An electric drill is one of the most common household tools. And it's very bad when it suddenly stops working. In such cases, I really want to repair the drill with my own hands.
Electric drill device diagram.
The design of a drill or hammer drill is quite simple. Different tool models mainly differ only in the difference in the arrangement of parts and the quality of their manufacture. The versatility of the operating principle and structures used allows you to make independent repair of the drill in most cases of malfunctions.
Any electric drill consists of a body, which houses the electrical and mechanical parts, and a chuck, in which the drill is mounted, on the main shaft of the drill. The electrical part usually contains:
Diagram of the percussion mechanism of the drill.
In turn, a two-phase AC motor consists of a stator and a rotor (armature) with a collector.
The mechanical part includes a gearbox and a bearing system. The gearbox transfers the rotation of the electric motor to the drill shaft, reducing the rotation speed. A more complex mechanical part in a hammer drill (hammer drill). The hammer drill's reducer provides the percussion-translational and rotational movement of the drill (drill). Its design, in addition to the gear, includes pistons (shock and flying), ram and firing pin.
A malfunction of the electrical part manifests itself in the form of a lack of rotation of the engine, i.e. when there is no indication that the engine is running (hum, vibration, etc.). If the impact drill does not turn on, and the cartridge is easily turned by hand, then we can safely talk about a malfunction of the electrical part. The same can be said if there is no speed control or reverse rotation. An expected malfunction in the electrical part is indicated by sparking during the operation of the drill. Temporary interruptions in the operation of the drill, extraneous noise can also indicate an electrical circuit.
Most often, a malfunction in the electrical part is due to wear of the contact brushes. If they are cut by 40%, then sparking and malfunctions can be observed. With more wear on the brushes, the electric motor simply does not turn on. The procedure for determining the culprit of a malfunction in the electrical part is recommended as follows (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 starting capacitor are checked. Then the contact buttons are removed and checked. Finally, the integrity of the motor windings is determined.
A clear sign of a mechanical problem is a jammed drill shaft. If the cartridge cannot be rotated by hand, and at the same time you can hear the hum of the electric motor when turned on, then the reason lies in the breakdown of the gearbox or bearing. The most common cause of mechanical failure is the failure of thrust bearings. A breakdown of the gearbox can also appear in the case when the chuck is turned by hand and the electric motor is running, and the rotation is not transmitted to the main shaft. A malfunction in the mechanical part can cause periodic malfunctions (temporary stoppages) of the drill, hum, grinding and insufficient shaft rotation speed. In rock drills, a malfunction in the mechanical part can remove the impact movement of the drill.
Finally, a malfunction can manifest itself in the drill chuck. So, it can be difficult to remove the drill when the cams do not open due to breakage in the engagement inside the chuck. Sometimes the malfunction manifests itself in the form of scrolling the chuck relative to the drill shaft. In this case, a malfunction occurs in the area where the chuck is attached to the shaft.
One of the most common causes of malfunction is wear or burning of contact brushes. The first signs of brush wear appear in the form of sparking in the contact area of the brushes with the electric motor armature and minor malfunctions of the drill when the load is increased.
The location of the contact brushes inside the drill.
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 be firmly attached to the brush holder. The electrical contact of the lead wire must be tightened well. The contact of the brush with the armature collector must be reliable. It is necessary to check the action of the spring.
Failure of an electric motor is the second largest cause of a drill malfunction. This is due to damage to the stator winding or armature. Such damage occurs due to a factory defect in the windings or improper operation of the drill (long-term operation without interruptions, the load in excess of the permissible load when the drill is jammed, etc.). As a rule, electrical breakdown of the winding is easily identified 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 megohmmeter for the value of resistance. There may be three types of wire damage - short circuit between turns, breakdown of a turn to the body, or wire breakage. Repair of the stator or armature is not carried out independently.
Drill motor connection diagram.
To replace the elements of the electric motor, the drill body is disassembled, the contact brushes and lead wires are disconnected, and the electric motor is removed together with the support bearings.
If necessary, retract the drive gear. The faulty element of the electric motor is disconnected and replaced with a new one or the old one is installed after repair (rewinding) by professionals.
