Comparison Grand DA-21BL DFR-Pro vs Grand DA-21UBL Pro

The number of beats per minute provided by a tool that supports the corresponding mode.

For more information about this mode, see "Functions", here we note that it can be provided both in drills and in screwdrivers and wrenches (see "Device"), and the meaning of the impact mode in these varieties is somewhat different. Therefore, the speeds differ: many drills are capable of delivering about 48,000 beats / min, or even 64,000 beats / min, while in screwdrivers and wrenches, 3200 beats / min are considered “classics of the genre”, and values above 3500 beats / min are practically do not meet.

The general meaning of this indicator is also directly related to the type. So, among drills, the difference in chiseling speed can be quite large. With these tools, more strokes improve overall productivity and efficiency, while fewer strokes improve accuracy and reduce the risk of damaging delicate materials. In screwdrivers and nutrunners, high speed also contributes to overall efficiency, but for most of these tools, the differences in this indicator are not significant enough to be noticeable in practice.

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.

Two points depend on the type of cartridge: the types of working tools (drills, screwdrivers, etc.) with which this or that model is compatible, and the method of installing / removing them.

— Key. As the name implies, you will need a special key to work with such a cartridge. The mount itself is usually designed for tools with round shanks (mostly drills) and includes three cams that, when clamped, converge towards the centre, clamping the tool installed in the chuck on the axis of rotation. The main disadvantage of this type of cartridge is the need to use a key: it can be lost and the mount becomes useless. In addition, installing and removing a working tool can be quite a long process. However, the keyed chuck is considered somewhat more reliable than the keyless chuck and more suitable for heavy work.

— Quick release. Similar to the keyed chuck described above, this type of chuck is designed primarily for drills with round shanks. Its main difference is the absence of a key — you can fix or remove the drill with the help of a hand, without any additional tools. Such chucks are slightly less suitable for work with high loads (for example, in hard materials and/or with large diameter drills), but otherwise they do not lose in any way with the key, and in terms of ease of use they are significantly superior.

— Under the beat. Bits are working tool...s used in screwdrivers and screwdrivers (see "Device"). The working side of the bit can have a flat, cruciform or other shape (star, trihedron, etc.), but the shank with which it is fixed in the cartridge is standardly made hexagonal. Accordingly, the bit chuck has a recess for such a shank. Fixation can be carried out mechanically, in the form of a simple latch, or with a magnet; in both cases, the mount is secure enough for safe operation, and the tool can be removed without much effort.

— Morse taper. A cartridge for one of the varieties of the tool cone — the so-called Morse cone. As the name implies, this mount involves a conical shank and a corresponding hole for it (often with an additional groove for the protrusion on the shank — for secure fixation and prevention of rotation). This option is found mainly in drills (see "Device"). Note that the Morse cone is available in several sizes that are incompatible with each other.

— Square. The type of chuck used in impact wrenches. Unlike all other varieties, the working tool for the “square” is not installed inside the cartridge, but is put on it from the outside. Squares can have several standard sizes, but these sizes are the same for both electric and hand tools. In fact, this means that nozzles from manual wrenches can also be used in electric models if the landing size is the same (and if not the same, you can use an adapter, although this is less convenient).

— None (threaded spindle). The absence of a cartridge as such: a thread located directly on the spindle is used to fasten the working nozzles. Almost all models with this feature are powerful professional tools designed for diamond drilling (see "Intended use") — for a number of reasons, it is the threaded spindle that is considered the best way to attach nozzles for such drilling. Note that the thread on the nozzle can be both external and internal; most spindles are compatible with both varieties, but there are exceptions. So this nuance needs to be specified separately.

Note that in some models two types of cartridges can be combined — for example, for a bit and quick-clamping. Usually, for this, the kit provides two different cartridges that can be changed as needed, but there are other options — for example, a spindle into which you can insert both a bit and a drill chuck (key or keyless). Anyway, this makes the tool more versatile and allows you to work with numerous working attachments.

The ability to quickly remove the cartridge and replace it with another, and, usually, by hand, without the use of additional tools. A quick change of cartridge is found mainly in drill drivers (see "Device"): in different modes, such devices require different types of cartridges (one for a drill, the other for a bit), and the ability to quickly change one type to another in some situations is extremely useful .

The largest diameter of holes that the tool can make when drilling with a conventional drill in wood.

The larger the hole diameter, the higher the resistance of the material, the more power the tool must provide and the higher the load on it. Therefore, the maximum allowable drilling diameter must not be exceeded, even if the chuck allows you to install a thicker drill bit — this can lead to tool breakage and even injury to others.

It is worth noting that some types of wood can have a fairly high density, and for them the actual allowable drill diameter will be, accordingly, less than the claimed one. However, this is true mainly for exotic breeds, which are extremely rare in our area.

The largest diameter of holes that the tool is capable of making when drilling with a conventional drill in metal.

The larger the hole diameter, the higher the resistance of the material, the more power the tool must provide and the higher the load on it. Therefore, the maximum allowable drilling diameter must not be exceeded, even if the chuck allows you to install a thicker drill bit — this can lead to tool breakage and even injury to others.

Also note that the drilling diameter for metal is usually indicated based on medium hard steel and other similar materials. For metals and alloys that have a significantly higher hardness and density, the allowable drill thickness will be less; however, such situations occur infrequently, and if you wish, you can find out about the features of working with various alloys x in special sources.

— 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 spirit 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 spirit. By the position of this spirit 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.

- 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.