Comparison Xiaomi Mijia Electric Screwdriver 24 in 1 vs Xiaomi Mijia Electric Screwdriver

Design describes the overall layout of the tool.

Nowadays, among drills and screwdrivers, you can find models with a pistol, angle, straight, combined pistol-angle, as well as an adjustable design. Here is a more detailed description of each option:

— Pistol. In models with this layout, the handle is perpendicular or almost perpendicular to the body, so that the tool is held in the hands similar to a pistol — hence the name. In general, the pistol design combines convenience, safety, practicality and low cost. Due to this, this option is the most common nowadays, it is widely used in all types of drills and similar tools (see "Device"). In fact, this is a traditional design for such units; other types of layout are used mainly in models designed for special conditions and/or with specific characteristics (see below for more details).

— Corner. The general shape of such tools resembles the letter G: a straight body of relatively large length, which also acts as a handle, and a cartridge bent 90 ° relative to the body. This design option is especially convenient when working in cramped conditions: with the help of an angled tool, you can get into narrow gaps that are inaccessible to traditional pistol-mounted units. On the other hand, the angular layout degrades accuracy somewhat;...it is also poorly suited for jobs that require strong pressure along the axis of rotation of the chuck.

— Direct. Tools of this design have an oblong body, part of which plays the role of a handle; and the axis of rotation of the cartridge in them coincides with the longitudinal axis of the body. This option can be found in two types of tools. The first is small low-power tools (mainly screwdrivers, screwdrivers and wrenches, as well as single models of drills, also characterized by low power). In such cases, a straight body is provided primarily for compactness — a pistol grip would increase the dimensions beyond reasonable limits. The second type of direct units is, on the contrary, separate professional drills with a diamond drilling function (see "Purpose"). Such drills are not designed to be held in hands and are used only with a stand (see "Complete set"); for this format of use, the direct layout is also optimal.

— Pistol / angle. In fact, they are tools of the pistol layout described above, which are supplied with an angular cartridge that allows you to turn the working nozzle 90 ° relative to the standard position. Thus, such models combine the capabilities of both layouts, while retaining the main advantages of a pistol design — convenience and reliability in holding. On the other hand, additional equipment affects the cost, and such versatility is not often required. So this option is not very popular.

— Adjustable. This category includes all models in which you can change the location of the cartridge and/or handle relative to the body. The most popular version of this design is the rotary handle, which allows you to switch the tool from a pistol format to a straight one and vice versa. See above for more on these types of construction, but here we note that the pistol layout is more reliable in holding and versatile, and the straight one is better suited for some delicate work and hard-to-reach places. It is also worth mentioning that the possibilities for adjusting the handle can be different: in some models it has only two extreme positions, in others you can choose the angle of inclination relative to the body. The second, somewhat less common variety of adjustable tools is devices with a rotary chuck. Here we are already talking about switching between a straight and an angular layout — the latter, we recall, is very appropriate when working in cramped conditions. However, the cartridge in such units, usually, can be installed not only at 90 ° relative to the body, but also in several intermediate positions. This further expands the customization options for the specifics of the situation.
Anyway, all adjustable tools are more versatile than non-adjustable ones, but they are more complex in design and less reliable. Therefore, this type of arrangement is found exclusively in low-power units, mainly battery ones (see "Power supply").

Specific purpose of the tool.

This parameter is specified if the device has a specialization that significantly distinguishes it from the same type of general-purpose tools. It can be either a core specialization that defines all application options (an example is diamond drilling), or an additional functionality that expands general capabilities (an example is threading). Here is a more detailed description of today's most relevant appointments:

— For diamond drilling. Diamond drilling(mainly with crowns) is used for materials of high hardness, which are not able to cope with conventional nozzles. Accordingly, the main features of a tool that allows such use are high power and the ability to carry significant loads. In addition, many (though not all) drills with this specialization are equipped with a stand (see below), a threaded spindle rather than a chuck is usually used to mount bits (see "Chuck Type"), and additional features often include water cooling. .

— For drywall. Specialization, found mainly in screwdrivers (see "Device"). One of the mandatory features for a tool with this purpose is a depth gauge — it reduces the risk of damaging a rather delicate material, which is drywall. In addition, when working with drywall, it is often necessary to tighten the fasteners “quickly and in large quantities”, and to speed up the work, the screwdriver can be equipped with a special...magazine nozzle; for more details, see "Complete set".

— For cutting threads. A feature found in some relatively low-powered tools, predominantly in the drill/driver format. For this, a special mode of operation is provided: first, the cartridge with the appropriate nozzle (die or tap) rotates clockwise, cutting the thread, and then in the opposite direction to remove / extract the nozzle. In addition, on the return stroke, the teeth of the nozzle pass over fresh cuts, clearing them of chips.