The switch (start button) and the rotational speed regulator in the drill are usually combined. The speed is regulated by pressing the button with different efforts. First, you should check the presence of voltage at the input and output terminals of the button. If there is no signal, then 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 cleaned with sanding paper. After that, the presence of voltage should be checked again. 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 must be soldered.
Drill button connection diagram with reverse.
The reverse rotation mechanism is based on a system of make and break contacts. Its prevention is carried out in the same way as the start button. In addition, you should check all the wires of the mechanism going to the brushes and the stator of the electric motor.
The reason for the impossibility of starting the electric motor may be the failure of the starting capacitor. Usually, a non-working condition of a capacitor is noticeable by a color change. But it is more reliable to measure its capacity and compare 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 (determination of the short circuit of the wires) and the resistance of each core.
A jammed chuck or a grinding noise indicates a failure of the gearbox or bearings.First of all, you should disassemble the drill body and inspect the condition of the gears in the gearbox. The wear of the mounting splines or the destroyed teeth of the gears indicate the failure of the part. This gear must be replaced. The gears are inspected along the entire circumference, smoothly turning the shafts by hand.
The bearings are checked by turning the shaft in them. If the shaft is sluggish, start by lubricating the bearings. If this does not help, then they are removed from the axle using a special puller. The bearing cage is scrolled by hands. If movement is difficult or extraneous sounds are heard, then the bearing should be replaced.
During prolonged use of the drill, the cartridge may fail. Sometimes this manifests itself in the impossibility of removing the drill - the adjusting sleeve does not rotate or, on the contrary, it easily scrolls, and the jaws do not move apart. This indicates wear of the gear joint in the chuck due to metal shavings and dust. In this case, the repair is reduced to replacing the cartridge. The chuck is usually fastened to the shaft with a left-hand thread and is fixed with a screw. The cartridge can be removed by unscrewing the screw and turning the cartridge in the opposite direction with force. In some models of drills, the chuck is installed using a tapered surface in an interference fit. In this case, it must be knocked out with light blows to the end from the side of the drill body.
VIDEO
The drill often breaks at the most inopportune moment. In order for this not to become a problem, you should know how to repair the drill yourself. You should understand the design of the drill used and determine the cause of the malfunction.
An electric drill in a home workshop takes a special place. Therefore, tool breakage is a big enough nuisance. Despite the complexity of the design, it is quite possible to make an independent repair.
2.button with power switch - can be equipped with
reverse switch (speed regulator);
3. shaft rotation speed regulator (or reverse switch);
4.Gearbox housing - carries out load-bearing functions for rotating
5. gears and reducer mechanism;
6. bearings of the shaft of the cartridge and the armature of the engine;
8. brush assembly of the electric motor;
9. chuck with drill or cutter holding mechanism.
The drill never breaks as a whole: one of the elements fails. Having understood the design and interconnection of the power tool assemblies, it will be easier to localize the malfunction.
Drill repair is carried out according to the principle "from simple to complex". You should not immediately disassemble the tool to the screw, and assess the condition of all nodes at the same time.
The drill does not turn on. We start with the power cord (at least before that, you should check the voltage in the outlet and extension cord). Having disassembled the case, we find the cable contacts, and "ring" them with a multimeter.
Important! Do not check the power cable with voltage applied! If the current-carrying conductors break, you can get an electric shock, or organize a short circuit.
We connect to the socket of the mains plug and the opposite terminal of the cord. Then we bend the cable several times along its entire length. Lost contact or its complete absence indicates the presence of an open circuit inside the insulation. If the fracture of the current-carrying conductor is close to the edge, the cable is cut and reconnected. It will just be a little shorter. If the gap is in the middle of the length, it is better to replace the wire. The splicing will be unsafe.
The cord is working properly - we check the switch. We connect the multimeter to the terminals, and press the key. A large current flows through the contacts, sparking occurs (especially when dust enters the case). Contacts can corny oxidized.We carefully disassemble the switch body and clean the contact groups with fine emery paper.
In case of breakage of metal parts, it is better to purchase a new unit.
If there is an additional contact group in the circuit between the switch and the electric motor (for example, a reverse switch or a speed regulator), we diagnose this node as well.
Next, we check the connecting wires from the switch to the motor brushes. If they are in order, we diagnose the brush assembly.
