How to measure the torque of a screwdriver

Filling out the breadboard

Once the mechanical design of the project is complete, we can start working on the circuit.

First, connect the power supply to the breadboard on the opposite side of the load cell. The power supply is located on the breadboard so that its power leads connect to the breadboard power rails.

There is a switch on the power supply that controls the output voltage. For this project we will be using 5 volts. There is also a power switch. For now, turn off the power.

measure, torque, screwdriver

Figure 14. Installing the power supply on the breadboard.

Now, before installing the HX711 on the breadboard, you need to complete the preparatory step.

The problem is that the HX711 board is almost the same width as the breadboard. If the HX711 is installed on a breadboard, we will not be able to connect it to the load cell.

Therefore, we will first place the jumpers.

The HX711 has four connections on the side closest to the servomotor. Use small pieces of wire to make the jumpers on the breadboard approximately five steps long.

When we place the HX711 over the installed jumpers, we will still have access to its pins to be able to connect other jumpers.

To make this step a little clearer, below is a photo.

Figure 15. Jumpers for HX711.

Once the jumpers are set, place the HX711 board next to the power supply. Make sure board pins match with installed jumpers.

Figure 16. Installing the HX711 board. Figure 17. HX711 board next to the power supply.

Finally, the Arduino Uno will be located next to the torque measurement tool.

Figure 18. Torque Measurement Tool and Arduino Uno next to it. Figure 19. Connection diagram of the torque measuring tool.

  • connect the GND pin of the Arduino board to the GND pin on the breadboard;
  • connect the GND pin of the HX711 board to the breadboard;
  • connect the black wire of the servo motor to the GND pin of the Arduino;
  • connect the Vin pin of the Arduino board to the Vcc pin on the breadboard;
  • Connect the VCC pin of the HX711 board to the Vcc pin on the breadboard.
  • connect the red wire of the servo motor to the 5V pin on the Arduino.
  • connect the yellow wire of the servo motor to pin D9 of the Arduino board;
  • Connect the DT pin of the HX711 board to the D3 pin of the Arduino board;
  • connect the SCK pin of the HX711 board to the D2 pin of the Arduino board.
  • connect the red wire of the load cell to pin E of the HX711 board;
  • connect the black wire of the load cell to the E- pin of the HX711 board;
  • connect the green wire of the load cell to pin A- of the HX711 board;
  • connect the white wire of the load cell to pin A of the HX711 board.

Figure 20. Load cell connection Figure 21. Power supply to the HX711 board Figure 22. HX711 board connections Figure 23. Power supply to the Arduino Uno board Figure 24. Servo motor connection Figure 25. Arduino Uno connections

Building a testing tool

The mechanical design of the testing tool is simple and consists of two 3D printed parts and a pair of fasteners.

No special printing parameters are required, so any hard plastic will work for the parts.

In fact, since aesthetics is not a priority for this project, you can use higher layer heights to speed up print times.

Figure 9. Printed project components in assembly.

The video below shows the installation process of the mounting inserts.

Build process

The first step in assembling the servo motor torque measurement tool is to install the mounting inserts to securely fix the servos and then remove them without damaging the 3D printed wireframe.

To install the insert, place it over the servo mounting hole. Then gently press in the insert using a soldering iron heated to about 120 ° C. Do not press too hard on the insert. Let the heat do the work for you and let the insert sink into the plastic. When the soldering iron is removed, the molten plastic solidifies around the insert, creating a very strong connection.

Figure 10. Fastening inserts installed in the printed frame. Figure 11. Fastening inserts installed in the printed frame.

Then install the load cell in the square hole, but with the arrow on the sensor pointing away from the servo.

The load cell must fit snugly and evenly to avoid force measurement errors.

Figure 12. Installing the load cell

Finally, a large flat surface on the printed frame is used for the breadboard.

The breadboard has an adhesive backing. Simply peel off the cover and glue the board to the 3D printed wireframe.

Figure 13. Breadboard adhesive backing.

How to measure torque of a servo using Arduino

Learn how to use Arduino to measure the torque of the servo motors you intend to use in your projects.

In everyday life, we are often provided with a number of statistics from various manufacturers, which at best have little connection with the experience of real users.

Smartphone manufacturers claim their batteries last longer than they actually do. Tech companies advertise all of their products as the smallest versions, and auto companies boast false fuel economy figures.

