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Any tool store can now offer a fairly large assortment of various welding machines of various price category. Most welding units, up to 70%, are occupied by welding inverters, and other "welders" fall on transformer-type devices. Not all people can buy industrial product for the production of electric welding, and some want to do it themselves.
Home welding machine will not be able to perform complex tasks, but for small jobs there will be enough power.
What is electric welding
Compound metal products between themselves by heating the metal with an electric arc and then fusing it into an integral seam is called electric welding. The main equipment in such a welding process is the welding machine, and the main tool for connecting metal things is the electrode. The welding unit serves as a source of alternating or direct current, which, by means of an electrode, ignites an arc that melts the metal. The quality of the welded joint when welding with direct currents is much higher than the same joint made by "change". The experience of an electric welder should not be discounted, although welding inverters that are popular today allow high-quality welding of metals almost the first time. That is why for most of the various welding works, welding machines are used that use a direct current type in their work.
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The simplest welding machine: instructions
For small home welding work, you can assemble a home-made compact machine with low power. This, of course, is not an inverter, but a necessary thing. When solving the problem of creating a welding "assistant", you can use various design features.
The simplest welding device is welding transformer with two windings: network and working. The network is calculated for the mains voltage, usually 220-240 volts, and the working one is calculated for a lower voltage from 70 to 45 volts, and the change in current usually occurs by changing the number of turns of the working winding, its taps. As iron for transformers, you can use old asynchronous motors or industrial step-down three-phase transformers of the TOZ type, etc.
The primary winding should be designed for 25 ampere current, the secondary or working one - for 160 A. This is reflected in the cross section of the wires used. For an approximate estimate of the current load per 1 sq. mm allow 10 A, for aluminum - 4 A. We determine the cross-sectional area of \u200b\u200bthe window of transformer iron in square meters. cm, then we find the number of turns of the windings, if right amount for one volt is defined as 48 divided by the sectional area of the iron window of the transformer. Calculating the device is half the battle, the main thing is to assemble it.
The product created according to calculations is the simplest welding device alternating current, the design of the apparatus depends on the materials used.
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Let's make a DC welding machine with our own hands
In order for AC welding machines to turn into DC "welders", it is necessary to limit the rate of current change with a choke and rectify the alternating current with diodes or a rectifier bridge.
Diodes must be capable of 200A output current and have sufficient cooling so that the first welding does not damage them. This fully applies to the throttle. The use of these devices in conjunction with an AC welding machine turns it into a DC machine. It becomes possible to weld with DC electrodes, and the range of weldable metals is expanding. Stainless steel and cast iron become available for welding. The welding machine can cook like an inverter, although here the welder needs quite a lot of experience.
A semi-automatic welding machine is a fairly popular device among professional and home craftsmen, especially those involved in body repair. This unit can be purchased ready-made. But many owners of inverter welding machines are wondering: is it possible to convert the inverter into a semiautomatic device so as not to buy another welder? Making a semiautomatic device from an inverter with your own hands is a rather difficult task, but with strong desire quite feasible.
To assemble the unit, you will need the following items:
- inverter welding machine;
- a burner, as well as a special flexible hose, inside which a gas pipeline, a wire guide, a power cable and an electric control cable pass;
- mechanism for uniform automatic wire feed;
- control module, as well as a motor speed controller (PWM controller);
- protective gas cylinder (carbon dioxide);
- solenoid valve for cutting off gas;
- coil with electrode wire.
To assemble a homemade semi-automatic from welding inverter, the latter must produce a welding current of at least 150 A. But it will have to be slightly upgraded, since the current-voltage characteristics (CVC) of the inverter are not suitable for welding with electrode wire in a shielding gas environment.
But more on that later. First you need to make the mechanical part of the semiautomatic device, namely the wire feed mechanism.
Wire feed mechanism
Since the feeder will be placed in a separate box, it is ideal for this purpose. computer system case. In addition, you do not need to throw away the power supply. It can be adapted to the operation of the broach mechanism.
First, you need to measure the diameter of the wire spool or, having outlined it on paper, cut out a circle and insert it into the body. There must be enough space around the reel to accommodate other components (power supply, hoses and wire feeder).
The wire pulling device is made from a windshield wiper mechanism from a car. Under it, it is necessary to design a frame that will also hold the pressure rollers. The layout must be drawn on thick paper in real scale.