The springs should confidently press the brushes against the anchor lamellas; we check the carbon elements themselves for wear. If necessary, we change: spare parts are included in the delivery set, or purchased in specialized stores. The armature contact strips can be oxidized or clogged. They can be gently cleaned with fine sandpaper.
A more complex breakdown is failure of the armature or stator windings. Using a multimeter, a short circuit is checked between the body of the unit and the contacts of the windings. Then the resistance is measured. The value should be the same on each winding, the variation in readings should be no more than 5%. Defective windings must be rewound.
This can be done on your own, or in a repair shop (in any case, it will be cheaper than buying a new engine).
Such breakdowns manifest themselves quite clearly. Extraneous noise, grinding, shaft jamming, etc.
The motor rotates slowly and the windings get very hot. Or, during normal rotation, a characteristic hum (grinding) is heard. Most likely - the rotor bearings are worn out or clogged. Having disassembled the drill body, we carefully take out the rotor. It is removed together with the bearings. By twisting the outer clip, you will immediately determine the malfunction. If the bearings rotate tightly, they must be flushed with a penetrating liquid (WD-40 or regular kerosene)
Important! Make sure that no liquids get into the armature winding! Otherwise, the insulating varnish may dissolve, and an inter-turn circuit will occur.
Then grease is placed between the clips for high-revving units. Lithol or graphite grease for automotive bearings will do.
If there is a backlash between the bearing races, the units must be replaced.
Dismantling is carried out with a special puller or with an open-end wrench.
If there are no balls, be sure to find them in the case. Dropped objects can get caught between engine or gearbox parts and damage the entire unit.
The bearings of the chuck shaft are diagnosed and repaired in the same way. Only dismantling them without a puller will not work.
If the mounting place of the outer bearing cage (bed) is worn apart (this happens when the bearing is jammed), you will need to make liners of thin sheet metal. Otherwise, beating will occur when the shaft rotates.
The engine rotates in normal mode, noise and grinding noise are heard from the gearbox housing. The shaft turns unevenly. Worn or destroyed gears of the reducer.
We disassemble the case and examine the gears.
It is advisable to wash the assembly of old grease and rotate the shaft 360 °, controlling the engagement of the gears. If a backlash or excessive wear of the teeth is detected, the mechanical part will have to be changed.
Perhaps a large amount of dust has simply accumulated in the gearbox housing. Together with the lubricant, an abrasive paste is formed. In this case, after flushing the assembly, simply add new grease.
Tip: The grease should be changed periodically without waiting for breakage.
Especially if you often drill stone walls.
The cartridge is broken. For cam devices (turnkey) this is a great rarity, the design is reliable and simple. The unit is exposed to dust, so the internal mechanism can easily jam. Most often, the gripper guides are clogged with small abrasive particles.
If the chuck does not twist well, it is enough to blow it out with compressed air and treat it with a penetrating lubricant.
Attention: The jaw chucks do not lubricate the inside!
It is quite difficult to disassemble a part without a special tool. If some component is mechanically broken inside, you still have to change the entire assembly.
But keyless chucks, on the contrary, are easily disassembled and repaired.
They are not as reliable and do not carry the load very well. To disassemble such a cartridge, it is enough to remove a pair of lock washers. You will easily find a broken or worn part that can be easily replaced.
There are two types of fastening: Morse taper, and threaded. In the first case, you need to inflict several blows with a small hammer on the back of the cartridge. After which it can be easily removed.
To unscrew the threaded fastener, the shaft is held with a wrench (there are special flats on the shaft).
There are no faults that cannot be corrected by hand. If a separate unit cannot be restored, only it changes, there is no need to buy a new drill.
To prevent breakdowns, you should adhere to simple rules:
After dusty work, blow out the ventilation holes and the interior of the cartridge. Keep the instrument clean.
Do not overheat the engine - take breaks for prolonged use.
Refill the grease on the rotating parts periodically.
The drill is considered one of the most popular DIY tools and is used in many types of work. Due to heavy use, tool parts can break and damage the device. Do not rush to the service center: it is quite possible to repair the drill with your own hands and save a lot of money.
If you know the device of the drill and the principle of operation of the tool, then self-repair of the product will not complicate you.