Servo motor manufacturers are no different. They present different metrics related to the amount of torque that their motors can generate.

Figure 1. Specification for the HS-422 servo motor from the Hitec website.

In this project, we will create a tool to measure the range of torque generated by standard sized servos.

This way, it will be easy to check if a particular servo will be able to generate the torque required for any project.

Using a strain gauge, an Arduino Uno, a 3D printed frame and a few other parts, you can simply place the servo motor in the test area and accurately measure the torque it produces.

Figure 2. Load Cell, Arduino Uno, 3D printed frame, and a few other parts required for this project. Figure 3. Components required for the project (top view). Figure 4. Components required for the project (closer view).

How to measure the torque of a servo motor

Torque is calculated by multiplying force by distance. In this project it will be a little difficult to get the force acting on the servo. To do this, you must use a strain gauge.

There are usually complex parts associated with the design and use of strain gauges, but for the purposes of this project, a strain gauge is a sensor that allows a computer to convert small voltage changes into force.

Figure 5. Load cell designed for a load of 20 kg, suitable for the highest level servo drives. Figure 6. White material on the strain gauge hides the voltage measuring cell.

Using a strain gauge, we can measure exactly the distance between the axis of rotation of the servo and the lever on the shaft of the servo.

Be aware that the servo will push the load cell when you try to rotate it.

Figure 7. Detail of the servo arm

By taking into account the force measurement from the load cell and the rotation and length of the servo arm, we can calculate the torque generated by the servo.


  • Arduino Uno;
  • strain gauge 20 kg;
  • load cell amplifier board HX711;
  • breadboard power supply;
  • solderless breadboard;
  • jumpers;
  • 4 x M4 inserts;
  • 2 screws M4 x 6 mm.

In addition to the above materials for testing, you will need a hobbyist sized servo.

Arduinio programming

When the mechanical and electrical assemblies are complete, the last step is to upload the firmware to the Arduino.

The testing procedure used by Arduino is relatively simple.

Arduino will drive the servo into the load cell. The resulting force on the load cell will create the reading that the Arduino will receive from the HX711.

The Arduino will repeat the measurements five times, taking five separate readings from the strain gauge. These five individual readings are then averaged to give the force the servo is applying to the load cell.

The distance between the center of rotation of the servo and the load cell is calculated based on the structure of the frame. Arduino can calculate the torque generated by the servo from the average reading and the distance between the load cell and the servo.

Test run

After all the work of assembling the test tool and programming the Arduino, we can finally measure the torque generated by the servos. But first, we need to install the servo to be tested into the measuring tool.

To install the servo, simply slide it into the case.

The servo must be positioned so that the motor shaft is closest to the load cell.

The servo wires will come out through a hole behind the load cell from where they can be connected to the Arduino.

Use at least two M4 x 6mm screws to secure the servo in place.

Figure 26. Installing the tested servo

This system can be operated entirely from the USB port of your computer.

If you are using only USB power, the servo will operate on 5V. Since servos usually operate on other voltages, you can also use the power bar on the breadboard. This will allow you to supply the servo with a higher voltage than 5V from the USB port.

After turning on the system, open the serial port monitor. You will be prompted to send the character ‘s’ on the port when you are ready to start the test.

Figure 27. Offer to start testing

At this point, the Arduino should start moving the servo arm away from the load cell, and as soon as testing starts, it will come back.

As the servo tries to move to a position inside the load cell, it will exert force on the sensor.

The Arduino will measure this force, convert it to torque, and send the results to the serial monitor.

Figure 28. Measurement results

Below is a video demonstrating the operation of the Servo Test Tool.

How to use a screwdriver? 5 basic rules

The screwdriver has become one of the most popular when working on interior decoration. This is explained by the widespread use of wall panels, suspended ceiling ceilings, and the use of wooden battens as cladding material. These works require the massive use of screws and a screwdriver to screw them into the surface. Therefore, the issue of correct operation of the device so that it works for a long time and reliably is relevant. In the article we will talk about cordless screwdrivers, as the most popular type of this tool.

Is it possible to drill with a screwdriver

If you have a model that has two modes of operation. drilling and a screwdriver. Usually professional models have such capabilities, for example Makita DF347DWE. It is not necessary to use a model that does not have a drilling mode, the engine may burn out, since drilling requires higher revolutions to reduce the load.

