Do-it-yourself spot welding can be very the necessary device in a home workshop. This device allows you to connect various metal elements and repair various structures at home. And most importantly, DIY production helps to avoid the significant costs associated with purchasing ready-made welding devices.

Do-it-yourself spot welding is a rather complex design and its creation requires certain skills in electrical engineering and plumbing, but despite all the complexity, you can safely get to work, armed with knowledge of installation principles. Home craftsmen have come up with different schemes and manufacturing technologies, which have been implemented and tested in real conditions. Positive reviews the operability of the devices indicates the possibility of assembling fairly reliable structures.

Basic essence of the process

Spot welding is a type of resistance welding, i.e. is a connection of metals by penetration of their melts into each other at point contact under load.

The principle of this process is based on the fact that the workpieces to be joined are tightly aligned and pressed on both sides by electrodes to which a short-term welding current is supplied.

Due to their own electrical resistance, when a high current passes, the materials are heated to their melting temperature, and the melts of the two workpieces are mutually mixed under load, which ensures a strong connection.

To reduce the heating zone (reduce the required power of the welding pulse), a minimum contact area is ensured - point-type electrodes are used.

Apparatus design

A spot welding machine includes two main parts - a welding pulse source and a contact block. The power source must provide automatic supply of a pulse with a current strength of about 150-250 A for 0.02-0.1 s when powered from a regular electrical network with a voltage of 220 V. A desirable condition is the ability to regulate the current for welding workpieces of various thicknesses and from different metals

The following requirements are imposed on the contact block: supplying a welding signal using a point electrode, pressing the workpieces to be welded, holding the workpieces until the melt has completely hardened after removing the pulse. Basically, the following design solutions are used: clamping workpieces between two point electrodes; one electrode is flat and the other is point; spotter – the role of the lower electrode is played by the workpiece itself.

Necessary tool

To make a spot welding machine with your own hands, you will need the following equipment and tools:

• welding machine;
• Bulgarian;
• electric drill;
• hacksaw for metal;
• milling cutter;
• soldering iron;
• file;
• chisel;
• hammer;
• pliers;
• screwdriver;
• metal scissors;
• calipers;
• metal ruler;
• spanners.

Making a power supply

A homemade spot welding machine is usually assembled based on a welding pulse source that uses the principle of capacitor discharge. Simple scheme such a source. A welding machine with such power is capable of welding sheets up to 0.5 mm thick and can be used for batteries to reliably connect Li-Ion batteries.

The required current strength in the form of a short-term pulse is created at the output of the secondary winding of transformer Tr3, while the required signal is provided by the discharge of capacitors C8-C9 to the primary winding. Thyristors T1 and T2 provide control of the capacitor discharge. Charge accumulation on the capacitor plates occurs when the auxiliary circuit of the transformer Current is turned on. Diodes D6-D7 are used to rectify the electrical signal.

The principle of capacitor discharge is as follows. During the period when the main circuit is turned off, capacitors C8-C9 are charged through the Current winding. When the main circuit is turned on (starting the welding machine), the capacitors are discharged into the Tr3 winding, while the discharge parameters are regulated by thyristors T1-T2, and the signal duration is provided by the Ru1-Ru2, R34 and C10 system. The cycle repeats completely when the device is turned off. The recommended characteristics of the parts are given, and the parameters of the current transformer are as follows: type 220/220 V, PEV-2 wire with a diameter of 0.5 mm is used for both windings, the number of turns is 90.

To weld workpieces up to 3-4 mm thick, the discharge power should be increased. A diagram of a more powerful current source is presented, which in principle does not differ from the previous case. The duration of the pulse is regulated by a time relay, and an MTT4K contactless starter is connected to the primary winding circuit of the output transformer, due to an increase in power.

Winding a power transformer

The output transformer is a fundamental part of the entire design of the welding machine, providing the necessary current supplied to the electrode. It is advisable to do it yourself as follows. The core will fit from an ordinary failed transformer - it is important that it has a steel plate structure and has a common cross section one element is about 65 cm².

