The easiest to manufacture are AC resistance spot welding machines with unregulated current. The welding process is controlled by changing the duration of the electrical pulse - using a time relay or manually using a switch.

Before considering the designs of homemade devices for resistance spot welding, we should recall the Lenz-Joule law: when an electric current passes through a conductor, the amount of heat generated in the conductor is directly proportional to the square of the current, the resistance of the conductor and the time during which the electric current flowed through the conductor ( Q=I 2 R t). This means that at 1000A current, about 10,000 times more energy is lost on poorly made connections and thin wires than at 10A current. Therefore, the quality of the electrical circuit cannot be neglected.

Transformer. The main component of any equipment for resistance spot welding is a power transformer with a high transformation ratio (to provide high welding current). Such a transformer can be made from a transformer from a powerful microwave oven (the power of the transformer should be about 1 kW or higher) feeding the magnetron.

These transformers are distinguished by their availability and high power. Such a transformer is enough for a precision welding machine capable of welding steel sheets 1 mm thick. If you need a more powerful spot welding machine, you can use two (or more) transformers (how to organize this is described below).

In a microwave oven, the magnetron requires a very high voltage (about 4000V) to operate. Therefore, the transformer feeding the magnetron does not step down, but increases. Its primary winding has fewer turns than the secondary, and the thickness of the winding wire is greater.

The output of such transformers is up to 2000V (a double voltage is supplied to the magnetron), so you should not check the performance of the transformer by connecting it to the network and measuring the voltage at the output.

Such a transformer requires a magnetic core and a primary winding (the one with fewer turns and a thicker wire). The secondary winding is cut off with a hacksaw or chopped off with a chisel (if the magnetic circuit is securely welded and not glued), knocked out with a rod or drilled out and picked out. The need for drilling arises when the winding is packed very tightly into the window and an attempt to knock it out can lead to destruction of the magnetic circuit.

When removing the secondary winding, care must be taken not to damage the primary winding.

In addition to two windings, shunts that limit the current can be built into the transformer; they must also be removed.

After removing unnecessary elements from the transformer, a new secondary winding is wound. To provide a large current close to 1000A, a thick copper wire with a cross-sectional area of ​​more than 100 mm 2 (wire with a diameter of more than 1 cm) is required. This can be either a single stranded wire or a bundle of several wires of small diameter. If the wire insulation is thick and prevents you from making a sufficient number of turns, then it can be removed and the wire wrapped with fabric insulating tape. The length of the wire should be as short as possible so as not to create additional resistance.

2-3 turns are made. The output should be about 2V, this will be enough. If you manage to cram more turns into the transformer windows, then the output voltage will be greater, therefore the current will be longer (in comparison with fewer turns of wire of the same diameter) and the power of the device.

If there are two identical transformers, then they can be combined into one, more powerful current source. This may be required when there are two transformers with insufficient power or when you want to make your own spot welding machine to work with thicker metal.

For example, in the case of insufficiently powerful transformers, each of the 0.5 kW transformers has an input voltage of 220V, the output voltage is 2V at nominal current 250A (the value is taken as an example, let the short-term welding current be 500A). Connecting namesake conclusions of the primary and secondary windings, we get a device in which, at the same voltage value (2V) nominal the output current value will be 500A (the welding current will almost double, and there will be more losses due to resistances).

At the same time, the connections in the circuit of secondary windings shown in the diagram must be on electrodes, that is, in the case of two transformers with a power of 0.5 kW there will be two identical wires with a diameter of 1 cm, the ends of which are connected to the electrodes.

If you make a mistake in connecting the terminals of the primary or secondary windings, there will be a short circuit.

If there are two sufficiently powerful transformers and you need to increase the voltage, and the dimensions of the magnetic circuit window do not allow you to make the required number of turns with a thick wire on one transformer, then the secondary windings of the two transformers are connected in series (one wire is pulled through two transformers), with the same number of turns on each transformer . The direction of the turns must be consistent so that there is no antiphase and, as a result, the output voltage is close to zero (you can experiment with thin wires first).