Advice! The connector for connecting the burner hose and the hose with the burner itself can be made by hand. But it would be better to buy a ready-made kit that has an affordable price.
The feeder should be installed in the housing so that the connector is in a convenient location.
In order for the wire to be fed evenly, all components must be fixed exactly opposite each other. The rollers must be centered in relation to the hole for the inlet fitting, which is located in the connector for connecting the hose.
as roller guides use suitable diameter bearings. on them with lathe a small groove is machined along which the electrode wire will move. For the body of the mechanism, you can use plywood 6 mm thick, textolite or durable sheet plastic. All elements are fixed on the basis, as shown in the following photo.
Used as primary wire guide axially drilled bolt. The result is something like a wire extruder. At the inlet of the fitting, a cambric reinforced with a spring is put on (for rigidity).
The rods on which the rollers are fixed are also spring-loaded. The clamping force is set using a bolt located below, to which the spring is attached.
Advice! If for some reason you do not have the opportunity to make a wire pulling mechanism with your own hands, then you can buy it in China. 12 V and 24 V mechanisms are available for sale. This case, since you are using a power supply from a computer, you will need a device powered by 12 V.
The basis for fixing the bobbin can be made from a small piece of plywood or textolite and trimming a plastic pipe of a suitable diameter.
Mechanics control scheme
To achieve good quality seam when welding, it is necessary to ensure that the wire is fed at a certain and constant speed. Since the motor from the wiper is responsible for the feed rate of the equipment, a device is needed that can change the speed of rotation of its armature. Suitable for this turnkey solution, which is also available in China and is called
Below is a diagram from which it becomes clear how the speed controller is connected to the engine. The regulator of the controller with a digital display is displayed on the front panel of the case.
Next, you need to install relay control gas valve . It will also control the start of the engine. All of these elements must be activated by pressing the start button located on the burner handle. In this case, the gas supply to the place of welding should be ahead (by about 2-3 seconds) of the start of the wire feed. Otherwise, the arc will be ignited in an atmosphere of atmospheric air, and not in a shielding gas environment, as a result of which the electrode wire will melt.
A delay relay for a homemade semiautomatic device can be assembled based on the 815th transistor and capacitor. To get a pause of 2 seconds, a 200-2500 uF capacitor will be enough.
Advice! Since the power comes from a computer PSU that outputs 12 V, instead of self-manufacturing module, you can use an automotive relay.
It is placed in any place where it will not interfere with the operation of moving parts, and is connected to the circuit according to the diagram. Can be used air valve from GAZ 24 or buy a special one designed for semiautomatic devices. The valve is responsible for the automatic supply of shielding gas to the burner. It turns on after pressing the start button located on the semi-automatic burner. The presence of this element significantly saves gas consumption.
But as already noted, the current-voltage characteristics (CVC) of the inverter are not suitable for the full operation of the semiautomatic device. Therefore, in order for the semi-automatic prefix to work in tandem with an inverter, in its wiring diagram minor changes are required.
Changing the I-V characteristic of the inverter
There are many schemes to change the I-V characteristic of an inverter, but the easiest way to do this is as follows:
- assemble the device using throttle from fluorescent lamp according to the scheme below;
- to connect the assembled device, you will need to assemble another block according to the following scheme;
- In order to prevent the inverter from triggering the overheating sensor, an optocoupler must be soldered (in parallel) to it, as shown in the following diagram.
But if the welding current is controlled in the inverter with a shunt, then you can collect a simple circuit of three resistors and a mode switch as shown below.
As a result, the conversion of a welding inverter into a semiautomatic device will cost 3 times cheaper than an already finished unit. But of course, for self assembly the device will need to have certain knowledge in the radio business.
This article begins a new section "Tools and fixtures", and the article will be somewhat unusual, that is, it will not be about what and how to make, but on the contrary, what should not be done.
Thanks to the amazing productivity of the inhabitants of the "Celestial Empire" and affordable cost, welding machines - "inverters" have firmly established themselves in the garages of many car owners. And for good reason: small size, light weight, wide and smooth current adjustment range, “soft” arc, low power consumption make this welding machine simply an invaluable assistant in many cases, but not always, a car “tin” is often too gentle for welding with an electrode . And then in the inquisitive minds of motorists, thoughts begin to be born: what if we add a burner, a wire puller and convert the “inverter” into a “semiautomatic” at low cost. I must say right away that this option will not work, nor will such an additive be added to a conventional welding machine on a transformer. Why? Read on.
