Every craftsman has a screwdriver. It has become a household necessity, practically replacing screwdrivers. But ask a person about the structure of this hand tool, only a few will answer this question, the rest will simply shrug their shoulders. Therefore, let's look inside the screwdriver and try to figure out what mechanisms and devices are there, and what they serve.
Rotation adjustment clutch
In order to prevent the thread from breaking off part of the screw and breaking the tool itself due to overload, the design of the screwdriver is equipped with a rotation adjustment clutch. It consists of a stopper, a washer, a threaded bushing and a spring. The device is connected to the cartridge parts. When a force exceeding the nominal one occurs, the load is transmitted through the spring to the cylindrical rods of the cartridge, and they exert an impact on the sleeve. As a result, the ratchet is activated and the chuck stops.
Technical specifications
Each model is completely individual, so sometimes choosing the right option is quite difficult. But it’s much easier to decide if you pay attention to the technical parameters of the device.
Note! All data can be found in the instructions included with the product. Your sales consultant can provide more information.
Based on the principle of use, devices of this type are divided into 2 groups - household (for infrequent work around the house) and professional (needed when performing extensive construction and repair work). Screwdrivers of 2 groups differ in power, chuck size, power supply, additional functions, and price. Naturally, the technical parameters will be different:
- It is recommended to buy household screwdrivers, as they are popularly called amateur screwdrivers, when the tool will be used rarely and for a short time. Typically, the device is lightweight, often battery-powered, inexpensive, and copes well with basic tasks. The rotation speed is rarely more than 400-500 revolutions per minute. The torque is about 10-15 N*m.
- If you constantly need to tinker with something or a person does professional repairs, then you will have to use a more serious version of the device. It can be used almost every day and for several hours. Professional screwdrivers are more powerful and can withstand high and prolonged loads during operation. They won't replace a drill, but with the right bit they can handle drilling into hard surfaces. The rotation speed of the cartridge can reach 1300-1500 revolutions in 1 minute or more, and the torque is 130 N*m.
Example of technical arrangement
The remaining technical characteristics are determined by the device model.
Electric motor
In every mechanism, the main function is performed by the motor. The screwdriver is no exception. It is the DC motor that is used in the hand screwdriver. It converts DC electrical energy into mechanical energy.
The screwdriver motor is a hollow cylindrical object, inside of which there are magnets and a rotor mounted on special brass supports. It is a steel cylinder with longitudinal grooves around its circumference. A wire with a high magnetic permeability coefficient is laid in these grooves. The armature winding is a closed system of conductors. After an equal number of turns, the rotor winding goes to the collector, which is a cylindrical structure made of copper segments insulated with layered mineral.
The brushes of the screwdriver motor are made of carbon and graphite, which ensures sliding contact with the rotating commutator. The purpose of the brushes is to transmit electric current from the stator to the rotor. Voltage is supplied exclusively to the brushes, and the direction of rotation of the motor directly depends on its polarity.
To securely fix the brushes on the commutator, use a clamping device in the form of spring-loaded plates. This mechanism ensures that the structural elements clearly correspond to their place, but at the same time leaves freedom of movement vertically. It maximizes the life of the motor as a whole.
This knowledge will be needed when performing maintenance and repair of the screwdriver. As a rule, the weak point in the motor is the windings, so you need to monitor the operation of the tool, especially when using it at extreme loads.
Screwdriver rating
According to professionals and ordinary users, the following tool models are the best:
- Screwdriver Makita DDF343SHE
. The leader in the rating is a battery-powered device with high power, electronic speed control, and a reliable drill fastening system. The package includes 2 removable batteries. - DeWALT DCD771C2
. Cordless screwdriver with stepwise power adjustment, the ability to hold a battery charge for a long time. - Hyundai D350
. The model is a representative of a high-power network device. The tool additionally performs the function of a drill. - DeWALT DW263K
. A network model with high power, equipped with reverse and a function for smoothly adjusting the number of revolutions. - Impact driver DeWalt DCF825M2
. A cordless tool called a wrench. The motor type is a brushless screwdriver, which includes two batteries. - Bosch GSR 1440-LI 1
. Cordless tool designed for working with wood and metal surfaces. The battery holds a charge for a long time, the device responds quickly to commands.
Planetary reductor
The other main mechanism of a screwdriver is a planetary gearbox. A separate housing is always provided for its placement. The planetary mechanism of a screwdriver is a set of gears with a common axis of rotation, consisting of 4 elements:
- a small central gear with external teeth located on the central shaft. It is often called solar;
- a large central gear with internal teeth called an epicycle;
- three gears with external teeth that mesh simultaneously with the sun gear and the epicycle. These elements are called satellites;
- a lever mechanism in the form of a spatial fork, called the “carriage”.
