How to make a spot device from a microwave. Homemade spot welding machine from a microwave

A simple electric arc welding machine can be made by anyone at home, without using any specialized equipment or circuits. All we need is just two microwave ovens that can be found in a landfill or two transformers from them.

We disassemble the microwaves and take out the transformers.

These transformers are step-up, that is, they convert 220 Volts into a voltage of about 2.5 kV, necessary for the operation of the magnetron. Therefore, their secondary winding contains a less thick wire and with a larger number of turns. Such a transformer has a power of about 1200 W.
To assemble an arc welding machine, we do not have to disassemble the core of these transformers. We will simply cut down and drill out the secondary high-voltage winding. Usually this winding comes from the top, and the primary winding is 220 V from the bottom.
The tool we need for our work.

Making a simple welding machine from a microwave with your own hands

We take the transformer and secure it so that it does not move. We take a hacksaw and cut off the secondary winding on both sides of both transformers. If you decide to repeat, be careful not to damage the primary winding.

Then we drill the winding with a drill with a metal drill, thereby relieving the internal stress of the metals, making it easier to knock out the remains.

We knock out the remnants of the winding.

We have two transformers with 220 V windings. The transformer on the left, above the winding, has a current shunt that separates the windings. To increase power, they also need to be knocked out. Such manipulation will increase the power of the transformer by 20-25 percent.
There is also a small low-voltage winding made of a pair of wires between the large windings - we also throw that out.

We take a stranded wire in plastic insulation with a cross-section of six squares and a length of 11-12 meters. You can take a more stranded wire, not coarse like in my example.

I wound about 17-18 turns on each transformer, 6 rows high and 3 layers thick.

The windings are connected in series. I wound everything with one wire, but you can wind each transformer separately and then connect it. The entire winding is very tight and should not dangle.

After winding is completed, we connect the high-voltage 220 V windings in parallel. I used automotive grade ferrules, insulated with heat shrink tubing.

I plug in the entire structure and measure the voltage on the secondary that I wound. The result was about 31-32 Volts.

Then I took a wooden board and screwed both transformers with self-tapping screws to make one unit.

When welding, I will use 2.5 mm electrodes and weld two pieces of iron 2 mm thick.
I'm happy with the result; it's quite suitable for household needs, considering that I actually got everything for free.

Watch the video of making an arc welding machine

Quite often in the practice of any owner, the need arises to connect metal parts. One such connection method is welding. But what to do if you don’t have a welding machine? Of course, you can buy it, but you can also make the simplest device yourself, and in almost half an hour.

Prologue

The simplest prototype of a welding machine - a lighting electric arc projector - was used back in the mid-twentieth century in film studios during the filming of films.

At home, it is possible to make a simple, rare homemade welding machine from a 200 W autotransformer. (An approximate diagram of an autotransformer is shown in the figure). The output voltage is regulated by rearranging the television plug in the sockets.

On the secondary winding of the transformer, you need to find two terminals at which the voltage will be about 40 V. All that remains is to connect the graphite electrodes to these terminals and the welding machine is ready! However, it must be taken into account that when using such an autotransformer for welding purposes, it is advisable to have a good knowledge of the basics of electrical safety, since galvanic isolation from the electrical network is not ensured.

The scope of application of such a homemade welding machine is quite wide: from welding metal products to hardening the working surfaces of the tool.

Examples of Voltaic Arc Applications

In the practice of radio amateurs, at times there is a need to weld or very strongly heat small parts. In such cases, there is no need to use a serious welding machine, because... To create high-temperature plasma it is not necessary to have special equipment.

Let's look at several examples of the practical application of the Voltaic Arc.

Welding filament magnetron with power buses

In this case, welding is simply necessary, although many, when faced with such a difficulty, replace the magnetron. But most often there are only two malfunctions: the filament breaks at the point (item 1) and the feed-through capacitors (item 2) fail due to breakdown.