Semiautomatic torch and welding wire
In order not to be unfounded: I have a DC welding machine on a transformer in my garage, and a few years ago I made a semi-automatic machine myself (also a transformer, which I successfully use), and this year I purchased an inverter welding machine (it’s hard to carry the transformer myself). I decided to test this possibility "empirically", especially since everything you need is available, and no costs are needed. I turned off the transformer in the "semiautomatic device", applied power from the "inverter", tried it ... To be honest - I tried it on different modes, regulated the current, changed the wire feed speed, cooked with gas and without ... a normal seam did not come out, it turned out to put it mildly "shit".
Now for some theory. Without this, in any way, but I will try to be as simple and concise as possible.
Types or types of welding.
MMA (ManualmetalArc). The most common type of welding is manual welding with stick electrodes coated with flux, by the way, this technology developed by our compatriot N.G. Slavyanov.
TIG (TungstenInertGas). Welding with a non-consumable (tungsten or graphite) electrode in a shielding inert gas (argon-arc welding). Invented by N.N. Benardos.
MIG (MechanicalInertGas). Mechanized supply of electrode material (semi-automatic or automatic) in an inert gas environment (argon, helium).
MAG (MechanicalActiveGas). Mechanized supply of electrode material (semi-automatic or automatic) in an active (carbon dioxide) gas environment. which interests us the most. By the way, alloyed wire (we use copper-plated wire) was also invented by our compatriots K.V. Lyubavsky and N.M. Novozhilov.
Now let's see how the power sources differMMAandMAG,and why they cannot be used one instead of the other.
To begin with, consider the conditions for the existence of an electric arc used in welding. In the above graph, it is noticeable
that the current-voltage characteristic of the arc (CVC) has three pronounced sections:
- descending section- which corresponds to a low current density,
- horizontal section– with average current density
- ascending section- which corresponds to a high current density.
So, at manual weldingMMA the process of arc burning occurs in the middle section of the CVC, preferably in its first third, while the arc ignites easily, keeps stable, the seams are even and the metal does not spatter (at the same time, fluctuations of the electrode (welder's hand) and changes in the arc length practically do not cause a change welding current. If the current density increases and the burning point of the arc shifts to the ascending section, then the arc becomes unstable, “hard”, the metal splashes, the seams come out torn and uneven.
When welding semi-automaticMAG the point of the arc should be located at the beginning of the ascending section of the I–V characteristic, with high density current, thus there will be a self-regulation of welding process.
Each type of welding must correspond to the power source of the welding machine, be it an inverter or a transformer. For clarity, another graph,
which depicts external current-voltage characteristics of power sources of welding machines.
Curve 1 corresponds to the steeply falling I-V characteristic of the power supply, which is almost perfectly matched for manual welding on direct current MMA, curve 2 - gently dipping current-voltage characteristic, curve 3 — rigid V-characteristic, providing self-regulation when welding with thin wire MAG.
Conclusion: DC manual welding power source is designed and manufactured with steeply falling CVC , which absolutely not suitable for welding wire electrode in semi-automatic mode . With regard to the inverter power source, alteration and reconfiguration of the control unit is required, but if you are not very strong in electronics, then it is better not to climb into a well-established mechanism.
The use of a semi-automatic welding machine makes it easier to work with metals. This technique can easily connect various alloys. You can make a semi-automatic welding machine with your own hands from an existing inverter, and homemade unit will be distinguished by versatility and functionality in use, allowing you to save on the purchase of industrial equipment.
Design features
A design feature of the semi-automatic welding machine is the constant supply of melted wire to the welding zone, which is used instead of metal electrodes. Wire feeding is carried out automatically, with the possibility of changing the speed of the flexible electrodes. The used welding wire will ensure constant contact of the surfaces to be joined, such material has a lower resistance compared to standard electrodes, which improves the quality of the connection.
