What can be cooked from squid: quick and tasty

Spot welding, as you know, is performed on specialized equipment, however, such a device can not only be found in serial production, but also made by hand: a transformer removed from an old microwave oven is useful for this. The resulting machine will give you the opportunity to perform high-quality spot welding using alternating current, the strength of which is not regulated.

The transformer is an essential element of any such device for spot welding: its task is to increase the value of the input voltage to the required value. To deal effectively with this, the device must have a high transformation ratio. Such transformers are equipped with large microwave ovens, one of which you need to find. When you find such a model of a microwave, you will need to very carefully remove the transformer from it.

The technology for assembling a spot welding machine can be seen in more or less detail in the video below. An example of this homemade device will help us illustrate the process of creating a dot. For a more in-depth look at the assembly details, read the full article.

We take out the transformer from the microwave

If a transformer with a power of 700-800 W is used in a home-made spot welding machine, then with its help you can connect metal sheets, the thickness of which reaches 1 mm. Such a transformer belongs to the category of step-up devices; to provide power to the magnetron, it is capable of generating a voltage of 4 kV.

The magnetron, which is equipped with any microwave oven, requires for its work high voltage... In this regard, the transformer connected to it differs in a smaller number of turns on its primary winding and a large one on the secondary. At the latter, a voltage of about 2 kV is generated, which then doubles due to the use of a special doubler. There is no point in checking the operability of such a device by measuring the voltage connected to its primary winding.

Remove the transformer from the microwave carefully. Do not handle a hammer or other heavy objects. Its base is unscrewed from the microwave, all fasteners are removed, and the transformer is carefully removed from the place of its installation. In a device removed from a microwave oven, you will need, firstly, its magnetic circuit, and secondly, the primary winding, which, in comparison with the secondary, is made of a thicker wire and has fewer turns.

Due to its uselessness, you will have to dismantle the secondary winding, for which a hammer and a chisel will already come in handy. In this case, it is very important not to damage or crumple the primary winding, therefore, it is necessary to act with the utmost care. If, when dismantling the secondary winding, you find shunts in the transformer used to limit the current strength, they must also be removed.

The secondary winding can be cut with a chisel

If the magnetic core of the transformer is not glued, but a welded structure, then it is better to remove the secondary winding from it using a chisel or a conventional hacksaw for metal. If the winding is very tightly packed into the magnetic circuit window, then by cutting the wires, it will be necessary to drill or pick it out. This must be done very carefully, since the magnetic circuit can collapse due to such manipulations.

After dismantling has been completed, wind up a new secondary winding. To do this, you will need a wire with a diameter of at least 1 cm. If you do not have such a wire in stock, you will have to buy it. At the same time, it is not at all necessary to purchase a solid stranded wire such a cross section, you can also use a bundle of several separate conductors, which in total will provide the required diameter. After installing a new secondary winding, your upgraded transformer will be capable of generating currents up to 1000 A.

If you want to make a spot welder more powerful, then the technical capabilities of one transformer may not be enough for you. Here it is necessary to use two such devices (respectively, disassembling two microwaves).

Subtleties of upgrading a transformer from a microwave oven

To make the secondary winding, you need to wind 2-3 turns on the core, which will ensure that an output voltage of about 2 V is obtained, and the strength of a short-term welding current is more than 800 A. This is quite enough for effective work spot welding machine. Winding this many turns can be difficult if the wire used has a thick layer of insulation. The solution to this problem is quite simple: you need to remove the standard insulation from the wire and wrap it with electrical tape having a fabric base. It is very important that the wire used for the secondary winding has the shortest possible length, which will avoid an unreasonable increase in its resistance and, accordingly, a decrease in current strength.

If you need to weld metal sheets up to 5 mm thick, keep in mind that this requires a more powerful spot welder. To do it yourself, you need to use two transformers connected in one circuit. It is imperative to follow the relevant rules when making such a connection. If you make a mistake and incorrectly connect the primary and secondary leads of the two transformers, a short circuit may occur. The correctness of the connection of the windings, if there is no marking on their terminals of the same name, is checked using a voltmeter.