How to use a screwdriver correctly and safely

Working with this tool is intuitive. But you need to know certain subtleties that reduce the risk of injury and tool breakage. So, how to screw a self-tapping screw with a screwdriver safely:

Read the instructions carefully BEFORE using the instrument for the first time, and not after something unpleasant has happened.

Correctly select the maximum torque at which the safety “ratchet” will work and the force will not be transmitted to the shaft. The tool is of course designed for maximum effort. But, firstly, constant work at the maximum reduces the service life. Secondly, the likelihood that the screwdriver can pull out of the hands increases. Thirdly, by learning how to correctly determine the maximum torque, you will reduce the likelihood of damage to the surfaces where you screw the screws. This is especially true for polished and fragile surfaces. For example, in the Bosch GSR 10.8 model, the maximum torque is 30 Nm, but 5 Nm can be set.

We choose the right mode of operation. It is not necessary to drill in the screwdriver mode, and even more so to tighten the screws in the drilling mode, where the speed is higher. The tool may simply be snatched from your hands.

Do not forget to control the direction of rotation. We tighten the screw. the cartridge should rotate clockwise, we unscrew it. against.

Do not change any cutting mode settings on the fly! This threatens to break the screwdriver and is unsafe.

Above, we talked about the rules of safe work relating directly to the screwdriver. Now about the general organization of work with this tool:

  • Work only with protective goggles and preferably with protective gloves, especially if you are drilling materials that can crack and “shoot” sharp fragments.
  • Before drilling, make sure that there are no electrical cables and other utilities in the area.
  • When tightening and unscrewing screws, as well as drilling small holes in diameter, do not lean on the screwdriver. The screw or drill bit may break and injure you.
  • Household and professional screwdriver models have different continuous operation times. In any case, it is! And it’s not worth bringing the instrument to a hot state.
  • After work, you need to disconnect the battery, remove the attachment, wipe the tool from dust.

Do I need to lubricate the screwdriver

This tool has a gearbox and it requires lubrication such as ELF MULTI MOS. The frequency depends on the model and the intensity of use. The following signs will indicate that your tool needs lubrication:

  • unpleasant “tearing” sound;
  • the chuck is difficult to rotate by hand.

You can lubricate with lithol, manol, silicone or Teflon grease.

How to store a screwdriver

Better separate from the battery. If you have a model with a nickel-cadmium battery, then before ending work and disconnecting the battery, it must be completely discharged. After removing the battery, it must be charged. Remember that Ni-Cd has a high self-discharge current, therefore, during long-term storage, it needs periodic recharging.

Charging the screwdriver

The most important part of the operation of the tool, on which the duration of the device’s operation largely depends. How to charge a screwdriver battery depends on its type. The most common lithium-ion batteries. Such a battery with its compact dimensions quickly charges and does not have a memory effect. The main disadvantage is a quick discharge in the cold and a high price.

Older models have nickel-cadmium batteries. They are cheap, reliable, but have a memory effect. That is, if you do not completely discharge them before charging, then gradually the battery capacity will decrease.

How much you need to charge the battery depends on its type and capacity. Li-Ion batteries gain charge most quickly. The battery of a household screwdriver takes an hour to charge. The same capacity Ni-Cd battery will charge for 7 hours.

How do you know if a screwdriver is loaded? The charger has an indicator, for example, for the DeWalt 572576-01 model, it is on the right. The red light is on. the battery is being charged, the green light. can be used. You can also focus on your own experience. By the charging time and the nature of the screwdriver’s work, you can judge the charging of its battery.

If you have a model with a nickel-cadmium battery, then you should know how to swing a screwdriver battery, which will inevitably decrease its capacity after several years of use. And if you use the tool incorrectly, that is, do not bring the battery to full discharge before charging, then faster.

In order to restore capacity, you need to know how to discharge a screwdriver battery correctly. And this means a smooth decrease in the charge, by connecting to it a twelve-volt light bulb with a power of 25.40 watts. After a complete discharge, charge the battery to the eyeballs and then discharge it again. Repeat the procedure at least 5 times. The capacity cannot be fully restored by such a procedure, but the operating time of the screwdriver can be significantly increased.