The picture shows a magnetron from a Kenwood microwave oven, which worked after repair for more than twenty years.

Of course, making a thermocouple is a completely hopeless task, but it happens that it needs to be repaired if the “ball” breaks. Typically, such thermocouples are found in multimeters that have a temperature measurement mode

If it is necessary to change the shape of the spring or make a hole, it should be taken into account that the hardened spring is too hard for drilling and too brittle for making a hole with a punch.

And in the case of hardening a steel tool (made from tool steel), it is enough to heat the working surface to a crimson color and cool it in a bath with machine oil. The figure shows a hardened screwdriver blade after machining the working edge.

Small welding work can be performed using a transformer with a power of 200 watts and an output voltage in the range from 30 to 50 volts. In this case, the welding current should be 10-12 Amps. There is no need to worry about the transformer overheating, since the arc burns only for a short time.

An ordinary laboratory autotransformer LATR with a current of 9 Amperes is also suitable. However, the full extent of the danger must be taken into account due to the fact that there is no galvanic isolation from the electrical network.

In order to prevent damage to the graphite roller of the LATR current collector, it is advisable to limit the input current by using a fuse. Then an accidental short circuit in the electrode circuit is no longer scary.

Electrodes can be any graphite rods of simple pencils (preferably soft).

The metal part of the electrical terminal block is used as a holder for the lead.

This figure shows an example of a holder using a terminal block, with one hole used to attach the handle, and the second to clamp the lead into the terminal.

In order to prevent melting of the disposable syringe (item 3) when the terminal block (item 1) is heated, fiberglass washers (item 2) are used. And for a standard connection to the cable, you can use the standard socket from the device (pos. 4).

So, the connection diagram is quite simple: one terminal of the secondary winding is connected to the holder, and the second terminal is connected to the part being welded.

There is another option for attaching the electrode holder using an electrical terminal. The second holder will be needed in case of welding metal products with the same melting point or if it is necessary to heat the metal product (hardening, changing shape).

Diagram for connecting two graphite electrodes to the secondary winding of a transformer.

To protect your eyes from corneal burns and from sparks, it will not be enough to use dark glasses due to the low density of light filters. The following device can be made: the frame of binocular glasses with the lenses removed can serve as a shield; The filter is attached using a stationery clip. Or you can use amateur radio glasses used in SMD technologies.

When welding copper with nichrome or steel, you will need flux. When a small amount of water is added to sodium tetraborate (borax) or boric acid, a paste is obtained, which is used to lubricate the welding areas.

The materials for making flux can usually be found at a hardware store. You can also use Borax insect repellent containing boric acid.

Scheme for connecting an analogue CCTV camera to a TV or computer

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 removing unnecessary junk, we take a copper cable (with a cross-section of 16mm2, determined experimentally) and wind 2 turns in the transformer windows.

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 are thinking about the design of the future structure.

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 the 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, we will consider simpler options for a do-it-yourself 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 cord.

Take these accessories from the disassembled microwave.

Also needed:

1. electrodes can be made from a soldering iron tip or thick copper wire;
2. copper holders for attaching electrodes (you will have to buy);
3. 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.

Using wooden blanks and self-tapping screws, we 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. We drill through holes in the side walls and levers, and secure them using 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 out the metal rods and remove the pliers to 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.

Your own welding machine is always useful on the farm, even if not often, but it is very necessary, and sometimes you just can’t live without it. Especially if you are used to making things yourself. Therefore, do-it-yourself microwelding, made from scrap materials and used household appliances, is just what we need.

We will not consider the option of buying a factory-made welding machine, since this will require money, but will immediately go down the path of making homemade mini welding at home. There are several quite accessible schemes for welding machines for self-production, but the simplest and most cost-effective one seems to be a contact or spot welding machine.

So that there is no immediate doubt about why we will describe the option as, for this we will clearly define that for this we will not need theoretical knowledge of the electrical engineering course and masterly mastery of plumbing skills. Everything will be simple, clear and accessible.

