DIY miniature welding machine. How to create a welding machine with your own hands. How to make a transformer welding machine yourself: materials and tools

It is difficult to do without a welding machine in construction, installation and repair. Usually they buy equipment in finished form. However, you can go the other way: make the welding machine yourself, because a self-made device will save a lot of money and will become an exciting thing for those who like to craft.

About connection methods, windings and electrode

Exist different kinds welding machines. The most common mistake novice craftsmen make is the desire to immediately make a complex device. Schemes for the production of a welding machine are easy to find on the Internet, it is best to give preference to the type of equipment, the manufacture of which will not cause significant difficulties and will not take much time. Repairing your own welding machine will not bring big problems and a significant financial outlay for the person who made the equipment.

A logical question immediately arises: which welding machine is best suited for working at home? Only small size. The best solution to the problem would be to create an apparatus from the devices already at the disposal of the craftsman. For work, a three-phase transformer is required. Primary must be connected. At the welding machine, this is done on the “triangle” magnetic circuit. This method is used only for the device, which is planned to be connected to a three-phase network with a voltage of 380/220 V.

The power supply and the specifics of the design of the apparatus are the task, the solution of which must be paid attention in the first place. If the power supply and the internal structure of the equipment do not match, this will lead to the fact that the equipment, which took time and effort to create, will pose a danger to human life and health. If the welding machine is to be powered from a single-phase 220 V network, the connection of the primary winding of the transformer must be made differently. The extreme rods of the magnetic circuits of the apparatus are connected in an anti-parallel manner. For such a welding machine, a different principle of fastening the secondary windings is used: a fixed circuit.

If the device is powered by a single-phase 220 V network, it also differs in the features of the additional winding. It is wound on all the windings of the electric wire that the welding machine has. What is it for? During welding, stepwise changes in the welding current occur. They need a ballast, whose role is played by an additional winding. Her distinguishing feature: 40-50 turns. For a small-sized welding machine, a two-stage regulation of the electric power supply is most suitable.

Beginners often choose the wrong electrode size for the device.

In order to make a DC welding machine yourself, you need a high-power power source that is capable of converting the rated voltage of a conventional single-phase network and providing a constant value of the corresponding current. This is necessary in order to create and maintain a normal electric arc.

For a high power power supply, the following components will be required:

1. Rectifier.
2. Inverters.
3. Current and voltage transformer.
4. Current and voltage regulators (to improve the quality characteristics of the electric arc itself).
5. Auxiliary devices.

There is a simple rule that will help you make the right choice: the stronger the electrical network and the thicker the wiring, the larger the electrode should be.
The main components of the welding machine:

1. Transformer magnetic circuit.
2. primary windings.
3. secondary windings.
4. Additional winding.
5. Remote capacitors.
6. Welding mode switch.
7. Contact temperature sensor and an audible alarm.
8. Welding mode switches.

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Why is concrete needed?

The body of the welding machine is an important issue. For the manufacture of cases of such equipment, it is customary to use specially prepared concrete. It should have a good indicator of plasticity. The one that most easily takes the desired shape and freezes in the shortest possible time is suitable.

The hull will require fine-grained sand and cement. The first should be 75% of the dry mix of concrete, the second - its fifth. The remaining 5% of the dry mixture is PVA glue and glass wool in a 1: 1 ratio. Instead of glue, water-soluble latex can be used.

Many novice craftsmen believe that making a welding machine is much easier than making its body. In fact, there is nothing complicated if you perform all the actions sequentially. Main mistake– Wrongly selected body thickness, it should not be less than 1 cm. The welding machine must be cleaned. Then the device is dried and only then proceed to the manufacture of the case. When the concrete has hardened, the welding machine must be processed from the outside. This requires an organic monomer.

For this task, styrene or methyl methacrylate is suitable. Once the concrete has been impregnated with the monomer, it is necessary to heat treat the surface. The temperature for these purposes must be at least 70 0 C. In this case, the polymerization of the monomer occurs. As a result of this procedure, a waterproof layer is formed on the body of the apparatus itself. After it, the welding machine will be protected from the effects of the external environment.

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The easiest way

Spot welding is most in demand in everyday life, but often a person simply does not have time to manufacture the complex interior of the welding machine. If it causes difficulties, you can resort to the most primitive solution to the issue. Check: what faulty household appliances are in the house.

If a microwave oven breaks down, do not rush to throw it away - with new electrical wiring, pieces of wood, clamps and tips - a spot welding machine can be made very quickly.

You will need:

1. Washers.
2. Self-tapping screws.
3. Staples.

They must correspond to the intended dimensions of the welding machine. If the broken microwave oven the transformer is working, it will become the basis of the new home-made equipment.

