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HomeTips & TricksThings you need to consider before buying the Screw driver!

Things you need to consider before buying the Screw driver!


What and how many types of screws are there?

There are machine screws and wood screws. Obviously in these two main types there are other variants for different construction materials and for special screwings. The screws differ mainly from each other in the shape and type of thread.

What is the rotation speed of a screwdriver?

The speed of a screwdriver varies from a minimum of about 100 revolutions per minute to a maximum of about 250 revolutions per minute. However, the speed varies depending on the model. An impact wrench can reach 3000 strokes per minute with a torque of 220 Nm.

What does Nm mean?

Nm is the abbreviation that indicates the newton per meter or newton meter. This is the unit of measurement of the mechanical moment in the International System of Units. It corresponds to the moment exerted by a force of a newton applied to the end of a one meter long rod and perpendicular to it, hinged at the other end.

What is the power of a screwdriver?

The power of a simple screwdriver varies on a scale from 3 to 8 Volts with a voltage ranging between 3.6 V and 4.5 V. Some models for sale may however offer an even higher voltage. A professional impact wrench can also reach a voltage of 18 Volts.

What does “volt” mean?

The volt is the unit of measurement of the electric potential and of the electric potential difference in the International System and therefore of the electric voltage.

What does “watt” mean?

Watt is the unit of measurement of electrical power.

What does “16 Volt Max” mean?

A “16 Volt Max” (14.4 V) battery pack consists of four individual battery cells. Each of these cells has two voltages: one nominal and one maximum. When a 3.6V Li-ion cell is charged, it actually receives a 4V charge. Only when it is discharged to a level of 50% does it reach the nominal level of 3.6V. The nominal value is calculated as follows: 3.6 V x 4 cells = 14.4 V. While the “Max” value is based on the maximum charge level: 4 V x 4 cells = 16 V.

What does “20 Volt Max” mean?

A “20 V Max” (18 V) battery pack consists of five individual battery cells. Each of these cells has two voltages: one nominal and one maximum. When a 3.6V Li-ion cell is charged it actually receives a 4V charge. In this case, the nominal value is calculated as follows: 3.6V x 5 cells = 18V. “Max” is based on the maximum charge level: 4 V x 5 cells = 20 V.

Which are the most powerful screwdrivers?

A particular category of screwdrivers is constituted by air devices which are, in turn, divided into impulse or linear screwdrivers. Even though they reach 650 nm per couple, they manage to keep small dimensions despite the type of processing for which they are very often intended. They are generally heavy equipment and typical of some categories of operators called to high torsional forces. These models, unlike the classic ones, perform small consecutive strokes providing rotation. Linear screwdrivers represent the ideal solution for those who want the maximum result from compactness without sacrificing the length of the device. Generally, these models are fed with compressed air and precisely because of their hexagon socket shape they are able to have greater working efficiency in particularly confined spaces.

What parameters must be taken into consideration when choosing a screwdriver?
Let’s see what are the fundamental parameters to consider when choosing a screwdriver.

Weight: it is important to always opt for a model with a not too low weight and this to better calibrate the performance. A model equipped with a non-slip handle and able to be used for any type of work usually weighs under 2 kg.
Shape: Cordless screwdrivers are available in three basic shapes; straight, pistol, or a combination of the two. Straight shape screwdrivers are suitable for small basic jobs. Pistol screwdrivers are perfect for getting into the most awkward corners and hard-to-reach areas. A mixed-shape screwdriver, on the other hand, contains both the characteristics of the previous two and can satisfy both situations with a single tool.
Number of revolutions per minute: if you aspire to obtain a good job and a good result, you must take into account the number of revolutions per minute which must not be less than 1000 otherwise we would have an approximate job. With increasing voltage, revolutions per minute usually also increase, which can start from about 600 up to over 2000. Drills at medium or medium-high speed are capable of offering 1200 to 1800 revolutions per minute. In the case of a hammer drill, we will talk about strokes per minute.
Voltage: this parameter is important for what concerns professional performance. Its value can vary from 9 up to 36 Volts. In fact, it is good to choose a model that is capable of delivering over 12 volts. Obviously it must be equipped with effective lithium batteries if you need to work without any mains socket. Industry experts advise against choosing models that drop below 9 volts. It is good to remember that the vaulting is closely linked to the maximum speed of the screwdriver. The ideal value should be 12-14 Volts at least. Currently the most common and required voltage is 18 Volts, as it is suitable for medium and large applications and which combines a structure that remains light and easy to handle and can be used perfectly even at home. For very large applications, such as concrete or stone work, a much more robust model with a voltage of 24 to 36 volts is required.

Maximum Torque: corresponds to the amount of power to be applied to the screw without the risk of “stripping”. It is measured in “Newton Meter”, Nm. Normally a good 12 volt screwdriver is around 30 Nm. By virtue of this, its speed is higher than that of a screwdriver with a lower voltage. A lower level torque wrench is perfect for simple daily tasks.
Reversibility: this is a feature that belongs to the screwdrivers in circulation and consists in the possibility of reversing the direction of rotation of the tip. It is, in fact, possible to operate a movement in both directions of rotation. The user therefore has the ability to screw but also to unscrew or correct any screwing errors.
Spindle lock: it is possible to use the electric screwdriver also in manual mode when it is supplied by the spindle. This feature locks the cordless tool in a straight position, in perfect hand screwdriver style.
Reverse Rotation: Some screwdrivers are also equipped with reverse rotation which allows you to extract screws easily and efficiently as they are inserted. It is a feature that makes work much easier and more comfortable.
Fast battery charging: screwdrivers with lithium-ion batteries have a fast, powerful and long-lasting charge. In fact, they last at least 3 times longer than normal rechargeable batteries. Some features allow a screwdriver to quickly charge the battery, typically within an hour or less.
Built-in light: Some models of cordless screwdrivers have built-in LED lights. An LED light helps to illuminate areas with little light. This function gives the possibility of being able to work even in poorly lit environments.

What are the torque settings and maximum torque?

The maximum torque is the maximum rotational force of the drill, which can be important if drilling hard materials such as concrete, for which a combi drill should be considered, with the impact function for extra drilling power .

Torque settings are more important when it comes to screwing, as putting too much energy into the screw can “shell out” the screw head. Getting everything right, so that each screw is flush with the surface, can be difficult, but some drills are easier to control at a slow speed than others.

Are the materials important in choosing the screwdriver?

Absolutely yes. Also because the eye wants its part but not only for this reason. The importance of the material is in a certain way linked to performance but also, and above all, to the safety of the screwdriver itself. Various materials are used to produce this kind of equipment. What changes is the sturdiness of the plastics and metal alloys used for the various tips which must ensure the durability of the tool over time, especially if it is heavily stressed when working on very hard materials, such as concrete or metal. It is therefore important during the selection phase to verify that the materials used by the manufacturer are reliable and safe. All this reduces dangers and unpleasant accidents.

What is the difference between a cordless screwdriver and an electric screwdriver?
Cordless screwdrivers are equipped with rechargeable batteries. They differ mainly in the type of battery fitted. Cordless screwdrivers are very comfortable and practical. In fact, they represent the right combination of quality, price and functionality. Compared to the classic screwdriver it is lighter and therefore easier to handle, they are equipped with a good sturdiness and batteries that ensure an ever longer duration that allows you to comfortably carry out your work without having to stop frequently to recharge it. The capacity of a cordless screwdriver is measured in Ampere-hours. The torque of these tools is too low to drill holes.

The electric screwdriver is equipped with a wire and plug that allows connection to the power outlet. They are usually powerful and robust and often do not have a mandrel since they mount the attachment for the insert directly.

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