Typically, in transformers, winding terminals of the same name are always marked. If for some reason they are unknown, then they can be determined by performing a simple experiment, the diagram of which is shown below.

Here, the input voltage is supplied to the series-connected primary windings of two identical transformers, and an alternating voltage voltmeter is connected at the output formed by the series connection of the secondary windings. Depending on the direction in which the windings are turned on, there can be two cases: the voltmeter shows some voltage or the output voltage is zero. The first case indicates that in both the primary and secondary circuits the opposite terminals of the corresponding windings are interconnected. In fact, the voltage on each of the primary windings is equal to half the input and is transformed in the secondary windings with the same transformation ratios. When the secondary windings are turned on as indicated, the voltages on them are summed up and the voltmeter gives twice the voltage value of each winding. A zero voltmeter reading indicates that equal voltages on the secondary windings of transformers connected in series have opposite signs and, therefore, any pair of windings is connected by terminals of the same name. In this case, by changing, for example, the sequence of connecting the terminals of the primary windings as shown in Figure (b), we will obtain at the output twice the value of the output voltage of each of the secondary windings and we can assume that the windings of the transformer are connected different names conclusions. Obviously, the same result can be obtained by changing the sequence of connecting the terminals of the secondary windings.

To make a more powerful spot welding machine with your own hands, you can connect more transformers in the same way, if only the network allows it. A transformer that is too powerful will cause a large voltage drop in the network, causing fuses to trip, light bulbs to flicker, neighbors to complain, etc. Therefore, the power of homemade spot welding machines is usually limited to values ​​that provide a welding current of 1000-2000A. The lack of current is compensated by increasing the welding cycle time.

Electrodes. Copper rods (rods) are used as electrodes. The thicker the electrode, the better; it is desirable that the diameter of the electrode is not less than the diameter of the wire. Tips from powerful soldering irons are suitable for low-power devices.

The electrodes must be sharpened periodically, because they lose their shape. Over time, they wear down completely and require replacement.

As already written, the length of the wire running from the transformer to the electrodes should be minimal. There should also be a minimum of connections, because There is a loss of power on every connection. Ideally, copper lugs are placed on both ends of the wire, through which the wire is connected to the electrodes.

The tips must be soldered to the wire (the wire cores must also be soldered). The fact is that over time (possibly at the very first start), oxidation of copper occurs at the contacts, leading to an increase in resistance and a large loss of power, which is why the device may stop welding. Plus, when crimping tips, the contact area is smaller than when soldering, which also increases the contact resistance.

Due to the large diameter of the wire and tip for it, it is not easy to solder them, but sold tin-plated solder tips can make this task easier.

Unsoldered connections between tips and electrodes also create additional resistance and oxidize, but since The electrodes must be removable; it is inconvenient to unsolder the old ones and solder in the new ones each time you replace them. Moreover, this connection is much easier to clean from oxides than the end of a stranded wire crimped with a ferrule.

Controls. The only controls may be a lever and a switch.

The compression force between the electrodes must be sufficient to ensure contact of the parts being welded with the electrodes, and the thicker the sheets being welded, the greater the compression force must be. On industrial devices, this force is measured in tens and hundreds of kilograms, so the lever should be made longer and stronger, and the base of the device should be more massive and can be attached to the table with clamps.

A large clamping force for homemade spot welding machines can be created not only with a lever clamp, but also with a lever-screw clamp (a screw tie between the lever and the base). Other methods are possible, requiring different equipment.

The switch must be installed in the primary winding circuit, because there is a very large current in the secondary winding circuit and the switch will create additional resistance, in addition, the contacts in a regular switch can be tightly welded.

In the case of a lever clamping mechanism, the switch should be mounted on the lever, then with one hand you can press on the lever and turn on the current. The second hand will remain free to hold the parts being welded.

Exploitation. It is necessary to turn the welding current on and off only when the electrodes are compressed, otherwise intense sparking occurs, leading to burning of the electrodes.

It is advisable to use forced cooling of the device using a fan. In the absence of the latter, you need to constantly monitor the temperature of the transformer, conductors, electrodes and take breaks to prevent them from overheating.