Semi-automatic welding is versatile, which allows using this technology to weld metals of various characteristics, including stainless steel, non-ferrous alloys, aluminum and others. master correct technique semi-automatic welding is not difficult. Homemade devices are easy to use, so they can be recommended to ordinary homeowners. Depending on their variety, semi-automatic machines may have an additional nozzle for supplying gas, and the joining of metals is carried out in a protective environment, which makes it possible to exclude the subsequent formation of corrosion in the weld.
The inverters for welding offered today in stores are versatile, and many of them have an implemented two-in-one function. With low power and dimensions, a two-in-one semiautomatic device can work with refractory metals and thick metal blanks.
Many homeowners who often have to perform welding work decide to manufacture such equipment themselves. The advantages of homemade semiautomatic devices from an inverter include the following:
Among the shortcomings of this technology and the equipment itself, one can note the high cost of semi-automatic devices, which, with characteristics similar to those of an inverter, can have a price two to three times higher. It is not surprising that many homeowners decide to make equipment with their own hands, which can significantly reduce costs without losing the quality of the completed apparatus.
DIY manufacturing
The easiest way is to make a homemade semiautomatic device from an inverter based on a powerful power unit. You can make an inverter yourself or use it from the equipment at your disposal. For a semi-automatic device, inverters with a capacity of at least 150 amperes should be used.
There are schemes for reworking equipment that allow you to set the power that will be enough for semi-automatic welding. A device of this type will be difficult to implement, therefore, only experienced radio amateurs who can make truly complex equipment can be recommended to use low-power power units.
Craft quality equipment it is possible if you have a starting circuit of a semi-automatic welding inverter on hand. The characteristics of such a unit include the following:
- Primary current - 8-12 A.
- Supply voltage - 220 or 380 volts.
- The open circuit voltage is 36-42 Volts.
- Welding current - 40−120 amperes.
- Voltage adjustment in plus or minus 20% increments.
it optimal parameters for a household welding semi-automatic device that will cope with metals of various refractoriness. Subsequently, using additional drawings to increase the power of the inverter, you can change basic characteristics, which allows the use of such equipment for domestic and industrial purposes.
Required Components
To make a semi-automatic garage welding machine with your own hands, you will need the following:
- Torch prefix for the inverter.
- Wire feeder.
- Robust inner hose for welding wire.
- Bobbin with wire.
- Sealed gas hose.
- Inverter control unit.
The easiest way is to place the inverter and the mechanical control unit in a separate box, for which they use blocks from an old computer. The presence of power in the system unit can significantly simplify the manufacture of equipment.
The roller mechanism for the wire can be made from a motor from a car windshield wiper. Under such a motor, a mechanism frame is designed, which is cut out of metal elements and welded or bolted together.
The burner and hose can be made independently from a gun from polyurethane foam and silicone. You can also purchase ready-made kits, which will ensure the safety of working with a semi-automatic device and simplifies its manufacture.
When making a wire feed mechanism, all the components used must be placed opposite each other, which will subsequently ensure a uniform supply of flexible electrodes. The rollers should be centered relative to the fitting in one slot, in the future this will allow you to smoothly change the wire feed speed. A diagram of the wire feed speed controller of a semi-automatic welding machine can be easily found on the Internet.
All used metal elements should be fixed on a sheet of plywood, thick plastic or textolite. Since electricity is supplied to the metal elements used, the grounding of each node should be checked. This will eliminate the possibility of short circuits, which can lead to serious damage to equipment.
Mechanics control scheme
A small electric motor and a broaching mechanism will be responsible for feeding the welding wire, the operation of which is controlled by a PWM controller. The quality of the welding performed will directly depend on the uniformity of the welding wire feed in working area. It is necessary to pay due attention to the correct manufacture of semi-automatic welding circuits.
A variable resistor of the controller is installed on the front panel of the inverter, after which they begin to assemble the relay for starting the motor and controlling the valve, which is responsible for supplying inert gas. The contact groups of the controllers must operate simultaneously when the start button on the burner is pressed.
The work of the gas supply must be adjusted so that the valve opens a few seconds before the wire begins to enter the welding zone. Otherwise, melting occurs in the atmospheric environment, after which the wire will begin to burn instead of the melt. It will be impossible to achieve a high-quality connection and a reliable welding seam when the wire burns.
To delay turning on the wire feed, you need to make a simple relay, which requires a capacitor and an 875 transistor. You can use the simplest relay from a car that connects to 12 volts on a computer power supply.
