How to assemble a PIT electric screwdriver correctly. Tool chuck

The correct use of an electric screwdriver

The electric screwdriver has successfully replaced not only different kinds of screwdrivers, but also wrenches and hex keys. This tool is also used instead of a drill. For construction workers and furniture makers, the electric screwdriver has become an indispensable aid. For it and in the home environment is constantly in use. There is a wide variety of models on the market. Despite the prevalence of screwdrivers in various areas of activity, not all users, especially beginners, know how to operate it. Proper use, maintenance, and storage of the power tool will extend the tool’s life as much as possible.

Screwdrivers are divided into two varieties according to the power supply method:

Recently, tools with a combined power supply have also appeared. They combine all the advantages of both types.

External and internal design of cordless and cordless models are essentially the same. In general, a power tool consists of the following design elements:

• housing;
• chuck;
• the power button;
• a switch for the direction of motor rotation (reverse);
• speed regulator (number of revolutions);
• A power-on lock button;
• Tightening torque regulator (torque switch).

The photo below shows the design of a cordless type electric screwdriver.

A number of models are additionally equipped with a backlight, which is structurally implemented in different ways. Not every product has a speed regulator and power button. Electric wrenches have a power cord, and cordless instead of it the accumulator of charge is installed.

The body of the power tool is most often made of plastic, much more rarely. of different metal alloys. For convenience, it usually consists of 2 halves. Inside the body there are such main parts:

The electric connection diagram depends on the model.

The electric screwdriver can be equipped with different types of chucks. The most common is the three-jaw quick-action version of this part. The chuck also consists of individual parts, which are shown in the photo below.

It should be taken into account that if the purpose of an electric screwdriver is highly specialized, it may introduce some design changes.

the principle of operation of both mains and cordless screwdrivers is the same. It consists of electrical power that drives an electric motor. Force and speed are transferred from the motor to the bit in the chuck through a gearbox and a shaft. It is already drilling a hole or screwing or unscrewing a fixture. The peculiarity of the process is that the electric motor of cordless models operates on AC 220 V, and cordless. on DC, whose value can range from 3.5 V to 36 V.

Faults that occur with an electric screwdriver

The most common malfunctions the user may encounter:

• The machine (e.g. Zubr) is not switched on. Causes: cable or plug, charge level, motor winding burnout, faulty start button.
• Sparks when operating. Causes: motor manifold or armature, defective brushes.
• The battery runs out quickly. Causes: expiry of service life, incorrect charging.
• The machine switches on by itself. Cause: Faulty start button.
• Brake does not work. Reasons: pushbutton or transistors.
• There is a gap in the chuck. Cause: bent gearshaft.
• Can’t hear the ratchet. Reasons: locking paddles are worn out, springs or ratchet pin is broken.
• The chuck is spinning. Cause: Gearbox is defective, pinion has to be replaced.
• Chuck jamming. Cause: the jaws are worn and have not been lubricated sufficiently.

The difficulty described above can only be repaired after disassembling the machine. Exception: Replacing the plug or wire. The presented information is usually enough to understand how to repair an electric screwdriver. If you don’t have the appropriate knowledge, you should call a service center or an expert.

For your information! Even the most well-known European manufacturers can’t guarantee trouble-free operation all the time. Any electric screwdriver can jam, and then it should be repaired.

Advantages and disadvantages of converting

Converting an electric screwdriver into a mains model has several advantages. Among the main advantages are the following:

• You will not need to periodically recharge the device;
• The power of the tool will not deteriorate because of a weak battery;
• you will not need to change batteries.

However, there are also disadvantages to such a conversion. The main disadvantage is that such a tool is more difficult to use in hard-to-reach places. You will have to buy a special extension cord.

Features of drilling with a screwdriver of different materials

How to properly use an electric screwdriver for different materials? If you plan to use the tool for different types of surfaces, it is worth choosing a device with the maximum number of modes. For home use, this is usually not required.

It is recommended to drill in soft materials at low RPM in order not to damage the surface. When working with metal, it is important to bore holes. This helps to avoid slipping of the drill bit.

Electric circuit

The tool is switched on by pressing the electric screwdriver button on the handle. This pushbutton is combined with a voltage regulator. at different pressures different voltages are applied to the motor, which is ensured by a pulse width modulator.

There is also a directional lever in the button setting area. This switch makes it possible to reverse the polarity of the signal applied, thus enabling reverse rotation. The motor is started via a sufficiently strong transistor, the opening process of which is controlled by a PWM generator.

The electrical signal is fed directly to the motor rotor through the collector. Graphite brushes of a certain size are used to ensure electrical contact.

Electrical Faults in an Electric Screwdriver

Having considered the basic elements of an electric screwdriver, let us proceed to the possible malfunctions and possible repair methods for an electric AEG screwdriver. And we will start with the electrical part. The main signs of malfunction of the electric component of an electric screwdriver are:

The tool does not turn on. The first thing you should pay attention to when repairing your Skil electric screwdriver is the battery. If you put it on the charger, and it did not help, then we arm ourselves with a multimeter and start troubleshooting. First of all we measure the voltage on the battery, it should more or less correspond to what is written on the battery. In the case of undervoltage, it is necessary to identify the faulty element: the battery or the charger.

