How to choose a cordless screwdriver

Recommendation points

• Which platform to choose
• Battery type
• Screwdriver gearbox
• Safety clutch
• Individual ergonomics
• Choice according to the specifics of work

Quality work is impossible without a good tool. With regard to installers, this rule works especially strictly, therefore, a tool such as a cordless screwdriver should not only be reliable, but also correctly selected for certain tasks, which we will discuss in this article.

Which platform to choose

The most important criterion for any cordless screwdriver is its platform, which is determined by the battery voltage. There are four main platforms, and each manufacturer takes one of them as the main reference point for their instrument or at least a separate series. Platform selection is a compromise between tool power and unladen weight.

Screwdrivers with a supply voltage of 18 V can be called the golden mean. This voltage allows the development of a torque of up to 100 Nm, while the tool remains fairly light. Most of the series of professional tools and some examples of amateur.

The 24 V platform is mainly used in high-quality and expensive screwdrivers. Due to the high voltage, the motor is less sensitive to overloads, which has a positive effect on the service life and reliability.

Platforms for 12 and 14.4 V are popular in the household segment and in all types of work, where compactness and low weight of the tool are more important than high power. In fairness, it should be noted that professional screwdrivers, Makita, Bosch and other flagships are often based on the 14.4 V platform. And yet, do not expect that such a screwdriver will drive a 120 mm dowel into a dense tree.

Battery type

The screwdrivers are powered by Ni-Cd, Ni-MH or Li-Ion batteries. The first two types are most common, Ni-Cd is the cheapest, can be stored for a long time in a discharged state and work at low temperatures. But their self-discharge is fast enough, moreover, they have a low specific capacity. Ni-MH batteries are discharged in idle time more slowly, more capacious than Ni-Cd, but they cost a little more, and the number of charge / discharge cycles is half that, about 600-700.

Li-Ion batteries are devoid of many disadvantages: they have a short charge time, practically do not discharge when idle. The advantages also include a higher (2-3 times) capacity, no “memory effect” and a long service life (more than 2000 cycles). The price for such a pleasure is appropriate: from 3 to 8 thousand rubles, that is, about 2-3 times higher than that of Ni-Cd, and lithium-ion batteries do not tolerate cold.

Screwdriver gearbox

Speed ​​is fundamental and differentiates the tool into the cordless drills and screwdrivers series. The latter have only one mode: slow rotation (400–500 rpm) with a high force (50–110 Nm), that is, they are used exclusively for screwing in. The advantages of such models include their simple design and reliability, but in almost any installation technology, it is necessary not only to fasten, but also to drill.

The drilling mode on screwdrivers is realized due to the overhead gearbox frame, which includes the second mode. When turned on, the number of revolutions is doubled, the torque on the spindle is reduced by the same amount. The drilling mode is usually rarely used, but it allows you to do with one tool instead of two. There are also three-speed screwdrivers, in which the third mode is designed for threading with machine taps. Their revolutions are very low, and the moment of force is colossal for a cordless tool..

Screwdrivers use compact planetary gearboxes, usually with three satellites, the carrier of which is rigidly fixed to the crown of the same, but smaller gear. When the power of the screwdriver is up to 20-25 Nm, the gears in the gearbox can be plastic, up to 50 Nm the use of a plastic case is allowed. In a powerful professional tool, plastic in the gearbox should not be present; instead, a body made by powder casting and gears made of high-alloy steel are used.

Safety clutch

The overload clutch is a separate element of the gearbox associated with an external handle – a torque limiting regulator. Unfortunately, it is not always possible to use a screwdriver as a torque wrench, often the scale graduation is purely arbitrary. But if the manufacturer indicates in the instructions a table of the dependence of the force on the position of the regulator, such a tool should be paid attention.

Structurally, this unit looks like a ratchet in the ring (outer) gear of the gearbox, which is pressed by an annular spring. One end of the spring is connected to the body, the other – to the rotating handle at the tool holder. Weak points include the wire rod and the spring itself, which, when used in the production of low-quality steel, quickly loses its elasticity or frays..

Individual ergonomics

A handy tool for the craftsman means more than just comfort. Screwdriver manufacturers strive to improve ergonomics by offering different body shapes and pad materials, weight distribution, and the location of control buttons. In general, the number of variations is large enough so that everyone can choose an instrument for their hand and style of work. The preference when choosing should always be given to a more convenient tool, even if this comes at the expense of power or reliability.

One of the main ergonomic criteria is the angle between the grip and motor axes. A common mistake of designers can be called an excessively large tilt of the handle back, because of which the palm becomes numb or tense and the callus between the thumb and forefinger is quickly rubbed. Switching the direction of rotation should be freely performed with one hand, check this when purchasing. Try tossing from one hand to the other and tossing the instrument into the palm, including with a flip, to finally make sure of good balance.

Choice according to the specifics of work

A screwdriver is not as versatile a tool as it might seem at first glance. The specifics of working with it are diverse enough for manufacturers to orient some of their models for a specific industry..

Compact screwdrivers are suitable for furniture assemblers (the battery does not protrude beyond the handle) for working in hard-to-reach places with a high enough force to screw in confirmations. The drilling mode in these models is almost never used; for this, another screwdriver with a more capacious battery is usually purchased.

GKL installation is the most common area of ​​application, especially for two-speed screwdrivers with a sufficiently high battery capacity (at least 2 Ah). The weight in the installation of drywall is especially important, therefore, the cladders use a tool with Li-Ion type batteries and a power of 35–50 N · m. Single-speed screwdrivers without collet are ideal for ceiling work.

For special installations, high power is very important so that the screwdriver can be used instead of a drill or hammer drill. Window installers and electricians, for example, use 18 V or 22 V impact drivers.