In everyday life, especially in a rural courtyard and suburban housing, there is a type of work on a mini-farm that is simply impossible to do without. This is the connection or cutting of any iron, non-ferrous metals and aluminum (in a protective gas environment) using electric arc welding. Hiring craftsmen for them is more expensive.

Why do you need a welding machine

Craftsmen without welding will not assemble a single mechanical device or mini-transport to facilitate work in the field, garden, orchard, transportation of a lot.

It is clear that you cannot become a welder in an instant, you need to learn or at least practice with professionals. And, of course, assemble it yourself or purchase a store device for the formation of an electric arc.

And our advice will help them navigate the range and models. Because this market is filled with both reliable in work, but expensive, and cheap, but useless due to poor quality or for primitive welding.

Typification of electric arc devices

Similar household devices are of the following types:

• types of current;
• three-phase for 380 v.;
• inverter.

Devices for home assembly are most suitable for people with little skills in an electric circuit based on currents - direct and alternating.

Although there are several variations with the first current, and a beginner can get confused in them. We recommend them for those trained in electricity.

And below we will consider how to make a welding machine with your own hands quickly and efficiently.

Transformers. These devices lower the voltage and increase the current to form an electric arc. For example, instead of 220 volts, you get 17-45, but with a current of up to six hundred amperes (home welding needs no more than 160 amperes, the optimum is two and a half hundred).

The current is adjusted in steps. You can make a simple addition to this from high-voltage triodes and diodes with adjustable resistance. Or connect a few turns of thick metal (copper) to reduce the current. The scheme of the welding machine is shown on the site, you can also see it on the video.

In addition, they also perform a second function - they generate direct current with the help of built-in rectifiers, also for welding.

The largest number of homemade products are created on the basis of the transformation of current and voltage in one direction or another. Their properties are enough for simple electrical work in everyday life.

Rectifier. It is also a welding unit, but for high-quality work and with a variety of metals. They are not made in everyday life. And to acquire such a device, by the way, is not cheap, it is worth it only for long welding processes and for creating especially strong seams.

For example, in case of major traffic accidents with significant damage to the car body. Given the thin metal, so as not to burn it and make the necessary connections, which are not inferior in strength to factory ones.

Inverters (from English - converters). First, about the classification of currents: there is direct (DC) and variable (AC).

Scientists from Edison to the equally famous Nikola Tesla have been interested in these transitions from one to the other. This is how the inverter welding machine was born.

The current transformation in it is multi-pass. The amplitude current turns into a direct current, and that, by means of a welding transformer, again goes out either in DC or in AC.

Both, looking at which the circuit is set, then turn into an electric arc with a gradual change in its parameters in the required ranges.

It is difficult to create it at home, but on sale it is massive, despite the significant high cost.

What is "cooking"?

The current strength depends on the tool that you use to weld - the electrode.

Its thickness is tied to the thickness of the parts to be welded: if they are equal to five to six millimeters, then the electrode should not be thinner than four. This is the maximum on homemade products.

You can reduce electricity consumption if you cook sizes with thinner cores (up to one and a half cm). In this case, the current will decrease by five times.

Installation of a welded unit in the form of a transformer

For this you need:

• a set of plates for a magnetic circuit - in the bazaars from burnt windings, buy inexpensively or in disassembly;
• large-section wire for both types of windings.

The basis for them is steel plates no thinner than a third of a millimeter. You assemble them into a rectangle with a large internal space, where the primary and secondary windings should fit on the two vertical sides.

The number of turns depends on the area of ​​the steel frame, it is easy to calculate it with a ruler and arithmetic. And divide the amount in half.

The thickness of the wire is calculated according to the following scheme: divide the installed kilowatts of the welder by two thousand and multiply by one with thirteen hundredths.

How is the construction of the welding machine assembled. First, the primary winding is wound, start layer by layer, isolate the entire winding, bring it to the contact plate with four fasteners: the beginning and end of the winding for connecting 220 V., two more taps from 165 and 190 turns. Taps - current variators.

The secondary winding goes like this: out of 70 turns 40-41, the primary is covered on top, the remaining turns go to the other side.

Also bring its ends to getinax (textolite) - from here the “plus” and “minus” will go one to the welding lever, the second to the part to be welded. The device is ready to work. Take a photo of a homemade welding machine.

During long-term operation, it is possible to repair the welding machine: tightening the fastening of the plates (vibrate), contact plates.

