Do-it-yourself drill repair is done if you have basic skills in this area. Otherwise, you may simply damage the tool or cause it to malfunction. The process of such work itself is not complicated, but you need to have an idea about every detail of the construction device.
Do-it-yourself drill repairs are carried out as needed. Usually, improper operation or technical problems render any tool unusable. It is possible that some parts turned out to be defective (manufacturers are not always conscientious), and this significantly reduces the performance of the drill.
Types of faults
Typical types of breakdowns include:
- Malfunction of the stator or armature (elements of the motor system).
- Unsuitability of brushes for work (their breakage or wear).
- Problems with the reverse switch or regulator.
- Unsuitability of support bearings.
- Poor quality clamp, which is located in the drill chuck.
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Replacing brushes
It is important that all spare parts are of high quality and reliable. In some cases, it is necessary to replace a part so that the tool can be used in the future. For example, brushes often become unusable, which impairs the performance of the drill. Thus, wear of the brushes located in the engine is the most common problem.
The brushes are located in brush holders on both sides of the gearbox.
However, this problem can be solved without leaving home. In most cases, such a tool element can be replaced without disassembling its body. Depending on the model, you simply unscrew the plugs from the installation windows, and then screw on the new brush. Older drill models require repairs that involve disassembling the body. That is, you need to carefully remove the body, remove the brush holders and remove the worn brushes from them.
You can purchase such a tool part at any hardware store. Sometimes a drill is sold with a kit that includes spare parts. There is no need to wait until the brushes are completely worn out (the size of the bristles is significantly reduced). Try to avoid this, as the gap between the brush and the commutator plates increases - then you will have to change the armature as well. What happens to the drill if the brush is not replaced in time? Sparking is observed when using the tool, and the collector plates begin to heat up quite strongly and gradually move away from the base of the collector itself. Thus, the anchor also becomes faulty.
How to determine the need to replace brushes? Experienced craftsmen know that the first sign of wear is increased sparking, which you can see in the ventilation slots in the design of the entire part. Another sign of the unsuitability of a tool element is chaotic movement and jerking during operation.
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Wiring or stator
Tools for repairing the drill cord: screwdriver, side cutters, indicator screwdriver, multimeter, electrical tape, soldering iron, soldering kit.
Drill repair also applies to the power cord. The performance of the cord can also be checked with an ohmmeter. The test is carried out as follows: you connect one probe to the contact of the power plug, and the second to the core of the cord. If you notice a lack of resistance, you need to change the power cord.
It would be necessary to diagnose the engine to ensure the suitability of the drill parts. In second place, after the brush breaks, is the anchor. As a rule, the stator and armature fail for 2 reasons: improper use of the tool and poor quality wire. Manufacturers make winding wires with double insulation and coat them with heat-resistant varnish, which extends the service life of the drill. Remember that they are cheap construction tools not always of high quality and reliable. Therefore, you cannot save on them to avoid problems in the first months of operation. However, improper use of a drill is no less harmful. If you overload the drill (do not give breaks during operation, the drill does not have time to cool down and overheats), soon there will be a need to make repairs. Installation involves rewinding the stator and armature, but work without special equipment is impossible manually. The best option There will be a complete replacement of the tool part, but only a master will be able to carry out the repair on his own.
To replace the stator or rotor of a drill, you must disassemble the drill. First, disconnect all the wires, then the brush and drive gear (as needed). Next, remove the engine along with its components - support bearings. To complete the repair, replace the unusable part of the tool and put all the parts back together. Malfunctions in the operation of the anchor can be determined by characteristic features; specific odor and increased sparking.
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Drill repair
Checking the power cable should begin with its continuity to the trigger key.
Common problems include the following:
- The drill does not turn on.
- The drill is heating up.
- The drill vibrates.
List necessary tools to fix a drill with your own hands:
- screwdriver;
- pliers;
- vice;
- insulating tape;
- brushes;
- cable.
Wire. If the drill does not turn on, then first of all, using a simple tester, check whether there is power in the outlet (extension cord). If there is power, move to the drill's power cord. Wipe the wire along its entire length with a dry cloth, and then inspect it from all sides for mechanical damage (cuts and cracks). Special attention It is worth paying attention to the bend in the place immediately after the wire comes out of the drill and plug. Also, the wire can burn out both inside without visible damage and outside. To ensure its suitability, you need to disassemble the drill and, having removed the wire, check it with a resistance tester. If a break is detected, it can be easily corrected by removing the damaged section and connecting the wire using electrical tape.
Brushes. The most important thing is a visual inspection. The brush should fit snugly against the rotor petals, as they serve as a conductor electric current. If there is a gap, open the fasteners and carefully, so as not to damage other parts and components, remove the used brush into place, place a new one and check for the presence of a gap.
Worn brushes contaminate the commutator, so when repairing the drill it needs to be cleaned.
Button. The button should not stick or move poorly. It needs to be wiped and vacuumed, removing all unnecessary growths. After eliminating the mechanical problems, check the button with a tester for the passage of electric current through the input and output contacts. If the result is negative, it must be replaced with a new one, since even if the button is opened and repaired, this will only give a temporary effect.
