The topic of the article is for handy craftsmen - we make the device with our own hands from improvised means. And a used microwave oven will help us with this. Or rather, a high-voltage transformer from it, which is suitable for connecting thin sheet metal at home.
Just don’t have to run headlong into the kitchen to disassemble your microwave. You can ask your neighbors for experimental material, find it at a landfill, or buy it second-hand for cheap.
So, we make spot welding with our own hands from the microwave. We need a transformer that consists of a welded core and primary and secondary windings.
We take it out of the old cracked oven. The desired power is 800 watts, the more powerful the better.
We will need a core and a primary winding (with a thicker wire). We remove the secondary winding, for example, cut it off with a chisel or saw it with suitable tools.
Sometimes, in the case of a tight fit of the secondary winding, in order to remove it, you have to disassemble the core and then glue it together.
After removal unnecessary trash, we take a copper cable (with a cross-section of 16 mm2, determined experimentally) and wind 2 turns in the windows of the transformer.
We securely attach copper lugs to the ends of the cable.
So, the main part for homemade spot welding from the microwave is ready. We think by design future design.
Appearance of the device
If the head works and the arms grow correctly, then the entire structure can be made of metal (reliably and beautifully). Let's look at a complex circuit first.
Internal structure of the device:
- transformer from a microwave with a wound copper wire;
- terminals for copper wire;
- 20 ampere circuit breaker for de-energizing the network;
- terminal block for connecting wires;
- computer fan with 12 volt transformer;
- diode bridge with capacitor;
- relay REK 74;
- 2 indicator lights;
- microwave button.
External microwave spot welding design:
- base with side walls;
- closing lid with handle;
- corners with bolts;
- 2 pieces of profile for pliers;
- soldering iron handle mounted on a hexagon while hot;
- spring from carburetor;
- electrodes are attached to the corners.
The angles allow you to change the angle of the electrodes for precise contact. Electrodes can be made from a soldering iron tip with sharp or blunt tips, in case of welding different materials it will be possible to change them. At the attachment point, the electrode rod is thinner with a thread cut for the nut.
Watch the video to learn how to make this type of spot welding yourself.
I understand that not everyone will make such a design. Therefore, let's consider more simple options DIY spot welding machine.
Simple welding machine body
A wooden structure is the simplest design that anyone can make. The photo below shows design ideas.
Let's take the last option as a basis: take a tape measure and take the dimensions of the prepared microwave transformer. Based on the measurements taken and our idea, we prepare wooden blanks for the device.
We make the upper lever (do-it-yourself spot welding pliers) with a recess. This is if you make a device with a closing lid. If the device is planned to be open, then a recess is not needed.
On the back wall we cut out suitable holes for the power button and wiring.
For beauty lovers: the blanks for the device can be painted in your favorite color.
Also, for do-it-yourself spot welding you will need the following materials:
- switch;
- handle for closed structure;
- circuit breaker (micrik);
- power wire.
Take these accessories from the disassembled microwave.
Also needed:
- electrodes can be made from a soldering iron tip or thick copper wire;
- copper holders for attaching electrodes (you will have to buy);
- self-tapping screws for assembling the structure.
We insert the prepared electrodes into the holders and clamp them with a screwdriver.
We secure the back wall with the screwed switch and power cord to the main board with self-tapping screws.
We also attach the microwave transformer with self-tapping screws to the base of the device. We screw one of the screws with a grounding wire, which we connect to the switch.
Also, we run a wire from the switch to the transformer, and we lead the second wire from the transformer to the circuit breaker, which we borrowed from the microwave.
You can do without a circuit breaker installed in series in the electrical circuit. It serves for convenience and is installed on the upper arm of the spot welding machine.
By using wooden blanks and self-tapping screws, close the electrical part. The top board must have a handle for carrying the device.
Device levers
We attach the electrical circuit breaker to the upper lever with a convenient slope.
We insert the pliers into the device and determine the attachment location by eye. Drilling through holes in the side walls and levers, and secure them with metal rods.
Using self-tapping screws, we attach the holders with contact electrodes to the end part of the pliers.
After assembly, the electrodes usually face in different directions; we bend them with our hands to center them.
To raise the upper arm, we screw it into it and into the body of the device using a self-tapping screw, not completely, and attach a spring or a tight rubber band to them.