All components on inexpensive models of screwdrivers can be made of plastic. This causes them to fail. On a professional tool, these elements are made of steel, which ensures uninterrupted operation of the screwdriver for many years.
Cartridge
When using the tool, various attachments for screws and drills are used. Their tip in the standard version is made in the form of a hexagon. To secure such attachments and to transmit rotation to them, there is a cartridge. This element is installed on the spindle. The chuck is secured with a special screw, which prevents it from loosening during rotation.
Screwdriver chuck diagram
The most common version of this unit is called three-jaw, self-centering and self-clamping. Inside the cartridge there is a recess with a hexagonal profile. The attachments are fastened by rotating the coupling, which allows them to be fixed between the cams. The coupling also contains a retainer. It can be used to clamp attachments, which prevents spindle rotation.
Related video: Screwdriver - a look from the inside
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Spindle speed adjustment
Another very important device of a screwdriver is the speed controller. The device circuit consists of a pulse-width controller and a switch based on a field-effect transistor. Control is carried out by a variable resistor. Depending on the force of pressure on the button, its resistance changes and, as a result, the spindle rotation speed increases or decreases. Thanks to the presence of changeover contacts, reverse rotation of the cartridge is carried out. It depends only on the direction of application of voltage to the screwdriver motor. All shifts are automated, so manual mode is excluded.
How to use a screwdriver?
When working with the tool, you need to observe some safety precautions, and before doing so, make the necessary settings:
- Install the required nozzle, selecting it according to the size of the fastener head.
- Select the optimal level of bit rotation speed using a special regulator.
- Adjust the screw depth of the fastener.
- If a corded screwdriver is used, it must be connected to the mains, and a battery must be connected to the cordless device.
- You cannot adjust the movement of the bit while the tool is running.
- Avoid getting moisture inside the device.
- Using a network device requires an uninterrupted supply of electricity, without voltage drops.
- Contact of the tool with grounded objects is prohibited.
- The screwdriver must be turned off periodically, allowing it to rest so that it does not burn out.
- It is recommended to wear protective clothing when working with the device.
How to charge a screwdriver?
Features and sequence of this process:
- A new battery will discharge during storage, so it must be charged three times before first use and then completely discharged.
- It is necessary to observe a certain temperature regime while charging the battery - 10-40°C.
- Charging time depends on the device model. It can be 0.5-7 hours. The exact period is indicated in the instructions for using the tool.
- It is recommended to discharge nickel-cadmium batteries before long-term storage, it is advisable to store nickel-metal hydride batteries in a charged state, and lithium-ion batteries can be charged at any time.
- If the screwdriver does not charge, the reasons most often lie in a malfunction of the charger, disconnection of the battery terminals or contacts. Check that these parts are not dirty or oxidized. The problem may also be in the battery itself, because its performance deteriorates over time.
Photo of DIY screwdriver repair
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Top 3 best models
The construction tools market offers a wide range of similar products. We have selected the 3 most successful models:
- Metabo BS 18 LTX. Screwdriver made in Germany. It has a quick-release chuck, powered by an 18 V battery. The maximum torque is 110 Nm, suitable for working with wood and metal. Additional options include spindle lock, built-in overload protection and speed adjustment. There is a hook for wearing on a belt. Sold in a case without battery and charger;
- DeWALT DCF887N-XJ. Compact brushless screwdriver from a famous American brand. It is painted in the manufacturer's traditional yellow-black color, which is convenient for searching in a cluttered object. Equipped with an internal hexagon chuck. There is a pulse mode and the possibility of shock operation. The brushless electric motor operates from an 18 V battery, the maximum speed is 3250 rpm. The minimum configuration does not include a case or an additional battery;
- Makita DTP141Z. Professional instrument with impact and pulse modes of operation. Maximum torque – 150 Nm. Suitable for working with wood, metal, and effectively unscrews rusted nuts. Equipped with a brushless electric motor and an 18 V battery. Battery and charger are not included. Chuck with hex mount. It is possible to turn on the backlight, the handle is rubberized and fits comfortably in the hand. Supplied in a box, tool weight – 1 kg.
When purchasing a tool for household or professional tasks, you should pay attention to the cartridge. The choice of nozzles according to the type of shank depends on this. As a rule, high-power impulse models are equipped with a hex chuck only.
Important ! The specific cost depends on the pricing policy of the store, as well as the configuration of the product. In large chain stores you can additionally purchase a storage case, a charger and a second battery.