The valve itself can be used from various automotive locking devices. The easiest way is to redo the air valve from the GAZ-24 car. You can also choose an electrovalve from a reducer from gas cylinders.
All available controls and the PWM wire feed controller of the semi-automatic welding machine are located on the front panel of the system unit. A ready-made inverter with a power of at least 150 amperes is connected to the control unit and the wire feed controller with gas. It remains to carry out a test run and, if necessary, make appropriate adjustments to the operation of the welding wire and shielding gas supply system.
During operation, the power unit of the inverter semiautomatic device will heat up, which can lead to damage to the inverter and control boards. Repair of the unit after such breakdowns will be extremely difficult. To avoid this, it is necessary to install temperature sensors and coolers inside the inverter and the system unit, which can effectively cool the operating equipment.
You can use an optocoupler, which is connected to a common control unit for the operation of the equipment. If the temperature inside the inverter is exceeded, the sensors will send appropriate signals to the executive relay, which will turn off the power supply until the device is completely cooled down.
Additionally, various coolers from old computers can be used to cool the system unit. Coolers will vary in size. You can choose a fan that will cope with high-quality cooling of the system unit, inside which there is an inverter and other automation. The cooler used is connected to a 12-volt power supply directly or through a thermal sensor, which, when the temperature inside the case rises, will send a signal to supply voltage. The control unit will turn on the fan, which guarantees rapid cooling of the body of the semi-automatic device.
Assembling a semi-automatic welding machine is not particularly difficult, so every homeowner can handle this job. It is only necessary to use a high-quality powerful inverter, and it is best to take a burner with a drive from industrial factory semi-automatic devices. This will greatly simplify the manufacture of equipment. On the Internet you can find various schemes execution of semi-automatic welding machines, which will not be difficult to implement. Such a device will differ in functionality and versatility in use..
Among beginners and professional welders, the inverter-type semi-automatic welding machine is the most popular device. For the first, it provides ease in acquiring welding skills, for the second it gives performance and a large set of additional settings.
Semi-automatic welding equipment can be useful for almost any welder, but it comes at a fairly high cost. If you have manual arc welding, you can convert it into a semi-automatic inverter type.
The semi-automatic welding machine is initially designed to work with filler wire in a shielding gas environment (inert or active). Its difference from conventional apparatus manual arc welding consists in the presence of a wire feeder, a gas cylinder, a special burner and a control unit for the supply of gas and additives.
The power supply itself in the form of an inverter is no different. If the feed mechanism is built into the inverter housing, then there is an additional wire connector.
Therefore, many owners of manual arc welding machines eventually have a desire to expand their capabilities and make a home-made semi-automatic device. It can be implemented very easily. There are several implementation options, which one to choose depends on the availability of funds, time and desire.
Multifunction devices
Some manufacturers of manual arc welding inverters, taking into account the desires of customers, have provided the required additional connectors. They help to convert the device into a semi-automatic device as quickly as possible.
Some models of inverter devices of the "Source" type on the rear panel have a key for switching the operating mode from MMA to MIG and a connector for controlling the on / off of the inverter. are usually completed with a 3 m euro hose with a burner at one end and a connector at the other.
The connector allows you to supply welding wire and shielding gas, in addition, a cable passes through it to supply control signals to the electric motor for drawing the filler and connecting the gas.
There is a special cable for connection to the inverter apparatus. It must be connected to the connector through which the welding current from the inverter was supplied to the electric holder. Now, in a semi-automatic, it will go to the MIG torch.
The second cable powers the feeder from the inverter, if provided with the appropriate connector, or from another low-power 12V DC source.
Before work, the required gas flow rate is set on the gas cylinder, and the feed rate of the additive is set on the broach mechanism. The inverter sets the welding current, the value of which depends on the thickness of the metal being welded.
Then they start welding. As you can see, the transformation of manual arc welding into a semi-automatic does not need to be altered, it is enough to buy the missing equipment. The only drawback is that the inverter will come with a puller attachment.
Tractor
In more difficult case the manufacture of a semiautomatic device consists in altering the arc welding inverter and creating a broach device from improvised materials. If you had to repair the inverter apparatus, then you can safely implement the second option.
