One of the most popular gadgets of home craftsmen is a screwdriver. However, this device sometimes breaks, like any other. If this happens, in some cases you can replace this tool with an electric drill. If the work with an electric drill can not be performed, you will need to take the screwdriver to the service center for the specialists to repair the tool. However, this can take a lot of time and money. Therefore, you can use another option - to repair the screwdriver with your own hands.
Screwdrivers are commonly used to assemble furniture both at home and at work.
Before you make repairs, you will need to familiarize yourself with the design of this device. In fig. 1 you can see this tool in disassembled form.
Elements that are needed in order to make a screwdriver:
- spare items.
The design of an ordinary screwdriver
Figure 1. The device screwdriver.
The main element is the start button, which performs several functions: turning on the power supply circuit of the electric motor and speed controller. If you press the button to the end, the motor supply chain will close with the contacts, as a result of which the maximum power will be provided. The number of revolutions in this case will also be the maximum possible. An electronic regulator is installed in the device, which consists of a PWM generator. This element is located on the board. The contact that is placed on the button will move along the board depending on the pressure on the button. From the placement of the element will depend on the level of the adjustable pulse to the key. The key is a field effect transistor. The principle of operation will be as follows: the stronger the master presses the button, the greater the pulse value on the transistor will be and the more it will open and increase the voltage on the electric motor.
Reverse rotation of the electric motor will be carried out by changing the polarity at the terminals. This process is carried out with the help of contacts that will be transferred by the master using a reverse handle.
Charger device for a cordless screwdriver.
In screwdrivers in most cases, single-phase collector electric motors of continuous current are installed. They are reliable, they are easy to manufacture and maintain. An ordinary screwdriver consists of the following elements:
The gearbox design will convert the high revolutions of the shaft of the electric motor into the low revolutions of the cartridge shaft. In screwdrivers can be planetary or classic gearboxes. The latter are rarely used. Planetary devices consist of the following elements:
- ring gear;
- sun gear;
The sun gear works at the expense of the armature shaft, its teeth drive the satellites that rotate the carrier.
A special regulator is used to regulate the forces that will be fed to the screw. Most often used 15 positions adjustment.Back to table of contents
Do-it-yourself screwdriver repair: electrical problems
The main signs of failure in this case will be:
- the screwdriver does not turn on;
- It is impossible to switch the reverse mode;
- It is impossible to adjust the number of turns.
Diagram of the device reducer cordless screwdriver.
The first step is to check the battery of the screwdriver. If the instrument was put on charge, but it did not help, then you need to prepare a multimeter and try to find a fault with it. First you need to measure the voltage on the battery. This value should approximately correspond to that indicated on the body. If there is a low voltage, then it will be necessary to identify the faulty element: a battery or a device for charging. For this you need to use a multimeter. This device must be included in the network, and then measure the voltage at idle at the terminals. It must be several B larger than that indicated on the structure. If there is no voltage, then you will need to repair the charging unit. If there is no knowledge in the field of electronics, it is recommended to purchase a new one.
If the battery is faulty, you will need to disassemble the unit, inspect all the places where the wires are held together and check their quality. If there are no damaged connections, you need to measure the voltage on all elements with a multimeter. The voltage must be 0.9-1 V or more. If there is a part with a lower voltage, then you need to replace it. Capacity and type of element must necessarily match the installed parts.
Scheme of the internal device screwdriver.
If the charger and the rechargeable battery are intact, but the screwdriver does not work, then this device should be disassembled. From the battery terminals is a few wires, you need to take a multimeter and measure the voltage at the input of the button. If the voltage is present, then you need to remove the battery, using clips to short the wires from the battery. The device should show the value of resistance, which tends to zero. In this case, the element is intact, the problem lies in the brushes or other details. If the resistance is different, then the button will need to be replaced. To repair the buttons, in some cases it is enough to clean the contacts on the terminals with an emery paper.
In the same way, you will need to check the reverse element. Repair is done by cleaning the contacts.
If the motor is running at high speeds, and the speed is not adjusted, the problem may be in the button or the transistor, which is used for adjustment.
The device gears gearbox screwdriver.
If the chains to the engine are intact, but the screwdriver does not work, then the problem is in the brushes. If these items are worn out, you will need to replace them.
The problem may be directly in the engine. To check the electric motor, you will need to disconnect the wires that are connected to the button. Next, using the same tool, you need to measure the resistance value on the pin fixing wires. If the value tends to zero, then the winding is broken. In this case, you will need to rewind or install a new motor.Back to table of contents
How to make a screwdriver: mechanical failure
It will be necessary to check the condition of the armature windings, since it is possible to purchase and change this element yourself. To check the anchor, it will be necessary to measure the resistance on the adjacent collector plates, along the entire perimeter. The value should tend to zero. If in the process of checking the plates with resistance different from zero are found, then the anchor will need to be repaired or replaced.
Mechanical problems can be defined as follows:
- In the process, the screwdriver makes strange sounds, which were not there before.
- The tool vibrates strongly during operation.
- Fight cartridge for clamping.
- The tool turns on, but cannot be used due to jamming.
If in the process of work the device emits extraneous sounds, it means that the bushings or the bearing have worn out. To eliminate this, you need to disassemble the electric motor, and then check the integrity of the bearing and the wear level of the sleeve. The anchor should roll freely, there should be no friction or skewing. These devices can be bought in the building supermarket and replace yourself.
The most frequent breakdowns of the gearbox design include the following:
- shaft malfunction;
- abrasion of the working gear base;
- break of a pin on which the satellite is fixed.
In all cases, you will need to replace defective gearbox components. All the above steps must be done carefully. Disassembly of the screwdriver must be done in a clear sequence, otherwise any of the parts may be lost.
Perform repair screwdriver can anyone, you only need to correctly identify the faulty item.