The quality of welding depends on the experience gained, which comes down mainly to maintaining the required duration of the current pulse based on visual observation (by color) of the weld point. More information about performing spot welding is written in the article Contact spot welding.

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Sooner or later, many people have a desire to purchase their own welding machine. But, unfortunately, such equipment is highly expensive, so many people prioritize making a homemade device. With the help of freely available diagrams, drawings and other step-by-step guidance for the upcoming event can become very simple and understandable.

Description and principle of operation

Currently, resistance spot welding is in great demand and is used in a wide variety of human activities. The tool is indispensable when repairing or producing metal parts. It can also be used for the manufacture of metal stairs, gates, individual structural elements and other details.

The operating principle of resistance welding is as follows: the electric current present in the key unit is capable of heating individual parts of a steel workpiece that are connected to each other. In this way, a special welded joint is formed - a seam. The quality of the result is determined by the type of material from which the product is made, as well as the density. In addition, when carrying out welding activities attention should be paid for the following features:

1. The welding circuit must have low voltage levels - from 1 to 10 watts.
2. The welding process continues for several seconds.
3. The welding pulse is characterized by high current strength.
4. The smaller the melting zone, the higher the welding quality.
5. The weld must cope and withstand heavy loads.

Correct adherence to such rules depends on final result of welding activities. Making a device with your own hands is quite difficult. In order for the task to be completed successfully, it is necessary to precisely learn a number of specific instructions and technological recommendations.

A simpler solution is to assemble a welding machine with variable current. Such a device is capable of controlling the welding process by changing the duration of the welding pulse that hits the workpiece. In addition, in order to successfully complete the task, it is necessary to equip a clock relay, which can be controlled automatically or manually.

Important design properties

Key unit of the welding device The spot type is a welding transformer that is often found in microwave ovens, televisions and other equipment. Rewinding of the winding is carried out only after determining the ratio of the required current and voltage, during the supply of which welding occurs.

To select the appropriate device control option, you must correctly assemble the main mechanisms. It is no secret that structural parts are selected taking into account the power and parameters of the transformer.

When manufacturing resistance welding systems, it is taken into account relationship between type of application and material properties, which can be processed. In most cases, welding pliers are attached to the main device.

When performing any assembly work, be extremely careful and thorough. Build quality must be maximum, otherwise further operation may become problematic. Wires are selected with the appropriate diameter and cross-section. If the circuit reliability is not good enough, the intensity of the required electric current will not be stable. In addition, there is an increased risk of sparks causing workers to stop welding.

Spot welding diagram

To make resistance spot welding yourself, carefully study the corresponding diagrams. The most popular of them effective in situations where metal sheets have to be processed with a thickness of one millimeter or wiring and rod with a diameter of up to 4 millimeters.

In this case, it is necessary to take into account the following features:

1. For welding, you should acquire equipment with an alternating voltage of 220 W.
2. As for the output voltage type when idling, it is 3-7 V.
3. The maximum welding current reaches 1.5 thousand amperes.

The entire design is characterized by a circuit diagram, which consists of power parts, an automated switch and a control circuit. If dangerous situations arise while performing a task, all you have to do to prevent them is press the switch. At the first node there is a transformer for welding T2 and a device for a contactless thyristor switch of a single-phase type, which connects the primary winding to the electrical power source.

As for the second scheme, it requires the implementation of a characteristic winding on the welding transformer using certain turns. On the primary winding there are lead-out sections, which are intended to adjust the output welding current taking into account the ratio of the secondary winding. Thus, the permanent connection of the network circuit remains at the first pin, and the operation of the power supply is regulated through the others.

Important detail of the system marked M TT4 K is distinguished by serial production. This module contains a thyristor switch that switches the load through contacts 1 and 3. The device can operate under loads with voltages up to 800 watts and currents up to 80 amperes. The composition of the scheme includes:

1. power unit.
2. chain for setting the mechanism.
3. relay k1.

Any transformer system with a power of up to 20 watts is used as a source of electrical power for welding equipment. At the same time, it is used when operating on a nominal network of 220 V. As for the voltage that is supplied on the second version of the winding, its indicators reach 22 V. To rectify the intensity of the current supply, you can install a diode bridge. The option of using any other nodes with similar parameters is also not excluded.