A primary winding of PEV or PETV wire with a diameter of 2.9 mm and a number of turns is wound onto the first post. The number of turns is 20. Transformer (cable) paper is placed under the winding and on top of it. The ends of the winding are fixed to a terminal block placed on the top of the core.

The output (secondary) winding is wound onto the second core stand in the form of two turns of a flat busbar. Such a bus can be assembled from 15-17 copper flat wires with a total cross-section of 200 mm² and wrapped for insulation with fluorine film or fabric insulating tape. It is recommended to lay transformer paper on top and bottom of the winding, and bring the ends of the winding to the terminal block.

If all of the above conditions are met, then you should get an output transformer with the following parameters: power 3000 VA; primary voltage – 220V, secondary voltage – 15V, current – ​​up to 220 A.

Contact block assembly

For home spot welding equipment, incl. spotter, the pistol-shaped contact block design is most often used. The electrode gun is assembled in the following sequence. Two plates of getinax or textolite 8-12 mm thick are selected, from which pistol-shaped figures 23-25 ​​cm long are cut out. The shape is arbitrary, taking into account ease of use. It is advisable to provide the following geometry: barrel width – 42-45 mm, handle width – 50-55 mm, handle length – 100-110 mm.

In the front part of the halves (barrel), symmetrical longitudinal semicircular grooves with a radius of 5-7 mm are made for installing the electrode. The length of the machined channel is 55-60 mm. At a distance of 30-35 mm from the extreme cut of the barrel, a rectangular groove is machined into the longitudinal groove for installing a nut, into which the electrode will then be screwed. A sample is made in the trigger area and a hole is drilled for mounting and fastening the start push-button switch. To align the two halves of the pistol, holes for screws are drilled: 4 pieces in the handle, 2 pieces each in the barrel and rear part. To ensure cable supply, grooves are made in the handle and between the trigger and the electrode channel.

The electrode is made of a copper rod with a diameter of 8-10 mm, and a thread corresponding to the fastening nut is cut at its tail end. The front end of the rod is sharpened in the form of a cone of about 15-20 mm, and the top of the cone is rounded. The total length of the electrode is selected on the order of 50-60 mm.

The welding gun is assembled in the following order. A nut is screwed onto the tail part of the electrode, and a supply wire is soldered to its end, which is connected to the start button. A push-button switch is placed in the trigger part with the button leading out into the hole. The button is connected to the electrode, and the supply wire is connected. The entire circuit fits into the corresponding grooves and grooves; the halves of the gun are combined and screwed together.

Even children have heard about the welding procedure. However, not everyone knows that there are many types of welding processes using various energy sources, which are impossible to do without. There is one type of welding that is used most often by home craftsmen - spot welding. The quality of the welding joint will depend on the experience gained, which mainly consists of maintaining the required duration of the current pulse based on visual observation of the weld point.

Spot Welding Procedure

Spot welding is used in industry and at home. In industry, spot welding is used for welding sheet blanks made of steel of different grades, non-ferrous alloys and metals of various thicknesses, profile blanks (channels, I-beams, angles) and intersecting rods. In everyday life, homemade spot welding is indispensable for repairs. household appliances, various works with cables, aluminum or repairing kitchen utensils.

The spot welding process consists of several stages. In the desired position, the parts to be connected are combined, placed between the electrodes and pressed together. After this, the parts are heated to a state of plasticity and subjected to plastic deformation.

When using automatic equipment in industrial conditions welding frequency often reaches 600 points per minute. For high-quality spot welding at home, it is recommended to maintain the speed of movement of the electrodes at a constant level and ensure a certain amount of pressure and contact of the parts being joined.

The parts are heated due to the passage of welding current as a short-term pulse, which has a duration of about 0.01-0.1 seconds, depending on the welding conditions. Such impulses are responsible for melting the metal in the area of ​​action of the electrodes and forming a common liquid core of the parts, the diameter of which is 4 - 12 millimeters.