Equipment installation

The screwdriver can be equipped with drills or nozzles for twisting and unscrewing screws. When the desired bit is selected, it is necessary to rotate the chuck sleeve counterclockwise until its jaws are separated by a distance sufficient to insert the drill shank or screw bits between them. Then the clamp is made in the reverse order. There are two types of cartridges:

Product Information: Torque Screwdriver Tester

  • the clamp is made without a key, but only by rotating the cartridge case by hand;
  • requiring pressure with a special key, which is inserted into the recess in the chuck and rotates it, leaning against the toothed rim, for example, as in the Dnipro-M 1/2 ″ x20 gear chuck.

How to remove a chuck from a screwdriver, for example, to lubricate it or replace it if it does not fix the nozzle poorly. In modern models, the chucks are screwed onto the shaft and, for reliability, are locked with a screw with a left-hand thread. This is how the cartridges are attached in Makita, Bosch, etc. screwdrivers. It is necessary to unscrew the screw and unscrew the cartridge by rotating counterclockwise. Detailed instructions on how to do this are available in the documentation for the tool.

How to remove a chuck from a screwdriver

Owners of screwdrivers sometimes need to remove the chuck from the power tool. This can be caused by various circumstances:

  • Repair, lubrication and cleaning of this unit.
  • The desire to replace this cartridge with another model (of a different design, size).

This operation does not require any special tools, skills and abilities. But, while performing it, it is necessary to remember some features that complicate the disassembly operations. Most three-jaw self-centering screwdriver chucks are keyless. That is, they have several differences from the usual (key types):

  • The unit has a plastic surface that can break down even with minimal mechanical stress on it with metal tools.
  • Very close location of the chuck to the drill body, with a small gap, which will not allow fixing the spindle with a pipe wrench or a vice.

Another factor that can complicate disassembly in the easiest way is the relative low power of the screwdriver (when compared with drills).

Using the L-shaped tool

This method is quite simple and safe, therefore it is a priority. You must perform the actions in the following sequence:

  • Make sure that the retaining screw is removed from the spindle end.
  • Fasten the L-shaped tool in the cams. Best Hex Wrench.
  • Set the torque regulator to the maximum value or put it in drilling mode.
  • Switch the direction of rotation of the spindle to reverse mode (counterclockwise).
  • Start the engine and allow it to reach maximum speed.
  • Bring the rotating L-shaped tool fixed between the cams to the fixed stop. For example, bench vice, gymnastic weight.
  • At the moment of impact of the fixed L-shaped tool, the chuck will be quickly screwed off the spindle.

Attention! The chuck unscrews very quickly, in less than one second. Therefore, it is necessary to provide that it falls from a minimum height, that is, the emphasis on which the L-shaped tool will be stressed should be as close to the floor as possible.

The second variant of this method is also possible:

  • After unscrewing the screw and fixing the faceted key (three-, four-, five-, hex) between the cams, we hold the screwdriver in one hand, and with the other we strike with a hammer (mallet) on the shoulder of the protruding tool so that the rotation occurs counterclockwise.
  • Thus, having “ripped off” the cartridge from its place, you can continue to unscrew it by hand.

This subtype of loosening is especially effective in cases where there is no voltage in the network (mains screwdriver), the battery is discharged or the power tool is inoperative.

The first required step! Unscrewing the fixing screw

The first, mandatory, step when removing the chuck from most household screwdrivers is to unscrew the fixing screw located at the end of the spindle between the cams. This fastener is designed to protect the quick-release assembly from self-“make-up” when working with a load in reverse mode (counterclockwise).

For example, when unscrewing old fasteners when it is necessary to increase the torque. In this case, the chuck can remain stationary, fixed with a bat in the surface to be treated, and the spindle will rotate “to the left” (counterclockwise) and unscrew itself from the fastening unit of the screwdriver.

To avoid such situations, manufacturers use a control screw with a “left” thread. It is he who must first of all be removed by performing the following steps:

  • Spread the jaws so that the tip of the screwdriver passes freely between them.
  • Unscrew the screw by turning to the right, as it has a “left” thread.

Attention! The grooves on the screw heads can be of various sizes and shapes (straight or cruciform). Therefore, it is necessary to have screwdrivers with different tips.

Screwing the keyless chuck off the screwdriver spindle
After the locking screw with “left-hand thread” has been unscrewed from the end of the spindle, you can remove the keyless chuck from the screwdriver.

Due to the fact that the gap between the coupling and the body is several millimeters, it is not possible to fix the spindle with a vice or pipe wrench. Therefore, there are several other ways to remove the cartridge.

