Origin of screwdrivers

Each tool is created to solve a specific range of problems. Therefore, it is worth starting to consider this issue with a brief excursion into history. It begins with the appearance in Ancient Rome of hand drills, which were driven by rotating the handle. Much later, only in the 19th century, electric drills were created, which increased the drilling speed tens of times due to the higher rotation speed of the electric motor compared to manual rotation of the rotor or crank.

Further evolution developed by “crossing” electric drills with other types of tools. We “cross” a drill with a jackhammer by including an impact mechanism in its design - we get a hammer drill. We change the gear ratio in order to reduce the speed and not tear off the heads or spoil the slots of screws and self-tapping screws - we get a screwdriver.

The evolution of the tool from the hand drill to the modern variety of devices.

Why is a screwdriver bad at drilling concrete?

An ordinary electric screwdriver, although it is a type of drill, is structurally “tailored” for other tasks. The key difference is the reduced chuck rotation speed. The operating speed of simple single-speed screwdrivers, which are used in construction and manufacturing, usually does not exceed 750 rpm (compare this figure with the characteristics of electric drills, which have a chuck rotation speed of at least 2500 rpm). This speed is only sufficient for drilling brick (ceramic brick is usually drilled in modes from 400 - 600 rpm), but not enough for drilling concrete (the optimal rotation speed of inexpensive drills for concrete with a diameter of 10 - 13 mm lies in the range from 900 rpm to 1100 rpm).

But more importantly, a conventional single-speed screwdriver does not have an impact mechanism. Therefore, it cannot effectively crumble concrete or brick at the point of contact of the drill with the material. In addition, the design of the gearbox, bearing assembly and limit coupling does not imply significant axial loads. Therefore, using a conventional screwdriver, it is possible to drill concrete only theoretically, but in practice, attempts to drill dense structural materials usually end in lengthy and fruitless picking, as well as accelerated wear of the tool.

Popular drills and drivers with impact mode

Drills/drivers and concrete drilling

Fortunately, in the “evolution tree” of hand-held power tools there is a “side branch” in the form of drills and screwdrivers, which are represented by a large assortment of corded and cordless models. They are the ones who can (with some reservations and stretches) drill concrete.

To confidently and quickly drill concrete using a drill-driver, you need:

  • sufficient power - to drill durable structural materials you need a tool with a power of 750 W or more;
  • impact mode - the function of axial impact, combined with rotation of the cartridge, allows you to effectively destroy concrete at the point of contact;
  • powerful battery - a cordless tool must be equipped with a battery with high current output in order to confidently rotate the drill in thick concrete;
  • correct equipment - for drilling concrete walls and ceilings, you need special concrete drills with carbide tips or diamond coating.
Special drills for concrete: DeWALT, Bosch and Hilti.

The difference between the impact mechanisms of a screwdriver and a hammer drill

It’s worth dwelling separately on the shock mode. The design of the impact mechanism of a drill-driver is fundamentally different from the design of a similar hammer drill assembly. There is no crank mechanism or “drunk” bearing inside the screwdriver, which would allow developing the high impact energy necessary for chiseling concrete. This function is implemented differently: the axial movement of the cartridge is created using two wavy washers (ratchets). When the engine rotates, the cartridge washer “jumps” along the protrusions of the stationary washer. A drill moves behind it, making reciprocating movements and crumbling the concrete a little at a time.

Wavy washers in the impact mechanism of a DeWALT drill.

The amplitude of movement of the drill tip is a fraction of a millimeter, and the impact force depends entirely on the force with which the operator presses on the tool. Therefore, the characteristics of drill-drivers do not indicate the maximum impact energy, and they are outright inferior to full-fledged hammer drills in terms of concrete drilling efficiency.

Inexpensive hammer drills

Limited tool capabilities

The possibilities of a screwdriver are far from limitless. Due to its technical characteristics, “tailored” for much simpler tasks, it will drill concrete five to ten times slower than drills and hammer drills that are more appropriate for this work. The diameter and depth of the holes that can be drilled with a screwdriver also leave much to be desired (the maximum size of the drill that can be clamped in the chuck allows you to drill holes for plastic dowels, but not for powerful anchors).

Therefore, a screwdriver is only suitable for occasionally making a hole in the wall. But it is simply not structurally designed for serial drilling of concrete. In order not to accidentally “kill” the tool when drilling a couple of holes for shelves or cornices, you need to have a little patience and beware of excessive loads on the engine and gearbox. Also, while working, you should monitor the temperature of the drill (if it gets too hot, the carbide tips may fall off) and allow it to cool in a timely manner.

Concrete is different from concrete

The concept of “concrete” covers a large number of materials. This includes lightweight cellular concrete (such as foam and aerated concrete blocks, which are used for laying external walls and internal partitions), and dense heavy concrete (used for pouring load-bearing frames of monolithic buildings and structures). There is a huge difference between them in density and strength. For example, the characteristics of typical aerated concrete blocks, from which the walls in your apartment or private house can be made, usually correspond to a strength class from B2.0 to B2.5. The strength of such a material does not exceed 25 - 35 kgf/cm2, which is significantly less than that of the cheapest M50 concrete. The strength of concrete grade M200, which is used for the construction of low-rise buildings, is much greater - up to 200 kgf/cm2. And in high-rise construction, concrete with a high cement content is used, the strength of which reaches 300 - 400 kgf/cm2. Therefore, even relatively inexpensive corded and cordless drills and screwdrivers with a power of up to 750 W can cope with drilling aerated concrete. But drilling dense reinforced concrete with granite filler is beyond the capabilities of even the most “advanced” models; this will require a powerful hammer drill with high impact energy.

Internal structure of reinforced concrete.

conclusions

There are screwdrivers that can drill into some types of graded concrete and concrete blocks. If you do not demand too much from them, then from time to time, using a drill-driver equipped with an impact mechanism, you can drill a couple of holes in a concrete wall. But this opportunity should be considered as a pleasant “bonus” to the main functions of this type of tool: tightening fasteners and drilling wood, plastic and metal.

And if we take into account the cost of the tool, then it is more profitable for an ordinary user to take a simple drill-driver with a two-speed gearbox and, in addition to it, a low cost hammer drill than to buy an expensive professional screwdriver “for all occasions.”