Rotor. After carefully wiping the rotor, carefully inspect the petals. Pay special attention to those places where there is contact with the brushes. There should be no scratches or burns in this place. Check the petals for resistance (internal break) with a tester. If the rotor is damaged, it cannot be repaired. Install a new one.
Overheat. As you know, the drill begins to overheat due to continuous operation. However, internal problems can also cause the tool to heat up. Poor contact in electrical circuit drills or improper assembly of components and assemblies, as well as excessive amount Lubricants cause the drill to overheat.
Vibration. Drill vibration occurs due to bearing wear. That is, as soon as you replace the bearings, the vibration will disappear.
Thus, the repair process itself requires certain skills. You need to have an understanding of the components of the drill, their location and repair methods.
An electric drill is one of the most common tools in household. And it’s very bad when it suddenly stops working. In such cases, you really want to repair the drill yourself.
The design of a drill or hammer drill is quite simple. Different tool models mainly differ only in the differences in the arrangement of parts and the quality of their manufacture. The versatility of the operating principle and design used allows you to independently repair the drill in most cases of malfunctions.
Design features of the drill
Any electric drill consists of a housing in which the electric and mechanical part, and the chuck in which the drill is mounted, on the main shaft of the drill. The electrical part usually contains:
- electric motor;
- contact brushes fixed in the brush holder;
- start button (switch);
- engine speed controller;
- reverse device;
- starting capacitor;
- power cord (cable).
In turn, a two-phase electric motor AC consists of a stator and a rotor (armature) with a commutator.
The mechanical part includes a gearbox and a bearing system. The gearbox transmits the rotation of the electric motor to the drill shaft, reducing the rotation speed. A more complex mechanical part in an impact drill (hammer). The rotary hammer reducer provides shock-translational and rotational movement drill (drill). Its design, in addition to the gear, includes pistons (impact and flying), a ram and a firing pin.
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Types of faults in the electrical and mechanical parts of the drill
A malfunction of the electrical part manifests itself in the form of a lack of engine rotation, i.e. when there is no sign of the engine turning on (humming, vibration, etc.). If the impact drill does not turn on, and the chuck is easily turned by hand, then we can safely say that the electrical part is faulty. The same can be said if there is no speed control or reverse rotation. This indicates an expected malfunction in the electrical part. Temporary interruptions in the operation of the drill, extraneous noise may also indicate an electrical circuit.
Most often, a malfunction in the electrical part is due to wear on the contact brushes. If they are drained by 40%, then sparking and malfunctions may occur. If the brushes wear out more, the electric motor simply does not turn on. The following procedure for determining the culprit of an electrical fault is recommended (as available). First, the tester determines the integrity of the cord (cable). Then the operation of the start button (switch) and the integrity of the start capacitor are checked. Then the contact buttons are removed and checked. At the end, the integrity of the motor windings is determined.
A clear sign of a mechanical problem is a jammed drill shaft. If you cannot turn the cartridge by hand, and you can hear the hum of the electric motor when you turn it on, then the reason lies in the failure of the gearbox or bearing. Most common cause Failure in the mechanical part results in destruction of the support bearings. Gearbox failure can also occur when the chuck is turned by hand and the electric motor is running, but rotation is not transmitted to the main shaft. A mechanical malfunction can cause the drill to intermittently malfunction (temporarily stop), humming, grinding, and insufficient shaft rotation speed. In rotary hammers, a mechanical failure can eliminate the drill's impact motion.
Finally, the fault may appear in the drill chuck. Thus, difficulties may arise in removing the drill when the jaws do not move apart due to a breakdown in the engagement inside the chuck. Sometimes the malfunction manifests itself in the form of the chuck spinning relative to the drill shaft. In this case, the malfunction occurred in the area where the chuck is attached to the shaft.
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Drill repair: replacing contact brushes
One of the most common causes of malfunction is wear or burning of the contact brushes. The first signs of brush wear appear in the form of sparking in the contact area of the brushes with the armature of the electric motor and minor malfunctions in the drill when the load increases.
Many drill models have simplified access to the brushes, and changing them is not difficult, and some drills require disassembling the body and removing the brush holder. The brushes must be replaced with new ones, equal in size to the failed brushes.
They should fit tightly in the brush holder. The electrical contact of the supply wire must be tightened well. The brush contact with the armature commutator must be reliable. It is necessary to check the action of the spring.
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Motor fault
Electric motor failure is the second most common cause of drill malfunction. This is due to damage to the stator or armature winding. Such damage occurs due to a manufacturing defect in the windings or improper operation of the drill ( long work without interruptions, load exceeding permissible when the drill jams, etc.). As a rule, electrical breakdown of the winding is easily determined visually or by the characteristic burning smell. If there are no visible manifestations, then the motor windings should be checked with a tester, ohmmeter and megger for resistance value. There are three types of wire damage possible: short circuit between turns, breakdown of a turn on the body or wire break. Repair of the stator or armature is not carried out independently.