After the correct connection of the terminals of the same name of two transformers, it is required to measure the value of the current strength that they form together. Usually, homemade transformers, intended for spot welding machines, which are planned to be operated in home workshops, are limited in current strength - no more than 2000 A. Exceeding this value will provoke interruptions in the operation of the electrical network not only in your home, but also in your closest neighbors. And this, naturally, will lead to conflicts. The value of the current produced by the connected transformers, as well as the presence of a short circuit in their circuit, is checked using an ammeter.

Another example of a spot weld assembly is shown in the video below:

What results can be achieved if, in accordance with the rules, two transformers that do not differ in high power are connected? If we take two identical devices with the following characteristics: power - 0.5 kW, input voltage - 220 V, output voltage - 2 V, rated current strength - 250 A, then by connecting their primary and secondary windings in series, you will get twice the rated current, i.e. 500 A.

In almost the same way, the short-term welding current will increase, but during its formation, significant losses will be observed, which is due to the high resistance of such an electrical circuit. Both ends of the secondary winding - wires Ø 1 cm - are connected to the electrodes of the spot welder.

Connection of 2 transformers according to scheme No. 1

If you have two powerful transformers at your disposal, but their output voltage is not enough for a home-made device, you can serially connect their secondary windings, which should have the same number of turns. Such a measure is resorted to if it is simply impossible to wind the turns on the secondary winding due to the insufficiently large size of the window on the magnetic circuit.

With such a connection, it is necessary to ensure that the direction of the turns on the secondary windings of the devices to be connected is coordinated, otherwise an antiphase may result, and the output voltage of such a combined device will be close to zero. To experimentally determine the correctness of the connection, it is advisable to use thin wires.

How to determine the terminals of the same name of transformers

If the terminals of the windings of the connected devices are not marked, then it is necessary to determine among them the ones of the same name in order to connect them to each other. This problem can be solved in the following way: the primary and secondary windings of two or more transformers are connected in series, a voltage is applied to the input of such a combined device, and an alternating voltage voltmeter is connected to the output terminals (terminals from the series-connected secondary windings).

Depending on the direction of connection, the voltmeter can behave differently:

• show this or that voltage value;
• show no voltage at all in the circuit.

If the voltmeter gives out any voltage, it means that there are opposite terminals in the connection circuit of both the primary and secondary windings. When connecting the windings in such an incorrect way, the following processes take place in them: the voltage supplied to the input of the primary windings of two connected transformers is halved on each of them; an increase in voltage occurs on the secondary windings, each of which has the same transformation ratio. The voltmeter at the output will register the total voltage, the value of which is equal to twice the input voltage.

If the voltmeter shows a value of "0", then this means that the voltages coming out of each of the series-connected secondary windings are equal in value, but have different signs thus, they cancel each other out. In other words, at least one of the pairs of windings combined into a circuit is connected by the same terminals. In this case, the correct connection of the circuit elements is achieved by changing the order of connecting the primary or secondary windings, focusing on the readings of the voltmeter.

Homemade spot welding electrodes

Choosing electrodes for a spot welding machine assembled by your own hands from a microwave, you should pay attention to the fact that their diameter corresponds to the diameter of the wire to which they are connected. Copper rods can be used as such elements, and tips from professional soldering irons are suitable for low-power devices.

During operation, electrodes for spot welding are actively worn out. To correct their geometric parameters, they must be constantly sharpened. Naturally, over time, such elements will require replacement with new ones.

The wires that connect the electrodes to the spot welder must be as short as possible, otherwise they will lose a lot of the power of the device. Power losses will also become severe if there are many connections in the electrode-spot welder electrical circuit. If you want to increase the efficiency of using your homemade equipment, it is better to solder copper lugs on the wires that connect the electrodes. By using such lugs, you will avoid power losses at the contact points due to the increased resistance of the crimp or any other connections.

The wires connecting the electrodes with the spot welder have a fairly large diameter, so special tips, previously subjected to tinning, will help to facilitate their soldering. Since the electrodes for such a device are removable, soldering is not performed in the places where they are connected to the tips. Of course, there is also a loss of power in such places, which are constantly exposed to oxidation, but they are much easier to clean than crimped tips.