Photo tips on how to make a welding machine with your own hands

In construction, installation and repair work welding machine is used. Usually the design is purchased ready-made, but you can make it yourself. In this case, there is a significant savings in money. Moreover, this process can captivate those who like to engage in the manufacture of something new.

Connections, electrodes and windings

In order to assemble the welding machine with your own hands, you need to decide on the scheme on the basis of which the work will be carried out. Even before the start of the main work, it is worth considering how the unit will be powered. If the voltage is higher, then the use of the device may harm human health.

Usually, a single-phase 220 V network is used to power the equipment. In this case, it is necessary to use an additional winding (special ballast), with the help of which the periodically changing electric current during the welding period.

Before assembling a welding inverter with your own hands, you need to purchase:

• Transformer magnetic circuit.
• Remote capacitor devices.
• Welding mode switch.
• Several types of windings (primary, secondary, additional).
• Regulatory devices that help to establish the optimal welding mode.
• Special heat sensors.
• A device that notifies you with sounds about the optimal mode of operation.

Why Use Concrete

Before you make an inverter welding machine with your own hands, you need to make a case. It is made of specially prepared concrete, characterized by a high degree of plasticity. This material is able to quickly harden and become the desired shape.

The hull is made from fine-grained sand and cement in certain proportions. You should take 75 percent sand, 20 percent cement. In addition to these components, it is necessary to add an equal amount of PVA glue and glass wool. Sometimes the glue is replaced with a water-soluble latex material.

Novice craftsmen believe that the unit is quite easy to assemble with their own hands, in comparison with the creation of its body. With sequential work, the structure is assembled quite quickly.

The body must be at least 1 cm thick. The welding machine is cleaned, followed by drying, after which the body is started to be made. After waiting for the concrete to harden, spend external processing aggregate using an organic monomer.

To cope with this task, experts recommend using styrene or methyl methacrylate. They help to heat treat the surface of the device. In this situation, a temperature above 70 degrees Celsius should be applied.

As a result of monomer polymerization, a waterproof layer is formed on the surface of the unit body. It is he who protects the surface of the structure from environmental influences.

Simple design

For the layout of the welding machine, you can use faulty household appliances. For example, you can use a failed microwave oven. Together with it, you should take electrical wiring, clamps, wooden parts and tips.

Taking all these components, it is possible in a short time, even with minimal knowledge in the field of technology, to produce the design of an apparatus for spot welding.

Parts inside the unit are fixed with self-tapping screws, washers or brackets of appropriate sizes. It is optimal to use a serviceable transformer of a broken microwave oven, from which equipment is made by hand.

Assembly process

They begin work by removing the secondary winding from the transformer. This operation requires accuracy. It is carried out with an angle grinder.

Next, the lamellar core is removed from the surface of the secondary winding. After carrying out the operation on the transformer, parts cut off on both sides can be found. With their help, the work will be better. Ideally, it is necessary to ensure that the insulating layer on the core is free of any defects.

Then the magnetic shunt is attached. During its normal functioning, the work of a do-it-yourself welding machine is carried out. Then the transformer is rewound using a thick wire made of copper material. If the core is damaged, it needs to be repaired. If the defect is minimal, then the site is isolated.

At the next stage, it is necessary to put the transformer on a wooden block, securing the top and bottom of the workstation with brackets. If the electrodes are attached qualitatively, then the unit will work better. If there are defects in the contacts, it will be difficult to weld the elements.

The fixation of the electrodes on the upper and lower parts of the bar is carried out with self-tapping screws. Then winding wires are connected to them. It is necessary to properly fix the copper terminals using pliers, which is usually very difficult for beginners. The structure is ready. Then it is necessary to check whether something can be welded using the unit, while it is important to follow the safety regulations.

Usually, it is not difficult to assemble a welding machine even for those people who have minimal technical knowledge. For this you can use step by step instructions with photos at all stages that exist a large number of on the Internet.

DIY welding machine photo

Inverter welding is a modern device that is widely popular due to the low weight of the device and its dimensions. The inverter mechanism is based on the use of field effect transistors and power switches. To become the owner of a welding machine, you can visit any tool store and get one useful thing. But there is a much more economical way, which is due to the creation of do-it-yourself inverter welding. It is the second method that we will pay attention to in this material and consider how to do welding at home, what is needed for this and what the circuits look like.

Features of the operation of the inverter

An inverter-type welding machine is nothing more than a power supply, the one that is now used in modern computers. What is the basis of the work of the inverter? In the inverter, the following picture of the conversion of electrical energy is observed:

2) The current with a constant sinusoid is converted into an alternating current with a high frequency.

3) The voltage value decreases.

4) The current is rectified while maintaining the required frequency.