After the part's current pulse ceases, the parts will be held for some time to allow the molten core to cool and crystallize. Like any technological processes, spot welding technology is characterized by advantages and disadvantages.

Its advantages include the mechanical strength of spot welds and high efficiency, as well as the possibility of automating welding work. A significant disadvantage is the inability to ensure the tightness of the weld.

Spot welding modes

The heating duration varies from thousandths to several tens of seconds and depends on the power of the machine and welding conditions. When welding steels that are prone to hardening and cracking, such as carbon steel, it is recommended to increase the heating time to slow down the subsequent cooling of the metal.

It is recommended to weld products made of stainless austenitic steels in reverse, with a short heating time. This is usually done to prevent the risk of heating the outer surface of the connection points to certain temperatures of structural transformations, which entails a violation of the anti-corrosion properties of the outer layer of metal.

A certain pressure between the electrodes ensures reliable contact of the parts at the joints. The pressure value depends on the type of metal being welded and the thickness of the parts that are connected. The level of pressure after heating is of great importance because its value is responsible for ensuring the fine-grained structure of the metal at the welding site, and the strength of the connection points becomes identical to the strength of the base metal.

By pressing the parts during the passage of the welding pulse, it is possible to ensure the formation of a sealing belt near the molten core, which prevents the molten material from splashing out from the welding area. To improve the crystallization of the molten metal, it is recommended to release the electrodes with a short delay after the welding pulse has passed.

Requirements for electrodes

Electrodes that are used for do-it-yourself spot welding must guarantee strength in the operating temperature range, high thermal and electrical conductivity, as well as ease of machining.

Special bronzes containing cadmium or cobalt, cold-rolled electrolytic copper, copper alloys containing chromium and tungsten-based alloys meet such requirements.

In terms of electrical and thermal conductivity, copper is significantly superior to bronze and its alloys, but in terms of wear resistance it is 5-7 times worse. Therefore, for the manufacture of electrodes, the best alloy is an alloy of the EV type, which is almost pure copper, which contains about 0.7% chromium and close to 0.4% zinc.

To reduce the wear of electrodes used in spot welding, it is recommended to practice intensive cooling with water. The quality of manual spot welding depends on the choice of electrode diameter. The diameter of the connection points should be 2-3 times the thickness of the thinnest connection element.

Homemade welding machine

For spot welding at home, you need to make a special machine. Homemade welders have a wide variety of configurations - from small portable models to fairly large spot welding machines. At home, it is usually customary to use tabletop versions, used for welding non-ferrous and ferrous metals.

Device assembly diagrams

The bulk of apparatus assembly diagrams are small spot welding schemes that contain a minimum number of necessary parts. True, the devices made in this way are not very powerful, but they can weld two sheets of iron, the thickness of which is 0.2 millimeters, or metal wires.

Before making a spot welder, it is necessary to remember the Lenz-Joule law: when an electric current passes through a conductor, the amount of heat that is released in the conductor is directly proportional to the resistance of the conductor, the square of the current and the time during which the current flowed through the conductor. This means that if the current was 1000 amps, the power would be lost approximately 10,000 times more on poorly made connections and thin wires than if the electrical current was 10 amps. Therefore, the quality of the electrical circuit cannot be neglected.

The basis of the entire operation of such a device is the creation of an electrical impulse that boils two parts of a metal part. To do this, you will need a small transformer; connect the part to be welded to its lower winding, and an electrode to the secondary winding.

You cannot connect the transformer to the power supply directly; for this, a special rectifier bridge with a thyristor is used. To create the necessary impulse, another source must be additionally installed in the device, consisting of another rectifier bridge and a transformer. Electricity will be collected in a capacitor, which serves as a collector and creator of the impulse.

To make a homemade spot welding machine work, press the “pulse” button on the handle of the gun, which is responsible for opening the capacitor-resistor circuit, which will provoke their discharge through the electrode. Watch a video on spot welding to understand how to do it correctly.

The thyristor in this circuit will act as a cathode that closes the rectifier bridge of transformer No. 1. Until the capacitor is completely discharged, the thyristor is in the open state. After this, release the “pulse” button and the capacitor will recharge. And everything will be repeated according to the same pattern.