Holding the cartridge with your hand

The easiest way is to hold the chuck with your hand. To do this, follow these steps:

  • Put on a work glove on the hand that will hold the cartridge.
  • Set the torque regulator to the maximum value or switch the screwdriver to drilling mode.
  • Make sure that the retaining screw is removed from the spindle end.
  • Bring the chuck jaws to the minimum clearance.
  • Holding the chuck with one hand protected by a glove, start the screwdriver to rotate in the opposite direction (counterclockwise). While the cams are diverging, the electric motor will pick up speed, and at the moment of their full disclosure, a kind of blow will be obtained, which should move the threaded connection. Now screwing the cartridge will not be difficult.

Attention! This is an unsafe way! It is forbidden to use it upon confirmation of at least one point:

  • Lack of work gloves.
  • The power of the screwdriver exceeds 500 watts.
  • Self-doubt.
  • Lack of good physical fitness (adolescents, women, elderly people).

If this method is not suitable for the above prohibiting reasons or turned out to be ineffective, then the following should be applied.

Removing the chuck from the disassembled screwdriver

All of the above methods involve removing the cartridge from the whole screwdriver. But a situation may arise when the power tool is disassembled. The chuck will be removed from the screwdriver together with the gearbox.

Then there are two ways to remove the cam assembly:

  • Secure the reducer between the jaws of the vise using soft spacers (eg wooden) to avoid damaging the body. Fix the L-shaped tool in the jaws, and try to “rip” the chuck with a hammer.
  • Select a socket wrench so that it fits snugly on the three pins of the gearbox (you can start with size 9).

Holding the cartridge with one hand, turn the key counterclockwise with the other.

The designs of most manufacturers of modern household screwdrivers with three-jaw keyless chucks are very similar, so disassembly methods are applicable to most models.

The easiest and safest way is to use an L-shaped faceted tool, clamped between the chuck jaws.

What is meant by torque?

Cordless screwdriver device.

Torque is a value that allows you to determine the level of stress on the equipment. Which option should you choose? It is usually 5-10 Nm, which is quite enough for safe and high-quality operation of the tool. This parameter is provided for most household and semi-professional models that can easily cope with tight self-tapping screws, drilling steel, concrete.

What should be the torque? You should pay attention to what the tool will be. For example, for a universal device, it is necessary to choose rather high torque values ​​so that the tool copes equally well with any type of work, be it self-tapping screws or structurally rigid materials. If you need a tool only for drilling wood, then you can prefer a model with a small moment from among the household ones. When choosing, you should pay attention to the number of revolutions. For example, 400-500 is enough for screwing in self-tapping screws. For drilling hard surfaces, it is best to use devices with a speed of 1200-1300 per minute.

Ratio of torque and screw diameter

When choosing a cordless or mains screwdriver, it is important to correctly determine the ratio of screw diameter and speed. This dependence is not too difficult to determine:

To tighten screws of different diameters, different speeds are required.

  • If the diameter of the screw is 6 mm, then the rotational speed during screwing in will be 10 Nm. For structurally soft or hard materials, the frequency will be 25 Nm.
  • If the diameter of the screw is 7 mm, then the torque when working with hard materials will be 27 Nm, and for soft materials. 11 Nm.
  • With a maximum screw diameter of 8 mm, the torque will be 30 Nm.

What does this ratio show? It is possible to determine which torque can be used for a given working screw diameter. The correct choice will not only make the work more efficient, but will also increase the quality, reliability and durability of the equipment. The operation will be completed much faster, the operator will spend less effort.

In network equipment, high power has little effect on the operation process, and batteries drain quickly. Therefore, it is necessary to have spare batteries and the ability to recharge those already planted. Usually, manufacturers provide spare batteries for professional tools, but for simpler models, at least one battery will have to be purchased separately. When choosing a screwdriver, it is necessary to take into account the presence of one more function. the reverse motion. It is necessary when the drill is stuck in the material. This reverse is usually electronic; to control it, you should use a two-position switch, which is located near the start button.

What should be the torque of the screwdriver?

The torque of a screwdriver is a significant parameter that you need to pay attention to when choosing. Be sure to take into account whether the tool will be used for homework or professional. There are various models on sale today that differ in their characteristics.

There are many models of screwdrivers from various manufacturers on the construction market, which differ depending on the power source, parts and functions.

Which torque is better?

