuck installed on gearbox output shaft.

If it is not a corded model, but a battery model, there are battery mounts on the housing handle to connect the battery, giving it a mechanical connection to the housing and an electrical connection to the collector motor. There is also a start button on the housing for starting the electric screwdriver. On some models, it is also used to adjust the speed of rotation by varying the pressing force.

As you can see, there can be electrical and mechanical faults in an electric screwdriver. Let’s take a closer look at them, with the signs by which the breakdown can be identified.

The design of the screwdriver cartridge

Screwdriver chuck mileage indicates that there are problems with the serviceability of the tool-reducer, which is located directly behind the electric motor. This is another reason why a screwdriver with a full return does not work.

Spare parts for planetary screwdrivers

The output shaft of this gearbox is the attachment point for the chuck; therefore, if we are talking about chuck mileage, we must keep in mind the mismatch of the gearbox shaft. The reasons for this may be as follows:

  • A) the curvature of the gearbox shaft;
  • B) wear and tear on the gears;
  • B) failure of the gearbox shaft support bearing;
  • D) maximum production of the pins on which the planetary gear satellites are mounted.

All of the above-mentioned factory-made parts are not subject to this repair. The problem of beating the screwdriver cartridge in this case is solved by replacing the parts of the gearbox with new ones.

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