- How to select replacement parts
- Electrical faults
- Engine problems
- Gearbox maintenance and repair
- Replacing the drill chuck
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..
How to select replacement parts
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.
Internal structure of the drill: 1 – network cable; 2 – noise suppression capacitor; 3 – start button; 4 – stator of the electric motor; 5 – engine bearing; 6 – brush holders with brushes; 7 – rotor collector; 8 – drill body; 9 – impeller cooling the electric motor; 10 – button for switching between normal and shock modes; 11 – gearbox housing; 12 – reducer; 13 – cartridge bearings; 14 – returnable spring; 15 – chuck holding the drill
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 there you will find everything you need for repairs: from buttons and brushes to motor rotors and gear 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 part to be replaced.
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 breakdowns with the electrical and switching parts. The electrical compartment of almost every drill is located in the handle, where the button is located. To access 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 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 electrical 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 the power cut by dialing.
Another common cause of breakdown is failure of a button or reverse switch. Try ringing the contacts to which the wires are connected for commutation. The faulty button can be replaced, you can try to repair it. By unscrewing a couple of small screws that hold the body together, you will gain access to the insides. Evaluate the condition of the lamellas (they can wear off or oxidize), check the ejection mechanism, 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 functional 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 tool, 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, please note 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. No dirt, carbon deposits or strong oxidation are allowed in this area. Wipe the manifold with a clean rag soaked in solvent, and rub it several times with fine sandpaper 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 also 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.
Gearbox maintenance and repair
With almost every drill disassembly, it makes sense to look into the gearbox to assess the condition and 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, blocking the motor spindle, estimate the backlash and the probability of overshoot at different points of transmission.
The professional tool can optionally have both a gearbox with a changeable transmission 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 their 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 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. Bearing replacement 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..
Replacing the drill chuck
Finally, the most trivial problem: the drill turns in the chuck, the clamping rate becomes 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 sleeve, 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.
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, where 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 off 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.