Trying a welding unit
Our spot welding is ready, we are testing the machine. Turn on the power and press the breaker with your thumb.
Sparking appears between the electrodes, but this cannot be done.
Thin sheets of metal can now be reliably joined with our device. If you have a vehicle, then homemade spot welding for welding a car will make it easier to repair the body.
To do this, we made the levers removable, just pull them out metal rods and after removing the pliers, you can weld large-sized metal and you can crawl into hard-to-reach places.
Also, there is a plus in removable electrodes, which are easy to replace if necessary.
Video: will tell you about the correct winding of a transformer and show the entire process of assembling a resistance welding machine.
P.S. We looked at how to make spot welding with your own hands using materials from a microwave oven. I note that many craftsmen have a problem; they cannot find a wire to wind the secondary winding on the transformer. You can take a demagnetization loop from an old TV, buy a meter of large-section wire, or assemble it from several thin ones.
Battery welding machine
Many craftsmen are tormented by the question of how to make a machine for spot welding batteries with their own hands? Friends, anything is possible!
What materials are needed:
- transformer (discussed above);
- copper plates for shooting electrodes;
- base (table, board, etc.);
- wooden lever, one is enough;
- support for the lever - metal profile;
- spring with fastenings;
- self-tapping screws and bolt with washers.
So, we already have a microwave transformer with a wound secondary winding. All that remains is to build the apparatus and electrodes for connecting the batteries.
The design of the future structure can be anything up to your imagination. Let's look at the simplest option.
We screw the support (profile) onto the base, drill a hole in the middle for the bolt and also attach a spring to the edge of the lever. We install the lever in the support, tighten the bolt, and attach the spring to the base of the device.
From a suitable copper plate we cut out 2 electrodes for homemade spot welding for batteries.
We attach them together with the wires at a slight angle to the free end of the lever.
We install the transformer itself with the power button as close as possible to the electrodes. The shorter the wires, the better.
The operating principle of the constructed device is simple: with one hand we press the lever to the material being welded, and with the other we turn on the current for a few seconds.
Video: will help you assemble a similar machine.
The simplest design for self-made has welding machine, based on the operating principle of contact or. Moreover, such do-it-yourself spot welding from a microwave will be the most accessible technology, not only in terms of the necessary knowledge base, but also in terms of the cost to achieve the goal.
Resistance spot welding is a method of joining workpieces in the form of rolled metal sheets or welding various piece products to structures: bolts, washers, rivets and much more. This resistance welding technology is most widely used in industries such as automotive, aircraft and instrument making.
Owning a spot welding machine provides a number of advantages and additional features, namely:
- the ability to weld products from sheet metal with small thickness;
- ability to weld low-melting metals;
- neat and durable weld seam.
The main advantage of resistance spot welding is that you can learn to work on it yourself, having only a basic level of knowledge. To do this, you need to practice a little and you will be able to achieve this when working on such a device. high performance, at relatively low costs Supplies and electricity.
Transformer
The main component of any welding machine using electricity for thermal bonding process various metals, is a power transformer, if you do not take into account modern electronic inverter welding equipment. 
The process of resistance spot welding is based on the Lenz-Joule law, which states that an electric current flowing through a conductor releases an amount of heat equal to the square of the electric current multiplied by the resistance of a section of this conductor per unit time:
Q = I**2 x R x t.
That is, with a current strength of, for example, 1000 amperes per small area contact will be highlighted a large number of thermal energy. Depending on the length of time the electric current passes, at first the thermal energy will be enough to melt the contact area of fusible materials aluminum sheets, and with prolonged contact - point melting of steel sheet.
Hence, one of the best candidates for making would be a power transformer taken from an old broken microwave. As a rule, the power of such step-up transformers from a microwave oven ranges from 700 watts to 1.5 kilowatts, which is quite enough.
Keep in mind: that as a welding transformer you can take any suitable power transformer with a power of about 1 kW, but the most convenient, in our opinion, is a voltage converter from a microwave oven; it is easier to convert it.
Step-by-step instruction
First of all, for this we will need a minimum of tools and devices, which, perhaps, any household, namely:
- a small angle grinder with a cutting wheel for metal;
- electric drill or screwdriver with drills;
- hammer and chisel;
- kit metalworking tools in the form of pliers, various screwdrivers, etc.