The list of such transformations of the electrical circuit is necessary in order to be able to reduce the weight of the apparatus and its dimensions. After all, as you know, old welding machines, the principle of which is based on a decrease in the magnitude of the voltage and an increase in the current strength on the secondary winding of the transformer. As a result, due to the high value of the current strength, the possibility of arc welding of metals is observed. In order for the current to increase and the voltage to decrease, the number of turns on the secondary winding decreases, but the cross section of the conductor increases. As a result, it can be seen that the transformer-type welding machine not only has significant dimensions, but also a decent weight.

To solve the problem, a variant of the implementation of the welding machine by means of an inverter circuit was proposed. The principle of the inverter is based on increasing the current frequency to 60 or even 80 kHz, thereby reducing the weight and dimensions of the device itself. All that was required to implement an inverter welding machine was to increase the frequency by a thousand times, which was made possible thanks to the use of field-effect transistors.

Transistors provide communication between themselves with a frequency of about 60-80 kHz. A constant current value comes to the power circuit of the transistors, which is ensured by the use of a rectifier. A diode bridge is used as a rectifier, and capacitors provide voltage equalization.

Alternating current, which is transmitted after passing through the transistors to the step-down transformer. But at the same time, a hundreds of times smaller coil is used as a transformer. Why a coil is used, because the frequency of the current that is fed to the transformer is already increased 1000 times thanks to field effect transistors. As a result, we obtain similar data as in the case of transformer welding, only with a big difference in weight and dimensions.

What you need to build an inverter

To assemble inverter welding on your own, you need to know that the circuit is designed, first of all, for a consuming voltage of 220 volts and a current of 32 amperes. Already after the conversion of energy at the output, the current will be increased by almost 8 times and will reach 250 amperes. This current is enough to create a strong seam with an electrode at a distance of up to 1 cm. To implement an inverter-type power supply, you will need to use the following components:

1) A transformer consisting of a ferrite core.

2) Winding of the primary transformer with 100 turns of wire with a diameter of 0.3 mm.

3) Three secondary windings:

- internal: 15 turns and a wire diameter of 1 mm;

- medium: 15 turns and a diameter of 0.2 mm;

- outer: 20 turns and a diameter of 0.35 mm.

In addition, to assemble the transformer, you will need the following items:

- copper wires;

- fiberglass;

- textolite;

- electrical steel;

- cotton material.

What does an inverter welding circuit look like?

In order to understand what an inverter welding machine is in general, it is necessary to consider the diagram below.

Electrical diagram of inverter welding

All these components must be combined and thereby obtain a welding machine, which will be an indispensable assistant in the performance of plumbing work. Below is circuit diagram inverter welding.

Inverter welding power supply circuit

The board, on which the device's power supply is located, is mounted separately from the power section. The separator between the power unit and the power supply is a metal sheet, electrically connected to the body of the unit.

To control the gates, conductors are used, which must be soldered near the transistors. These conductors are interconnected in pairs, and the cross section of these conductors does not play a special role. The only important thing to consider is the length of the conductors, which should not exceed 15 cm.

For a person who is not familiar with the basics of electronics, reading this kind of circuit is problematic, not to mention the purpose of each element. Therefore, if you do not have skills in working with electronics, then it is better to ask a familiar master to help you figure it out. Here, for example, below is a diagram of the power section of an inverter welding machine.

Scheme of the power part of inverter welding

How to assemble inverter welding: a step-by-step description + (Video)

To assemble the inverter welding machine, you must perform the following work steps:

1) Frame. As a body for welding, it is recommended to use an old system unit from a computer. It fits best because it has required amount holes for ventilation. You can use an old 10-liter canister that you can cut holes in and place the cooler. To increase the structural strength of the system housing, it is necessary to place metal corners, which are fixed with bolted connections.

2) Assembly of the power supply. An important element of the power supply is the transformer. It is recommended to use 7x7 or 8x8 ferrite as the basis of the transformer. For the primary winding of the transformer, it is necessary to wind the wire across the entire width of the core. Such an important feature entails an improvement in the operation of the device when voltage drops occur. As a wire, it is imperative to use copper wires of the PEV-2 brand, and in the absence of a bus, the wires are connected into one bundle. Fiberglass is used to insulate the primary winding. From above, after a layer of fiberglass, it is necessary to wind the turns of shielding wires.

Transformer with primary and secondary windings to create inverter welding

3) Power part. The step-down transformer acts as a power unit. Two types of cores are used as a core for a step-down transformer: W20x208 2000 nm. It is important to provide a gap between both elements, which is solved by placing newsprint. The secondary winding of the transformer is characterized by winding turns in several layers. Three layers of wires must be laid on the secondary winding of the transformer, and PTFE gaskets are installed between them. Between the windings, it is important to place a reinforced insulating layer, which will avoid voltage breakdown to the secondary winding. It is necessary to install a capacitor with a voltage of at least 1000 volts.