It is possible to determine the serviceability of the charger with a multimeter, for this purpose we plug it into the network and measure the no-load voltage on the terminals. It should be a couple of volts more than the nominal voltage printed on the unit. If there is no voltage. the charging unit is defective. For such a repair electric screwdriver Interskol, you need a knowledge of electronics, otherwise it is easier to buy a new.

If the problem with the battery, then to repair the electric screwdriver Makita with your own hands, you need to open the unit with the elements. After you disassemble the block you need to carefully examine all the places where the wires are connected and check the quality of soldering. If all connections are intact, take a multimeter and measure the voltage at each element. Each element must have a voltage of at least 0.9V to 1V. If you find a cell with a lower voltage. you need to replace it. The main thing is that the capacity and type of cell should match the others (i.e.е. If NiCd, you need also NiCd). You can learn more about battery repair from the article: “Repairing the battery of an electric screwdriver with your own hands”.

If the battery and the charger are working, but the electric screwdriver will not turn on, you need to disassemble the electric screwdriver. There are two wires going from the battery terminals to the push button, take multimeter and measure voltage at button input (battery is inserted). If there is voltage at the input, then remove the battery and use the alligator clips to short-circuit the wires from the battery. Set the device to measure the resistance in ohm. Press the button as far as it will go and measure the voltage at the output of the button. The device should show the resistance value tending to zero, if it is so. the button is serviceable, the problem is either in the brushes or in other elements of the electric motor. If the tester shows a breakage, it is necessary to replace or repair the button. You can try to repair it yourself, since it often happens that the contact on the terminals is missing due to burning, it will be enough to clean with sandpaper and assemble. The main thing is not to hurry and act carefully while disassembling the button, otherwise all the parts will fly apart and you will have to break your head for hours. how to assemble.

Similar actions should be taken in the absence of reverse. Place one probe of the device on button input wire, the second, on electric motor contact or button output, as it is more convenient. Switching of reversing handle. If everything is OK, the device will register some resistance value, if it is “silent. The reversing contacts have a faulty conductivity. The order of disassembly and cleaning of contacts is similar to the above described, as well as when repairing an electric Kalibr screwdriver.

The motor works at the maximum rpm, and there is no rpm adjustment? The reason of the failure can be either in the button itself or in a regulating transistor.

If all circuits up to the electric motor are good, but the tool does not work. the defect may be connected to the brushes. Ideally, the brushes should be changed when their length, wiped out by 40% of their original length. If the brushes are worn out. replace them with new ones, if the brushes are okay. the problem is with the rest of the electric motor. To check the motor you need to disconnect the wires that come from the button. After you have disconnected wires, using multimeter measure the value of resistance on the contacts of wire fastening. If the value of resistance is small and tends to zero, most likely, there was a breakage of the winding, either rewinding or a new motor is needed.

You can check the integrity of the armature windings, because the armature can be bought and replaced by yourself. To check the armature, measure the resistance at two adjacent collector plates, all the way around. The normal value is “0”. If during the inspection you find two plates next to each other, with a value different from zero. the anchor requires repair or replacement.

Assembly of the power supply for an electric screwdriver in a battery case

It is convenient to convert the electric screwdriver into a network screwdriver, using the case of its battery. In this case the internal stuffing is used:

Conversion of the Chinese unit to 24 V

PSU Chinese-made output voltage 24 V (maximum current of 9 A) is not difficult to buy in places of sale of radio components. Most screwdrivers are designed to work with 12 or 18 V. For this reason it is necessary to lower the output voltage of the Chinese product to the right value. Make it easy, even with a superficial knowledge of radio and electrical engineering.

Modernization of the power supply is carried out as follows:

• Solder out with the soldering iron permanent resistor R10 resistance 2320 Ohm, which is responsible for the output voltage;
• In its place solder adjustable resistor with a maximum resistance of 10 kOhm, setting this parameter to the value of 2300 ohms in advance, so that the built-in protection is not triggered when turning on the made device into the network;
• supply power to the converted unit;
• Turn the trimmer regulator to set the desired output voltage, checking its value with a multimeter.

To connect a multimeter, simply use its probes to touch the appropriate pins on the output of the remodeled product. In doing so, the switch of the measuring device must be set to the DC voltage range. If the power tool to be upgraded is designed to work on 12 V, then you must ensure that the current at this voltage does not exceed the maximum value of 9 A. Otherwise, the created device will quickly fail due to overloading.

Homemade plug-in power supplies

To energize the electric screwdriver from the mains, you can also assemble a home-made power supply (IP). You need a 60 W electronic transformer, such as a Taschibra or Feron. It is not necessary to remake them. The final circuit of the power supply to assemble is presented in the photo below. All parts with their markings and main parameters are clearly visible on it.