We install electrodes on the welding machine

As already mentioned above, an electrode for resistance welding can be made from a copper rod or a tip from a professional soldering iron if the power of the device is low. The wire from the device is connected to the electrode using a copper tip, which is connected to it by soldering.

The tip is aligned with the electrode using a bolt connection, which must be very reliable so that an increase in resistance at the point of unreliable contact does not lead to a loss of power of the spot welder. To make such a connection, holes of the same diameter are made in the electrode and tip.

The bolts and nuts with which the electrodes and lugs will be connected to the wires are best chosen from copper or its alloys, which have a minimum electrical resistance. Elements of such connections, which greatly simplify the maintenance of the contact welding apparatus, are not difficult to make with your own hands.

Homemade spot welding controls

Controlling a spot welding machine (especially one made from a microwave oven with your own hands) is not particularly difficult. For this, two elements are sufficient: a lever and a switch. The compression force between the electrodes, for which the lever is responsible, must ensure reliable contact of the parts to be joined at the point of welding. To fulfill these important requirements, the linkages of such devices can be supplemented with screw elements, which provide an even greater compression force. Naturally, such an element of a spot welder must have a very high reliability.

On serious production equipment, which is used to join sheets of steel of considerable thickness, compression elements are installed that create a pressure of 50 to 1000 kg, depending on the need. And on spot welding machines used for irregular and uncomplicated work in a home workshop, it is enough for such a mechanism to create a pressure of up to 30 kg. For convenience and ease of operation on a spot welder, its clamping lever is made longer, this will also increase the compression force to the required value.

For a homemade home appliance, a lever, the length of which will be 60 cm, is quite enough. With the help of such a lever, the applied force can be increased 10 times. Accordingly, if you press on the lever with a force of 3 kg, then the electrodes and the parts to be connected will be compressed with a force of 30 kg. So that such a lever does not move the device itself when pressed, the base of the equipment must be securely fixed on the surface of the desktop with a clamp.

The switch, which is responsible in the device for supplying current to, is connected to the circuit of the primary winding of the transformer, the current in which is much less than in the secondary. If you connect the switch to the secondary winding, then it will create additional resistance, and its contacts will be tightly welded under the influence of a strong current.

If a lever is used as a clamping mechanism, then it is better to place the switch directly on it, then the second hand will be free (it can be used to support the parts to be welded).

The peculiarities of working on home-made equipment for spot welding are that current should be applied to the electrodes only when they are in a compressed state. Otherwise, you will encounter intense arcing of the electrodes and, as a result, with their active burning. You can get an initial experience of working on such a device with the help of a training video.

The electrodes of spot welding equipment actively heat up during operation. In addition, the transformer and the conductive elements of such a device are subject to intense heating. A simple cooling system should be provided to avoid excessive heat, which can lead to failure of spot welding equipment. For this, they often use regular fan... You can also take breaks from work necessary to cool the elements of the apparatus.

The holding time of the electrodes under current in a compressed state during the welding process can be monitored visually, focusing on the color of the dot at the junction, or using a special relay for this.

It is obvious that making a spot welding machine based on a microwave transformer is not difficult at all, having carefully studied the presented videos and photos of the assembly process and taking into account the recommendations voiced.

(votes: 6 , average rating: 4,83 out of 5)

When performing various renovation works sometimes it becomes necessary to reliably fasten together thin metal sheets or their fragments. The ideal option in this case is the use of electric.

Unlike devices designed for manual electric arc welding, which have long become familiar attributes of home workshops, devices for resistance spot welding are much less common.

The main thing is that the selected cable goes through the magnetic circuit window. Two turns are wound with the selected conductor at the location of the removed secondary winding. Now you can do the first test of a DIY microwave transformer for spot welding.

The ends of the cable are stripped of insulation. Observing safety rules, connect the microwave transformer to the 220 volt network. Using a voltmeter, measure the voltage at the secondary terminals (that is, at the terminals of the welding cable).

If the voltage is between 2 and 4 volts, everything is in order. After that, the operation of the transformer is checked in the spot welding mode, that is, in the short circuit mode.