The system unit is ideal as a housing for the inverter-type semi-automatic broach device. It is quite easy to open, yet roomy and durable.
This will allow you to simply adjust the pressure of the rollers and install the wire spool. In favor of the system unit and the fact that it is easy to make holes in the right places, and there is a built-in power supply for 12 volts. It is needed to power the additive broach drive and the gas valve.
For the necessary fasteners, it is necessary to make mock-ups of built-in components from improvised materials and try them on inside the box. After making sure that the selected layouts are correct, you can start manufacturing fasteners.
You can buy a semi-automatic coil ready-made or make it yourself. It is very easy to manufacture. The diameter of the jaws should be 200 mm, and the cylinder on which the wire will be wound should have a diameter of 50 mm, so that it can be used as an axis plastic pipe with the same denomination.
The feed mechanism will require two pressure and one guide roller, spring. As a broach motor, it is possible to use an electric motor from the wipers. As a base on which the parts will be attached, you need to use a metal three-millimeter sheet.
Holes are drilled in the plate in the right places for attaching the rollers and the motor shaft of the future semiautomatic device. Since one roller is a pressure roller, an oblong-shaped hole is drilled for it.
A clamping spring will press on it from above, the force of which is regulated through a screw. The roller and bearings are mounted on one side of the plate, and the motor on the other. A feed roller is mounted on the motor shaft.
The resulting device is installed inside the system unit so that the place of alignment of the rollers and the axis of the MIG torch connector are in the same plane. This will prevent the crease of the wire when pulling. To straighten the additive during unwinding, a tube is installed in front of the rollers.
Control node
To supply gas and additives to a semi-automatic welding machine, you will need:
- 2 relays;
- diode;
- PWM regulator;
- capacitance with transistor and resistance;
- solenoid valve;
- wires.
A valve is required to allow gas to enter the welding zone. All components can be purchased at the sale of used parts.
The control schemes in an inverter-type semiautomatic device may be different, but their essence is simple and is as follows.
Pressing the button on the burner switches both relays. The first energizes the valve that opens the gas supply.
The second relay supplies power to the wire feed motor. But its inclusion occurs a little later due to the filter low frequencies in the form of an RC chain formed by a capacitor and a resistor.
Sometimes it is required to pull the wire without gas supply. For this case, an additional button is provided, which provides a broach, bypassing the gas relay.
Self-induction from the valve is removed by connecting a diode. To power the burner from the MIG inverter, you need to install an additional one next to the euro connector, through which the current will flow.
When the button on the burner is turned on, the gas flow begins, after a while the additive is supplied. The delay time is regulated by the selected capacitance and resistor values. A pause in an inverter-type semi-automatic device is necessary to protect the weld pool from the effects of atmospheric air with gas.
When the button is turned on, voltage is supplied to the capacitance. Gradually, it charges, when a certain value is reached, the transistor opens, which causes the relay to turn on.
Burner
A burner for an inverter-type semi-automatic welding machine can also be made by yourself, but it is easier to purchase inexpensive model with sufficient welding current.
With self-production, you still need a euro connector and a supply cable if you want to get an aesthetic semi-automatic welding machine as a result. In addition to the welding current, the length and flexibility of the hose must also be considered.
Excessive softness of the hose leads to a kink and, accordingly, to the braking of the wire. A good addition is a spring or a strong rubber seal at the junction of the hose with the burner and the connector. This will not allow him to break in these places.
inverter
The manual arc welding inverter also needs to be redone. Although it can be used without alterations, the welding quality will then be lower than that of semi-automatic factory welding machines. It's all about the volt-ampere characteristics. The difference is minor, but it does matter.
To eliminate these differences, you will need a toggle switch, three resistances, one of which is variable.
To adjust the characteristic, it is necessary to install a divider in front of the shunt that controls the current. By changing the parameters of the divider, an adjustment will occur. The toggle switch is needed to switch the inverter operating mode from manual arc to MIG.
As a result of the refinement of the inverter and the independent manufacture of the filler wire drawing device, semi-automatic type welding equipment is obtained with good parameters. At the same time, save money and get a lot of pleasure from the fact that you did everything yourself.
If you have to engage in professional welding, then it is better to purchase a ready-made semiautomatic device. To date, the choice of these devices is wide, and it is quite possible to choose a budget model of acceptable quality.
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