Device features and design

Currently, there are several functions of the control circuit. If it is necessary to turn on k1 for a given period of time, you need to set this period correctly, determining the specific time for applying electronic pulses to the elements being welded.

The electrical circuit design contains capacitors: from c1 to c6 with characteristic electrolytic properties. Their voltage is 52 V. In addition, you need to use a capacitor with a capacity of 46 μF.

The main power unit of the mechanism is the transformer. It acts as a converter from one type of electricity to another. In this case, it is customary to use a 2.5 A magnetic wire. It is better not to use the old winding, but to install electric cardboard rings at the end of the magnetic wire. They are folded along the inner and upper edges. The next step is to wind the magnetic circuit with lattic fabric in three or more layers. To successfully complete the winding, you should use the following wires:

1. primary winding with a diameter of 1.5 millimeters, which is impregnated with a varnish composition.
2. the second version of the winding with a diameter of about two centimeters, which is equipped with multi-core insulation of organosilicon origin.

When making the first winding, it is important to arrange intermediate type terminals. Then the winding is impregnated with a special varnish, and the primary coil is wound cotton tape, which is also impregnated with a varnish composition. Then the process of secondary winding begins, as well as further impregnation with varnish.

Manufacturing pliers for welding equipment

If you want to make homemade spot welding, you must take a responsible approach to the design of the pliers. Today, two types of such elements are used:

1. stationary.
2. remote

The first solution is characterized by ease of operation, as well as high-quality and reliable insulation, which is due to firmly connected node sections. True, such pliers are characterized by one drawback - in order to provide clamping force, you need to apply physical force.

The version of external pliers is particularly easy to use and compact in size. To control the efforts of the pliers, it is enough to change the length of their extension behind the device. Bolts, bushings and washers are installed at the connections of such parts for more reliable waterproofing.

When making parts It is customary to use copper rods or beryllium bronze. You can also use a tip from a soldering machine with high power ratings. As for the diameter of the electrode, it must match the diameter of the wire to which it is connected.

In order for the welding cores to have good quality, the ends of the electrodes are narrowed and made small.

Microwave spot welding

It's no secret that purchased models are very expensive, so it makes sense to give preference to homemade solutions. To make a productive installation, you can use a large microwave oven. It is the dimensions that determine the power of the future device..

If you don't have a microwave, try looking for one at a flea market or buying one from your neighbors. Such a purchase will not be a big investment. In the future, all that remains is to disassemble the microwave and remove the high-voltage transformer from it.

Be careful, because even in a disassembled state without a direct connection to the electrical network, individual components of the equipment may be electrocuted.

The main parts of the transformer are represented by a core and two types of winding - primary and secondary. To connect the core, you can use two thin welds. Get rid of them in advance, which can be done with a hammer and a hacksaw. You can also use a grinder, which will allow you to get to the transformer windings without damaging them. To remove the secondary winding, just cut the secondary with careful movements.

Ultimately, you will have access to the core from the transformer, which consists of two parts.

The next step is to carry out the secondary winding of the transformer part. Here you will need to use a copper cable with the same cross-section as the transformer slot. It is necessary to wind about two turns. Using standard two-part epoxy resin, join the two halves of the core together. To make the process especially successful, try fixing them in a vice.

Don't forget to check the voltage level at the output of the transformer mechanism. It should not exceed the 2 volt mark. In this case, the minimum current value varies within 850 A.

Then you need to start manufacturing the body of the welding material. At this stage, you can use wood or high-strength plastic. There are several holes on the back panel. One of them is responsible for the electrical supply, and the second is for turning the system on and off.

Conclusion

If the body part is dry, you can proceed to assembling the device by connecting the working units together. Then you need to cut two pieces of copper wire with a size of about 25 millimeters. They act as electrodes, which are fixed in the holder using a regular screwdriver. Then you need to secure the switch with a thick cable, which will prevent it from falling out. The transformer is fixed using ordinary self-tapping screws. It is also important to take care of the grounding, which is fixed to one of the terminals.