To check the working current of the future spot welding machine from the microwave transformer, the stripped ends of the welding cable are securely connected to each other using a bolted connection.

They cover the secondary conductor with a clamp meter and briefly turn on the transformer. The short-circuit current value is monitored by the current clamp indicator. If its value is about 500 amperes or more, then everything is done correctly.

Assembling the apparatus

In order for a spot welding machine made from a microwave to be used, it must be equipped with a lever for clamping workpieces, contact point electrodes and a switch.

The lever providing point compression of the workpieces, as well as the housing for the transformer, can be made of wood. At the ends of the arms of the lever are electrodes made of thick copper rods. Welding cable leads are connected to reliable bolted electrodes. A switch is located in a convenient, easily accessible place.

Now your DIY microwave spot welding is ready to go. The workpieces to be welded are placed between the electrodes, clamp them with a lever and turn on the current. This is how welding takes place.

From the old microwave oven you can make various fixtures and fittings for the garage. One of these is microwave spot welding, which makes it possible to connect metal elements and structures made of sheet steel up to 5 mm thick.

And if you have an unnecessary microwave oven with a working power transformer lying around at home, then it can be easily adapted for these purposes. It is the transformer that will act as the main working element of the welding machine.

This article of the construction magazine will tell you in detail about the manufacture of spot welding, which will definitely come in handy for working in the garage.

The main element of the welding machine is a power transformer, which has a large transformation ratio. The microwave transformer, which is used to power the magnetron, meets just such conditions. Its power can be 700-800 W, and even more than 1 kW.

You should know that low-power microwave transformers are suitable for making spot welding for working with metal, the thickness of which will be no more than 1 mm. If you need to make the spot welding machine more powerful, it is recommended to connect the two microwave transformers together.

Also, in addition to the transformer, for the manufacture of spot welding from the microwave, some materials will also be required.

First of all, these are:

• Profile pipe or other rolled metal for the manufacture of a handle with a base (wooden blocks can also be used);
• A spring by means of which the handle will be thrown up;
• A canopy to make the handle of the welding machine movable;
• Copper bus for the manufacture of electrode holders;
• Copper rods will be used as electrodes for microwave spot welding;
• Piece copper cable in insulation with a diameter of at least 1 cm. If the cable does not fit into the transformer, then the insulation will have to be removed, after which it is imperative to wrap the cable with several layers of ordinary electrical tape.

After all of the above materials are found, you can safely start making a welding machine for spot welding with your own hands.

First of all, you need to remake the microwave transformer, so that at the output of the secondary winding, there would be approximately 2 V. For these purposes, the factory secondary winding is completely removed from the microwave transformer and a new one is wound with a thick copper cable.

In total, you will need to make 2-3 turns of the secondary winding on the converted power transformer. You can remove the old secondary winding from the transformer with a hammer and chisel, but you need to act very carefully so as not to damage the primary winding. It is needed safe and sound for the normal operation of the spot welder.

When the transformer is redesigned, you can take up the manufacture of other parts of the welding machine. You can use two pieces to craft controls shaped pipe, 60 cm long, which are connected by a canopy. You can go the other way and make a base with two supports, between which the spot welding control lever will be located.

In general, controls can be made from anything, even from wooden blocks, if microwave spot welding will be used for some small work. Clamps for electrodes deserve special attention, which will be best made from a copper bus, then drilling holes for bolts in them.

It is the bolts that will subsequently hold the electrodes for spot welding, for which it is recommended to use a copper bar (the larger its diameter, the better). In order for the welding machine to turn on only when the handle is pressed, a switch should be placed between it and the base. It should only be connected through the primary winding of the transformer to avoid heavy loads.

Microwave spot welding will be an excellent tool in the hands of a master. Such a homemade welding machine can be used to make other homemade products and metal crafts, the ideas of which are very, very many on the Internet.

We continue the cycle theme.
When I cycled to work, it was inconvenient to carry in a backpack - my back sweats. It is inconvenient to carry on the trunk - the package slips and strives to get into the spokes. You need a small basket for the trunk, which would keep a small load from falling. Since such small baskets are not made, it was decided to do it yourself. To assemble such a basket you need contact welding, she can also cook batteries.
The process of assembling the trunk basket, battery batteries, and the welding itself is described below.