Regardless of the model or manufacturer, all of these electrical tools consist of a typical set of basic components.
Any do-it-yourself drill repair must begin with a visual inspection of all parts. The principle here is simple - from simple to complex, that is, first we check the cord, wiring, contacts, various fasteners, then we start testing the blocks and the engine. It does not always come to a complete disassembly of the product, but in practice you need to be prepared for such a development of events. How to disassemble a specific model, the instruction manual will help.
Regardless of the build quality and manufacturer, the following malfunctions occur quite often:
the electric motor fails due to a breakdown of the armature or stator;
extreme wear of brushes;
bearing problems;
the speed control button does not work;
the contacts of the start button are oxidized or burned out;
breakage of the chuck holding the drill due to wear of the jaws.
If you decide to repair an electric drill yourself, then first you need to diagnose and find a malfunction. It is rarely possible to repair a failed part on its own, as a rule, it is simply replaced with a new one.
Before disassembling the drill, make sure it is disconnected from the mains. Any disassembly begins with the removal of the fasteners. Then we unscrew the screws and self-tapping screws, remove the upper part of the product - all the components remain in the lower part. Drill wiring diagram quite simple - there is no need to separately describe all the elements, everything is already intuitive.
Naturally, for models with electronic adjustments, it is much more difficult, but it is unlikely that it will be possible to repair a drill with such units on your own, it is better to entrust this to specialists from the service center.
When the power goes out, you just need to change the position of the product - the reason lies in the cable, most likely one of the wires broke ... It is necessary to disconnect the drill from the mains and check with a multimeter cable. You can use the simplest option - a light bulb and a battery in the same circuit.
Attention! Pulling the cord when the drill is plugged in is strictly prohibited, in order to avoid a short circuit - you will have to rewind the motor winding.
After checking, you can bend it as you like so that find the place of the cliff , then a part of the cable is cut off, the wires are stripped and new contacts are created for connection. When a break occurs in the middle of the cable, then it must be completely replaced with a new one. True, thrifty users prefer to connect broken wires by soldering, followed by reliable isolation of the repair site, but there is no longer complete trust in such a wire.
This part has a very simple design, but if a problem occurs, it will prevent the drill from starting. Its work is simple: the key slides in a special block and closes the contacts with a pusher finger. From long-term operation inside the block dust accumulates , which prevents the button from moving and blocks it, preventing the contact circuit from closing. The defect is easily eliminated - open and remove dust with a brush.
Important! Never try to lubricate the sliding surfaces of the button - the dust will mix with the grease and deplete, resulting in the entire unit being replaced.
Not all users know that power from the mains is transmitted to the rotor using brushes made of graphite - during normal operation, constant arcing occurs between them and the rotor. There are times when a wad of dust is crammed between the armature and the brush, and since the dust is a dielectric, the drill will not work until we remove the dust and restore contact.
During use, the brushes gradually decrease, because their lower part is erased. Periodically they need to be inspected and changed - it's easy to do, you just need to have a new set in stock.
When you notice strong sparking in the area of \ u200b \ u200bthe brushes, and have recently changed them, this can happen due to rotor problems or its manifold.
For a thorough check, carefully remove the rotor from the stator. Contacts can be charred or have scale - you need to clean them with sandpaper strictly in the direction of rotation. The reason the appearance of dross there can be long-term work at maximum speed. How to check if the rotor is working properly? Ring the adjacent lamellas with a multimeter - their resistance should be identical.
Do not forget check winding - whether there was a short circuit with the magnetic circuit case. In the event of a breakdown, the faulty winding is rewound independently or taken to a service center.
A visual inspection must be done periodically: in case of overheating, when the product was operated at maximum loads, the protective varnish could melt and occur turn-to-turn closure ... In this case, the winding will burn out, and the electric motor is unsuitable for further operation. The check is done in the same way as in the case of the rotor - we check the windings with a multimeter. If a breakdown is detected, the stator winding must be rewound.
Leading manufacturers of impact drills pay special attention to the protection of the winding wires, because their products operate in a special mode.
Why is the device still not working if you checked everything and ruled out breakdowns in the electric circuit of the drill? There can be only one answer - the non-working state of the product arose due to the presence of mechanical faults.
