How to Remove the Gear from the Shaft of a Screwdriver Motor
The screwdriver can be repaired independently, having studied its structure and principles of operation of individual units.
Device and screwdriver malfunctions
All screwdrivers are arranged approximately the same. They consist of the following functional units:
- start button;
- pulse width regulator;
- electric motor;
- planetary reductor.
All components of the device are in a strong and aesthetic case, which has a rubberized handle, control and adjustment buttons, as well as a slot for installing the battery (if the screwdriver is designed only for 220 V operation, it does not have a battery).
When you press the start button, the screwdriver may not be squeaking. This is a normal occurrence of DC motors at startup and at low speeds.
Why and how to adjust the ratchet
A ratchet screwdriver is a clutch designed to limit the force during rotation of the chuck. Its presence in the power tool can be determined by a rotating ring with numbers. Some users do not understand the meaning of the coupling and do not touch it. Using a ratchet, you can adjust the screwing depth of the screw. In too soft material, the fastener cap is easily recessed and can pass through. When using small fasteners, very high torque can destroy it. A ratchet prevents the cutting of a slot from self-tapping screws and the wear of a screwdriver bit. To determine the desired value on the control ring, make several passes, starting with the minimum.
If the screwdriver has a drilling mode, then the last icon on the coupling will be the icon with the image of the drill. In this position, maximum torque is used.
Frequent screwdriver malfunctions
Since all modern screwdrivers have a standard device layout, their malfunctions, as a rule, are also typical. The main defects of this tool include:
- battery malfunction;
- brush wear;
- button breakage;
- runout of a cartridge;
- lack of response to attempts to turn on or off;
- interruption work.
You can fix all these failures yourself if you have experience working with measuring and soldering devices. In some cases, you will have to change the components completely, since not all parts are sold separately. If repairing the gearbox or motor is too complicated for you, these elements can be completely replaced or taken to the workshop.
DIY screwdriver repair
To eliminate most of the malfunctions of a screwdriver, it needs to be disassembled, that is, removing the case and disconnecting the main components from each other.
How to disassemble a screwdriver
The screwdriver is disassembled in the following sequence:
- Remove the battery.
- Remove the screws connecting the two halves of the housing.
The case of the screwdriver consists of two parts connected by a fairly large number of screws. in order to disassemble it, you need to find all the attachment points
The screwdriver button is integral with the switching mechanism, which is connected to the engine, so when separating the button from the socket on the case, you must be careful not to break the wires
In order to disconnect the gear of the screwdriver from its engine, it is necessary to unscrew the four screws located at the contact point of the two plastic casings
Video: how to disassemble a screwdriver
The chucks in different models of screwdrivers may differ slightly from each other. They can be attached to the shaft in three ways:
- Morse cone.
- Threaded connection.
- Threaded connection with fixing screw.
To determine the method of attaching the cartridge, you need to read the inscription on its sleeve:
- the marking “1–6 B10” means a Morse cone. Used nozzles with a shank diameter of 1 to 6 millimeters. The coding "B10" indicates the size of the cone. Take a hammer and knock out a cartridge by striking the body;
- inscriptions like “1,0–11 M12x1,2” or “2–13 mm ½-20 UNF” mean metric and inch threads.
If the cartridge is threaded, you must perform the following steps:
- Release the cams of the cartridge.
- If there is a screw inside, unscrew it clockwise (the screw has a left-hand thread).
- Take a 10mm hexagon wrench.
- Insert the short edge into the cartridge and tightly clamp in the fists.
- At low speeds, start and immediately turn off the screwdriver so that the long edge of the hexagon hits the table. Instead of turning on the device, you can simply hit the key with a hammer. The thread moves and the cartridge is unscrewed.
In order to remove the cartridge, you need to hold the hex key in it and start the engine at low speeds until the key hits the table
Video: how to remove a threaded chuck using a hex wrench
If these methods do not help, disassemble the screwdriver and remove the gearbox assembly. Take the L-shaped tubular wrench (most often 19 ”) and unscrew the chuck, holding the gearbox securing bolts on the back with the cap wrench. She will give the necessary emphasis, with which you can unscrew the cartridge by hand.
Video: how to remove a cartridge with a pipe wrench
To disassemble the cartridge, you need to remove the cap at its base. The plastic plug is gently poked with a knife. Metal. knocked out by hammer blows on the base of the cartridge:
- Take a large bolt, insert it into the cartridge and slightly tighten for alignment. The bolt head should protrude above the cartridge for two to three centimeters.
- Hammer the bolt head. The cartridge will pop out of the case.