"Welding body"- microwave transformer.
The secondary winding was removed with a hacksaw, the plates between the primary and the secondary were removed. I recommend it with a hacksaw, with a dremel or grinder, it is easy to damage the primary winding, but it is still needed. In the window of the secondary winding, a wire PV3 of 70 square millimeters was wound (pushed, hammered) into 4 hands, 1 meter is enough. The wire goes very hard, two people refueled.
Tinned copper tips are soldered onto the wire with a gas torch, but it was not possible to solder pure copper ones. Electrodes are attached to the tips - 10 squares of copper for welding batteries and rectangular for welding a bar or sheet.



In the case of rectangular electrodes, they allow you to cook both a wire, if the electrodes are flat on a plane, and a sheet if you turn the upper electrode by an angle, as in the photo.
Rectangular electrodes are plates from the current transformer installation kit, they were not useful during electrical installation, but here they are.

"Brains of Welding"- a self-made timer on the PIC16F628A microcontroller, the link to which is in the title of the review.
It was purchased from the Chinese Super Electronic market store, I am not doing it the first and I think it will not be the last. When ordering at $ 15-30, it sends by mail with a normal track, packs well, does not mess with the bundle. At the same time, his prices are usually minimal or close to them.
In addition to pikuhi, it was purchased
-, 10 items, 5 pcs. - $ 2.7 lot 50 pcs.
- 50 pcs $ 1.28
- 10 pieces $ 4.8
- 10 pcs 1.6 $
- - 10 pieces $ 13.8

The scheme is taken as a basis from

The power unit was taken from the circuit, it was decided to write the firmware myself.
The scheme did not like the use of two buttons - the encoder is faster and more convenient to control, a small range of shutter speeds.

I have already reviewed the power supply, a 5v stub has been added to it. Two supply voltages 5v main and 12v control go to the controller. When the power is turned off, the voltage 12v starts to fall first, it goes through the resistive divider to the controller's leg (blue trimmer, set 3v). The controller sees zero on the leg, saves the parameters and goes to sleep.

The output of the PIC leg gives a signal to the optocoupler, the optocoupler opens the thyristor, which in turn turns on the trance primary. No parts heating was noticed. It is possible to use a solid state relay as in the previous article on this resource. I also used a solid body in the past as a welder, but the optocoupler + thyristor is smaller and cheaper when purchasing 10 pieces.

The encoder was purchased,
It already has pull-up resistors, the encoder is not only spinning but also pressed.
When you press the encoder, the digit begins to blink smoothly (made a change in brightness along a sinusoid) - it shows the number of pulses up to 9, that is, you can cook with a repeated or triple pulse, the pause between pulses is equal to the pulse duration, the duty cycle is 50% in general. When the encoder is pressed again, it memorizes the parameter into memory (checks whether it has changed) and switches back to the operating mode.

Indication on two LED seven-segment indicators, indication is dynamic.

When welding, both hands are usually needed free; to start welding, a pedal was made - a bell button.

When turned on, the timer for 1 sec shows-reminds the number of pulses.
Then the shutter speed indication
.2 -0.02sec
0.2 -0.2 sec
2.2-2.2 sec.
maximum 9.9 seconds, minimum 0.01 seconds
When you press the pedal and work out the shutter speed, - -
The tweezers should not twitch when working out the exposure, it turned out not very clearly.
timer operation 1.33 min

Physically, the timer is assembled in the case of the power supply unit of the HP printer; a board is used from it, as a carrier element and a power connector, a fuse and filtering capacitors at the input.
Something is assembled on racks, something is glued on hot melt glue, in general, all the elements of the collective farm. Oddly enough, everything works.

For the faint of heart and perfectionists, don't look at giblets

Welding nails 4 + 4mm.