To replace the elements of the electric motor, the drill body is disassembled, the contact brushes and supply wires are disconnected, and the electric motor is removed along with the support bearings.
If necessary, remove the drive gear. The faulty electric motor element is disconnected and replaced with a new one, or the old one is installed after repair (rewinding) by professionals.
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Checking electrical components
The switch (start button) and the rotation speed regulator in the drill are usually combined. The speed is adjusted by pressing the button with different force. First, you should check the presence of voltage at the input and output terminals of the button. If there is no signal, then you need to carefully remove the button housing and inspect all contacts. As a rule, burning or sticking of contacts is determined visually. All contacts must be thoroughly wiped with alcohol and sanded with sandpaper. After this, you should check again for the presence of voltage. If there is no signal, the button should be replaced with a new one. The cause may be a violation of electrical contact with the wire. In this case, the wire should be soldered.
The reverse rotation mechanism is based on a system of normally open and closed contacts. Its prevention is carried out similarly to the start button. In addition, you should check all the mechanism wires going to the brushes and the motor stator.
The reason for the inability to start the electric motor may be the failure of the starting capacitor. Usually the non-working state of the capacitor is noticeable by a change in color. But it is more reliable to measure its capacity and compare it with the nominal value.
Checking the electrical part begins with determining the integrity of the power cord (cable) using a tester or ohmmeter.
The resistance between the contacts of the plug is measured (determining the short circuit of the wires) and the resistance of each wire.
The drill is the most common power tool in everyday life and construction. But sooner or later the device may require repair. Read below to learn how to troubleshoot basic problems yourself.
Design and malfunctions of an electric drill
Drills can come in different sizes and colors, but the pattern inside is always the same.
The main components of an impact drill:
- Metal gearbox housing.
Induction rings.
Capacitor.
Network cable.
Reverse button.
Speed regulator.
Electric motor.
Start button.
Button to switch between normal and shock modes.
A simple drill without an impact mechanism does not have a metal gear housing. The shaft and gear bearings are inserted into the drill body.
Main drill malfunctions:
- Doesn't turn on. Causes: damage to the power cord, wires inside the drill, start button, or start capacitor.
- Engine malfunctions.
- Broken or worn brushes.
- Sparks, smokes, crackles, bad smell. The reason is the brushes or the motor.
- Loss of power occurs due to a faulty armature.
- Damage to the power, reverse, and speed control buttons.
- Bearing wear.
Poor chuck clamp.
Engine faults:
- Shaft deformation.
- Making an anchor.
- Failure to secure the poles to the frame in the stator.
- Short circuit to body or between turns.
Winding wire rupture due to overload or abrasive dust.
All of these faults, with the exception of engine faults, are easy to fix yourself. Engine repair is possible if you have certain skills and knowledge. Sometimes it's easier to take it to a workshop or buy and install a new one. Installing any new unit is cheaper than repairing it in a workshop, since professionals charge for one replacement equal to the cost of the unit.
Video: drill device
- The drill should not operate for more than 20–25 minutes continuously after being plugged in.
- It is necessary to clean the cartridge from dirt and lubricate it.
Do not overheat the device to the point of burning your hands.
Do not use very dull drills.
DIY drill repair
In order to find the fault, the drill must be disassembled.
How to disassemble the tool
Some drills have an additional handle and a drill depth limiter.
It is necessary to loosen the clamp and pull the handle through the chuck.
For other models, an additional handle is screwed into the drill body.
If there is a pad on the drill handle that connects the two halves of the body, then it is pryed off with a flat screwdriver and removed.
- Unscrew all fasteners and remove top part housings. Note that the two screws where the housing holds the chuck shaft are shorter than the others.
- Unscrew the screws securing the cord to the body. Carefully remove the wires and other components of the drill from their grooves.
- Remove the brushes and brush holders from their sockets.
The chuck with the shaft and large gear 2 is easily detached from the drill body. Remove the metal housing of the gearbox 1 along with the motor. There is a ball on the shaft that cannot be lost, because it will be difficult to pick up the same one.
Remove the stator.
Remove the gear housing from the motor spindle.
Replacing brushes
Signals for checking the condition of the brushes are sparking in the commutator area, a decrease in speed and heating of the drill. If these problems do not exist, then the condition of the brushes should be checked periodically. If at least one of the brushes is worn by 40 percent, replace both. Disassemble the drill body. The brushes are removed along with the brush holders. Some models have plugs on the body that can be unscrewed.
Brush removal plugs
The brush is removed from the brush holder and a new one is inserted in its place.
Video: replacing drill brushes
Power button, soft start and speed controller
The drill speed controller can be combined with a soft start, either placed in a separate wheel on the body, or the wheel is installed on the start button.
Design and principle of operation of a button with a speed controller:
The speed controller, as well as the soft start, fails due to a faulty microcircuit. If it is located separately from the power button, disassemble the case, disconnect the contacts and replace it with a new one. If the regulator is mounted on a button, disassemble the housing and remove the power button from it.