— For precision work. A tool originally designed for jobs that require precision and precision. Most of these models are screwdrivers (see "Device"), which have a very thin and light body that is comfortable to hold in your hand and allows you to make the most accurate movements. Note that the downside of this convenience is very low power; in fact, for more than "fine" work, such a tool is usually not designed.

— Automotive. A tool designed for use in a car — both for repairing the car itself (for example, changing a wheel), and for other work in the "field conditions", where the most convenient (or even the only available) power source is the car's on-board network. Accordingly, all car models have the ability to connect to such a network — usually through a standard cigarette lighter socket, although terminals for working directly from the battery can be supplied in the kit. And some automotive tools come with their own batteries; see "Food" for details.

— For spot welding. A specific type of drill designed for drilling connection points between spot welded parts. Such drills are especially popular in a car service — it is there that it often becomes necessary to remove a separate part welded “by points”, and the easiest way to do this is by drilling individual points. The specificity of such work lies in the fact that the junction cannot be drilled through — the working nozzle (drill or crown) must pass only through the upper layer of metal, almost without affecting the lower one. This means that the depth of drilling must be controlled very precisely. To do this, special limiters are used in spot welding drills, which look like clamps and allow you to set the drilling depth with an accuracy of fractions of a millimetre.

Torque is the maximum force with which this model is capable of turning the working nozzle.

Higher torque gives more options, it allows you to cope with complex tasks such as drilling in hard materials, unscrewing stuck screws and nuts, etc. On the other hand, a lot of force requires corresponding power — and this, in turn, affects the dimensions , weight and cost of the tool itself, and also puts forward increased power requirements (mains power, battery capacity or pressure / compressor performance). And for some tasks, excessive torque is basically unacceptable, so for maximum versatility, it is desirable to have torque control — and this affects the cost even more. And the more steps, the more optimally you can configure the tool to perform a particular type of work. So the general rule is this: when choosing, it is worth considering the specifics of the planned work, and not chasing the greatest working effort.

Detailed recommendations on choosing the optimal torque for different types of tools (see "Device") can be found in special sources. Here we note that it is of key importance primarily for screwdrivers, although it is also given for other types of tools. At the same time, in the “weakest” models, the maximum working force does not exceed 15 Nm, in the most powerful ones it is more than 150 Nm.

Type of reverse provided in the design of the tool.

The reverse allows you to switch the direction of rotation of the nozzle; see "Functions" for details. It also indicates the type of switch responsible for this function. The varieties of such switches nowadays are very diverse: slider, flag, brush on the engine, on the start button, gyroscopic, on the keyboard toggle switch, and also combined with a flow switch or ratchet mechanism. Here is a detailed description of each of these varieties:

— Crawler. Switch in the form of a slider with two opposite positions. Usually, it moves in the direction "back and forth" relative to the tool chuck — this format is considered the most practical. The sliders are quite simple and at the same time convenient and visual, especially when used in screwdrivers and wrenches: by moving forward (away from you), the direction of rotation is set to twisting, by moving backward (toward yourself), respectively, to unscrewing. However, such devices are widely used in other types of instruments (see "Device") and are generally the most popular option nowadays.

— Combined with the flow switch. The most popular type of reve...rse in pneumatic tools (see "Power Source"); not found in other models. The flow switch itself is actually a speed controller, most often in the form of a distinctive rotary knob or lever. And if this regulator is combined with a reverse, this means that it can deviate from the neutral position in two directions, and the direction of rotation will depend on which direction the flow switch is shifted.

— Flag. A switch in the form of a flag, usually installed above the start button and thrown to the right and left. One of the advantages of a checkbox is that it is right at your fingertips and can be toggled with almost no unnecessary movement (which is not always available for a slider). On the other hand, this option is mainly suitable for drills, and in screwdrivers and wrenches, the checkbox is not as intuitive as the same slider. And in general, this type of reverse for a number of reasons is much less common.

— Brush (on the engine). Reverse switch installed directly in the tool motor and based on the use of a special movable brush holder. By changing the position of the brushes in the motor with the help of such a mechanism, it is possible to change the direction of its rotation. One of the key advantages of this method is that it allows you to achieve maximum power in any direction of rotation without any special tricks. In addition, such an adjustment has a positive effect on the engine resource. On the other hand, brush switches are quite complex and expensive, and therefore are installed mainly in a powerful professional tool.