Welding result

Trunks, 1 kg of galvanized wire 3 mm was enough for both trunks, the price is about $ 1.5-2
My cell is 4 * 4cm, my wife's cell for a bicycle bag is 5 * 5cm

Welding batteries for screwdrivers

Remains of galvanized

UPD.
Larger photo added

Brief description of the principle of operation and assembly:
Resistance welding - the process of forming a permanent welded joint by heating the metal passing through it electric shock and plastic deformation of the joint area under compressive force. (Wiki)
That is, a large current and compression force is needed. In industrial devices, the compression force and current are electronically controlled; there are welders with hydraulic compression. The simplest ones are where they are squeezed by hands, as in my version. The current is also needed. A microwave transformer allows you to replace the secondary winding, instead of a step-up we put a step-down one. Voltage of great importance does not have, the current is sufficient. When using large transformers, damage to the wiring is possible, the primary winding currents in the microwave transformer are in the region of 15-20 amperes, a good home option.
In addition to the power section, which provides current and sometimes clamping, an electronic section is sometimes needed. Can be put into the primary winding circuit breaker at 16A, as in the driveway, and with the help of it by hand "by eye" set the time delay of the current impact on.
For example so


If you want a little convenience, hold with both hands, then you can add a button. But not every button will withstand currents of 15 amperes, for this you can use a solid-state relay or a starter. If the starter coil or solid state relay input is low voltage, not 220V, then a power supply is needed. This option is in the next picture.


The power supply gives 12 or 24 or any other safe voltage, it turns on the relay / starter through the K button, it is convenient to press with your foot and the button does not fade.
At long exposures of the order of 2-5 seconds and for large details it is permissible. But when welding batteries, plates 0.1-0.2 mm thick are usually used and short exposures of the order of 0.01-0.1 seconds are required. Such exposures are difficult to work out with your hands, exceeding the exposure time is a burn through the plates, and sometimes the battery, but they are not cheap.
For repeatability of the result, put electronic timer, which forms the necessary short exposures.
The next picture is a diagram with a timer.


In total, almost the most advanced option - a transformer with a replaced secondary, a timer button, a power supply, can be combined to taste. For example, if the timer is 220v, then the power supply is not needed, but the leg may get fry if the pedal is 220v.

Brief assembly instructions:
-Find the microwave, disassemble, remove the trance (it is 2/3 the weight of the microwave).
-Check if the primary winding is live, it is usually wound with a thicker wire, ring. Do not turn on! The appearance of high voltage on the secondary winding and the transformer case is possible.
-Carefully remove the winding with the thinnest wire if thick live. Clamp in a vice, cut with a hacksaw or any other not very powerful tool, the remnants are knocked out.
-Remove the shunts (plates between the primary and secondary windings).
-There are a few more turns of the filament winding. It can also be deleted.
-Wind the secondary winding into the vacant window. For welding batteries, 35 squares of copper are enough, for thicker materials 70-100mm. You may need to remove factory insulation and insulate with heat shrink / tape. Two to three turns are usually sufficient. The wire is called PV3 * 70 or welding wire. Maybe PV5 * 70, but I have not seen such.
- Terminate the wire. Tinned copper tips are usually used, copper tips. You can crimp or solder them, or both.
-Fix the electrodes at the ends of the wire. For welding batteries, 10 squares of copper (PV3 * 10) are enough, For thicker metals, electrodes are made from a copper bar large diameter, sharpened at the ends. How better connection electrodes and wires, and the shorter the wire, the more current and better welding.
- Add timer, button, body to your liking. An LED can be added to the upper electrode arm to illuminate the work area. You can add another winding for 3-5 turns and solder a 5V buzzer to it (I have a white wire in the photo), it will beep when welding.

Link to firmware

RV2 adjust to 3v, below log. 0 and the command goes to be saved to memory.
Motor encoder, two buttons to turn it, trigger button and encoder button
B ports for indicator - ABCDEFG-2345610
my indicators are sc56-11gwa, that is, a common cathode.

Oscillograms
the title shows the shutter speed per second.
In the first exposure 0.01 sec, one by one manually, 5 pulses to the right of 0.01
the rest are all 5 pulses by the automatic machine after a pause equal to the shutter speed.

Electric Bicycle Battery Welding