Bearings do not work ... Dust gets into the grease due to the breakthrough of the stuffing box, so they wear out quickly and can jam at some point. It is easy to eliminate: we wash the bearing in kerosene, change the oil seals, fill in new grease, better than a special composition for products with high rotation speeds.Broken reducer - a very serious breakdown, you need spare gears, or you will have to replace the entire module. It is only necessary to install the same model. If the drill is a common modification, then it is not a problem to buy spare parts for it in stores.Experts consider one of the most difficult malfunctions breakage of cartridge parts .
During work, drilling waste often gets into the inner part of the chuck, they mix with the lubricant, which wedges the inner jaws. The cartridge must be disassembled, all parts are washed and lubricated before assembly. If extreme wear is found, then the part must be replaced; if the base or sleeve is severely worn, the entire block should be replaced.
We tried to tell you about all the failures encountered during the operation of electric drills. Remember that DIY repairs are always much cheaper than buying a new product.
VIDEO
Quite often, breakdowns occur in the operation of any power tool, especially when it is used intensively. In such cases, it is very possible to repair a drill with your own hands if you have the desire and certain skills.
It is generally accepted that tool breakdowns are most often caused by improper operation and not high-quality components. As you already know, now there are a lot of all kinds of power tools on the market, which are divided into professional or household ones, or, in other words, power tools are of high-quality assembly and not very.
But, despite the presence of a high-quality assembly with high-quality components, for various reasons, there are malfunctions in the operation of the electric drill. Typical or typical malfunctions include the following:
1.Various malfunctions of the motor (failure of the stator, armature)
2.Burn or wear on brushes.
3. Failure of support bearings.
4. Failure of the speed controller button (start button).
5. Various other problems such as problems with the chuck.
I want to say right away that repairing a drill with your own hands does not mean repairing some part that is out of order, most often this is impossible without special equipment and special knowledge. The task of repair is to find the cause of the problem and replace the failed part with a new one.
Photo-1. Electric drill device.
In order to try to repair the drill, you first need to find the cause of the problem.
In order to better understand all the intricacies of the problems, you need to know what the assembly of an ordinary drill consists of, or you can call it another name, the term device. Also, I recommend that you familiarize yourself with working principle hammer drill.
The drill device consists of:
1.-capacitor, 2-switch button, 3-engine speed controller, 4-reverse switch, 5-brush holders with brushes, 6-bearings, 7-rotor (armature) collector, 8-motor stator winding, 9-built-in impeller fan, which serves to cool the electric motor, 10-metal gear housing, 11-reduction gear, 12-return spring, 13-clamping chuck, 14-electric drill housing.
In order to try to find the cause of the problem, the first thing you need to do is unscrew the body mounting bolts, get to the components and carefully examine everything. As already mentioned a little above, the problems are most often typical and therefore we will consider some of them that are most often encountered.
1.Wear of brushes of the electric motor.
Photo-2. Brush holders with brushes.
Photo-3.Installation windows for brushes with plugs.
Photo-4. Electric motor assembly.
Photo-6. Visual inspection of the electric motor.
1.Electric turn-to-turn breakdown.
3. Damage to the magnetic circuit or breakdown on the case.
It is possible to determine the cause of the malfunction of the stator or rotor winding ourselves, but it is not possible to carry out high-quality repairs without having special equipment and knowledge.
Photo-8. Determination of a break in the stator winding.
A turn-to-turn short circuit can be found in sections of the winding wire. The turns of the wire may be crumpled, strongly pressed against each other or there are conductive objects or particles between the turns. If such faults are found, you should proceed to elimination. If this is not possible, then the part should be replaced with a new one ...
Photo-9. Button for turning on the electric motor.
1. Replace the button with a new one.
2. Try to open it and repair it.
The button for turning on the electric motor shown in photo-9 has a built-in regulator of the speed of the electric motor and a built-in regulator of the direction of rotation of the rotor-reverse. This is a rather complex design and therefore the button should be disassembled carefully, it is not uncommon for its further use after disassembly to become impossible. many small parts that, when opening the case, can simply fall out of there. After disassembly, you should clean the clamps from carbon deposits, and correctly assemble it back, then check for operability.
Photo-10.Another design of the switch button.