— On the start button. Reverse switch combined with start button. Such a combination button is usually made in the form of a "rocker", and the direction of rotation depends on which side of the rocker the user pressed; pressing the same button immediately starts the engine. This design allows you to easily and quickly change the direction of rotation — for this you do not need to be distracted by individual switches, just move your finger slightly and press the other half of the start button. This is especially convenient for screw and wrench drivers, as well as screwdrivers; in fact, most of the models with this type of reverse belong to these types.

— On a keyboard switch. The control method, in many respects similar to the reverse on the start button described above, also uses a rocker switch. The key difference is that in this case the direction switch is made separately from the start button — that is, the user must first select the direction of movement, and then press "start". This option does not have any particular drawbacks, but it also does not differ in convenience, and therefore it is extremely rare.

— Gyroscopic. A rather rare and specific type of reverse, found exclusively in screwdrivers (see "Type"). In fact, there are no external switches in such a tool — instead, a built-in gyroscope is used to track body rotations. Accordingly, to select the direction of movement, you need to rather sharply turn the tool around the longitudinal axis in the appropriate direction and smoothly return it to its original position (speed can be adjusted in the same way — for example, the farther the turn, the higher the speed will be). This control method is very simple and intuitive, but it is rather complicated in technical implementation and requires increased accuracy in handling the tool. That is why gyroscopic reverse is extremely rare nowadays.

— Combined with a ratchet mechanism. Another rather rare option, found exclusively in wrenches — mostly pneumatic, less often battery-powered (see "Power"). The ratchet mechanism, we recall, is responsible for ensuring that the working part of the tool rotates in only one direction. And the reverse is controlled through a mechanical switch, which is directly connected to this mechanism and changes its settings, setting one or another direction of rotation.

The total weight of the tool is usually the device itself, without attachments. For battery models (see "Power Source"), usually, the weight is indicated with a standard battery installed; for battery-powered models, the weight can be given both with and without batteries, but in this case this point is not particularly important.

Other things being equal, less weight simplifies work, increases accuracy of movement and allows you to use the tool for longer without tiring. However, note that high power and productivity inevitably increase the mass of the tool; and various tricks to reduce weight increase the price and can reduce reliability. In addition, in some cases, a massive design is more preferable. First of all, this applies to work with a large load — for example, drilling holes of large diameter, or making recesses with impact: a heavy tool is more stable, it is less prone to jerks and shifts due to uneven material, vibration of mechanisms, etc.

It is also worth noting that specific weight values are directly related to the type of tool (see "Device"). Screwdrivers are the lightest — in most of them this figure does not exceed 500 g. Screwdrivers and drill drivers are more "heavy": their average weight is 1.1 – 1.5 kg, although there are many lighter ( 0.6 – 1 kg) and heavier ( 1.6 – 2 kg or more ) models. And clas...sic drills and wrenches have the greatest weight: such a tool must be quite powerful, so for them 1.6 – 2 kg is an average, 2.1 – 2.5 kg is above average, and many units weigh more than 2, 5 kg.

— Impact mode. Ability to work in the so-called shock mode. Usually, this mode is turned on and off at the request of the user, and its meaning and features may be different, depending on the type of instrument (see "Device"). So, in drills, strikes are carried out along the axis of the drill, and their frequency is usually several thousand per minute — this has a positive effect on productivity and allows you to more effectively cope with hard, dense materials (although such a drill can not be replaced anyway). In turn, in screwdrivers and wrenches, it would be more correct to call the impact mode pulsed: in this format of operation, the tool nozzle does not rotate uniformly, but in separate jerks, usually at a frequency of about 3K per minute. It also improves work efficiency, which is especially useful when driving self-tapping screws into dense material and unscrewing old, “stuck” fasteners.

— Engine brake. A device that additionally slows down the engine when the tool is turned off. The engine itself (and, accordingly, the working nozzle) after turning off can rotate for quite a long time by inertia; the brake stops this rotation almost immediately, so you do not have to keep the tool on weight for too long.

— Power button lock. A function that allows you to lock the power button in the pressed position. Usually, it looks like an additional button insta...lled either on the start key itself or not far from it. This function is very convenient in situations where the tool has to be used for a long time without interruption — for example, when drilling several dozen holes at once: it is easier to fix the start button in the on position than to keep it pressed all the time, additionally straining the finger on the working hand. And the lock is turned off, usually, in the simplest way — for example, by briefly pressing the same start button.

