Comparison Grand DA-21Li vs Zenit ZShA-1213 A Li-1K

The speed of rotation of the working nozzle provided by the tool.

If a single number is indicated in this paragraph (for example, 1800), it can be either a standard, constant, or maximum rotation speed. This refers to the maximum speed if the tool has more than one speed (see "Number of speeds") and/or a speed controller (see "Functions"). In turn, two or three numbers through an oblique line (for example, 1100/2300/3400) are indicated only for models that have the corresponding number of individual speeds. Each of these numbers indicates the standard (and in the presence of a speed controller — the maximum) number of revolutions at one of the speeds.

Anyway, when choosing a tool by the number of revolutions, it is worth considering both its general type (see "Device") and the specifics of the intended work. Detailed recommendations on this matter are quite extensive, it makes no sense to give them in full here — it is better to turn to special sources. We note only a few general points. So, high -speed drills nowadays are considered to be drills capable of delivering more than 3000 rpm. In general, high speed contributes to productivity, but there is also a downside: increasing the speed (for the same power) reduces torque — accordingly, the efficiency of working with stubborn materials and large diameter nozzles decreases. Therefore, it makes sense to specifically look for a "high-speed" tool only if speed is of key impor...tance; it doesn’t hurt to make sure that the model you choose can provide the required efficiency and torque.

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.

The type of gearbox provided in the design of the tool.

A gearbox can be simply described as a mechanism that transmits rotation from an electric motor to a chuck. In this case, usually, the rotation speed decreases, due to which the torque increases. Different types of gearboxes differ just in the number of speeds that can be obtained at the output. The simplest variety of such mechanisms is single-speed, they are as simple as possible, compact and reliable. At the same time, in a tool with a 1-speed gearbox, speed control may well be provided — due to electronic circuits that allow you to adjust the engine speed. On the other hand, reducing the actual speed by means of electronic control does not lead to an increase, but to a decrease in torque.

More advanced are multi-speed gearboxes, usually having 2 to 4 speeds. Such mechanisms are analogous to a gearbox in a car: the speed in them is regulated by changing the gear ratio, so that a decrease in speed leads to an increase in torque, and vice versa. Such an adjustment is considered more practical than the electronic one described above; the downside is the complexity and high cost of multi-speed gearboxes.

The number of speeds provided in the design of the tool.

First of all, let's clarify that "speed" in this case means high-speed mode. The number of revolutions at each "speed" can be either fixed or adjustable (if there is an appropriate regulator — see "Functions"). Thus, the presence of several speeds can have different meanings. In some models, changing the speed mode is the only option for adjusting the speed; in others (if there is a separate speed controller), changing the mode sets only the maximum speed of rotation of the nozzle, and its actual speed is smoothly changed by the controller (which may also have its own, additional speed limiter).

As for the specific number of speed modes, in many models it is only one. Accordingly, the revolutions in such a tool either do not change at all, or are controlled only by the mentioned regulator; this is often sufficient for simple tasks. However, 2-speed tools are also very widespread — this design provides additional tuning options and at the same time remains relatively simple and inexpensive. And in fairly advanced models, you can find three, or even four or more speed modes; in some cases, this number reaches 8 or even more, which allows you to use speed switching as a full-fledged speed controller.

When choosing according to this characteristic, it should be...taken into account that, other things being equal, a larger number of speeds gives more features for setting operating parameters, but complicates the design and increases its cost.

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.

- Corner nozzle. A nozzle that allows you to rotate the axis of rotation of the cartridge by 90 ° relative to its original position. Such a device is indispensable for making holes, as well as twisting and unscrewing fasteners in some hard-to-reach places (for example, in narrow grooves or a profile).

- Eccentric nozzle. Replaceable nozzle designed to shift the axis of rotation of the cartridge slightly away from its original position. In this case, the direction of the axis remains the same. Like the corner nozzle, such a device is intended mainly for working in certain hard-to-reach places (in particular, near walls and edges of workpieces).

