Another area requiring close attention is the keyless chuck. It happens that he also fails. Repair consists in replacing it. To remove the quick-release device, you need to unscrew the screw inside the chuck. Please note that the screw is left-handed, so it must be unscrewed by turning it clockwise.
Then a hex key is inserted into the chuck with the short side, clamped and pulled off the thread with a sharp hammer blow. After that, it is unscrewed by hand on the thread. She is normal, right-handed.
After reading the article, we can conclude that the best screwdrivers for use in the household are Bosch tools. They practically do not fail. Their main problem is regular wear and tear due to long-term use or negligence.
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A screwdriver is a tool often used in the professional field during repair and construction work, as well as in everyday life. Like any electromechanical device, screwdrivers are prone to malfunction. This device is not a complex device, and in the event of a malfunction, the repair of the basic malfunctions of the screwdriver can be done by hand.
Below is a figure showing the internal structure of the battery device.
In screwdrivers, both collector electric motors and brushless motors (do not have electric brushes) can be installed.
If your screwdriver breaks down, then the malfunctions of this unit may be as follows.
All faults, except for the electrical plug, can be eliminated only after disassembling the device.
To disassemble the device, follow these steps:
disconnect the battery pack from the body of the device;
unscrew all the fasteners holding the 2 halves of the device together;
remove the upper part of the case;
remove all contents from the body of the device;
carefully disconnect the start button from the case without damaging the wires connecting it to the engine;
remove the speed switch;
disconnect the motor, gearbox, coupling and cartridge by unscrewing 4 screws;
To unscrew the cartridge, you need unscrew the screw , which can be seen inside the mechanism when the cams are open. Unscrew the screw clockwise as it has a left-hand thread. After that, the chuck must be unscrewed from the gearbox shaft by turning it to the left (right-hand thread).
If you have a battery pack, the first step is to check the batteries in the battery pack by disassembling it. There are collapsible and non-collapsible blocks. In the second case, you will need to carefully insert a screwdriver into the place where the block walls are glued and, slowly, separate them.
Further, it is necessary measure voltage on all "banks". The voltage rating is indicated on the case of each battery. The voltage should be slightly lower than indicated, but the same on serviceable batteries. Defective batteries will differ significantly from the rest in terms of voltage output - they will need to be replaced. New batteries can be purchased online.
It is important to solder them correctly, that is, in series: the plus of one battery is connected to the minus of the other, and the plus of the second with the minus of the next, etc.
If you are the owner network screwdriver , then the verification algorithm is somewhat different. First, you need to unscrew the body of the device and remove one half of it. Take the tester and ring the power cord for an open. In the case of a working cord, you need to check the start button. With the button pressed, check if there is a circuit on its output contacts. If the button is faulty, it will need to be replaced or repaired. How to do this will be discussed later. With a working button, the problem may lie in the electric brushes or the motor.
Below is the electrical diagram of the cordless screwdriver.
It can be seen from the diagram that 2 wires from the battery are suitable for the button, and 2 wires go out of it to the engine. Also, 3 wires are connected to the button from the transistor, which is responsible for adjusting the speed. To understand the structure of the screwdriver button, it must be disassembled. All wires going to this part do not need to be unsoldered. They will not interfere with disassembly.
Take off push mechanism (red) from its seat. Do this with gentle rotational movements, while simultaneously pulling the part in the direction opposite to the button, being careful not to break the jokes.
Next, remove button cover ... In the places indicated by the arrows in the figure, using a knife and a screwdriver, it is necessary to pry and push out the latches, and then remove the cover.
Removing the cover, you will see reverse compartment ... But the button mechanism will still be unavailable. Using a soldering iron, separate the 2 elements (indicated by an arrow in the next figure).
Carefully pull out the element numbered 1, then remove the cover that covers the compartment with the device turning on mechanism.
Holding the return spring, remove the mechanism from the case.
In the faulty button, you will see the erased pads.