— Speed controller. Possibility to additionally limit the revolutions of the tool. By itself, smooth adjustment is available in almost all modern models: the harder you press the start button, the higher the speed. This allows you to directly "on the go" adjust the mode of operation of the tool to the specifics of the situation. And this regulator allows you to set the maximum speed of rotation, so that even when you press the button “to the stop”, the speed of the working nozzle does not exceed the specified value. This function is indispensable for some jobs that require precision — in particular, when processing delicate materials, for which too high a speed is fraught with damage.
Separately, we emphasize that the presence of a speed controller has nothing to do with the number of speeds (see above). For example, a tool may well have several speed modes, in each of which the speed can be further limited using a regulator.

— Maintain momentum. A feature that allows you to maintain a constant speed of rotation of the nozzle, regardless of the load on it. Without special adjustment, at a constant engine power, the rotational speed inevitably drops with increasing load and increases with a decrease. And the revs control system monitors the resistance on the nozzle and, if necessary, changes the power in such a way that the rotation speed remains constant. This has a positive effect both on the quality of work and on the service life of the nozzles and the entire tool.

— Electronic engine protection. A system that protects the engine from critical overloads — for example, in the event of a jammed drill — and overheating. If the motor load or motor temperature is exceeded, the power to the instrument is automatically turned off to avoid damage to the instrument.

— Brushless motor. The presence of a brushless (brushless) motor in an electric tool. Such motors are noticeably superior to traditional collector motors in terms of efficiency, which can significantly reduce energy consumption without sacrificing power; this is especially important for cordless tools (see "Power Source"), where this feature is predominantly found. In addition, brushless motors are quieter and produce virtually no sparks during operation, making them perfect for working in high fire hazard environments. Their main disadvantages are traditional — the complexity of the design and high price.

— Safety clutch. A device that protects the engine from damage during a sharp increase in load (for example, due to jamming of the drill). In such cases, the safety clutch disconnects the motor shaft from the tool chuck, avoiding overloads. Note that such devices can be both reusable and disposable — the latter are destroyed when triggered, and to continue working, you will need to install a new clutch.

— Backlight. The built-in lamp for illumination of a place of work. This feature can be useful both in the evening/night time, and in hard-to-reach places where there is little penetration of outdoor lighting, as well as in situations where this lighting is too dim. Note that in addition to built-in light sources, modern tools can also be equipped with separate flashlights; for more details about them, see "Complete set".

— Display. Own display, which can display various information about the operation and status of the device — for example, the torque or rotation speed set in the settings, and in battery models, there is also a battery charge indicator. Such a screen provides additional convenience and visibility, however, in general, this is a rather specific function that is extremely rare in modern power tools — for example, a speed or torque indicator can be provided directly on the regulator, and a conventional LED can be provided as a charge indicator, giving signals by blinking or colour change.

— Synchronization with a smartphone. The ability to connect the instrument to a smartphone or other gadget (such as a tablet) via Wi-Fi or Bluetooth. Such a connection is usually used to adjust operating parameters such as speed or torque; doing this through a mobile application is often more convenient than through the controls on the instrument itself. And some models with this function also allow you to set password access: the tool simply will not respond to the start button until the correct password is entered on the control gadget.

— Built-in bubble level. Built-in device to control the angle at which the tool is located to the horizon. As in ordinary levels, the role of the scale in such devices is played by a sealed flask with marks applied to it, containing a brightly coloured liquid and an air bubble. By the position of this bubble relative to the marks, the position of the entire tool is determined — namely, its correspondence to the vertical, horizontal, or pre-set tilt angle (the latter option, however, is almost never found in the built-in levels). At the same time, purely hand tools usually provide a single-axis level that reacts only to deviation from the horizontal forward or backward, and models with the ability to mount on a rack (see below) can also have a circular level that controls compliance with the vertical and determines deviations from it in any direction.

— Revolving mechanism for bits. A mechanism for storing and quickly changing bits used in tools for the corresponding purpose — mainly screwdrivers, but also some screwdrivers (see "Device"). In accordance with the name, the main part of the mechanism is a drum like a revolver, in the compartments of which the bits are stored. The mechanism is located behind the cartridge, and the choice of bits usually occurs as follows: you need to pull back a special casing or handle (if at that moment there was another bit in the cartridge, it will return to the drum), by turning the drum, select the compartment with the desired nozzle, and then move the casing / handle to its original position by pushing the nozzle out of the drum into the chuck. This feature significantly speeds up and simplifies the replacement of nozzles, and also reduces the risk of losing them. On the other hand, the revolving mechanism significantly affects the price and weight of the tool, and its capacity is usually limited to 6 – 8 nozzles. Thus, such a tool is usually also equipped with an adapter for installing bits in the traditional way, from the outside of the cartridge.