Transformers for the secondary winding from old TVs

To ensure air circulation between the windings, an air gap must be left. A current transformer is assembled on the ferrite core, which is connected to the positive line in the circuit. The core must be wrapped with thermal paper, so it is best to use a cash register tape as this paper. The rectifier diodes are attached to the aluminum heatsink plate. The outputs of these diodes should be connected with bare wires, the cross section of which is 4 mm.

3) inverter unit. The main purpose of the inverter system is the conversion of direct current into alternating current with a high frequency. To ensure the increase in frequency, special field-effect transistors are used. After all, it is transistors that work to open and close at a high frequency.

It is recommended to use more than one powerful transistor, but it is best to implement the circuit based on 2 less powerful ones. This is necessary in order to be able to stabilize the frequency of the current. The circuit cannot do without capacitors, which are connected in series and make it possible to solve such problems:

Inverter on aluminum plate

4) Cooling system. Cooling fans should be installed on the case wall, and for this you can use computer coolers. They are necessary in order to ensure the cooling of the working elements. The more fans you use, the better. In particular, it is mandatory to install two fans to blow the secondary transformer. One cooler will blow over the radiator, thereby preventing overheating of working elements - rectifier diodes. Diodes are mounted on the radiator as follows, as shown in the photo below.

Rectifier bridge on the cooling radiator

Photo of thermostat

It is recommended to install it on the heating element itself. This sensor will be triggered when the critical heating temperature of the working element is reached. When it is triggered, the power to the inverter device will be turned off.

Powerful fan for cooling the inverter device

During operation, inverter welding heats up very quickly, so the presence of two powerful coolers is prerequisite. These coolers or fans are located on the body of the device so that they work to extract air.

Fresh air will enter the system through the holes in the device case. The system unit already has these holes, and if you use any other material, then do not forget to provide fresh air.

5) Board soldering is a key factor, since the entire circuit is based on the board. It is important to install diodes and transistors on the board in the opposite direction to each other. The board is mounted directly between the cooling radiators, with the help of which the entire circuit of electrical appliances is connected. The supply circuit is designed for a voltage of 300 V. The additional location of 0.15 μF capacitors makes it possible to dump excess power back into the circuit. At the output of the transformer, capacitors and snubbers are located, with the help of which overvoltages are damped at the output of the secondary winding.

6) Setting up and debugging work. After the inverter welding is assembled, it will be necessary to carry out a few more procedures, in particular, to set up the functioning of the unit. To do this, connect a voltage of 15 volts to the PWM (pulse width modulator) and power the cooler. Additionally included in the relay circuit through the resistor R11. The relay is included in the circuit in order to avoid power surges in the 220 V network. It is imperative to control the switching on of the relay, and then apply power to the PWM. As a result, a picture should be observed in which rectangular sections on the PWM diagram should disappear.

Homemade inverter device with a description of the elements

You can judge the correct connection of the circuit if, during setup, the relay outputs 150 mA. In the case when a weak signal is observed, this indicates an incorrect connection of the board. It is possible that there is a breakdown in one of the windings, therefore, to eliminate interference, it will be necessary to shorten all the supply wires.

Inverter welding in the case of the system unit from the computer

Device health check

After carrying out all the assembly and debugging work, it remains only to check the performance of the resulting welding machine. To do this, the device is powered from the mains 220 V, then high current strength is set and the readings are verified using the oscilloscope. In the lower loop, the voltage should be in the range of 500 V, but not more than 550 V. If everything is done correctly with a strict selection of electronics, then the voltage indicator will not exceed 350 V.

So, now you can check the welding in action, for which we use the necessary electrodes and cut the seam until the electrode burns out completely. After that, it is important to control the temperature of the transformer. If the transformer simply boils, then the circuit has its drawbacks and it is better not to continue the workflow.

After cutting 2-3 seams, the radiators will heat up to a high temperature, so after that it is important to let them cool down. For this, a 2-3 minute pause is enough, as a result of which the temperature will drop to the optimum value.

Checking the welding machine

How to use a homemade device

After the home-made device is included in the circuit, the controller will automatically set a certain current strength. If the wire voltage is less than 100 volts, then this indicates a malfunction of the device. You will have to disassemble the device and again re-check the correct assembly.

Using this type of welding machine, it is possible to solder not only ferrous, but also non-ferrous metals. In order to assemble a welding machine, you will need not only knowledge of the basics of electrical engineering, but also free time to implement the idea.