So let's get started:
Important! Under no circumstances damage the primary winding; it is the main element of the future welding transformer. It can not be removed from the core.
- We are making the secondary winding of our future welding transformer. To do this, we need a piece of insulated copper wire with a cross-section of approximately 50 mm2 or about 8-10 mm in diameter (visually a finger thick) and a length of 70-100 centimeters. The main condition when choosing such a wire is that it must be new and undamaged.
We wind this copper conductor onto the central magnetic core of the steel core of our transformer so that we get two or three full turns. Moreover, this must be done in such a way that the turns on the magnetic core are the middle of the copper conductor, and the remaining ends are approximately equal in length.
- We collect welding transformer. To do this, we install the disassembled parts of the steel magnetic circuit in place exactly as they were, having previously lubricated the contact points epoxy resin or other glue suitable for these purposes. We clamp the entire structure in a vice and wait for the glue to completely harden.
Of course, if possible, these parts of the magnetic circuit can be welded, but it is necessary to reliably protect the transformer windings from possible damage from molten metal or sparks.
- We fix the manufactured welding transformer on the platform; for this it is best to take some insulated base in the form of a durable plastic plate, wooden board or thick plywood. Dimensions are approximately 150 mm in width and from 300 to 700 mm in length, which will further determine the depth of the workpiece to be welded.
The transformer itself should be covered with a protective box, in which it is necessary to make ventilation holes for natural cooling.
- Next, we make welding contacts. Moreover, one of them must be stationary and withstand heavy loads, so we make it from a durable bracket, which is rigidly fixed to the base of the transformer. Using a copper tip, we connect one of the ends of the secondary winding wire to this bracket.
Another 
The contact must be made movable so that it can evenly close with the stationary one, but in a non-working state be normally open. To do this, we make the design of the second contact in the form of a lever, which we fix to the base and spring it with an elastic rubber band or a steel spring. We attach the welding contact bracket to the lever, to which we connect the second, remaining wire of the secondary winding of the welding transformer.
The easiest way to make welding contacts is from a copper rod 10-20 mm in diameter, making cone-shaped points at the ends. You can, of course, use rods specially designed for contact welding made of tungsten or based on beryllium bronze alloys with zirconium.
- Finally, we make the electrical part, that is, we connect the primary winding to a 220 V network. To do this, you can also use the power cord with a plug from our disassembled microwave oven, especially since it is no longer needed there.
To automate the welding process, it is necessary to make a switch. The best option for these purposes is the so-called mic or push-type switch; it can also be taken from the microwave; it will be located in the door opening locking circuit.
We place the microswitch on the break in the primary winding, that is, the 220 V network, and it is most convenient to position it by securing it to the movable contact lever.
Attention! All contacts and exposed parts of the 220 V electrical circuit of the welding machine manufactured by us must be carefully insulated using PVC electrical tape.
- That's it, spot welding from the microwave is ready. All you have to do first is practice to understand how the basic welding processes proceed for various metals, depending on the shape and thickness of the products. But after that you can start practical application yours for its intended purpose.
DIY spotter from the microwave
We described how to make one of the design options for resistance spot welding with your own hands. Although, with the same ease, based on the same power transformer from a microwave, you can make other circuits, including a spotter for carrying out bodywork welding work by car. To do this, instead of stationary clamping contacts, we make elongated flexible contacts, using the same insulated copper wire with a cross-section of 50 mm in diameter, but no less than 2 meters long for each welding electrode.
One of the contacts will be ground and is made in the form of a copper terminal with large area contact. The second electrode will be directly welding and is made in the form of a metal rod with a strong stop, at the end of which a special pointed copper contact is made at the end for simple spot welding.
But to produce a real spotter that is not inferior to industrial designs, you will also need to perform, at a minimum, electrical diagram control and formation of a welding pulse, and you will also have to spend a lot of money on various components and consumables to carry out full-fledged body repair work.
If you have your own experience in the manufacture and use of homemade resistance spot welding machines, then share it in the comments block.
It is difficult to overestimate the importance and necessity of a device for performing spot welding at home. In this way you can connect fence rods, make a cage for a pet, or attach a holder to a ladle. welding equipment industrial production It has high price. A good solution is to make spot welding from a microwave with your own hands.