If you need a more powerful spot welding machine, then you can make it yourself using the same parts and components: a semiconductor thyristor, a welding transformer and a time relay. True, you will need a more powerful transformer for this. And certain components must have completely different technical characteristics.

Main unit

The easiest to manufacture is an alternating current welding machine with an unregulated current rating. The work process is controlled by changing the duration of the electrical pulse - using a time relay or using a manual switch.

The main component of any spot welding equipment is power transformer, which has a high transformation ratio, which helps provide high welding current. It is best to use the device for this serial production, for example, OSM - 1.

Leave the primary winding of the transformer unchanged, remember that it must contain at least 200 turns. Replace the secondary winding with a more powerful one; it is recommended to use wire PV Z - 50 or PEV 2/1.9.

You can also make a similar transformer from a transformer from a microwave oven. Such transformers are characterized by high power and availability. In addition, the price of spot welding will be low. One transformer from a microwave is enough for a homemade precision welding machine that will weld exclusively steel sheets whose thickness is 1 millimeter.

If you need a more powerful device, then you can use two transformers or more. If you have two identical transformers, you can combine them into one current source for working with thick metals. In a similar way, you can connect more than two transformers, if the network allows it.

But remember that a transformer that is too powerful causes a significant drop in voltage in the network, leading to blinking lights, tripping fuses and complaints from neighbors. Therefore, the power of a homemade spot welding machine is usually limited to values ​​that provide a welding current of 1000-2000 Amps. The lack of current can be compensated by increasing the welding cycle time.

Electrode design

It is customary to use copper rods as electrodes. The thicker the electrode you use, the better. It is good if the diameter of the electrode is no less than the diameter of the wire. For homemade, not very powerful devices, tips from high-power soldering irons are suitable. It is recommended to sharpen the electrodes periodically because they lose their shape. Over time, the electrodes wear down completely and require replacement.

The length of the wire that goes from the transformer to the electrode should be minimal. Remember that there must be a minimum number of connections because each connection incurs power loss. It is advisable to put copper lugs on both ends of the cable to connect to the electrodes and install spot welding.

Solder the lugs to the wire, and solder its cores too. The fact is that at the contact site, over time, and maybe even during the first start, copper oxidation occurs, which leads to an increase in resistance and large power losses, which is why your spot welding machine may stop welding altogether.

Due to the large diameter of the wire tip and the wire itself, they are not easy to solder, but this task can be made easier by purchasing tinned solder tips. Unsoldered connections of tips and electrodes also create resistance and oxidize, but since removable electrodes are needed, when replacing each time it is inconvenient to unsolder the old tips and solder new ones.

Make the bottom electrode stationary and isolate it from the mounting bolts and cheeks with washers and adhesive tape. To secure the electrodes in the holders, you can use two bolts or brass washers. Move the holders with electrodes to their original position using a spring. A homemade welding machine for spot welding is connected to the network using a circuit breaker, which is designed for a current of at least 20 Amps.

Controls

The only controls are a switch and a lever. The compression force between the electrodes must be sufficient to ensure contact between the parts between the electrodes. Remember that the thicker the sheets you are welding, the greater the compression force. Too much clamping force on homemade devices can be created using a clamp - lever or lever-screw. Other methods that require different equipment are also possible.

The switch must be installed in the primary winding circuit, since there is a large current in the secondary winding circuit, and the switch additionally creates resistance. The switch in a lever clamp situation must be mounted on the lever so that you can press the lever with one hand and turn on the current. And with your second hand you will hold the parts to be welded.

It is necessary to turn off and on the welding current only with compressed electrodes, otherwise intense sparking will occur, which leads to burning of the electrodes. It is recommended to use a forced cooling procedure using a fan. In the absence of a fan, it is necessary to constantly monitor the temperature of the transformer, electrodes, and conductors and take breaks to prevent them from overheating.