Inverter welding is an indispensable thing in the garage of any owner, so if you have not yet acquired such a tool, then you can make it yourself.

The welding machine is a fairly popular device among both professionals and home craftsmen. But for domestic use, sometimes it makes no sense to buy an expensive unit, since it will be used in rare cases, for example, if you need to weld a pipe or put up a fence. Therefore, it would be wiser to make a welding machine with your own hands, investing a minimum amount of money in it.

The main part of any welder operating on the principle of electric arc welding is a transformer. This part can be removed from old, unnecessary household appliances and made into a homemade welding machine. But in most cases, the transformer needs a little refinement. There are several ways to make a welder, which can be both the simplest and more complex, requiring knowledge in radio electronics.

To make a mini welding machine, you will need a couple of transformers taken from an unnecessary microwave oven. A microwave is easy to find with friends, acquaintances, neighbors, etc. The main thing is that it has a power in the range of 650-800 W, and the transformer in it is working. If the stove has a more powerful transformer, then the device will turn out with higher current rates.

So, a transformer removed from a microwave oven has 2 windings: primary (primary) and secondary (secondary).

Resale has more turns and a smaller wire cross section. Therefore, in order for the transformer to become suitable for welding, it must be removed and replaced with a conductor with a larger cross-sectional area. To remove this winding from the transformer, it must be cut on both sides of the part with a hacksaw.

This must be done with special care so as not to accidentally touch the primary winding with a saw.

When the coil is cut, its remains will need to be removed from the magnetic circuit. This task will be much easier if you drill the windings to relieve the stress of the metal.

Do the same with the other transformer. As a result, you will get 2 parts with a primary winding of 220 V.

Important! Don't forget to remove the current shunts (shown with arrows in the photo below). This will increase the power of the device by 30 percent.

For the manufacture of the secondary, you will need to purchase 11-12 meters of wire. It must be multi-core and have cross section of at least 6 squares.

To make a welding machine, for each transformer you will need to wind 18 turns (6 rows in height and 3 layers in thickness).

Both transformers can be wound with one wire or separately. In the second case, the coils should connect in series.

The winding should be made very tight so that the wires do not hang out. Next, the primary windings need connect in parallel.

To connect the parts together, they can be screwed to a small piece of wood board.

If you measure the voltage on the secondary of the transformer, then in this case it will be equal to 31-32 V.

With such a home-made welder, metal 2 mm thick is easily welded with electrodes with a diameter of 2.5 mm.

It should be remembered that cooking homemade apparatus follows with breaks for rest, since its windings are very hot. On average, after each used electrode, the device should cool down for 20-30 minutes.

Thin metal with a unit made from a microwave will not be able to cook, as it will cut it. To adjust the current, a ballast resistor or choke can be connected to the welder. The role of a resistor can be performed by a piece of steel wire of a certain length (selected experimentally), which is connected to a low-voltage winding.

AC Welder

This is the most common type of apparatus for welding metals. It is easy to make at home, and it is unpretentious in operation. But the main disadvantage of the apparatus is large mass of step-down transformer, which is the basis of the aggregate.

For home use, it is enough that the device produces a voltage of 60 V and can provide a current of 120-160 A. Therefore, for primary, to which a 220 V household network is connected, a wire with a cross section of 3 mm 2 to 4 mm 2 is required. But the ideal option is a conductor with a cross section of 7 mm 2. With such a cross section, voltage drops and possible additional loads will not be terrible for the device. From this it follows that for the secondary you need a conductor having a diameter of 3 mm. If we take an aluminum conductor, then the calculated cross section of the copper is multiplied by a factor of 1.6. For resale a copper bus with a cross section of at least 25 mm 2 is required

It is very important that the winding conductor is covered with rag insulation, since the traditional PVC sheath will melt when heated, which can cause an interturn short circuit.

If you did not find a wire with the required cross section, then it can be make your own from several thinner conductors. But at the same time, the thickness of the wire and, accordingly, the dimensions of the unit will increase significantly.

First thing, the basis of the transformer is made - the core. It is made of metal plates (transformer steel). These plates should have a thickness of 0.35-0.55 mm. The studs connecting the plates must be well insulated from them. Before assembling the core, its dimensions are calculated, that is, the dimensions of the “window” and the cross-sectional area of ​​​​the core, the so-called “core”. To calculate the area, use the formula: S cm 2 \u003d a x b (see figure below).