- Additional handle. A modern tool, even a relatively low-power one, can be quite massive, and for maximum accuracy and reliability it may be necessary to hold it with two hands at once. Using an additional handle for this is more convenient and safer than looking for a place to grip on the body. The handles themselves are usually mounted near the cartridge perpendicular to the axis of rotation and may have different design features.

- Depth stop. A device that allows you to limit the depth of drilling. The most popular version of such a limiter is a rod in a special mount, installed parallel to the drill. Before starting work, this rod is shifted so that when the desired depth is reached, its end rests on the surface of the material,...preventing the drill from moving further.

- Store nozzle. It looks like a kind of store or disk, into which a tape with self-tapping screws is “charged”; and a special block is installed in front of the cartridge, designed to supply self-tapping screws. This design allows you to tighten the screws as quickly as possible and without unnecessary movements: just load the tape from the magazine into the feed unit, start the engine and alternately press the working part of the tool to the desired points on the material.

- Lantern. A classic flashlight for illumination in low light conditions, in contrast to the built-in illumination system, is a separate device. Such a separate device is not very convenient to hold in your hand during work - in such cases you can’t take the tool with both hands, and this creates problems in some situations. On the other hand, often the situation allows you to put or hang a lantern without taking up your hands; and sometimes in this way you can even organize the lighting more successfully than using the built-in backlight. In addition, the flashlight can be used independently.

- Case (bag) included. The presence of a case or bag in the delivery set of the drill. Cases are usually called hard suitcases; bags, unlike cases, are soft, which allows them to be packed more tightly together with other things, but reduces the degree of protection. In any case, this feature makes the tool more convenient to store and carry: the complete bag or case is optimally suited for this model, in addition, they can hold drills, spare batteries and other additional accessories.

- Rack. Mostly professional drills for diamond drilling are completed with racks(see "Purpose"). This design is a stand (base) with a guide rail fixed on it, along which the tool can move using a special mechanism. According to the fastening of the rail, the racks are divided into two types:

• Non-inclined stand. A structure with a rigidly fixed rail, which is usually located vertically, perpendicular to the base; accordingly, the axis of rotation of the installed tool also remains always vertical. Such racks have more limited capabilities than inclined ones. On the other hand, they are simpler, cheaper and more reliable (there is no movable mount in the design that can become loose); and for most work, the vertical position of the tool is fine.
• Tilt stand. Stands in which the rail is fixed on a swivel mount and can deviate from the vertical at a certain angle. Accordingly, such a device allows you to direct the crown not only vertically, but also at an angle; this can be important for some non-standard tasks. On the other hand, a movable structure is more complex, expensive and less durable than a fixed one; therefore, it is worth paying attention to this option if the possibility of inclined drilling is fundamental for you.

- A set of drills. The presence of drills in the kit eliminates the need to purchase them separately and allows you to use a drill (or other tool with drill functions) right out of the box. True, the specific assortment of drills can be different - besides, it is often an entry-level set of 5 to 7 devices for the simplest tasks like drilling wood. However, even such a set will be useful if the tool is purchased for domestic use or simple work that does not require specialized nozzles. We also note that such equipment is especially convenient when buying a “first tool for a beginner”, when there are no drills on the farm yet and one way or another you will have to buy them.

- A set of bits. Bits, we recall, are nozzles in the form of screwdriver heads, which are also used in screwdrivers. As in the case of drills, the presence of such nozzles in the kit eliminates the need to purchase them separately and makes it possible to use the tool immediately after purchase. The specific set of bits is worth specifying further, but most often it includes at least flat and cross bits in a fairly large variety of sizes. And in general, such sets are quite extensive - even in relatively inexpensive tools, the number of complete bits can be measured in tens.