Thus, today buying a welding machine is a small problem. In any specialized store you can find spot welding machines of various capacities from different manufacturers. However, not all devices meet the requirements of home craftsmen. And to assemble such a device yourself, you just need to ask how to make spot welding, prepare a diagram of the device, components and parts for assembly, as well as a soldering iron.

In amateur radio practice, resistance welding is not often used, but it still happens. And when such a case comes, but there is neither the desire nor the time to make a good and large machine for spot welding. Yes, even if you do it, then later it will lie idle, since its next use may not come.
For example, you need to connect several batteries in a circuit. They are connected with a thin metal strip, without soldering, since batteries are generally not recommended for soldering. For such purposes, I will show you how to assemble a simple spot welding machine with your own hands in about 30 minutes.

• We need an AC transformer with a secondary winding voltage of 15-25 Volts. Load capacity doesn't matter.
• Capacitors. I took 2200 uF - 4 pieces. You can have more, depending on the power you need to get.
• Any button.
• Wires.
• Copper wire.
• Diode assembly for rectification. You can also use one diode for half-wave rectification.

Diagram of a resistance spot welding machine

Assembling the welding machine

Watch the assembly and testing video

Spot welding machines are not used as often in everyday life as arc welding machines, but sometimes it is impossible to do without them. Considering that the cost of such equipment starts from $450-$470, the profitability of its purchase is questionable.

The way out of this situation is resistance spot welding with your own hands. But, before we tell you how to make such a device yourself, let's look at what spot welding is and the technology of its operation.

Briefly about spot welding

This type of welding is contact (thermomechanical). Note that this category also includes seam and butt welding, but it is not possible to implement them at home, since complex equipment will be needed for this purpose.

The welding process includes the following steps:

• the parts are combined in the required position;
• they are secured between the electrodes of the device, which press the parts;
• heating is performed, as a result of which, due to plastic deformation, the parts are firmly connected to each other.

A production spot welding machine (such as the one shown in the photo) is capable of performing up to 600 operations within a minute.

Process technology

To heat the parts to the required temperature, a short-term pulse of high-power electric current is applied to them. As a rule, the pulse lasts from 0.01 to 0.1 seconds (the time is selected based on the characteristics of the metal from which the parts are made).

When pulsed, the metal melts and a common liquid core forms between the parts; until it hardens, the welded surfaces must be held under pressure. Due to this, as it cools, the molten core crystallizes. A drawing illustrating the welding process is shown below.

Designations:

• A – electrodes;
• B – parts to be welded;
• C – welding core.

Pressure on the parts is necessary so that, when pulsed, a sealing belt is formed along the perimeter of the molten metal core, preventing the melt from flowing outside the zone where welding occurs.

To provide Better conditions To crystallize the melt, the pressure on the parts is gradually removed. If it is necessary to “forge” the welding site in order to eliminate inhomogeneities inside the seam, increase the pressure (do this at the final stage).

Please note that to ensure a reliable connection, as well as the quality of the seam, it is first necessary to treat the surfaces of the parts in the places where welding will take place. This is done to remove oxide film or corrosion.

When is it necessary to provide reliable connection parts with a thickness of 1 to 1.5 mm, capacitor welding is used. The principle of its operation is as follows:

• the capacitor block is charged with a small electric current;
• the capacitors are discharged through the parts being connected (the pulse strength is sufficient to ensure the required welding mode).

This type of welding is used in those areas of industry where it is necessary to connect miniature and subminiature components (radio engineering, electronics, etc.).

Speaking about spot welding technology, it should be noted that it can be used to connect dissimilar metals together.

Examples of homemade designs

There are many examples on the Internet of creating machines that produce spot welding. Here are some of the most successful designs. Below is the diagram simple device for spot welding.

For implementation we will need the following radio components:

• R - variable resistance with a nominal value of 100 Ohms;
• C – capacitor designed for a voltage of at least 25 V with a capacity of 1000 μF;
• VD1 – thyristor KU202, the letter index can be K, L, M or N, you can also use PTL-50, but in this case the capacitance “C” must be reduced to 1000 μF;
• VD2-VD5 – diodes D232A, foreign analog – S4M;
• VD6-VD9 – D226B diodes, they can be replaced with a foreign analogue 1N4007;
• F – 5 A fuse.