Contact pads wear out quickly due to the poor quality of the metal. Fine metal dust from worn out contacts accumulates between them and closes the pads.As a result of this, a spontaneous start of the apparatus occurs.
Remove metal dust using cotton wool dipped in alcohol. If this fails, you can scrape it off with a knife. After these actions, the spontaneous start of the device will stop.
If the speed regulator does not work, then the transistor has burned out, which must be replaced.
To check the condition of the brushes, you must disassemble engine , bending back the "antennae" located at the end of the body.
Then, with light blows of a hammer on the motor shaft, knock the rotor out of the housing.
In this case, first, the cover is removed, in which the electric brushes are located.
The next photo shows that the collector has black color ... This means that it will get dirty with dust from the brushes. As a result of contamination of the collector, as well as the grooves between its plates, the engine power decreases and the brushes spark. It is necessary to wipe the collector with cotton wool soaked in alcohol and clean the grooves with a needle.
The following photo shows what a clean manifold looks like.
If the brushes are worn out, they will need to be replaced. Some models of screwdrivers are difficult to find on sale original brushes ... But you can find brushes that are suitable in size, then trim them on a grinder and connect (solder) to the brush holders.
Sometimes, in order to replace the brushes, you will need to saw a groove in them. It depends on how you attach them.
To better understand how the brushes are replaced, you can use the following video.
The engine brake is a device that stops the rotation of the armature at the moment the start button is released. In screwdrivers, this function is implemented by closing the plus and minus of the motor when the button is released. As a result, a large self-induction occurs, and there is spindle lock (with a lot of sparking from under the brushes). If the engine braking does not work, then it will be necessary to replace the regulating transistor or start button.
Mechanical failures of the screwdriver include malfunctions of the ratchet, gearbox and chuck of the apparatus.
If the ratchet does not work on the screwdriver, then you will need to disconnect it from the gearbox for troubleshooting. Sometimes special rods are installed in the coupling, which regulate the force, and in some devices, instead of rods, 2 balls are installed in each hole. They are pressed by a spring, which, when the adjusting ring is twisted, presses on the balls.
In most cases, repairing a screwdriver ratchet consists in cleaning its components from dirt and applying new grease.
If unusual noises are heard in the gearbox, or the spindle rotates in jerks, with slipping, then the failure of the gears of the mechanism, the worn-out teeth on its body, may be the cause.
Gears most often break if they are made of plastic (used in cheap machines). If this happens, then they must be replaced.
In the next photo you can see the device of the gearbox.
The reason that the spindle does not rotate when the engine is running may be the wear of the plastic teeth inside the gear housing.
To restore the mechanism to work, it is necessary to disassemble the gearbox (it is better to photograph the disassembly process) and screw it in place of the worn teeth small bolt , ground down to the required size. The place where you will install the bolt must be screwed. It should be located strictly opposite the plastic tooth located on the inside of the case.
Make such markings on the back of the case, opposite the first one.
Next, drill holes in the marked places.
Screw the bolts of the required length into these holes, having previously grinded off so that they are flush with the other plastic teeth. After adjusting the bolts, you can assemble the gearbox with the required amount of lubricant on the gears.This completes the repair of the screwdriver gearbox.
To start repairing this unit, you must first remove the chuck from the screwdriver ... For this, a complete disassembly of the screwdriver is not required. How to unscrew the keyless chuck is described above.
Frequent chuck malfunctions include incomplete output of one of the cams, as shown in the following photo.
The cause of the malfunction may be worn out thread on the nut clamping the cams, or worn teeth on the cams themselves. To verify this, you will need to disassemble the cartridge.
Disassembly and repair of the screwdriver chuck is done as follows.
It is necessary to hit with a hammer on the part protruding in its center. In order not to deform this part, you can lay a small piece of wood.
The top section will not be enough and further chuck disassembly will be required. To do this, lightly clamp the bolt into the cams and hit it with a hammer.