— Water cooling(coolant). The tool has a coolant — a liquid cooling system (most often plain water) supplied to the working nozzle using a built-in pump. Such a system performs several functions at once. Firstly, it actually cools the nozzle, preventing damage due to overheating. Secondly, the liquid somewhat reduces friction at the point of contact, further reducing the load on the nozzle and increasing its durability. Thirdly, water absorbs dust generated during drilling, this dust does not fly into the air and does not enter the lungs of people around; and cleaning up after work is much easier. On the other hand, water cooling systems are quite expensive and bulky, and with relatively simple work and low loads, it is quite possible to do without coolant.

— Soft start. A function that provides a smooth spin-up of the tool motor, with relatively little acceleration. This is achieved by limiting the starting current. Without such a limit, the current drawn by the motor at the time of starting can be quite high, causing the motor to start very abruptly, which increases the risk of letting go of the tool. In addition, current surges can lead to overloads in the network used for power. Soft start allows you to eliminate these phenomena to some extent. Note that it is used only in mains-powered models — the motors in cordless tools are not so powerful that they have the actual “troubles” described for them.

Rated battery voltage for which the cordless tool is designed (see "Power Source").

Manufacturers select the battery voltage taking into account the performance characteristics of the tool and the power supply required to achieve these characteristics. In fact, this means that most often this parameter can be ignored at all when choosing. The only exceptions are some specific situations — for example, if the "household" already has a battery of the same company and you want to evaluate its compatibility with the selected model, if the selected tool is supplied without a battery and you want to immediately order a power source for it, or for accurate comparison of batteries by capacity (see below for more details). But after the purchase, the voltage data can also be useful for finding chargers in addition to or to replace the "native" charger.

As for specific values, in many models the voltage does not exceed 10 V — this is often quite enough. However, much more popular options are 11 to 15 V and 16 to 20 V. There are also higher voltages, but much less frequently.

The type of battery installed in the battery-powered tool (see "Power Source").

— Ni-Cd(nickel-cadmium). The most "old" option found in modern power tools. It is distinguished by high reliability, resistance to temperature extremes and good charging speed even with high capacity (which is important, given the "voracity" of the power tool). The main disadvantage of this type of batteries can be called a pronounced "memory effect" — a decrease in battery capacity if it is set for charging without being completely discharged. In addition, Ni-Cd cells are considered environmentally unsafe. Nevertheless, they are still widely used in tools — not least due to their low cost with decent performance.

— Ni-Mh(nickel-metal hydride). Such batteries were created as a development of the nickel-cadmium batteries described above. Retaining all the main advantages of their predecessors, they are at the same time devoid of most of the shortcomings — in particular, they are practically not subject to the memory effect. Of the own disadvantages of this option, it is worth mentioning a slightly lower durability and higher cost than the original Ni-Cd.

Ni-Zn. Nickel-zinc batteries are the next evolutionary step after nickel-metal hydride. They have no memory effect, have lower self-discharge rates (compared to Ni-Mh) and extremely low internal resistance, which makes...it possible to charge the battery at an accelerated pace using high current. At the same time, Ni-Zn batteries are sensitive to deep discharge and overcharging.

— Li-Ion(lithium-ion). A type of battery originally developed for use in portable devices; however, with the development of Li-Ion technology, it has also been used in power tools. The main advantage of such batteries in this case can be called a high capacity with small dimensions and weight. It is also worth noting that they are not subject to the memory effect and are able to charge quite quickly. On the other hand, this option is not without its drawbacks — this is, first of all, sensitivity to too low or elevated temperatures, as well as a high price.

Note that the tool may allow the use of batteries of a different type — for example, replacing a Ni-Mh battery with a more advanced Li-Ion. However, such a possibility must be explicitly stated in the documentation, otherwise normal performance is not guaranteed (and in the worst case, even breakdowns and fires are possible).

The capacity of the battery supplied with the respective tool (see "Power Source"). The most modest capacity values in modern power tools do not even reach 1 Ah, such batteries are found mainly among electric screwdrivers(see "Device"). And in powerful professional models there are batteries for 3 – 4 Ah and even more.

Theoretically, the higher the capacity, the longer the tool will be able to work on a single battery charge. However, in fact, things are far from being so clear cut. First, the ampere-hour is a fairly specific unit; its features are such that only batteries with the same voltage can be directly compared by the number of ampere-hours. With a difference in voltage, you need to convert the capacitance to watt-hours and use them for comparison. Secondly, the actual battery life of the tool depends not only on the properties of the battery, but also on the power consumption and other performance characteristics. Thus, it is possible to compare different models in terms of battery capacity only with the same supply voltage and similar capabilities.