If you carefully follow all the recommendations and step-by-step instructions, the process of assembling the welding machine will be successful. In this case, you can reduce all costs, depriving yourself of the need to buy expensive professional equipment.

Welding plays an important role in technical processes. One of its types, spot welding, is the joining of parts together at one or more points. A spot welding machine can significantly reduce the final cost and reduce production time, especially if made by yourself.

Welding strength

The strength of the weld is affected by the size and material of the area. And it is affected by:

• Electrode size.
• Contact area.
• Surface condition.
• Exposure time and current magnitude.
• The size of the surface with which the electrode was in contact.

Precision welding has its niche for application - connecting parts to each other from 0.002 microns to 20 mm. During the process, the current value is measured in hundreds of amperes, and the resistance of the surface and electrodes is minimal.

Advantages of spot welding:

Process used both at home and in industry. It is used to weld the following materials:

• Sheet metal.
• Products made of non-ferrous alloys and steel.
• Bent and sectional profiles.

In everyday life, tools, household utensils, and kitchen equipment are repaired using spot welding. The process consists of combining parts in a certain position. They are fixed between themselves and the electrodes surfaces are heated using electric current before welding. The main thing is to accurately fix the part in the desired position and hold it during the welding process. The thermal impulse melts the metal in the contact zone, connecting the two surfaces into one.

Types of spot welding machines

The simplest spot welding machine is controlled manually; the welding current and operating time are set each time. Requires experience with a specific device. Quite a simple design, easy to make with your own hands.

The devices come in three varieties:

Portable devices are not inferior in their characteristics to stationary ones. The welding machine, made in the form of hand pliers, is capable of joining metal 5 mm thick. And with the help of a manual locking drive, a force of 150 kg is achieved. Ease of use, high quality welds, low price, distinguishes this type of device from its competitors.

Inventory devices are small in size, multifunctional, and easily connected to a household network. And even the high price does not reduce their popularity.

DIY spot welding machine

The simplest one to make at home is a spot welding machine, in which the current strength is not adjustable. And the process is controlled by changing the duration of the electrical pulse; for this, a switch or time relay is used.

The welding machine works on the principles of the Lenz-Juol law: electric current passing through a conductor releases heat, which is directly equal to the square of the current, time and resistance of the conductor. This means that at a current of 1000 A, on thin wires and poorly made connections, the losses will be 10,000 times greater than at 10 A.

Transformer

The main element of any equipment for spot welding is power, with an increased transformation effect (to obtain a normal welding current). It can be take in a powerful microwave (from 1 kW and above), it powers the magnetron. Convenient for its availability and good characteristics. The transformer’s performance is sufficient for spot welding 1 mm steel sheets. To obtain more power, use 2 or more parts.

To operate a magnetron in a microwave oven, you need an increased voltage of 4000 V. Therefore, an increased transformer is used. It has fewer turns on the primary winding than on the secondary, but the thickness of the wire is greater.

The performance of such transformers is up to 2000 V (in a microwave it doubles before being fed to the magnetron), you should not connect them to the network and measure the output characteristics. From this part we need a primary winding (which has a thicker wire and fewer turns) and a magnetic circuit.

The wires are cut with a chisel or a hacksaw (if it is welded and not glued), or they are picked out and drilled out (if the winding is packed very tightly, when knocking it out will destroy everything). When removing the secondary winding wires, try to be careful so that do not damage the primary winding. There are also shunts in the transformer that limit the current; they also need to be cut off.

After carefully removing the necessary elements, the secondary winding of the transformer is updated. To achieve current ratings of 1000 A you need to use a copper cable with a cross-sectional thickness of 100 mm² or more. This can be a bundle or stranded wire. If the external insulation prevents you from obtaining the required number of turns, then it is removed and replaced with fabric insulating tape. The wires should be as short as possible to avoid unnecessary resistance.

No more than 3 turns are made. You will get 2 V, this is enough for home needs. But if you need more current then make more turns, so you will increase the power indicators. Multiple transformers can also be used. This is a good option when you have 2 identical ones, but their characteristics individually are not enough to weld metal of the required thickness.