When the inside of the cartridge falls out, its analysis is complete. You will see nut consisting of 2 halves ... Most often, malfunctions in the chuck arise from this part. The thread on it wears out and the cams slip when tightened. Therefore, there is an incorrect centering of the latter.
Also, the thread can be worn on the cams, which, like the nut, must be replaced. But if you do not find the necessary parts to change them, then you will need complete replacement of the cartridge ... When assembling the cartridge, the cams must be installed at the same level, in a compressed state, after which a nut consisting of 2 halves is put on, and after that the whole structure is placed in the body. When the malfunction is eliminated, you can assemble the screwdriver.
In practice, finding spare parts for a cartridge is troublesome. It is easier to buy a new chuck, since its price is not so high, within 300 rubles.
VIDEO
One of the most sought-after tools for home craftsmen is the screwdriver. However, this device sometimes breaks like any other. If this happens, in some cases you can replace this tool with an electric drill. If work cannot be done with an electric drill, you will need to take the screwdriver to a service center in order for specialists to repair the tool. However, this can be time consuming and expensive. Therefore, you can use another option - do it yourself repair the screwdriver.
Screwdrivers are commonly used to assemble furniture both at home and in production.
Before making repair work, you will need to familiarize yourself with the design of this device. In fig. 1 you can see this tool exploded.
Elements that are needed in order to make a screwdriver:
multimeter;
clamps;
sandpaper;
spare parts.
Figure 1. The device of the screwdriver.
The main element is the start button, which performs several functions: switching on the power supply circuit of the electric motor and the speed governor. If you press the button all the way, the motor power circuit will be closed by contacts, as a result of which the maximum power will be provided. The number of revolutions in this case will also be the maximum possible. An electronic regulator is installed in the device, which consists of a PWM generator. This element is located on the board. The contact that is placed on the button will move along the board depending on the pressure on the button. The level of the adjustable impulse per key will depend on the placement of the element. A field-effect transistor is used as a key. The principle of operation will be as follows: the more the master presses the button, the greater the value of the pulse on the transistor and the more it will open and increase the voltage on the electric motor.
The reverse of the rotation of the electric motor will be carried out by changing the polarity at the terminals. This process is carried out using contacts that will be thrown by the master using the reverse handle.
Charger device for cordless screwdriver.
In screwdrivers, in most cases, single-phase continuous current collector motors are installed. They are reliable and easy to manufacture and maintain. An ordinary screwdriver consists of the following elements:
The gear structure will convert the high speed of the electric motor shaft to the low speed of the chuck shaft. Screwdrivers can have planetary or classic gearboxes. The latter are rarely used. Planetary devices consist of the following elements:
ring gear;
sun gear;
satellites;
drove.
The sun gear works by means of the armature shaft, its teeth drive the satellites that rotate the carrier.
A special regulator is used to regulate the forces that will be applied to the screw. Most often, 15 adjustment positions are used.
The main signs of a malfunction in this case will be:
the screwdriver does not turn on;
it is impossible to switch the reverse mode;
it is impossible to adjust the number of revolutions.
Diagram of the gearbox of the cordless screwdriver.
The first step is to check the battery of the screwdriver. If the tool was put on charge, but this did not help, then you will need to prepare a multimeter and try to find the malfunction with it. First you need to measure the voltage on the battery. This value should approximately correspond to the one indicated on the case. If there is an underestimated voltage, then it will be necessary to identify the faulty element: a battery or a charging device. To do this, you will need to use a multimeter. This device must be plugged into the network, and then measure the no-load voltage at the terminals. It should be several V more than that indicated on the structure. If there is no voltage, then it will be necessary to repair the charging unit. If there is no knowledge in the field of electronics, then it is recommended to purchase a new one.
If the battery is faulty, then you will need to disassemble the unit, inspect all the places where the wires are fastened and check their quality. If there are no damaged connections, you need to measure the voltage on all elements with a multimeter. The voltage should be 0.9-1 V or more. If there is a part with a lower voltage, then it will need to be replaced. The capacity and type of the element must necessarily correspond to the installed parts.