Replacing a button is easier than disassembling and repairing it, because there are many small parts in it. But if you decide, then carefully disassemble the button body so as not to lose the jumping springs.
- Using a knife or flat-head screwdriver, carefully pry up the latches and latches. Remove the cover.
The contact pads are erased and dust is formed, which settles inside the plastic box. Dielectric surfaces become conductors of electric current. Because of this, the speed and soft start are not regulated. Remove metal dust with cotton wool soaked in alcohol. The contacts can be scraped with a knife, but not with sandpaper, so as not to spoil their surface.
Remove the chip from the other half of the button body. Ring all elements. Replace damaged ones.
Often internal cleaning the button body restores its operation.
Reverse does not work or the drill does not turn to the right
When the rotor rotates forward, the end of the first stator winding is connected to the first brush. In reverse to the second. This switching occurs in the reverse button. If the drill stops turning in one direction or the other, it means the circuit is not closing. It is necessary to diagnose the button and, in case of malfunction, replace it or disassemble it and clean the contacts.
The reverse rings out in several steps:
- Set the reverse flag to the right position.
- Insert the multimeter leads into the two holes on one side of the reverse button. Check if the device beeps. Now insert the probes into the two holes on the other side. There is a sound signal on both sides, which means the right reverse position is working.
- Now set the reverse to the left position.
Insert the probes into the two holes, but with different sides buttons. Then into the other two holes. Check beep multimeter.
If there is no ringing at least at one stage, the button is faulty. You can take it apart. If the contacts close in both positions of the switch, then clean them and ring again. If it doesn't help, then replace the button.
Take a pin, insert it into the hole and remove the wire. Remove all wires in the same way.
Wires from the stator and brushes are connected to the reverse. They are connected diagonally, so draw a diagram so as not to confuse them later. Or tape labels to each wire.
Connecting a drill to a cable without a button
Remove the power button. It includes two cores network cable. If the drill had a reverse, then two wires come out from the stator and brushes. There are four in total. To connect them to the two cores of the network cable, do the following:
- Connect the two ends of different stator windings to each other and connect to the brush.
Connect the other two connected ends of the stator and the wire from the second brush to the network wires.
Carefully insulate connections.
Low and high rotation speeds
If the drill does not work at low speeds, check the soft start and speed controller. If it only runs at low speeds and gets hot, additionally check the motor brushes and commutator wear.
Drill won't turn on
Charge the battery in the cordless drill. If this does not help or the drill is corded, remove the top cover of the case and check the following elements with a multimeter:
Power cord.
Start capacitor.
Start button.
Contacts.
If all wires and contacts are intact, press the start button and check the operation of the engine.
The drill crackles but doesn't spin
Disassemble the housing and turn on the engine. If it works, it means that the teeth of the large gear of the gearbox have worn out. If the motor does not work, check the brushes, stator and rotor windings.
Rotor repair
Before taking the device for diagnostics, inspect the commutator and winding.
It may be damaged. If the wiring is melted, the burnt insulating varnish will leave black marks or a specific smell. You may see bent or crumpled coils or conductive particles, such as solder residue. These particles cause short circuits between turns. Commutator damage: raised, worn or burnt plates.
Carry out diagnostics with a multimeter:
The anchor can be saved if the balance is not disturbed. If during operation of the device you hear an intermittent hum and there is strong vibration, then this is an imbalance. This anchor must be replaced. And the winding and commutator can be repaired. Small short circuits are eliminated. If a significant part of the winding is damaged, it can be rewound. Worn and badly damaged lamellas should be sharpened, extended or soldered. In addition, you should not undertake anchor repairs if you are unsure of your capabilities. It is better to replace it or take it to a workshop for repairs.
To replace the armature, you need to disassemble the drill, remove it from the stator and disconnect it from the gearbox.
Video: replacing the drill rotor
A collector that is not very worn out can be corrected by grooving. But if the plates have worn down to the plastic base or are partially burnt out, then restoration is carried out by soldering or galvanic extension.
If the collector has been completely worn out, then after soldering it will last no more than a month active use. And plates that are not completely damaged after such repairs can withstand several replacements of brushes and do not get desoldered. You will need to cut the copper plates to size and solder them with a large number solder. File off the excess and sand it.
When electroplated, reduced copper is very hard.
The service life of the collector is like new. Galvanic extension can be used to restore both a completely erased collector and partially damaged plates. The restored commutator must be sharpened and the plates separated using a drill or hacksaw blade.
Rewinding the armature
- Write down or sketch the direction of the winding.
- Use a hacksaw or wire cutters to remove the frontal parts of the winding.
Carefully, without damaging the slot insulators, knock out the rods of the remaining parts of the winding using a hammer and metal chisel.
Use a file to remove any remaining impregnation. Count the conductors in the slot and measure the diameter of the wire. Draw a diagram. Cut cardboard sleeves for insulation and insert them into the grooves.
After winding, weld the section leads to the collector plates. Check the winding with a tester.
Impregnate the winding with epoxy resin.