Preparation

The main part of all electric welding machines is the power transformer (if we do not consider modern electronic welding equipment, also called inverters). Therefore, first of all, we will need to get it from somewhere and the most suitable and affordable option for this will be an old broken microwave oven. And the larger it is, the better for us. More precisely, the more powerful its transformer will be and the stronger our welding will be.

If you want, it’s not a problem to find an old microwave by looking for it either from your closest friends (those who are richer), or by looking at free bulletin boards, where they are often offered for a nominal fee. Of the insides of the microwave oven, we will be interested in only one detail - the high-voltage transformer.

Here we will immediately determine, without going particularly into technical calculations, that contact welding made from such a transformer from a microwave will be capable of generating a welding current from 800 to 1000 amperes. This current is quite enough to weld together strips of metal up to 2 mm thick, even stainless steel, which is a difficult task for simple welding.

Preparing the welding transformer

A high-voltage microwave transformer is a steel core made up of thin steel plates and two copper wire windings located inside it. We will need the winding that looks smaller, it is considered primary and will be wound from a thicker conductor. The other winding (the one that is larger) will be secondary and we simply do not need it. This is what needs to be removed from the transformer first.

To do this, you need to disassemble the transformer, or rather, its core, which is made up of steel plates, tightly compressed and fastened together with two thin welds. Here we will need to cut these welding seams, for which we can use either a hacksaw or a grinder with a thin circle.

Keep in mind! There may be transformers held together by an outer tin casing and bolts. In this case, simply unscrew the bolted connections and carefully unclench the casing. That's it, there shouldn't be any problems with further disassembly.

Perform this operation of disassembling the transformer very carefully, since we will still need the primary winding, so under no circumstances bend or scratch it when removing it. But we don’t stand on ceremony with the secondary winding, it can be cut and pulled out using a hammer and chisel in parts, it will be much easier.

As a result, we have a complete and undamaged primary winding of the transformer and its steel core in the form of two separated parts.

Next, we wind the secondary winding of our future welding transformer. Here we still have to buy a piece of new copper wire in insulation with a cross-section of 50 mm2 or about 8 mm in diameter. To do this, we take it and wrap it around the central W-shaped magnetic circuit of the core, making two full turns. We will need a total of about 50 cm of such copper wire, taking into account the output to the welding contacts, the only condition is that the winding must be made so that it is the middle of the conductor.

Then we assemble the transformer, while the primary winding should remain in its place, and our new winding made of copper wire should be placed instead of the secondary. We fasten the two parts of the core using ordinary two-component epoxy resin and clamp the entire structure in a bench vise for a day. After the epoxy has dried, the transformer is completely ready for use. Photo

Assembly of the structure

Having made test measurements with a simple tester when connecting the primary winding to a 220 V network, we have a voltage of about 2 V on the secondary winding, but with an electric current of approximately 800 A (this is not measured, but calculated - we take our word for it here). This current strength is more than enough to make a strong welded connection between two metal plates.

Now we make the body. To do this, you can use any available materials, such as wood, plywood, sheets of durable plastic or galvanized sheet. The main thing is to place the transformer itself and the lower contact on a solid base, since one of the conditions is strong contact of the welding electrodes with the surface to be welded, which, in turn, is possible with the application of great effort.

All that remains is to make the welding contacts and the mechanical part of our welding machine will be completed. One of the contacts will be located at the bottom and it will be motionless, so it is better to make its base from a wooden block 30 cm long, this will make it easier to attach it to the base. At the end of the bar, using a manufactured bracket, we attach a welding electrode, to which we connect one of the wires of the power winding of the transformer.

Welding electrodes for microwelding can be made with your own hands from a copper rod with a cross-section of 5 to 10 mm in diameter, making a small point at the end at the point of contact with the surface to be welded. It is better, of course, to use tungsten rods or special electrodes for resistance welding made from a beryllium bronze alloy with zirconium additives.