Diagram of the internal structure of the screwdriver.
If the charger and the rechargeable battery are in good working order, but the screwdriver does not work, then this device should be disassembled. Several wires go from the battery terminals, you need to take a multimeter and measure the voltage at the input of the button. If voltage is present, then you need to remove the battery, use the clamps to short-circuit the wires from the battery. The device should show a resistance value that tends to zero. In this case, the element is OK, the problem lies in the brushes or other parts. If the resistance is different, then the button will need to be replaced. To repair the button, in some cases, it is enough just to clean the contacts on the terminals with sandpaper.
In the same way, you will need to check the reverse element. Repair is carried out by cleaning the contacts.
If the electric motor runs at high speeds, and the speed cannot be adjusted, then the problem may be in the button or transistor that is used for adjustment.
The device of the gears of the screwdriver reducer.
If the chains to the engine are in good order, but the screwdriver does not work, then the problem is in the brushes.If these elements are worn out, they will need to be replaced.
The problem may be directly in the engine. To test the electric motor, you will need to disconnect the wires that are connected to the button. Next, using the same tool, you need to measure the resistance value at the wires fixing contacts. If the value tends to zero, then the winding has broken. In this case, you will need to rewind or install a new motor.
You will need to check the condition of the armature windings, since this element can be purchased and changed by yourself. To check the anchor, it will be necessary to measure the resistance on the adjacent collector plates, along the entire perimeter. The value should tend to zero. If, during the check, plates with a resistance that differs from zero are found, then it will be necessary to repair the armature or replace it.
Mechanical problems can be identified as follows:
In the process of work, the screwdriver makes extraneous sounds that were not there before.
The tool vibrates strongly during operation.
Fight of the chuck for the clamp.
The tool turns on, but it is not possible to use it due to jamming.
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If during operation the device emits extraneous sounds, this means that the bushings or the bearing are worn out. To fix this, you will need to disassemble the electric motor, and then check the integrity of the bearing and the level of wear of the sleeve. The anchor should rotate freely, there should not be any friction or distortion. These devices can be bought at a construction supermarket and replaced by yourself.
The most common failures of the gear structure include the following:
shaft malfunction;
abrasion of the working base of the gears;
break of the pin on which the satellite is fixed.
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In all cases, it will be necessary to replace the defective gearbox elements. All the above steps must be followed carefully. Disassembly of the screwdriver must be done in a clear sequence, otherwise any of the parts may be lost.
Anyone can repair a screwdriver, you just need to correctly identify the faulty element.
A wonderful invention, a cordless or cordless screwdriver, like all power tools that work a lot and intensively, tends to break at the most inopportune moment. It takes a long time to repair through the service department, and sometimes not very high quality. In addition, the breakdown is not always so serious that it takes several precious days to fix it. It is easier and faster to repair a screwdriver with your own hands, especially if you have some experience with such a tool.
Most often, in a screwdriver, those parts and assemblies that experience the highest load during operation break down. If you look at the internal structure of the screwdrivers, shown in the photo, it becomes clear that the tool consists of four main components:
Cartridge with a reducer;
Electric motor;
Start or start button;
Rechargeable battery.
Of the listed parts of the screwdriver, any component, with the exception of the battery, is subject to real repair. The plastic case and the power cord, the mount for the battery practically do not break if you do not drop the tool from a great height. Even so, the crack can be repaired with polyurethane or epoxy glue, and the cord can be simply replaced. If the crack is more than 4 cm, then along the edges of the crack, drill two rows of holes with a drill and pull off with a thin steel wire. This method of restoring the body of a power tool, despite its barbaric appearance, provides strength at a new level.
Any attempt to repair a screwdriver battery usually ends in failure of the charger or engine.Do not try to open the cylindrical cells of the battery, the lithium ion filling may ignite.