- Equipment. The term "equipment" means at least several types of working nozzles, and sometimes additional accessories. For example, if such equipment is indicated for a drill-driver, then this model is almost guaranteed to be equipped with both drills and bits (and possibly more specific accessories). A specific set of equipment should be specified separately.

- Extension. The purpose of such an accessory is clear from the name: it allows you to increase the working length of the tool. In other words, when you install an extension bat or other equipment, it is further from the body; the extension itself is made quite thin. This accessory is used mainly in models with the functions of a screwdriver or wrench: it allows you to reach deep-seated fasteners that are inaccessible in the usual configuration. And in many models, the extension cord is also made flexible, which further expands its capabilities.

- Magnetizer. Device for magnetizing bolts, screws and other similar fasteners. Found in individual screwdrivers; the working tooling of such tools is also made of magnetic material, due to which the magnetized fastener effectively “sticks” to the tooling and does not need to be supported separately.

- Case insert. Interchangeable insert (or several inserts) to adjust the complete case to the specific situation. For example, a regular insert can only have space for a tool and a charger, and a replacement one can also accommodate a second spare battery. Specific features should be specified separately.

- Charger(charger). A device for charging the batteries used in the tool with the appropriate power supply. For models supplied with such a device, the charger model may be additionally specified in the characteristics. This information can be useful not only for finding a spare or replacement charger, but also in case the household has other cordless tools and / or batteries for them. The fact is that many manufacturers nowadays use universal batteries that are compatible with a whole set of tools from the same brand; so, for example, a complete charger for a drill may be quite suitable for a cordless grinder from the same manufacturer.
On the other hand, a lot of modern cordless tools come without a charger at all. This option will be optimal, first of all, if a compatible memory is already available, and there is simply no need to overpay for a second device. In addition, the lack of a charger will be appreciated by those who want to choose this accessory separately, without relying on the manufacturer's decision.


Note that the above list is not complete - modern tools can be supplied with other additional items, including very unexpected and original ones - like a fitness tracker or even a radio-controlled car.

The number of batteries supplied with the respective tool (see "Power Source"). Also, this paragraph may indicate the presence of a built-in battery.

The most popular configuration option with a battery nowadays is 2 batteries. This provides additional benefits that are especially useful for long-term continuous use of the tool. So, when the charge of one battery is exhausted, you can quickly change it to another; while one battery is in use, the other can be charged. This minimizes or eliminates interruptions in charging. Some tools for the same reasons can be equipped with three batteries, however, such sets are much less common, since they are more expensive and do not have fundamental advantages. Single battery kits are also not particularly common: these are mostly entry-level tools designed for small amounts of work, when charging breaks are quite acceptable.

In addition, quite a few modern cordless tools come without batteries. This configuration assumes that the user himself will purchase batteries at his discretion (many models are compatible with several brands of batteries at once). In addition, this option may come in handy in case the battery is already on the farm. This happens quite often, since many well-known manufacturers use universal bat...teries suitable for different types of branded power tools. So a battery, for example, from a previously purchased jigsaw or grinder may well be compatible with a screwdriver from the same company.

As for non-removable batteries, this is a rather rare and specific option. Such tools are as compact as possible, but the batteries themselves cannot be quickly changed — so you will inevitably have to take breaks for charging during work. Therefore, this method of supply is typical for low-power tools — mainly screwdrivers (see "Device"). In them, small size is more important than a long period of continuous operation, in addition, a low capacity allows you to achieve good battery life even with small sizes (and, accordingly, capacity) of batteries.

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 capacity of the battery that comes with the corresponding tool (see “Power source”). The most limited 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 with 3 - 4 Ah or even more.

In theory, the higher the capacity, the longer the tool can work on a single battery charge. However, in practice, everything is far from so simple. Firstly, ampere-hours are 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. If there is a difference in voltage, you need to convert the capacity into watt hours and use them for comparison. Secondly, the actual autonomy of the tool depends not only on the properties of the battery, but also on 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.