A screwdriver is a tool that is necessary for carrying out various kinds of work. This is not only construction, but also many home repair work, for example, assembling furniture, installing communications. In order to choose the right equipment, attention should be paid to the torque, which determines the comfort and quality of work. For example, you don’t need too powerful a tool to assemble furniture. If you plan to install an interior partition, then you need to take more professional equipment that will perfectly cope with the task.

Drills and screwdrivers are used to mix building mixtures, you just need to purchase a construction mixer nozzle.

The torque of such tools must be sufficient to mix even the most viscous mixtures and solutions, to ensure their uniformity, high quality.

For mixing concrete and other viscous mixtures, special nozzles are used.

If you want to use mortar nozzles, the torque must be sufficient to handle mixtures of not only low viscosity, but also high. The choice of model depends on the planned work. If a screwdriver is required to be used for mixing liquid mixtures, then the torque may not be too high. If the tool is purchased for working with viscous mixtures, then it is necessary to already prefer professional devices, the turnover of which is high.

Equipment that will be used for a variety of jobs must have a speed controller. Then the torque can be changed depending on what kind of work needs to be done. When choosing a screwdriver, you need to look to ensure that the latch for the control button always works, and not only with maximum effort. In the first case, the tool can be used for any work with the most convenient conditions. The torque value can be changed. It is recommended to buy models that have manual or electronic control. They have a dedicated step-down transformer that works great with liquid mixes when the voltage drops.

Screwdriver models

The screwdriver is the most commonly used tool that is indispensable for construction and repair activities. Manufacturers today offer a variety of models that can be applied under different conditions. This tool is convenient for manual work, it is necessary for tightening / unscrewing screws, screws, self-tapping screws, for drilling and even for stirring building mixtures.

By power source, the tool is classified into:

The cordless screwdriver is powered by the supplied battery.

  • Rechargeable models powered by special batteries. They increase the weight of the tool, but make it easier to work in hard-to-reach places.
  • Network devices that require connection to the electrical network. They have a limited reach due to the length of the cord, although extension cords can be used.

By purpose, the equipment can be divided into:

  • models for construction / renovation work;
  • for production shops, workshops, auto repair shops;
  • for industrial enterprises;
  • for household use.

There are professional, semi-professional, household models on sale. When choosing, attention should be paid to the torque, which shows what kind of work the screwdriver can handle.

What to do when working with viscous mixtures is required?

It is not so rare that a screwdriver with an impact function is used for mixing viscous mixtures. To do this, you should choose equipment with high power, since ordinary household ones already with the assigned work may not be able to cope, the effort will not be enough. The torque of this device must be high, i.e. you should buy professional equipment. It is possible to use mechanical built-in gearboxes, they make it possible to use the equipment even at 1st speed. It is necessary to provide a cooling system, it is important to prevent overheating of the motor.

If a screwdriver will be used to assemble shelves or install a conventional cornice, then more power is not needed, the torque will not matter much. If the equipment is purchased for frequent use, and it will be necessary to perform various work related to the preparation of mortars, then you must choose from semi-professional and professional tools. They will provide all the required conditions for high-quality work.

Choosing a home screwdriver, you need to pay attention to its numerous parameters. You should immediately decide whether you need a professional tool or not a very powerful household one. After that, you should familiarize yourself with the proposed set of functions, technical characteristics, among which torque takes an important place.

What is Newton?

If you write “Newton” with a capital letter, then this is the name of the scientist, after whom the unit of measurement is named, with which force is measured.

Well, when it comes to the unit of measurement, then “Newton” is written with a lowercase letter, and denoted as “H”.

As a unit of measurement, scientifically speaking, 1 N is a force that changes in 1 second the speed of a body weighing 1 kg by 1 m / s in the direction of the force.

If it is somewhat simpler, then we can say this: in order for a body weighing 1 kg to move and increase its speed by 1 m / s with each second, then a force equal to 1 N must be applied to it.

Still not clear? Then take an object with a mass of 100 g in your hand. Here is the force of gravity that attracts this object to the ground and will be approximately equal to one newton. Why approximately? Because the force of attraction at different points of the Earth is somewhat different and the standard of one Newton will be the gravity of a body weighing 102 g, located at sea level on the surface of the Earth at a latitude of 40 degrees.

The maximum torque of the screwdriver is

Getting familiar with the characteristics of any screwdriver, you will surely come across such a parameter as torque, which is measured in newton meters (Nm). Not everyone remembers from the school physics course what this means. And in this article I will try to explain what the torque of a screwdriver is.