Repairing a screwdriver begins with disassembling the case. To do this, you need to unscrew several self-tapping screws, after which the screwdriver body is divided into two halves, opening up access for repair to all the main units of the power tool.
Most of the screwdrivers of popular brands are assembled using modular technology, from ready-made assemblies, so repairs in most cases are carried out according to the following scheme:
Dismantling the device, carrying out diagnostics and determining the parts required for repair;
Purchase of the kit necessary for the repair in the online store;
Transfer of mounting elements from a burnt-out part to a new one, installation in the housing and testing of the repaired part. If the parts were identified by the markings and the model of the screwdriver correctly, then the repair work will definitely be successful.
In some domestic models, you can perform a deeper repair of the planetary gearbox, for example, with the Caliber screwdriver, as in the video:
VIDEO
But in most cases, owners prefer to carry out SKD tool repairs.
The idea of a piece-by-piece repair has led to the fact that performing maintenance or replacing consumables in a screwdriver becomes a real problem. It is known that engine brushes have a certain resource, after which they need to be replaced. For example, if you are trying to replace brushes and repair a Makita screwdriver, then be prepared for the fact that it will be easier to buy and install a new motor than to find and replace old ones.
All Bosch power tools are renowned for their reliability. All the most important parts - the motor, the gearbox, the chuck - are manufactured with a large margin of safety, so the repair of a Bosch screwdriver is usually the result of improper handling or the result of force majeure. However, every Bosch screwdriver model has its weak points. For example, in the GSR 14.4 model, the weak point is the fastening of the chuck on the gearbox shaft; when trying to pull the drill out of the hole, the chuck may fly off the shaft.
In this case, the repair of the Bosch screwdriver is carried out according to the following scheme.
Initially, you need to disassemble the screwdriver body and pull out the monoblock "motor-reducer".
In order to gain access to the internal structure of the gearbox during diagnostics, you need to remove the fasteners and slightly turn the gearbox housing relative to the engine.
Next, the four steel spring clips are removed. After removing the gearbox, the reason for the repair becomes visible. This is a worn annular groove in the motor shaft into which a snap ring is inserted. The entire repair of a Bosch screwdriver boils down to deepening the groove with a cutter and assembling the tool in the reverse order, as in the video:
VIDEO
In principle, a not bad network screwdriver company Interskol has a drawback that is characteristic of most networked power tools. First of all, it is the short cord of the power tool. If you have to do roof repairs, you must pull on the carrier at the same time and be careful not to snag it on other tools during the repair process.
After several years of use, most corded screwdrivers require a cord revision. At some point, the Interskol screwdriver will need to be repaired, since the tool began to turn on only in one position. This is a typical sign of a broken contact on the power button. Before ringing the chain, you need to remove the housing mount and remove the cover.
The button is a box with a trigger and four screw contacts, two of which go to the speed regulator, the rest are used to connect the mains power supply. If you try to ring the cord with a tester, then one of the contacts will show a break. You should not disassemble the button itself, it is a fairly reliable unit, it very rarely fails, so any attempts to see what's inside usually end in breakdown.Disassembly of the button is necessary only if the trigger is not held by the latch, or the return spring is broken.
To repair a screwdriver, it is enough to loosen the screw clamps of the power cord contacts, cut 3-4 cm, clean and press the ends into brass clips, install them in the box contact sockets and fix with screws. You do not need to repair the cord, but simply replace it with a more convenient network cable in a soft rubber sheath of a suitable length and cross-section.
Video (click to play).
We should also mention the repair of the electric motor. Low-speed collector DC motors are used in almost all models of screwdrivers. In many cases, speed control is carried out using an electronic board that generates 12 V DC voltage pulses with different duty cycle. If the engine suddenly stops starting, do not rush to disassemble and repair it; in many cases, disassembly means its residual loss. Check the work of the board, in 90 cases out of 100 the problem lies precisely in it.