But despite this, it also has a rather complex design, so I can say that most often, if it fails, it cannot be repaired and requires replacement.
When buying another button for turning on the engine speed, you should take the old one with you or rewrite its data on paper, since there are different models of drills and, accordingly, different buttons with different data.
Chances are that having bought a new button in a store with the same parameters, you will not be able to install and fix it in the body of an electric drill. Since the possible existing differences in the design of the button will not allow this. Therefore, the best option for you is to take the button with you and buy exactly one.
In the event of abnormal noises in the form of a rumble or rattling sound when working with an electric drill or when there are frequent wedging of the chuck, these are signs of a malfunction in the gearbox. Such malfunctions can only be eliminated by replacing worn parts. In order to better understand the causes of malfunctions in the gearbox. , I recommend reading the article hammer drill working principle .
Photo-11. Electric drill reducer.
1-ratchet, 2-large gear.
Photo-12.Typical damage in the gear housing.
Photo-13. Replacing the drill chuck.
Replacing the power cord Check the power cord for faults as follows:
2. Using a single-line indicator (probe).
A probe or a single-strip indicator will show you the presence of voltage on only one wire of the power cord. If a break exists on the neutral wire, then what can be done? But everything is very simple, the plug must be rearranged in the outlet and then the neutral wire will turn into a power cord. Or use A more advanced measuring instrument such as a tester. Most often, a visual inspection of the appearance of the power cord gives positive results. If any faults are found, it is best to replace the power cord with a new one. In this way, accidental electric shock can be prevented.
VIDEO
How annoying it is when a drill, the faithful and irreplaceable assistant of any home craftsman, suddenly fails. We have prepared a small reference manual in which we described typical malfunctions of electric drills and how to fix them yourself.
During disassembly and maintenance of the drill, you may encounter the fact that some parts are worn out and need to be replaced. This is a common practice, however, you should not try to replace third-party components or, even worse, look for complex workarounds. A typical and gross mistake is when a conventional toggle switch is attached to the outside of the handle instead of a broken standard button. This "tuning" is unsafe and should be avoided.
Moreover, today the market for spare parts for power tools is available and extensive. If you bought a tool in a large chain store, then, most likely, you will also find everything you need for repairs there: from buttons and brushes to motor rotors and gearbox parts.
All you need is to determine the manufacturer of the drill and the exact name of the model, this information is mandatory on the nameplate. The problem is that different modifications of the same model can have both compatible components and absolutely unsuitable ones. Focus on the appearance, do not be lazy to clarify the main dimensions and dimensions of the replacement part.
With the components of the drive mechanism, everything is somewhat simpler due to the high degree of unification: the bearings are marked on the protective rings of the separators, and nomenclature codes are stamped on the gears. Practice shows that you can pick up spare parts for all popular models of the tool, including representatives of the foreign series of the professional tool. In the category of exceptions, only drills over 30 years old, but even for them it is quite possible to find a donor.
We will begin the description of common failures with the electrical and switching parts. The electrical compartment of almost every drill is located in the handle, where the button is located. To get access to it, most often you have to disassemble the drill completely. It is not difficult, but it may be difficult to snap off the case: in addition to a few screws, it is held on to the latches. Having halved the case, remember the location of the elements and wiring, or better - take a picture, because the layout can be very intricate.
The main symptom of an electrician's malfunction is that the drill simply does not turn on. Try to move the power cord with the button pressed in the place where it comes out of the case: a core fracture in this place is the cause of 90% of all malfunctions, if it occurs, the drill will give signs of life. You can also determine if the power supply is broken by dialing.
Another common cause of breakdown is failure of a button or reverse switch. Try to ring the contacts to which the wires are connected, for the presence of commutation. The defective button can be replaced, you can try to repair it. By unscrewing a couple of small bolts that hold the body together, you will gain access to the insides. Evaluate the condition of the lamellas (they can be worn out or oxidized), check the ejection mechanism for proper operation, the cleanliness of the printed circuit board and the presence of burns on the main contacts.
Malfunctions of a small printed circuit board or a potentiometer inside the button, which act as a speed regulator, cannot be treated on their own. The drill in such cases either does not turn on at all, with a fully operational contact group, or works at a constant speed. The button will have to be changed.