But it is known from practice that if a core is made with an area of ​​​​less than 30 cm 2, then it will be difficult to obtain a high-quality seam with such an apparatus due to a lack of power reserve. Yes, and it will heat up very quickly. Therefore, the cross section of the core must be at least 50 cm 2 . Despite the fact that the mass of the unit will increase, it will become more reliable.

To assemble the core, it is better to use L-shaped plates and place them as shown in the following figure until the thickness of the part reaches the required value.

At the end of the assembly, the plates must be fastened (at the corners) with bolts, then cleaned with a file and insulated with fabric insulation.

Now we can start transformer winding.

One caveat should be taken into account: the ratio of turns on the core should be 40% to 60%. This means that on the side where the primary is located, there should be fewer turns of the secondary. Due to this, at the start of welding, the winding with more turns will be partially switched off due to the occurrence of eddy currents. This will increase the current strength, which will positively affect the quality of the seam.

When the winding of the transformer is completed, the network cable is connected to the common wire and to the 215 turn branch. Welding cables are connected to the secondary winding. After that, the contact welding machine is ready for operation.

DC device

To cook cast iron or stainless steel, a DC apparatus is required. It can be made from a conventional transformer unit, if its secondary winding connect rectifier. Below is a diagram of a welding machine with a diode bridge.

Scheme of a welding machine with a diode bridge

The rectifier is assembled on D161 diodes, capable of withstanding 200A. They must be installed on radiators. Also, to equalize the current ripple, you will need 2 capacitors (C1 and C2) for 50 V and 1500 uF. This circuit also has a current regulator, the role of which is performed by the inductor L1. Welding cables are connected to contacts X5 and X4 (direct or reverse polarity), depending on the thickness of the metal to be joined.

Computer power supply inverter

It is impossible to make a welding machine from a computer power supply. But using its case and some parts, as well as the fan, is quite realistic. So, if you make an inverter with your own hands, then it can easily be placed in the PSU case from the computer. All transistors (IRG4PC50U) and diodes (KD2997A) must be installed on radiators without the use of gaskets. For cooling parts, it is desirable use powerful fan , such as Thermaltake A2016. Despite its small size (80 x 80 mm), the cooler is capable of 4800 rpm. The fan also has a built-in speed controller. The latter are regulated using a thermocouple, which must be mounted on a radiator with installed diodes.

Advice! It is recommended to drill several additional holes in the PSU case for better ventilation and heat dissipation. The overheating protection installed on the radiators of the transistors is set to operate at a temperature of 70-72 degrees.

Below is the basic circuit diagram welding inverter (in high resolution), which can be used to make a device that fits in the PSU case.

The following photos show what components a homemade inverter welding machine consists of, and how it looks after assembly.

electric motor welder

To make a simple welding machine from the stator of an electric motor, it is necessary to select the motor itself that meets certain requirements, namely, that its power is from 7 to 15 kW.

Advice! It is best to use a 2A series motor, as it will have a large magnetic circuit window.

You can get the right stator in places where scrap metal is accepted. As a rule, it will be cleaned of wires and after a couple of blows with a sledgehammer it will split. But if the body is made of aluminum, then in order to remove the magnetic circuit from it, stator needs to be annealed.

Preparation for work

Place the stator with the hole up and place bricks under the part. Next, stack the wood inside and set it on fire. After a couple of hours of roasting, the magnetic core will easily separate from the body. If there are wires in the housing, they can also be removed from the grooves after heat treatment. As a result, you will receive a magnetic circuit cleaned of unnecessary elements.

This blank should be well saturate with oil varnish and let it dry. To speed up the process, you can use heat gun. Impregnation with varnish is done so that after removing the screeds, the package does not spill.

When the blank is completely dry, using the grinder, remove the ties located on it. If the ties are not removed, they will act as short-circuited turns and take power from the transformer, as well as cause it to heat up.

After cleaning the magnetic circuit from unnecessary parts, you will need to make two end caps(see picture below).

The material for their manufacture can be either cardboard or pressboard. You also need to make two sleeves from these materials. One will be internal, and the second - external. Next, you need:

• install both end plates on the blank;
• then insert (dress) the cylinders;
• wrap all this structure with keeper or glass tape;
• impregnate the resulting part with varnish and dry.

Transformer manufacturing

After carrying out the above steps, it will be possible to make a welding transformer from the magnetic circuit. For these purposes, you will need a wire covered with fabric or glass-enamel insulation. To wind the primary winding, you need a wire with a diameter of 2-2.5 mm. The secondary winding will require about 60 meters of copper bus (8 x 4 mm).

So, the calculations are done as follows.