We make the upper contact in the form of a lever. For this you can also use a wooden block or a not very massive metal profile in the form of a small diameter pipe. The only thing is that on a metal lever the design of fastening the welding electrode will be more complicated, since it will also need to be insulated. We must provide a spring at the base of the movable contact lever so that the lever in its normal state is constantly in the upper position. To do this, you can use a steel spring or an elastic rubber band.

Finally, we complete the electrical circuit of the mini welder by connecting a wire with a standard plug for a 220 V network to the ends of the primary winding of our power transformer, and it is imperative to provide a 220 V switch. For this, both an old wire from a microwave oven and any switch designed for a voltage of 220 V and a current of 5 A, it is better if it is a push-type microswitch (micrik).

Important! Do not forget to properly insulate all electrical connections and contacts.

That’s it, your hand-made mini welder for your dacha or home is ready and, as it turns out, making it yourself is not so difficult. Now you can safely weld small flat parts from various metals, but for this you will need to practice and gain practical skills.

You can also watch the video on how to make resistance spot welding with your own hands and how you can use it.

I really needed a spot welder and I decided to make it myself from an old microwave oven. In this article I will describe the detailed process of creating it. It is mainly needed for soldering thin sheet metals together, for example, for fastening batteries together using a thin metal bar, since they are afraid of overheating, you cannot simply solder them with a soldering iron. This spot welding from a microwave transformer is capable of delivering current up to 800 Amperes.

Parts and tools:

• An old unnecessary microwave, or rather a transformer from it;
• Terminal block;
• A piece of copper wire with a diameter of 1.7 mm;
• Power multi-core cable with a diameter of 8 mm;
• Power adapter 12 V and 0.5 A;
• Computer power supply, or rather its metal case;
• 220V switch;
• Momentary button;
• Wooden slats;
• Spring.

How to make spot welding with your own hands, step-by-step instructions:

We will need an old unnecessary or non-working (well, naturally with a working transformer) microwave oven; the larger it is, the more powerful the transformer can be there. So, we take out this part we need from it; I came across an 800 Ampere transformer.

Then we disassemble the computer power supply, leaving only the iron case and the 220V power connector, into which we will place all the spot welding stuffing.

We place the transformer, timer board and power adapter in the case, try on and mark all the necessary holes that will need to be drilled in the future.

We will need to get rid of the secondary winding (the one with the thinner wire) of the microwave transformer and wind our new winding with the power cable. In order not to disassemble the transformer plates, you can first cut off the winding on one side with a chisel by hitting it with a hammer, then do the same on the other side. Then just knock out the remaining wire hairs, I did this with a drill.

Now, instead of the old windings, we wind new ones with a power cable, I got 2 turns. We put this transformer in the case, where the grille is, we make two holes for the coil leads, thread them through, and we also make holes in the bottom of the case for the trans fastenings.

Add a power switch to the back panel.

I will show you a complete diagram of connecting all parts:

We cut off the plug from the power adapter, since it takes up extra space and we solder directly to the power connector with wires. We solder all the parts of the future spot welding with wires; I connected the timer to the transformer with terminals. I connected a non-latching button to the timer. Using a variable timer resistor, the pulse time for welding is set; the appropriate time is selected when welding the parts.

Using metal corners, we attach a wooden strip to the body of the welder.

We take out the terminal blocks with screws from the terminal block and put them on the stripped cable contacts, clamp them with the screws. Now we screw them to the rail with screws.

We also place the release button in the same rail for convenience by drilling a hole for it.

We make electrodes from copper wire with a diameter of 1.7 mm, twisting them in this way (but if you have thick wire, you can turn them into more beautiful contacts), grind the ends so that they are sharp:

We fix them in the terminal blocks:

Now we need to add a spring that will return the contacts of the resistance welding machine to their place. To do this, we will screw another wooden strip to the top cover.