Stator repair
Checking the performance of the stator with a multimeter:
- Set the resistance mode to 200 Ohms. Connect the probes of the device to the ends of one winding. One means an open circuit, and zero means a short circuit between the turns. If it shows resistance of more than 1.5 ohms, then check the second winding. Both windings should have approximately the same resistance.
Now it is necessary to check the absence of breakdown to ground, that is, the winding is short-circuited with the metal stator housing. Set the multimeter to maximum resistance mode. Connect one probe to the end of the winding, the other probe to the metal stator housing. A unit indicates the absence of a breakdown.
You can rewind a damaged stator winding yourself. This is much easier than rewinding the armature. For high-quality winding of coils you will need enamel wire and electrical cardboard.
Replacing armature bearings
The armature has two bearings different sizes. The larger one is located on the impeller side. The bearings are removed with a special puller. But if it is not there, then you need to hang the anchor on metal plates so that the bearing is above the plates and the anchor is below. Tap the shaft with a piece of wood to dislodge it from the bearing.
A long ¼-inch socket is used to crimp the new bearing shaft.
Take the head and rest it against the inner race of the bearing.
Tap it with a hammer.
Place the metal gear housing onto the bearing.
Tap it lightly with a hammer to get it into place.
If the drill battery does not charge
If the battery does not hold a charge, disassemble it. It consists of several batteries. Check the voltage in each with a tester. Replace the non-working element.
Diagnose the charger:
The support plate flies off
The drill can be used for grinding various materials using special nozzles. For this, a support plate is purchased.
It can be plastic or rubber. The sandpaper is attached to it in two ways: with Velcro or with a pressure washer. Plates have their disadvantages:
Therefore, it is better to purchase a plastic support plate with a pressure washer. Or with a movable shank. These plates are the most reliable and easy to use.
But if you happen to have a rubber plate, you can remake it.
Replacing the impact mechanism
Impact drill gear elements:
When you start the drill, the motor and spindle rotate. Rotation is transmitted from the spindle to the large gear of the gearbox. When the blow is turned on, the shaft goes deeper into the gearbox housing, and the teeth connect and engage. The shaft rotates and the ratchets bounce off each other. A reciprocating motion is formed. When the drill starts working without impact, the switch itself plays the role of a limiter. It prevents the shaft from descending into the gearbox housing so deeply that these teeth touch each other. There are types of switches:
There is a bearing in the gear housing on the switch itself. When the shockless mode is turned on, the shaft rests against this bearing.
Some drills do not have a bearing, but have a notch on the switch shaft. When the shaft hits it when turning the switch, it falls through and the shock is activated.
Third models have a switch bar with a hole. The principle of operation is the same. When modes are frequently switched, wear develops on the bar, and the blow stops turning off, since the shaft is in a recessed position.
If the impact mechanism wears out, the unit must be replaced.
Drill chuck repair
The chucks that are installed on modern drills are divided into the following types:
- Key. One of the most common types. To secure the equipment, you will need a wrench, which is used to firmly tighten the cartridge in three holes. Typically used in impact drills, where the chance of turning the drill during operation is significantly higher than with a hammerless drill.
Quick-clamping. There are single-coupling and double-coupling, metal and plastic. Replacement of equipment occurs without the help of a key. It has a drawback - it is not the most reliable fixation.
Morse cone. This cartridge is universal and very reliable. The equipment fits in it like a glove and does not turn. Any other type of cartridge can be installed on a Morse taper using an adapter. This chuck is not installed on household drills.
If you need to replace the drill chuck, open the jaws and check for the screw that secures the chuck to the shaft. If it is present, it needs to be unscrewed. A screw that is difficult to unscrew is treated with WD-40 aerosol or brake fluid. Unscrew the cartridge itself from the shaft. In the case of a Morse taper, the cartridge is knocked off the shaft with a mallet or wooden stick. It fits in the same way.
Not every chuck will fit every drill. Chucks vary in size and the diameter of the rig they can hold. If the outer diameter of the new chuck is larger, you will not be able to attach an additional handle to the drill. Check the match between the chuck threads and the drill spindle threads. For drills of different functionality, the chucks are different. For example, there are cartridges that are only suitable for hammerless drills or cannot operate in reverse rotation. And there are universal chucks that fit all types of drills. Keyless chucks and key chucks with the same thread are interchangeable. Regardless of their size. If you do not need to put an additional handle through the cartridge, then this replacement option is possible.
From clogging construction waste The equipment is poorly clamped into the chuck by the jaws. Therefore, it must be disassembled and cleaned. And replace damaged parts. Particularly difficult is the analysis of the key cartridge.
The clip fits tightly onto the bushing, so we will use a hammer and a vice.
- Place the chuck on the vice so that the bushing with the jaws faces up.
- Place a metal plate on top and hit it with a sharp blow with a hammer. The sleeve with all its contents will go down.
- Remove the clip and the washer, consisting of two halves. Remove the jaws. Number them and seats on the bushing so that they fit into their sockets during assembly.
- Put all the parts back. Put on the clip. Insert the chuck into the vise, but now with the jaws facing down. The cams should be hidden inside. Place a metal plate on the base of the bushing and drive it into the cage.