Video: removing a plastic plug from a screwdriver chuck
Common cartridge malfunctions:
- crookedly pinches bits;
- play between bits and cams;
- cams jerk out.
To find out the reasons and eliminate them, follow these steps:
- Disassemble the cartridge.
- Remove the flare nut, which consists of two parts.
- Unscrew the clamping jaws.
- Check the condition of the threads on the nut and on the cams, replace the defective parts.
In the process of working on cams or a flare nut that controls their work, a thread may develop or crumble, then these parts must be replaced
Video: analysis and repair of a cartridge with a metal plug
Three types of batteries are used in screwdrivers:
- Nickel Cadmium (Ni-Cd). They can be charged many times, but they have a memory effect. If you do not wait for the full discharge and begin to charge the battery, then its capacity will gradually decrease. Swing the battery before first use. Discharge and recharge it three times to maximize capacity.
- Nickel Metal Hydride (Ni-MH). A feature of such batteries is a less pronounced memory effect, but a high self-discharge current. If you intend to store a screwdriver without use for more than a month, be sure to fully charge its battery.
- Lithium-ion (Li-Ion). These batteries charge quickly, but do not tolerate frost. They can be charged when convenient.
Видео: How to Remove the Gear from the Shaft of a Screwdriver Motor
Store all types of batteries separately from the screwdriver and charger. For long periods of non-use, they need to be recharged once a month.
If the battery does not hold a charge, disassemble it. It consists of several batteries. Check the voltage tester in each. The value of the operating voltage is indicated on the housing (it is the same for all elements). Replace broken batteries.
The battery of a screwdriver consists of several elements, which you can call and find and replace those that have failed
Video: eliminating fast battery drain
If the battery cannot be removed, the locking button is most likely stuck. It is necessary to remove the upper part of the case, disconnect the battery, disassemble it and adjust the button.
Frequent damage to the charger:
- the fuse is on;
- network cable breaks;
- the primary winding of the transformer breaks;
- diodes break through.
If we disassemble the charger of the screwdriver, then we will see a step-down transformer and a board. Through the mains voltage is supplied to the primary winding of the transformer. The thermal fuse is connected in series with the network winding, so it overheats first and prevents the winding from breaking. From the secondary winding, the voltage passes to the diode bridge. If charging transmits current, yellow is formed around the diodes. Transformer windings overheat, diodes break through.
The charger of the screwdriver consists of a step-down transformer and a board with electronics
- Measure the resistance on the primary winding with a multimeter. If it is not there, it means that the circuit is disconnected and the voltage does not reach the primary coil. The fuse is located beneath the transformer insulation next to the wires connecting to the network. Check it with a tester.
- If the fuse is intact, check the power cord; it may be broken.
- If the wire is OK, check the windings. In case of breakdown, replace the transformer.
Video: diagnostics and repair of the charger
A malfunction of the start button can lead to the following malfunctions of the screwdriver:
- self-propelled guns appear;
- the device does not turn on;
- the device is unstable.
From the button, two wires go to the battery terminals and two to the engine. If there is a transistor, then it is connected by three wires. Make sure the problem is in the button:
- Connect the battery. Press the button and tester measure the voltage at its output, it should be absent.
- Remove the battery and remove the upper motor wire from the button housing.
- Connect the motor directly to the battery. To do this, take two wires of the required length and connect them to the battery terminals. Connect the other ends of the wires to the motor housing and to the wire that was inserted into the button. If the engine is running, then the button is faulty.
Video: diagnostics and replacing a screwdriver button
Button repair sequence:
- The wires coming from the button do not need to be soldered. Carefully, so as not to damage the base, remove the push part of the button that does not fall into the interior of the case. This should not be done in a jerk, but slowly rotated and pulled towards yourself.
- Remove the protective cover. Take a knife and a flat screwdriver. Pry and release all latches. Pull out element number 1 and remove the cover of the inclusion compartment under number 2. If the contacts are slightly burnt, they must be cleaned. But if they burn out completely, then the button is best replaced. It is sold complete with wires. If the contacts are intact, then move on.
- Holding the spring, carefully remove the trigger mechanism. Look inside. Perhaps, due to the poor quality of the metal, the contact pads wiped off and dust formed, which settled inside the plastic box. Accordingly, dielectric surfaces began to conduct electric current. This is one of the reasons for spontaneous operation of the device. The second reason is a failed transistor. Remove metal dust with a cotton moistened with alcohol. Contacts can be scraped off with a knife, but not with sandpaper, so as not to spoil their surface. Now reassemble everything in reverse order. Replace the burnt transistor. Turn on the tool.