Necessary equipment for spot welding
To perform welding work, equipment is required that can convert electric current in the network with a frequency of 50 Hz into high frequency. In this case, the voltage of 220 V is reduced to a safe 12 V, and the current rises to a value sufficient to melt the metal.
The spot welding process occurs according to the following scheme:
- Accumulation of charge in a capacitor.
- Metal plates are placed between two copper electrodes.
- During the circuit, a powerful impulse is generated and the metal at the point of contact melts.
- Cooling down.
To create a spot welding device, you will need the following parts and devices:
- transformer;
- terminals, button;
- copper rods - 2 pcs.;
- set of capacitors;
- automatic 20 A;
- relay REK74;
- two LEDs and a diode bridge;
- fan (suitable from a computer).
Sequence of work with a transformer
The most important and required part in the manufacture of a device for spot welding from a microwave, it is a transformer. Before you pull it out, you will need to disconnect all the fasteners and unscrew the base. The secondary winding is not required for the manufacture of the welding machine; it must be removed. This is done with a hammer and chisel, a hacksaw, or a grinder. Work is carried out with care, trying not to damage the primary winding.
For a new secondary winding, you can use a cable with a cross-section of 50 mm 2, which approximately corresponds to a diameter of 1 cm. The main thing is that it is new, without defects or damage. Choose convenient option: stranded in common insulation, or several wires collected together.
The secondary winding is wound around the core in 2-3 turns so that its middle part falls on the core. Exceeding the length will result in an undesirable increase in resistance. The main difficulty in creating a secondary winding is the lack of space. To make work easier, you can remove the factory coating on the cables and use homemade rag insulation; when assembling, cover the outside of the cable with grease or grease.
The power of the converted microwave spot welding transformer is designed to produce welding current at 800 A, which is sufficient for welding metal 3 mm thick or rods with a diameter of 3 mm. For greater thickness, use two transformers connected in series. Such a device will be able to deliver current up to 2000 A.
Manufacturing of electrodes
The spot welding process occurs when the electrodes are short-circuited. The following are used as electrodes:
- tip from a professional soldering iron;
- copper rods with a diameter of 10–20 mm.
Before work, the electrodes are sharpened into a cone shape. You can use special tungsten rods.
During welding work, the electrodes become dull and wear out. With constant use of a spot welding machine, they will need to be changed and sharpened. Therefore, the electrodes are attached and centered using bolts. To eliminate voltage losses at contact points, all other parts are made monolithic or connected by welding. For subsequent fastening of the secondary winding, a terminal is soldered to the ends of the cable.
Features of manufacturing the working part of the welding machine
The working part of the device consists of a lever on which copper electrodes are attached. The fixed lower base must be very stable because it bears heavy loads. It is made from a durable bracket, timber or profile.
The movable upper lever must be unlocked in the non-operating position to provide access to the product. For girth use a rubber band or a rigid spring. Electrodes are attached to the levers, trying to achieve precise alignment.
A pulse button is installed on the top part; it is connected to the primary winding of the transformer, where the current value is lower. When making the device, you can use the button installed on the microwave door. Cables are connected to the electrodes. To prevent future breakage and damage, they are secured to a bracket.
Levers are chosen to be half a meter long - such dimensions make it easy to install parts and do not require much effort during operation. For ease of operation of the lever, a handle is attached to its upper part. You can use an old soldering iron blank. To ensure stability, for a while welding process The lower arm of the device is clamped on the table using a clamp.
Manufacturing of the working case
For homemade spot welding machines, choose the simplest case, consisting of a base, side walls and a top cover. Connect the parts using:
- Corners.
- Self-tapping screws.
Holes are made in the side parts, through which the power cable. A special tape is attached to the top cover for easy transportation.
The spot welding machine does not have a front part. Working pliers are placed in the resulting hole. A fan from the computer provides ventilation during the welding process; it is attached to the back of the machine. There are no ventilation holes. To control the welding time, you can install a special relay. Experienced welders focus on the color of the point at the welding site.
It is important for motorists and homestead owners to have on hand a device for welding metal parts. Industrial goods in the retail chain are not cheap - from 3,000 rubles. Do-it-yourself microwave welding will completely replace it.
The main element of the welding machine
The basis of the homemade product will be a transformer from an old microwave oven.