1. 20 turns of wire with a diameter of at least 1.5 mm should be wound on the core, after which 12 V must be applied to it.
2. Measure the current flowing in this winding. The value should be about 2 A. If the value is greater than the required, then the number of turns must be increased, if the value is less than 2A, then reduced.
3. Count the number of turns obtained and divide it by 12. As a result, you will get a value that indicates how many turns per 1 V of voltage.

For primary winding a conductor with a diameter of 2.36 mm is suitable, which needs to be folded in half. In principle, you can take any wire with a diameter of 1.5-2.5 mm. But first you need to calculate the cross section of the conductors in the coil. First you need to wind the primary winding (at 220 V), and then the secondary. Its wire must be insulated along its entire length.

If you make a tap in the secondary winding in the area where 13 V is obtained and put a diode bridge, then this transformer can be used instead of the battery if you want to start the car. For welding, the voltage on the secondary winding should be in the range of 60-70 V, which will allow the use of electrodes with a diameter of 3 to 5 mm.

If you have laid both windings, and there is free space left in this design, then you can add 4 turns of a copper bus bar (40 x 5 mm). In this case, you will receive a winding for spot welding, which will allow you to connect sheet metal up to 1.5 mm thick.

For case manufacturing metal is not recommended. It is better to make it from textolite or plastic. In places where the coil is attached to the body, rubber gaskets should be laid to reduce vibration and better insulation from conductive materials.

Homemade spot welding machine

The finished spot welding machine has a rather high price, which does not justify its internal “stuffing”. It is arranged very simply, and it will not be difficult to make it yourself.

To make a spot welding machine yourself, you need one transformer from a microwave oven with a power of 700-800 watts. It is necessary to remove the secondary winding from it in the manner described above, in the section where the manufacture of a microwave welding machine was considered.

The spot welding machine is made in the following way.

1. Make 2-3 turns inside the manitoduct with a cable with a conductor diameter of at least 1 cm. This will be the secondary winding, which allows you to get a current of 1000 A.
   
   
2. It is recommended to install copper lugs at the ends of the cable.
   
   
3. If you connect 220 V to the primary winding, then on the secondary winding we will get a voltage of 2 V with a current strength of about 800 A. This will be enough to melt an ordinary nail in a few seconds.
   
   

   

4. Followed by make a case for the device. Good for base wooden plank, from which several elements should be made, as shown in the following figure. The dimensions of all parts can be arbitrary and depend on the dimensions of the transformer.
   
   

   

5. To give the case a more aesthetic appearance, sharp corners can be removed using a hand router with an edge moulder mounted on it.
   
   

   

6. On one part of the welding tongs, it is necessary cut a small wedge. Thanks to him, ticks will be able to rise higher.
   
   

   

7. Cut holes on the back wall of the case for the switch and the mains cable.
   
   
8. When all the details are ready and sanded, they can be painted with black paint or varnished.
   
   
9. From an unnecessary microwave, you will need to disconnect the mains cable and limit switch. You will also need a metal door handle.
   
   

   

10. If you do not have a switch and a copper rod lying around at home, as well as copper clips, then these parts must be purchased.
    
    
11. From the copper wire, cut 2 small rods that will act as electrodes and fix them in the clamps.
    
    

    

12. Screw the switch to the rear wall of the device.
    
    
13. Screw the back wall and 2 posts to the base, as shown in the following photos.
    
    

    

14. Attach the transformer to the base.
    
    
15. Next, one mains wire is connected to the primary winding of the transformer. The second network wire is connected to the first terminal of the switch. Then you need to attach the wire to the second terminal of the switch and connect it to another output of the primary. But on this wire you should make a gap and install in it microwave interrupter. It will act as a welding start button. These wires must be long enough to accommodate a breaker at the end of the clamp.
16. Fasten the cover of the device with the handle installed on the racks and the rear wall.
    
    
17. Fasten the side walls of the case.
    
    
18. Now you can install the welding tongs. First, drill a hole at their ends into which the screws will be screwed.
    
    
19. Next, attach the switch to the end.
    
    
20. Insert the pliers into the housing, after placing a square bar between them for alignment. Drill holes in the pliers through the side walls and insert long nails into them to serve as axes.
    
    

    

21. Attach copper electrodes to the ends of the clamps and align them so that the ends of the rods are opposite each other.
    
    

    

22. To make the top electrode rise automatically, screw in 2 screws and fix the elastic band on them, as shown in the following photos.
    
    

    

23. Turn on the unit, connect the electrodes and press the start button. You should see an electrical discharge between the copper bars.
    
    
24. To check the operation of the unit, you can take metal washers and weld them.
    
    

    

In this case, the result was positive. Therefore, the creation of a spot welding machine can be considered completed.