The cause of the malfunction of the button may be burnt contacts, metal dust or a burnt transistor
Inspection and repair of the force regulator
Behind the cartridge is an adjusting ring with a spring that controls the force and snaps the cartridge away from the gearbox. This spring presses on the balls, which abut against the protrusions of the ring gear of the gearbox. Disassemble the ratchet, check the integrity of all its elements. Remove dirt with a rag dampened with alcohol, grease balls.
Video: ratchet repair
Gearbox disassembly and repair
The main elements of the gearbox:
They are made of metal and plastic. An annular gear is a cylinder with internal teeth along the entire circumference. Satellites move along the teeth.
The first carrier has two gears at both ends. The first solar is the engine drive gear. She enters between the satellites of the first carrier. The second solar on the opposite side sets between the satellites of the second carrier. In a two-stage gearbox, the second carrier is connected to the shaft on which the cartridge is worn. The three-stage gearbox has another mechanism. All these parts are located inside the ring gear.
The engine transmits the rotation to the first stage satellites through the sun gear. The first carrier rotates the second stage of the satellites. If there is a third step, then the second carrier will rotate it. Satellites of all stages rotate inside the ring gear. The last carrier rotates the cartridge shaft. With each transmission of torque, the speed drops.
Gearbox disassembly sequence:
- Cartridge removal.
- The unwinding of the body.
- Disconnecting the gearbox from the motor.
- Plate removal.
- Removing all parts from the chassis.
When disassembling the gearbox, all parts are removed sequentially: first satellites of the first stage, and then the second
Arrange all the parts of the disassembled gear in order, so that later it is easier to assemble.
- If a rattle is heard during the operation of the screwdriver or it twitches, then the gearbox has defects. During operation, you have to make lateral pressing and heavily load the tool. Because of this, the gearbox shaft bends and a noticeable runout occurs. In this case, the assembly changes assembly.
- If the support sleeve and shaft bearing are worn, they can be replaced with similar ones.
- Breakage of the pin of the satellite is accompanied by the start and instant stop of the engine. Replace the carrier or gearbox.
- Wearing gear teeth also requires replacing the gearbox.
Often, gearbox repair is reduced only to cleaning and lubrication. Do not overdo it with grease, otherwise the device will work poorly.
Video: disassembling, assembling, cleaning and lubricating the gearbox
Graphite brushes are located at the end of the engine on the connection side with the button. They can be located inside the engine housing under the rear cover or outside. If at least one of the brushes is worn by 40%, change both. Check your contacts. The following signs indicate wear on the brushes:
- the engine runs jerkily;
- sounds unusual for normal operation are heard;
- the smell of burning.
When removing and installing the brushes, you need to hold the holders, otherwise, under the action of the spring, they can scatter quite far
Video: replacing engine brushes
The screwdriver uses a DC motor in a cylindrical case with magnets. Inside is an anchor with windings and brushes. To check the motor, disconnect the gearbox and the wires leading to the button, and measure the resistance of the armature winding with a multimeter. Lack of readings indicates a break, and a very low value indicates a short circuit. The collector resistance is measured on the shaft and each plate. It must be zero. Faults in the anchor lead to shutdown during operation, loss of power, sparking and smoke.
Video: testing the winding of the armature and collector plates with a multimeter
Often when the engine fails, the gear remains intact. Since in most engines it is pressed onto the shaft, its removal takes place with some difficulties. Buy a special puller or use the tools at hand. Do not try to do this with pliers or a nail puller. you will bend the shaft and spoil the gear teeth.
- Take a piece of profile or channel. Make a longitudinal groove angle grinder.
- Insert the shaft into the groove perpendicular to the profile and pry off the gear.
- Lay the profile on two hard surfaces so that the engine hangs between them.
- Take a nail and gently tap the edge of the shaft with a hammer. The gear will slip easily.
- Put the gear onto the new engine with a hammer and a hard surface.
Video: remove the gear from the engine shaft
The screwdriver is cracking but not twisting
If there is a crack in the screwdriver, first try changing the position of the speed controller. Perhaps he was not involved. If this procedure does not help, disassemble the tool.
- If the engine is spinning, disconnect the chuck. Check the rotation of the gearbox shaft and the condition of the motor gear.
- If the shaft does not rotate and the gear is intact, disassemble the gearbox. Check the condition of the teeth of the satellites and gears.
- If the engine does not work, check the brushes, windings and anchor.
Now you know how to disassemble, assemble and repair a do-it-yourself screwdriver.