It provided power to the magnetron and generated up to 4 kilowatts due to high coefficient transformation. In large ovens its power is 700–800 watts. The unit created on it will be able to connect thin metal.
You will need:
- Transformer (if you need a unit more power, you will need two).
- Installation platform.
- Large gauge copper wire.
- Long lever.
- Clamp.
- Cable and insulating material.
- Electrodes.
- Chisel or hacksaw.
- Ampere-voltmeter.
Removing the microwave oven
The electromagnetic emitter and inverter in it required high voltage. Therefore, the converter has fewer turns on the primary winding and more on the secondary. The latter generates a voltage of 2 kilovolts, which is then increased using a doubler.
To make a spot welding machine from a transformer:
- Carefully remove it by removing the housing and disconnecting the fasteners.
- We remove the secondary winding without damaging the primary.
- We remove the shunts that limit the current.
- Using a stranded wire with a cross-section of 1 cm or assembled into a bundle of several thin ones to the same diameter, we wind two or three turns of a new winding.
To prevent thick insulation from complicating the winding operation, remove it and wrap it with fabric insulating tape. To ensure that the resistance does not increase and the current does not decrease, the wire must be as short as possible.
Rework
The converted converter will provide the required output voltage and current of up to 1,000 amperes, which will allow micro-spot resistance welding of thin sheet metal.
For a more powerful unit, you will need two upgraded parts, as described above, connected in series in a chain. Such a welding machine will be able to weld five-millimeter metal fragments.
Identical windings of both converters and their correct combination will avoid the formation of antiphase, as well as short circuits!
Check the assembly accuracy and mark the pins. The serial connection is shown in the diagram.
Measure the values of the “spark” indicators with an ampere-voltmeter.
If the original devices had a power of 0.5 kilowatts, then with an input voltage they gave an output of 2 kilovolts and 250 amperes. In a pair, the latter will increase to 500. In order not to create interruptions in the power grid, it should be no higher than 2,000 amperes.
The same process occurs during welding. But due to the increasing resistance, when the ends of the secondary winding with a large cross-section are connected to the electrodes, significant losses are created.
Electrode preparation
For them, use copper rods or soldering iron tips.
Their diameters strictly correspond to the cross-section of the wires, which should be as short as possible to avoid power losses. It is more effective to solder electrodes to reduce the resistance at the crimp point on the contacts.
To make them replaceable, do not solder the wire-to-tip connections themselves. Connect them by bolting by drilling holes same size. It is better to use copper nuts and bolts, which have less resistance.
Control
It is enough to make a switch and levers that ensure a sufficient fit of the welded parts. To increase the pressing force, add screws to the mechanism. For convenience, equip the 60 cm long clamping lever with a durable rubber ring. It will lighten the load force, and the elastic band will fix it.
This is usually enough for work in a home workshop. To prevent the device from moving on the work table when pressed, its platform is secured with a clamp.
The switch is connected to the primary winding so that additional resistance and overheating do not appear at the contacts. For convenience, it is better to place it on the upper arm.
Attention! The equipment should only be turned on with the electrodes compressed, otherwise strong sparking will occur and the contacts will burn!
During operation of the transformer installation, the wires and tips become hot. So think about how to cool them down. Will do household fan. And while working, take breaks periodically.
Work principles
They are almost no different from the processes when using an industrial welding machine. After compressing the workpieces and touching the electrodes, voltage is applied, and a voltage appears at the welding site. electric arc. Its plasma melts metal, connecting parts.
A residual voltage remains at the bonding site for some time, which can be reduced by not immediately disconnecting the contacts after the process is completed.
As you can see, with the necessary skills, the availability of initial elements and tools, it is quite possible to make a welder yourself. It will be an excellent help in the household and will save your money.
Reading time: 6 minutes
Many home craftsmen are wondering how to make a spot welding machine. A homemade welder is much cheaper and can be repaired inexpensively and quickly, if necessary. Also, homemade devices withstand careless storage better. Their design is much simpler, and a homemade welder rarely contains expensive components.
In this article we will briefly explain what spot welding is. And how to assemble a welding machine with your own hands for spot welding. You will also learn how to make microwave spot welds. And the question “How to make spot welding?” won't seem so difficult to you.