In simple terms, the torque of a screwdriver means the maximum force that it can transmit to a screw or self-tapping screw. It is clear that the higher the torque, the more this force will be.

What does all this affect? On how much, for example, a large self-tapping screw or a screw in length and diameter you can screw into this or that material. And besides, if you take two screwdrivers with different torque and do the same job with them, then the mechanism of the screwdriver with more torque will wear out less. Therefore, it can be said that the magnitude of the torque also affects the tool life.

And what is a newton meter?

Again, if you use a quote from Wikipedia, then “one Newton meter is equal to the moment of force created by a force of 1 N relative to a point located at a distance of 1 m from the mowing line of the force action”.

With regards to the screwdriver, I will explain it as follows. A screwdriver chuck has an axis around which it rotates. Take a screwdriver and place it horizontally with its axis of rotation. Then we take an L-shaped metal bar, in which one of the sides is 1 m long, and the other (no matter how long) will be clamped in the chuck. So, if the side of the bar, which is 1m, is placed horizontally and a weight of 100 g is suspended on its opposite end from the screwdriver, then we will get a torque acting on the cartridge, approximately equal to one newton meter. And if you hang, for example, a load of 4 kg, then we get 40 Nm.

Therefore, if a screwdriver states, for example, that its maximum torque is 40 Nm, then this means that the screwdriver’s motor through the gearbox transfers to the chuck such a force as if we had actually assembled the above structure and suspended a load of 4 kg. We will not take into account the mass of the bar itself.

This is what the torque of a screwdriver is.

Well, in conclusion, I must say that the maximum torque is achieved when the start button is fully pressed. In addition, on two-speed screwdrivers at different speeds, the torque will also be different. on the first more, on the second less.

Also, screwdrivers have a special regulator with a scale with marks from 1 to 15, 20 or another number (as the manufacturer decides) and the last mark in the form of a drill (in this position, you can and should drill), which limits the torque. That is, if you set the regulator to one of the numerical marks, then when a certain value of the moment is reached, the screwdriver does not turn further, but clicks. But if you put the regulator in the “drill” position, then the screwdriver will not click, but will try to tighten what it turns to the last. At the same time, the above numbers do not mean the actual moment itself, but simply show how much more or less you do it (just to navigate faster when working)

I hope I managed to explain the essence of the torque of the screwdriver. On this I take my leave. until we meet again!

How to Set the Torque for Preset Torque Screwdrivers

Torque is the main characteristic of a screwdriver. It determines the diameter of the screw and its screwing depth, as well as the material (wood, concrete, steel, etc.).

The torque is determined by the power of the tool, which depends on the engine and battery. The documentation for the device usually indicates the maximum possible diameter and length of the screw. At the same time, the maximum possible torque reaches 60 Nm, for a domestic tool it is 10-12 Nm.

The efficiency of a screwdriver is significantly increased if it can be used in a pulsed mode (chiselling like a hammer drill).

Types of screwdrivers

According to the power source used, the tool is:

Rechargeable. Cordless screwdrivers are used in everyday life and at work. Battery capacity is 1.5Ah and above, voltage is 10-12V (household) or 18-36V for professional. The most common are nickel / metal / hybrid batteries. Lithium and nickel cadmium are also used. The choice of a cordless screwdriver is very suitable for new buildings where power has not yet been supplied.

Network screwdriver. Powered by a 220V network, the disadvantage is the presence of a network cable (length limitation, some inconvenience during operation).

Pneumatic used in series production, where there are permanent pneumatic power mowing lines.

By the type of work performed, screwdrivers are divided into two groups:

Household (home, amateur). They are used for a small amount of work. minor (episodic) repairs, one-time work (changing doors, assembling furniture).

Professional used for large volumes of work in construction, furniture production, etc.

Special attention should be paid to tools that combine 2 functions. drill screwdriver.

Choosing a screwdriver

First of all, you need to determine its exact purpose:

For home use a simple tool with max. torque 10-12Nm, voltage 12V and battery capacity from 1.2Ah.

For professional work the recommended parameters are as follows:

Max. torque. 60-120 Nm;

battery capacity. more than 3Ah;

such tools are more expensive and require certain skills to operate.

If necessary, you can choose a combined tool. a drill screwdriver, which is often very convenient.