For example, if you have 2 transformers with a power of 0.5 kW, with an input voltage of 220 V, with a rated current of 250 A and an output voltage of 2V. By connecting the terminals of the secondary and primary windings, we get a device in which the rated voltage is 2 V, the output current is 500 A (the welding current will also double).

When creating a device, electrodes must be used in the secondary circuits of the device. That is when using transformers of 0.5 kW, they are tied together with wires with a diameter of 1 cm, and the ends to the electrode. If you make a mistake when connecting the terminals of the secondary and primary windings, this will lead to a short circuit.

When you use two powerful transformers and you need to increase the voltage, but the size of the magnetron window does not allow you to add the required number of turns of wire, for this the secondary windings are connected in series. It is necessary to coordinate the direction of the turns, otherwise you can get antiphase, which will lead to an output voltage equal to zero (to correctly understand this point, conduct an experiment with thin leads).

The terminals of the same name are marked on the transformers, but if your device does not have one, you can check it. To the primary windings of transformers voltage is supplied, and a voltmeter is connected to the secondary windings. There can be two results: the device shows voltage or not.

The first case indicates that the circuits of the primary and secondary windings are connected together by opposite terminals (the voltage on the primary winding is equal to half the input, which is converted in the secondary winding, where it is summed up and gives a double value). The zero value of the voltmeter shows that the voltage values ​​on the secondary windings are opposite, which means that one of the pairs of windings is connected by the same terminal.

To increase the performance of your spot welding machine, you need to connect several transformers, but they should not exceed the network performance, otherwise the total voltage will drop when using it. Limit yourself to 1000–2000 A; for domestic conditions, this current strength is enough.

Electrodes

Copper rods are used as electrodes. The greater the thickness, the better, but its diameter should not be less than that of the wire. If you have a low-power device, then soldering iron tips will do.

Electrodes require periodic pumping, as over time they lose their shape and become unusable. The shorter the wire length, going from the electrode to the transformer, the better. The number of connections should be minimal; they also waste power. Ideally, copper tips are attached to the ends, to which the electrodes are connected. Oxidation occurs at the point of contact of copper, to avoid this they are soldered together. This connection is easier to clean.

When using crimping, the fastening area is much smaller, which increases losses.

Control

The device is controlled by a switch or lever. The electrodes must be fastened with such force as to ensure normal welding. The thicker the sheet of metal, the higher the indicator. On industrial devices it reaches 100 kg. Make the control lever long and strong, and the device itself more massive, with the possibility of stationary mounting. Additional force can be added when spot welding using a screw clamp.

The switch is connected to the primary winding circuit, otherwise it will add resistance, and its contacts will melt during operation.

If you use a lever clamp mechanism, then mount the shutdown button on it. It is very convenient to press the lever with one hand and control the work. The second hand controls the welding of parts.

Exploitation

The device must be turned on and off when the electrodes are compressed, otherwise the electrodes will spark and burn. Forced ventilation will greatly facilitate operation, otherwise you will have to monitor the temperature of the transformer, electrodes, conductors and take frequent breaks. In the meantime, while you empirically find the temperature conditions of the elements, something may burn out irrevocably.

To carry out spot welding efficiently, you need experience in bringing together two surfaces of a material, welding with a current pulse, and determining the readiness process by color and appearance.

When carrying out spot welding with your own hands, follow safety precautions; if sparks and molten metal occur, stop work immediately. Operating a faulty device is very dangerous.

Spot welding in industry is used to connect non-ferrous and steel sheets, profile blanks, corners and other elements. At home, it is used to repair car bodies and home appliances.

Welding machines on the market are expensive, so many craftsmen make these units with their own hands from improvised materials. With the help of such a homemade device, you can carry out repairs or manufacture structures, which will significantly save money on the purchase of a new device and the services of a specialist.

Contact welding unit, handmade, allows you to connect parts not only from thin sheet iron, but also to weld channel corners for the manufacture of stairs, profiles for shelving and much more. Everyone knows that resistance welding is performed on special equipment in industrial production. However, you can make such a contact welding machine yourself using a microwave.