Hide your fists.
Check the integrity of all parts. Replace damaged ones.
Use a brush to remove any debris from the parts. Rinse with kerosene or diesel fuel. Lubricate the CV joint with grease. It is better than Litol in that it does not allow moisture to pass through and is intended for highly rubbing mechanisms.
You can repair the drill yourself by studying its structure and the principles of operation of individual components.
If you have certain skills, repairing a drill at home is quite simple. From the numerous cases of drill breakdowns, several characteristic malfunctions can be identified, which are caused by improper operation of the power tool or defective elements from the manufacturer. Such typical breakdowns include:
- failure of engine elements (stator, armature);
- brush wear or burnt;
- breakdown of the regulator and reverse switch;
- wear of support bearings;
- poor quality clamp in the tool chuck.
Drill structure (the simplest Chinese electric drill):
1 - speed regulator, 2 - reverse, 3 - brush holder with brush, 4 - motor stator, 5 - impeller for cooling the electric motor, 6 - gearbox.
Electric drill structure: 1 - stator, 2 - stator winding (second winding under the rotor), 3 - rotor, 4 - rotor commutator plates, 5 - brush holder with brush, 6 - reverse, 7 - speed controller.
Replacing brushes.
The most common type of breakdown is wear of the motor brushes, which can be replaced yourself at home. Sometimes, brushes can be replaced without disassembling the drill body. For some models, it is enough to unscrew the plugs from the installation windows and install new brushes. For other models, replacement requires disassembling the housing; in this case, you must carefully remove the brush holders and remove the worn brushes from them.
Brushes are sold at all normal power tool stores, and often an extra pair of brushes is included with a new electric drill.
New brushes
Don't wait for the brushes to wear out. minimum size. This risks increasing the gap between the brush and the collector plates. As a result, increased sparking occurs, the collector plates become very hot and may “move away” from the base of the collector, which will lead to the need to replace the armature.
You can determine the need to replace the brushes by increased sparking, which can be seen in the ventilation slots of the housing. The second way to determine this is the chaotic “jerking” of the drill during operation.
Power cord.
The cord is checked with an ohmmeter, one probe is connected to the contact of the power plug, the other to the core of the cord. Lack of resistance indicates a break. In this case, repairing the drill comes down to replacing the power cord.
Electric motor diagnostics.
In second place, in terms of the number of drill breakdowns, can be placed the malfunction of engine components and, most often, the armature. Failure of an armature or stator occurs for two reasons - improper operation and poor-quality winding wire. World-famous manufacturers use expensive coil wire with double insulation with heat-resistant varnish, which significantly increases the reliability of engines. Accordingly, in cheap models the quality of insulation of the winding wire leaves much to be desired. Improper operation comes down to frequent overloading of the drill or prolonged operation without breaks to cool the engine. Do-it-yourself drill repair by rewinding the armature or stator, in this case without special devices impossible. Only complete replacement of the element (exclusively experienced repairmen will be able to rewind the armature or stator with their own hands).
To replace the rotor or stator, it is necessary to disassemble the housing, disconnect the wires, brushes, remove the drive gear if necessary, and remove the entire motor along with the support bearings. Replace the faulty element and install the engine in place.
An armature malfunction can be determined by a characteristic smell, an increase in sparking, and the sparks have a circular motion in the direction of movement of the armature. Pronounced “burnt” windings can be seen upon visual inspection. But if the engine power has dropped, but there are no signs described above, then you should resort to help measuring instruments- ohmmeter and megger.
Windings (stator and armature) are subject to only three damages - interturn electrical breakdown, breakdown to the “case” (magnetic circuit) and winding breakage. A breakdown to the housing is determined quite simply; it is enough to touch any winding output and magnetic circuit with the probes of a megohmmeter. A resistance of more than 500 MΩ indicates no breakdown. It should be taken into account that measurements should be carried out with a megger with a measuring voltage of at least 100 volts. By taking measurements with a simple multimeter, it is impossible to accurately determine that there is definitely no breakdown, but you can determine that there is definitely a breakdown.
It is quite difficult to determine the interturn breakdown of the armature, unless, of course, it is visible visually. To do this, you can use a special transformer, which has only a primary winding and a break in the magnetic circuit in the form of a trench for installing an armature into it. In this case, the armature with its core becomes a secondary winding. Rotating the armature so that the windings alternate in operation, we apply a thin metal plate to the armature core. If the winding is short-circuited, the plate begins to rattle strongly, and the winding heats up noticeably.
Often, an interturn short circuit is detected in visible areas of the wire or armature bar: the turns may be bent, crumpled (i.e., pressed against each other), or there may be some conductive particles between them. If so, then it is necessary to eliminate these short circuits by correcting bruises in the tire or removing foreign bodies, respectively. Also, a short circuit can be detected between adjacent collector plates.
You can determine whether the armature winding is broken if you connect a milliammeter to the adjacent armature plates and gradually turn the armature. In whole windings a certain identical current will appear; a broken winding will show either an increase in current or its complete absence.