It is also necessary to pay attention to battery charging. If a household battery can be charged for 3-6 hours, then for a professional this time is 40-60 minutes. For reliable operation, it is recommended to have a set of 2 batteries.

The tool can be equipped with special gearboxes to reduce the speed of the electric motor. Gearboxes are usually planetary type, which are small in size, weight at a sufficiently high gear ratio. Such gearboxes easily switch to drilling (drill) mode. In modern screwdrivers there is a torque regulator that allows you to screw in screws with the required force, which prevents thread stripping, grinding of splines and

First, a little background. When choosing a screwdriver, every slightly savvy user will certainly have a question about the torque that he can provide. On this forum, almost half of the topics are devoted to this issue, but there was no consensus. And this is connected, apparently, with the fact that every manufacturer understands by this term who is in what is much. And every tool seller also has his own opinion on this matter. The result is complete confusion. And if the soft / hard moment can still be found in the parameters of the instrument (Although who understands what by this and remains a mystery, therefore it is absolutely impossible to compare instruments by these parameters. For example, an instrument with a smaller soft moment for some reason, judging by the description, can drill holes of a larger diameter or screw in larger self-tapping screws (for some reason, without mentioning their length). Or the ratio of blocking moments at the 1st / 2nd speed does not correspond to the ratio of the speeds themselves. Miracles.), then the information about the range clutch actuation is a mystery covered in darkness. For some reason, almost all instrument manufacturers (with the exception of literally two or three brands) hide this parameter as a state secret. Although, it would seem, what is easier. trying on and listing in the catalog? I was interested in this question in the first place, since the torque limiting clutch is almost the main part of any screwdriver. At least that’s what makes it different from a regular drill.
In short, I decided to check everything myself. I started by looking for torque meters. Such things were found pretty quickly, but I was not ready for their cost. started at a thousand dollars. And then I decided to make such a device myself. In theory, there is nothing complicated here. What is 1 Nm torque? This is the moment created by a force of 1N applied to a 1m long arm. If to the end of a 1m arm we suspend a weight of 1kg, then we get a moment of 9.81Nm (since gravity = mg, and g = 9.81N / kg)). If this shoulder is reduced by 9.81 times, then 1kg will just create a torque of 1Nm. From here the diagram of the device is immediately obtained (see photo). We make a lever with a length of 10.2 cm and hook it to the usual steelyard. I used an electronic balance wheel with a range of up to 20kg, a graduation of 0.01kg and an accuracy of 0.02kg. Since the lever of the required length can be made quite accurately and it is easy to maintain the perpendicularity of the lever and the axis of the balance, the accuracy of our device will actually be determined by the accuracy of the balance. Thus, we have got a torque meter with a range of 0-20Nm and with an accuracy of 0.02Nm. Not every industrial design can boast of such parameters.
Unfortunately, it was not very good to measure the clutch actuation moment with such a device. When the clutch starts to work (crackle), then the moment begins “jump”. And this electronic steelyer takes time to set the readings, i.e. it measures a certain average value, not the maximum, after which the clutch is triggered. Here we need, apparently, some kind of mechanical (non-inertial) balance bar with fixing the maximum value (well, that is, a peak detector). But this device measures the static moment very successfully. And here the results somewhat (to put it mildly) surprised and puzzled me.
I first tried to measure the maximum torque using a simple screwdriver, a pistol grip screwdriver and a small ratchet wrench (see photo). The results are as follows (and, I must say, quite expected):

  • simple screwdriver 3Nm
  • screwdriver with pistol grip 6Nm
  • ratchet wrench 12Nm
    And I really tried my best.
    I was surprised by the results of screwdrivers in position “drilling”. The spindle was tightly blocked and the static blocking moment was measured:
  • Metabo PowerMax (1st speed, “drilling”) 3.8 Nm (with passport data 15 Nm.). I thought the battery might be dead. I put it fully charged, it turned out 4.8 Nm and this moment fell before our eyes due to the discharge of the battery. On the next attempt, the same 3.8 Nm was obtained.
  • AEG BBS 14 KX Raptor (1st speed, “drilling”) 18Nm (with a static blocking torque according to the passport 40Nm.).
    And how do you order this to be understood?
    I’ll try again with the old Metaboy, I’ll bring it from the dacha.

Give all the shura to OlegCh for measurements! Find out the truth.