Assembling the device

To manufacture the unit you will need the following parts and tools:

To understand how to make spot welding with your own hands, you need to understand the operating principle of this device. The main part will be the transformer. Its main purpose is to increase the input voltage to the desired value.

For successful operation, the product must have a greater transformation; the more powerful the device, the thicker the steel can be welded. For example, a device from a microwave oven has a power of 850 W, which means that it can be used to weld sheets up to 1 mm thick.

Electrical diagram

Such a transformer is one of the step-up devices and is capable of generating a voltage of about 3.5 kV. To convert it for resistance welding, a calculation must first be made. And only then proceed to dismantling and subsequent assembly of the main unit of the welding machine. To do this, remove the transforming device from the microwave body.

After which you need to remove the secondary winding and wind new 2-3 turns with a thickness of at least 10 mm over the cross-section of the core, while not forgetting to leave the ends of the cable of sufficient length to connect to the holder. If it is difficult to find such a wire, you can combine several cords into one bundle, thus achieving the desired thickness.

Such a winding will provide an output voltage of about 2 V and a current of about 850A, while it is necessary to use a wire of as short a length as possible in order to reduce the resistance and, accordingly, the current. If you have to weld parts up to 5 mm thick, you will need a resistance welding machine with a more powerful transformer.

And since the microwave oven is used as a basis, then you will have to connect two similar transforming devices according to the circuit. In this case, certain conditions must be observed when connecting the same terminals of the primary and secondary windings to each other, otherwise a short circuit may occur.

When connecting two transformers, you need to calculate the combined current strength, which should not exceed 2 thousand A. If it is too high, the wiring in the house may not be able to withstand it, and in addition, voltage surges will occur, which can lead to conflicts with neighbors.

Copper rods are used as electrodes, and the thicker the electrode, the better. Soldering iron tips are suitable for such low-power units. Electrodes must be adjusted regularly so that they do not lose their conical shape. As mentioned above, the wire should be of a minimum length and contain as few connections as possible along its length, since power loss occurs along them.

Controls and Operation

To carry out work on a welding machine, made from a microwave, needs control. It consists of a lever and a switch, and the handle must be of such length as to ensure close contact of the welded product between the electrodes.

You can weld from a microwave with your own hands or, in other words, turn on the device only with compressed electrodes, otherwise there will be strong sparking and burning of the contacts.

The quality of the connection depends on the duration of the current pulse. In this case, you need to visually monitor the color of the weld point and turn off the device as soon as it turns beige. This moment of shutdown is very important, since if the electrodes are overexposed to each other, a hole may form at the welding site, and if underexposed, the mating parts will not connect.

But everything comes with experience. As soon as the spot welding machine will be obtained from the microwave, the repair process will be greatly simplified, and the services of professionals will not be needed.

What else can you do with a microwave oven?

If a microwave oven becomes unusable, the question of its disposal arises. But don’t rush to send it to a landfill - many other useful things can be made from the device.

Attention! Before you begin disassembling the microwave, you need to discharge the capacitor by shorting it to the housing. This precaution is due to the high voltage charge remaining for a long time.

What can you make from a microwave with your own hands? Let's start with simple designs:

Scientific research does not dictate the conditions of our living, but only tries to explain and use it for our benefit. Use your imagination to get the necessary and wonderful things, amaze your relatives and friends, and most importantly, yourself with how beautiful the world is inside and around us.

There are often situations in which it is necessary to connect metal products or repair various structures. To deal with this, you need to know how to make spot welding yourself. The apparatus for carrying it out can be assembled independently at home. This will greatly simplify the entire process and save you from large financial costs.

Homemade spot welding is a rather difficult undertaking that requires special equipment and skills for such work. However, with the right approach, you can significantly simplify the process and get the job done in the shortest possible time.

This method of joining metal parts has many advantages. All of them make spot welding one of the most commonly used. Among the positive aspects it is worth highlighting the following:

Among the many advantages, there is one drawback. Experts consider this type of connection to be leaky.