Do not forget to also check the reliability of the crimping of the terminals, the integrity of the insulation, the presence of oxides on the contacts. The electrical circuit of the drill is extremely simple, the main thing is to remember the order of connecting the wires.
A less common class of problems is extraneous noise when working with a drill. It can be both a crackling and a mournful hum. It is not worth operating the drill in this state, the engine malfunction is evident.
The electric motor in the drill is a single-phase collector; in order to remove it from the case, it will also need to be disassembled into two symmetrical parts. For a more powerful class of instrument, the central part of the body is made in one piece, like on angle grinders. To get it, you will have to unscrew the front gear unit and completely remove the handle.
If, when turning on the drill, an electric arc is clearly visible through the rear ventilation grill and the motor is humming, the problem is worn out or burnt out brushes. In different models, access to their replacement can be provided both without disassembling the case at all, and exclusively from the inside. When choosing replacement brushes, pay attention to both the dimensions and the cross-sectional profile. Sometimes it makes sense to temporarily put the brushes remaining after the previous replacement, but not completely worn out. When installing them, keep in mind that for brushes from different sides there may be a difference in the angle and density of lapping, do not confuse.
The motor armature has a collector with thin lamellas through which current is transmitted to the windings. In this place, dirt, traces of carbon deposits or strong oxidation are unacceptable. Wipe the manifold with a clean rag soaked in solvent, and rub it several times with fine emery paper if necessary. If the wires of the windings are unsoldered from overheating, the connection can be restored with POS-40 solder.
Of course, engine malfunctions can lead to complete failure of the tool, for example, if the windings are broken or short-circuited. The drill in such cases either does not turn on at all, or “hums” while standing still. It is possible to determine whether damage has occurred in the stator or rotor by following the traces of the melted blackened varnish, or by performing a continuity test. Both the stator and the impeller armature are available as replacement parts.
At almost every disassembly of the drill, it makes sense to look into the gearbox to assess the condition and degree of wear of the transmission parts. For most household tools, the gearbox is extremely simple and consists of two flat gears made of hard plastic or metal. Try to crank the gears, locking the engine spindle, evaluate the backlash and the probability of overshoot at different points of the transmission.
The professional tool can optionally have both a gearbox with a shifting gear and an adjustable overload clutch. Malfunctions of both elements are completely visual, they simply cease to perform their functions. Unfortunately, these parts are practically not repairable, and therefore the possibility of modular replacement is provided.
You will need a circlip remover to replace the gears. Do not lose the key when removing the gear, replacement will be difficult to find. When the gearbox is disassembled, it is recommended to completely remove the armature in order to check the smoothness of the movement and the presence of play in the bearings. An awl can be used to remove the protective covers of the separator to visually make sure that it is intact. Replacing bearings is carried out by cold pressing; it is better to use a copper tube or a wooden block with a longitudinal hole as a mandrel.
After completing work with the gearbox, remove the remaining grease and fill the transmission chamber with new molybdenum paste to about 2/3 of its volume. Make sure that no foreign objects get inside the drill during the repair process and reassemble in the reverse order.
Finally, the most trivial problem: the drill turns in the chuck, the clamping rate has become very low. And not everyone has an idea of how to remove a cartridge for replacement.
Let's start with the most complex examples: in drills with a power of over 600-800 W, the chuck can have a wedge-cone fit. The spindle is made with a bushing, into which the shank of the collet chuck is inserted. To remove it, you need to find a hole on the side of the sleeve, insert a powerful screwdriver into it and pry the end of the shank, pushing it out. If there is no hole, the sleeve is clamped in a vice, and light blows are applied to the chuck with a hammer through a wooden block. In this case, the blows alternate at diametrically opposite points from four sides.
Video (click to play).
In low-power drills, the spindle has an external right-hand thread at the end, onto which the chuck is screwed, and a hole in the center with a left-hand thread, into which the shunt bolt is screwed. This bolt has a head for a square or Phillips screwdriver and must be removed. Then, blocking the engine impeller with a nail, try to rip the cartridge counterclockwise with a sharp but moderate force. If the thread boils, the drill will have to be disassembled to clamp the spindle together with the driven gear in a vice.