The T1 transformer will need to be made by yourself. To do this, proceed as follows:

• buy a ferrite ring (NM2000), which has dimensions of 28169 mm;
• Use a file to file away the corners;
• wrap the ring with insulating tape.

All parts of the circuit are fastened to the aluminum plate (3mm or thicker), which will also serve as a conductor. Then install the assembled power supply into the battery case.

Visual control of the device will be carried out by the LED lamp H1.

You can take ready-made parts also from energy-saving lamps and from other devices. But then the circuit will be different, such as in the photo below. To solder them requires some knowledge of radio engineering.

The above schematic corresponds to a power supply with a ballast lamp, the photo of which in the assembly is shown below. In this case, the bulb performs the function of backlighting in addition.

Using prefabricated units in modifications

Inside the old battery case you can put any PSU, designed for 220 V, as long as it has the right size and the desired output voltage. Power supplies with the right characteristics can be bought at flea markets or in amateur radio stores. To install a purchased power supply for an electric screwdriver instead of the battery, proceed as follows.

• Disassemble the purchased product beforehand.
• Adapt it as needed, upgrading it to suit your needs. If necessary, the connecting wires are lengthened, the transformer and microcircuit are placed separately. For better cooling of the board, it is equipped with a radiator.
• After that, the parts are mounted in the case from the battery pack, which also make holes through which the air will be dissipated when circulating heat.

All built-in parts inside the housing must be securely fastened.

Particular attention should be paid to the insulation of current-conducting parts between each other. this will prevent short circuits.

The degree of modernization of purchased power supply depends on the compliance of its original parameters with the required values for the power tool. In order not to make a mistake with the size of the purchased power supply they take the battery case with them and try on the selected product according to it.

Diagnosis and troubleshooting of the electric part of an electric screwdriver

If you have a rechargeable device, the first thing to do is to check the batteries in the battery pack by taking it apart. There are collapsible and non-collapsible blocks. In the second case, it is necessary to carefully insert a screwdriver into the bonding place of the walls of the unit and, slowly, separate them.

Next, you need to measure the voltage at all the “banks”. The voltage rating is printed on each battery pack. The voltage should be a little lower than indicated, but the same on good batteries. Faulty batteries greatly differ from the rest in voltage and must be replaced. New batteries can be purchased online.

It is important to solder them correctly, that is, in series: the plus of one battery is connected to the minus of the other, and the plus of the second battery to the minus of the next, etc.д.

If you own a corded electric screwdriver, then the testing algorithm is a little different. First, you need to unscrew the housing of the device and remove one half of it. Get a tester and “test” the power cord for a breakage. If the cord is intact, check the start button. Check when the button is pushed to see if there is a circuit on its output pins. If the button is defective, it must be replaced or repaired. How to do this will be discussed below. If the button is working, the problem may lie in the electric brushes or motor.

Button repair

Below is a schematic diagram of a cordless electric screwdriver.

From the diagram, you can see that the button has 2 wires to the battery and 2 wires to the engine. Also connect 3 wires from a transistor to the button, which is responsible for speed regulation. To understand the electric screwdriver button, you have to take it apart. All wires to this part can be unsoldered. They will not interfere with the disassembly.

Remove the push button mechanism (red) from its seat. Do this with careful rotary motions, while pulling the part to the opposite side of the button, taking care not to break the screw.

Next, remove the button cover. Using a knife and screwdriver you will lift and push out the latches in the places indicated with arrows in the figure, and then remove the cover.

Once you take off the cover, you will see the reverse compartment. But the button mechanism will still be inaccessible. Using the soldering iron, disconnect the 2 elements (arrow in the following illustration).

Carefully take out the element number 1, then remove the cover that covers the mechanism compartment of the machine.

Hold the return spring and remove the mechanism from the body.

In a faulty button you will see worn contact pads.

Contact pads wear out quickly due to poor metal quality. Fine metal dust from worn-out pins is building up between the pins and shorting out the pads. This results in the machine starting up by itself.

Remove the metal dust using absorbent cotton and rubbing alcohol into it. If this does not succeed, it can be scraped off with a knife. After these operations the spontaneous start-up of the appliance will be discontinued.

If the speed regulator does not work, it means that the transistor is burned out and must be replaced.

Replace the brushes

To check the condition of the brushes it is necessary to disassemble the motor by bending back the “tendrils” located on the end of the housing.

Then, with a light hammer blows on the motor shaft, knock the rotor out of the housing.

This will first remove the cover, which houses the electric brushes.

In the next photo you can see that the manifold is black. That means it is contaminated with dust from the brushes. As a result of contamination of the collector, as well as the grooves between the plates, the engine power and sparks brushes. You need to wipe the manifold with absorbent cotton soaked in alcohol and clean the grooves with a needle.

The following photo shows what a clean manifold looks like.

If the brushes are worn out you will need to replace them. It is difficult to find original brushes for some screwdriver models. But you can find brushes that are the right size, and then on a sharpening machine to trim them and connect (solder) to the brush holders.

Unnecessary repair

Not all units and parts need to be repaired, in some cases it is better to replace them with other elements.