It is necessary to make a digression to tell how to make the TR1 transformer. It is made on the basis of Sh40 iron, with a set thickness of 70 mm. For the primary winding you will need PEV2 wire Ø0.8 mm. The number of turns in the winding is 300.

To make a secondary winding, you will need a Ø4 mm stranded copper wire. It can be replaced with a tire, provided that its cross-section is at least 20 mm 2. The number of turns of the secondary winding is 10.

Video: do-it-yourself resistance welding

As for TR2, any of the low-power transformers (from 5 to 10 W) will be suitable for it. In this case, winding II, used to connect the backlight lamp “H”, should have an output voltage within 5-6 V, and winding III – 15 V.

The power of the manufactured device will be relatively low, ranging from 300 to 500 A, maximum pulse time up to 0.1 sec (provided that the ratings “R” and “C” are the same as in the diagram shown). This is quite enough for welding steel wire Ø0.3 mm or sheet metal if its thickness does not exceed 0.2 mm.

Let us present a diagram of a more powerful device, in which the welding electric current of the pulse will be in the range from 1.5 kA to 2 kA.

We list the components used in the circuit:

• resistance ratings: R1-1.0 kOhm, R2-4.7 kOhm, R3-1.1 kOhm;
• capacitances in the circuit: C1-1.0 µF, C2-0.25 µF. Moreover, C1 must be designed for a voltage of at least 630 V;
• VD1-VD4 diodes - D226B diodes, replacement with a foreign analogue 1N4007 is allowed, instead of diodes you can install a diode bridge, for example, KTs405A;
• thyristor VD6 - KU202N, it must be placed on a radiator with an area of ​​at least 8 cm2;
• VD6 – D237B;
• F - 10 A fuse;
• K1 is any magnetic starter that has three pairs of working contacts, and the winding is designed for ~220 V, for example, you can install PME071 MVUHLZ AC3.

Now we’ll tell you how to make transformer TR1. The LATR-9 autotransformer, such as shown in the photograph, is used as a basis.

The winding in this autotransformer has 266 turns, it is made with copper wire Ø1.0 mm, we will use it as the primary. We carefully disassemble the structure so as not to damage the winding. We dismantle the shaft and the movable roller contact attached to it.

Next, we need to isolate the contact track; for this purpose, we clean it from dust, degrease it and varnish it. When it dries further, we insulate the entire winding using varnished cloth.

As a secondary winding we use copper wire with a cross-sectional area of ​​at least 80 mm 2. It is important that the insulation of this wire is heat resistant. When all conditions are met, we make a winding of three turns.

Setting up the assembled device comes down to calibrating the scale of the variable resistor that regulates the pulse time.

We recommend that before starting welding, you experimentally establish the optimal time for the pulse. If the duration is excessive, the parts will be burned, and if it is less than necessary, the strength of the connection will be unreliable.

As already written above, the device is capable of delivering a welding electric current of up to 2000 A, which allows you to weld steel wire Ø3 mm or sheet steel, the thickness of which does not exceed 1.1 mm.

Arc welding machines are used in everyday life. Such devices are easy to find on the open market, and they have a relatively low cost. However, situations arise when resistance welding may be necessary. This device has a fairly high cost, and its purchase may not be profitable. To save money, spot welding is done by hand.

Spot welding works using a powerful short-term electrical pulse supplied to the electrodes from an inverter. The parts are heated to their melting temperature, then they are connected to each other. Remains strong at the junction point weld, which arose between two electrodes. The peculiarity of the work is that the place of spot welding is limited by the diameter of the electrode used.

Before combining the two metal parts, they are pressed tightly against each other. After resistance welding, they need to be kept under pressure.

Spot welding allows you to weld metal in small areas of a car body during body work, solder wires and small parts together, and repair electronics.