A break in the stator windings is determined by connecting an ohmmeter to the disconnected ends of the windings; the absence of resistance indicates a complete break.
Speed regulator and reverse.
The presence of voltage at the input terminals of the power button and absence at the output terminals indicates a malfunction of the contacts or components of the speed controller circuit. You can disassemble the button by carefully picking up the latches of the protective casing and pulling it off the button body. A visual inspection of the terminals will allow you to judge their performance. Blackened terminals are cleaned of carbon deposits with alcohol or fine sandpaper. Then the button is reassembled and checked for contact; if nothing has changed, then the button with the regulator must be replaced. The speed controller is made on a substrate and is completely filled with an insulating compound, so it cannot be repaired. Another typical malfunction of the button is the erasure of the working layer under the rheostat slider. The easiest way out is to replace the entire button.
Repairing a drill button with your own hands is only possible if you have certain skills. It is important to understand that after opening the case, many switching parts will simply fall out of the case. This can be prevented only by smoothly lifting the cover initially and sketching the location of the contacts and springs.
The reverse device (if it is not located in the button body) has its own changeover contacts, and therefore is also susceptible to contact loss. The disassembly and cleaning mechanism is the same as the buttons.
When purchasing a new speed controller, you should make sure that it is designed for the power of the drill, so with a drill power of 750W, the regulator must be designed for a current of more than 3.4A (750W/220V=3.4A). And by the way, the regulator of the drill in the photo is not original, and in order for it to fit into the body, the lower part of the trigger was cut off.
The lower part of the trigger is cut off
Wire connection diagram, and in particular the drill button connection diagram, in different models may vary. The most simple circuit, and best demonstrating the principle of operation is the following. One lead from the power cord is connected to the speed controller.
Electrical diagram of a drill. "reg. rev." — electric drill speed regulator, “1st rotation station.” - first stator winding, “2nd station exchange.” - second stator winding, “1st brush.” - first brush, “2nd brush.” - second brush.
In order not to get confused, it is important to understand that the speed controller and the reverse control device are two various details, which often have different bodies.
The speed controller and reverse are located in separate housings. The photo shows that only two wires are connected to the speed controller.
The only wire coming out of the speed controller is connected to the beginning of the first stator winding. If there were no reversing device, the end of the first winding would be connected to one of the rotor brushes, and the second rotor brush would be connected to the beginning of the second stator winding. The end of the second stator winding leads to the second wire of the power cord. That's the whole scheme.
A change in the direction of rotation of the rotor occurs when the end of the first stator winding is connected not to the first, but to the second brush, while the first brush is connected to the beginning of the second stator winding.
Drill reverse circuit
This switching occurs in the reverse device, so the rotor brushes are connected to the stator windings through it. This device may have a diagram showing which wires are connected internally.
Diagram on the reverse of an electric drill (in the photo the reverse is disconnected from the speed controller)
Electric drill reverse connection diagram
Black wires lead to the rotor brushes (let the 5th contact be the first brush, and let the 6th contact be the second brush), gray wires lead to the end of the first stator winding (let it be the 4th contact) and the beginning of the second (let it be 7- th contact). When the switch is in the position shown in the photo, the end of the first stator winding with the first rotor brush (4th with 5th), and the beginning of the second stator winding with the second rotor brush (7th with 6th) are closed. When switching the reverse to the second position, the 4th is connected to the 6th, and the 7th to the 5th.
The design of the electric drill speed controller provides for connecting a capacitor and connecting both wires coming from the outlet to the controller. The diagram in the figure below, for better understanding, is slightly simplified: there is no reverse device, the stator windings to which the wires from the regulator are connected are not yet shown (see diagrams above).
Connection diagram for the button (speed control) of the drill.
In the case of the electric drill shown in the photo, only two lower contacts are used: the far left and the far right. There is no capacitor, and the second wire of the power cord is connected directly to the stator winding.
Connecting an electric drill button
Read about the principle of operation of the speed controller in the article about the device of a drill.
Gearbox.
The presence of extraneous sounds, grinding and jamming of the cartridge indicates a malfunction of the gearbox or gear shift mechanism, if any. In this case, it is necessary to inspect all gears and bearings. If worn splines or broken teeth on gears are found, then it is necessary complete replacement these elements.
Bearings are checked for suitability after removing them from the armature axis or drill body using special pullers. While holding the inner race with two fingers, you need to rotate the outer race. Uneven slipping of the race or “rustling” when turning indicates the need to replace the bearing. A bearing replaced at the wrong time will lead to jamming of the armature, or, in best cases, the bearing will simply turn in its seat.
Replacing the drill chuck.
The chuck is subject to wear, namely the clamping jaws, due to dirt and abrasive residues of building materials getting into it. If the cartridge needs to be replaced, it is necessary to unscrew the locking screw inside the cartridge (left-hand thread) and unscrew it from the shaft.
In conclusion, I would like to add: when assembling the drill after repairing it, make sure that the wires are not pinched by the top cover. If everything is in order, the two halves will collapse without a gap. Otherwise, when tightening the screws, the wires may become flattened or cut.