Spot resistance welding is a technology that allows you to form weld using one or more welded points. The more points and the larger their diameter, the stronger and more durable the seam. Both homemade spot welding and expensive industrial devices work on this principle. Below is a diagram of spot welding.
The spot welder can produce up to 600 weld spots per minute. Of course, resistance welding from a microwave cannot boast such productivity, but even with the help homemade apparatus You can achieve relatively good quality seams.
- This is a type of resistance welding. Therefore, this technology is based not only on heating the metal to form a weld point, but also on compressing the part between two metal electrodes. The point is formed by the welding current, which passes from one electrode to another through the part, heating it. At the same time, the part is compressed between two electrodes. This is how the seam is formed.
Powerful spot welding is capable of forming a point on a part up to 2 cm thick. A homemade machine has much more modest characteristics, but with its help you can still weld without problems thin sheets metal without loss of quality. This feature can be useful when repairing a car body in a garage or when welding thin sheet metal.
Scope of application
Industrial spot welding machines can be used in many areas. They are used for welding large and complex metal structures, as well as when assembling ships, space rockets and cars. Spot welding with a small electrode size, it is capable of forming weld spots on small microcircuits, without losing its functionality.
Homemade resistance welding from a microwave oven cannot boast such a wide range of applications. But it can still be used for welding all types of steels: low-carbon, alloy, heat-resistant, anti-corrosion, as well as various alloys. Thus, you can determine for yourself in which cases the use of a homemade device will be justified.
Do-it-yourself spot welding from a microwave can be used in radio electronics or for minor car body repairs.
Next we will tell you how to do resistance welding on your own. Spending a minimum of time and money on this matter. Do-it-yourself spot welding from a microwave is inexpensive and requires a minimum of knowledge to make it.
DIY spot welding
To make a spot welder from a microwave, it is enough to know the basics of electrical engineering and have minimal skills in this area. To make this, you will need a microwave transformer, so you don’t have to purchase the entire microwave. It is enough to find the transformer itself. And if you have a non-working or old microwave oven at home, you can make spot welding from a microwave oven almost free of charge.
Below detailed video with all the explanations, where it is clearly shown and explained how spot welding is done from a microwave transformer.
Making such spot welding is very inexpensive and takes only a couple of hours. As a result, you get a fully functioning welding machine. It is easy to store, can be inexpensively repaired, and does a good job of its main task - forming weld points.
Of course, there are also. But the instructions shown in the video are the most popular. This is due to the low cost and abundance of parts that will be needed to manufacture the device. Even in small town You can easily find all the necessary components.
Feasibility of manufacturing
Yes, homemade spot welding is inexpensive, but is it really worth spending time on it when you can just go to the store and buy a ready-made machine? Everyone finds the answer to this question themselves.
We believe that everything depends on your needs, goals and finances. There are many reasons for making a homemade welder: from simple savings to interest. Some people simply cannot afford to buy a device or cannot find it on sale in their city. Some people like to do everything with their own hands and trust their own experience more than manufacturers.
Do not forget that cheap spot welding machines, although they look better than homemade ones, are not so reliable and sometimes it is not easy to repair them on your own. And is it necessary to waste energy on an inexpensive welder when you can assemble your own? We think it's not necessary.
If you do not have sufficient knowledge to assemble a homemade welding machine, then it is better not to do it. This may be dangerous to your health. Also, you should not engage in self-assembly if you are still willing to spend a decent amount on a quality device. It will still give you more options than a homemade one.
By the way, about possibilities. This is another reason to buy a spot welder rather than assemble it yourself. The simplest homemade welder is limited in its functionality, and sometimes is not able to satisfy all your needs. Don’t expect great performance from a homemade device. If you need to form hundreds of weld spots per minute, then take a closer look at store-bought machines. Homemade device designed for more modest tasks.
In short, it's up to you to decide. In some situations, making homemade spot welding is completely justified and advisable. But there is no denying that sometimes this is a waste of time and effort.
Instead of a conclusion
Here's everything you need to know about self-assembly spot welding machine. contact welding It is not as difficult to make with your own hands as it might seem at first glance. If you have minimal skills in electrical engineering, you can assemble a welding machine from a microwave transformer. You don't even have to look for the entire microwave. On sites selling used goods you can find the transformers themselves, taken from old ones microwave ovens. This option is even cheaper than buying a whole microwave.