Welding of any product occurs according to the same principle. At the same time, it is important to carefully carry out all operations and not miss even the most insignificant nuance. Only in this case can you achieve an ideal seam and its strength.

The whole technology consists of several stages:

Preparatory activities

The basis for the successful completion of any type of work is considered to be proper preparation. It allows you to take everything you need to carry out a smooth process. To successfully carry out contact welding from a welding machine with your own hands, you need to choose the right electrodes and all the necessary tools.

The main attribute of contact welding is the electrode. With its help, the entire process is carried out, so it is very important to buy the best option for a specific job.

The electrode performs the function of supplying current to the parts being welded and compressing the metal. As a rule, it is made from alloys with high thermal conductivity. The tip is exposed to the greatest impact. It heats up to enormous temperatures and wears out very quickly. Because of this, it is necessary to constantly sharpen it during work. The most commonly used tip shape is a cone.

As a rule, electrodes are quite expensive, so it is very important to extend their service life as much as possible. To do this, you must comply with the following conditions:

1. To weld products from a particular material, it is necessary to select the optimal types of electrodes for it.
2. Do not use fine tips for heavy welding.
3. Use a water jacket.
4. Observe the storage conditions for the electrodes and avoid their mechanical damage.

Materials and tools

To carry out contact welding with your own hands, you need to make the appropriate unit. It is done using a certain set of tools and a minimum amount of materials available to everyone. While working on the device you will need:

After all preparatory activities have been completed, you can begin to work on the device. Its assembly is carried out in several stages and can take a significant period of time.

The spot welding machine is made on the basis of a pulse source using the principle of capacitor discharge. Thanks to it, you can connect parts up to 0.5 millimeters thick.

Features of this power source:

If necessary, you can use the diagram of the device used. With its help, it will be easier for beginners to achieve the desired result.

The discharge of capacitors is carried out as follows:

1. When the main circuit opens, the installed capacitors are charged.
2. After turning on the welding machine, they are discharged onto the winding. The discharge strength is changed using thyristors.
3. The entire cycle is repeated when the device is turned off.

When welding larger workpieces (up to 4 millimeters thick), it is necessary to increase the discharge power several times.

One of the main components of a spot welding machine is the output transformer. With its help, the required current is supplied to the electrode. You can make such a device yourself and use it in the overall design. To do this you need to follow a few simple steps:

If everything is done correctly, you will get a transformer with a power of 3 thousand watts.

Assembly of contact blocks

For the manufacture of a spot welding machine, a pistol-shaped contact block is most often used. The process of assembling it is quite labor-intensive and can take a lot of time.

Step-by-step instruction:

Safety precautions

Any welding process, even in the case of do-it-yourself microwelding, must be carried out in compliance with safety measures. This will not only preserve your health, but also prevent many negative consequences. In addition, the welder must use special protective equipment that will protect him from exposure to hot metal and electric current.

Among the main safety requirements it is worth highlighting the following:

1. Grounding of all potentially dangerous parts of the equipment. This measure will help avoid electric shock.
2. Before starting work, you must check the serviceability of the device.
3. Wear protective equipment to help avoid electric shock.
4. All controls must not be under high voltage.
5. The device must use wires with a large cross-section.
6. Use gloves that will protect your hands from accidentally flying metal splashes, as well as a special head shield. The latter will protect the welder’s eyes from the negative effects of a bright flash.
7. Use respiratory protection or perform work in a well-ventilated area. This is necessary to ensure that harmful fumes released during operation do not enter the lungs.
8. All emergency shutdown buttons must be in working order. However, access to them must not be blocked by any objects.
9. It is advisable to fence off the work area with shields to avoid various negative consequences that arise in the event of an unforeseen situation.
10. The risk of injury from moving parts of the machine must be reduced as much as possible.

Spot welding is a rather labor-intensive undertaking that requires not only special devices, but also certain operating skills. Moreover, the entire process can be carried out at home and obtain the desired result at minimal cost. With the right approach to the matter and compliance with safety precautions, you can increase the likelihood of a positive outcome of the case and reduce the risk of any injuries.