How to make spot welding with your own hands from a microwave

A mini resistance welding machine is made with your own hands from some microwave spare parts. For a homemade unit you will need to remove the following components:

1. Transformer.
2. Switch.
3. Power cord.

Removing the transformer

The separation of the transformer from the microwave is carried out according to the following algorithm:

• The microwave oven is disassembled.
• All fastenings are removed.
• The transformer is removed from its seat.
• The microwave parts necessary to create a device for spot welding are dismantled.

The extracted transformer has a power of 700-800 watts. This is enough to ensure the connection of metal sheets up to 1 millimeter thick. To manufacture a more powerful spot welding machine, this part is being modernized.

On a transformer, the primary and secondary windings differ in thickness and number of turns. The secondary winding is removed from the part using a chisel and hammer. In this case, all operations are carried out carefully, otherwise the magnetic circuit may be damaged. In this case, the transformer will be damaged.

Instead of the dismantled winding, use a wire whose thickness is at least 1 cm. 2-3 turns need to be wound around the core. This simple upgrade allows you to increase the output voltage to 1000 A.

For spot welding machine with increased power use two connected modernized transformers.

Transformer Upgrades

When creating spot welding from a microwave, it is necessary to upgrade the welding transformer:

• When dismantling the secondary winding, limiting shunts can be found. They are also removed.
• The fewer turns of the new secondary winding are created, the lower the resistance of the wire will be, and the greater the current. The cable should not be excessively long.
• When winding a new secondary winding wire, difficulties may arise due to the thick insulation. Care should be taken to replace the standard rubberized insulating layer with electrical tape that has a fabric backing. Such a wire should provide an output voltage of 2V and a short-term current of 800A.
• The performance of the point device depends on the correct connection of the two transformers. The elements are connected in a circuit. It is necessary to correctly connect the primary and secondary windings of the transformers. This can be done using special markings. If they are missing, then measurements must be taken using a voltmeter.
• The design of a spot welding machine used in home workshops involves the creation of a device with a power of no more than 2000A. Otherwise, there will be a load on the home network, which will lead to power outages. This circuit also involves checking the current strength and the presence of short circuits using an ammeter.

After creating the electrical part, install the grounding and switch of the spot welding machine. The part is taken from the microwave. Next, the body, levers, holders and electrodes are made.

Creation of electrodes

Electrodes for spot welding are involved in the supply of current, perform a pressing function and remove excess heat. To create these components, copper is used; this material is resistant to mechanical and chemical influences (the base metal contains impurities in the form of 0.7% chromium and 0.4% zinc). From various videos on the Internet, you can get detailed information about metals suitable for creating electrodes.

Pliers for welded materials vary depending on the type of metal being processed. Thus, tips made of copper plates and having a flat working surface are suitable for connecting ordinary steels. Resistance welding of aluminum, copper, and high-carbon alloy steels is performed using electrodes with a spherical working surface. To make connections in hard-to-reach places, shaped electrodes are used.

The electrodes must be tightly fixed to the holder. To do this, the landing parts are given a cone shape, and some are threaded.

The electrode diameter should be at least twice greater thickness of the parts being joined.

Making the holder

Equipped with control levers. They can be made from high-strength plastic or wood. To lift the levers, use a regular rubber band; fasteners for electrodes are installed at the ends of the parts. The holders are not screwed to the device, and this is due to the fact that in some cases, to perform contact welding, you will need to use each element separately. The levers are fixed with a screwdriver or nail.

Battery spot welding

When creating spot welding, car batteries are also used. This device is used when soldering batteries and connecting small parts when repairing electronics. The design of the resistance welding machine consists of a power source, a relay, a special block and two copper wires. The working ends of the wires are stripped, they act as electrodes.

Electronic repairs and complex body work involve the use of spot welding. Weld It turns out durable, and the small working area allows resistance welding of small parts. However, a serial resistance welding machine is quite expensive. It is cost-effective to create a spot weld from a microwave or. If you follow all the nuances of design and safety precautions, you will get a functional device capable of fastening sheets of metal up to 5 millimeters thick.