Flattened wire.
So, the article by Alexey Sidorkin:
I think that every person has had more than one event or incident in their life for which they could not find a suitable explanation, remaining a secret for a long time. for a long time. This happened with my drill.
My son-in-law Dmitry acquired this Bosch PSB 500 RE drill in May 1998 to furnish his newly acquired apartment. At that time, not everyone had such a prestigious tool (power 500 W, speed control, reverse rotation, possibility of impact mode - “perforator”) on the farm. The purchase aroused quiet envy - I had a simple Soviet drill without any bells and whistles. My daughter gave the Bosch drill later after the tragic death of her son-in-law during an accident in 2002.
Of course, my use of the tool was not “every day from morning to evening”; the drill was used for everyday needs, as in most ordinary families, plus summer season at the dacha.
Fig.1. General view drills BoschPSB 500 RE.
The drill worked properly, successfully performing all its options and functions... and suddenly 5-6 years ago the speed regulator stopped “obeying” - no matter the position/setting of the regulator wheel/handwheel, when you press the trigger, the drill immediately made full revolutions without any smoothness. The first thing that came to mind as to why there were no low speeds was that the drill’s speed control circuit had “burned out”. But by that time, other tools appeared on the farm, including a screwdriver and another drill in the village, and the operation of the Bosch drill in low speed mode was not so relevant, and we never got around to fixing the problem.
Just recently I had to carefully work with a drill, and its high speed turned out to be very inappropriate, and there were no other tools with a chuck at hand. There is a repair shop not far from the house household appliances. They told me that the speed controller (hereinafter referred to as RO) for the Bosch drill is only “made to order”, wait at least 2 months, the cost of work is 500 rubles.
I decided to figure it out on my own, after all, I’m an adjuster energy equipment, albeit retired.
He's an adjuster himself, but he went to the workshop? If it’s urgent, and for a couple of hundred (previously it was called “per bottle”), then there’s no point in “uncovering your rifle,” others should also be allowed to live.
I opened the drill, disconnected the RO (two detachable knife-type electrical contacts, two “for screws” and one fastening screw power wire- rice. 2).
Rice. 2. Connecting the speed controller in the drill.
The drill speed controller is a separate unit. In Fig. 3, almost life size two halves (cover and body) of an already opened RO, the material is plastic, the halves are fixed between each other “with latches”.
Rice. 3. Drill speed controller with cover removed
Figure 3 shows: 1 – contact group; 2 – sliding contacts; 3 – resistor strips; 4 – adjusting screw handwheel; 5 – trigger return spring.
The housing of the speed controller for the drill contains a contact group 1 and sliding contacts 2 in the form of two spring plates, driven by pressing the trigger and returning to their original position under the influence of the return spring 5.
The cover contains a capacitor (bottom) and a board (top) with electronic elements and two resistor strips 3, along which, when the trigger is pressed, contacts 2 slide to smoothly change the speed of the tool. A special lubricant is applied to the resistor strips to protect the strips, reduce friction and prevent sparking of the sliding contacts.
An adjusting screw with a handwheel 4 on the trigger limits the depth of the trigger press and the distance/length of sliding of the contacts 2 along the resistor strips 3, thereby determining the range of regulation and maximum speed drills. If the adjusting screw is turned out completely, then the trigger, when fully pressed, closes the contact group to direct connection the drill engine, bypassing electronic adjustment elements, and the engine operates at the highest possible speed (3000 rpm).
The drill speed controller circuit is almost identical. The only differences are in design and dimensions.
The scope of my work included checking the precise operation of the trigger when pressed, the interaction of the parts of the contact group, the rotation of the adjusting screw, leveling the distribution of lubricant on the resistor strips, and cleaning accessible areas from accumulated dust and dirt. No malfunctions, malfunctions or suspicious aspects were found. In other words, I carried out a small inspection, after which I assembled the drill, turned it on and... the speed controller is working as if nothing had happened!
Thus, repairing the Bosch drill speed controller was reduced to simple cleaning!
Many assumptions could be made regarding the reasons for the temporary malfunction of the drill - from a blow or an unnoticed fall of the tool to problems with electronic components. However, an analysis of the situation still tends to disrupt the operation of the “sliding contacts - resistor strips” pair for some unknown reason; it is enough for a speck (particle) to simply get under one of the sliding contacts - and that’s it, there will be no adjustment. This is also indicated by turning on the tool immediately at full speed, which is only possible when the contact group is triggered.
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But, whatever you say, it turns out that the instrument turned out to be he's an electrician himself and repaired himself!
Question from a reader
Reader Alexander contacted me by email with the following request:
Good evening. I came across your blog where you repair a Bosch drill. I have a similar problem, but I have almost nothing to do with electronics. Stupidly I disassembled the trigger of a Bosch GSB 1600 RE drill. Everything worked great before, I put it together somehow, now the soft start doesn’t work. Perhaps I’m putting the parts in the wrong order and in the wrong place. I am attaching a photo of the disassembled one. I hope this helps, the drill is good.