A semi-automatic welding machine is a fairly popular device among professional and home craftsmen, especially those involved in body repair. This unit can be purchased ready-made. But many owners of inverter welding machines are wondering: is it possible to convert the inverter into a semiautomatic device so as not to buy another welder? Making a semiautomatic device from an inverter with your own hands is a rather difficult task, but with strong desire quite feasible.

To assemble the unit, you will need the following items:

• inverter welding machine;
• burner, as well as a special flexible hose, inside which a gas pipeline passes, a wire guide, power cable and electrical control cable;
• mechanism for uniform automatic wire feed;
• control module, as well as a motor speed controller (PWM controller);
• protective gas cylinder (carbon dioxide);
• solenoid valve for cutting off gas;
• coil with electrode wire.

To assemble a home-made semiautomatic device from a welding inverter, the latter must generate a welding current of at least 150 A. But it will have to be slightly upgraded, since the current-voltage characteristics (CVC) of the inverter are not suitable for welding with electrode wire in a shielding gas environment.

But more on that later. First you need to make the mechanical part of the semiautomatic device, namely the wire feed mechanism.

Wire feed mechanism

Since the feeder will be placed in a separate box, it is ideal for this purpose. computer system case. In addition, you do not need to throw away the power supply. It can be adapted to the operation of the broach mechanism.

First, you need to measure the diameter of the wire spool or, having outlined it on paper, cut out a circle and insert it into the body. There must be enough space around the reel to accommodate other components (power supply, hoses and wire feeder).

The wire pulling device is made from a windshield wiper mechanism from a car. Under it, it is necessary to design a frame that will also hold the pressure rollers. The layout must be drawn on thick paper in real scale.

Advice! The connector for connecting the burner hose and the hose with the burner itself can be made by hand. But it would be better to buy ready kit which has an affordable price.

The feeder should be installed in the housing so that the connector is in a convenient location.

In order for the wire to be fed evenly, all components must be fixed exactly opposite each other. The rollers must be centered in relation to the hole for the inlet fitting, which is located in the connector for connecting the hose.

as roller guides use suitable diameter bearings. on them with lathe a small groove is machined along which the electrode wire will move. For the body of the mechanism, you can use plywood 6 mm thick, textolite or durable sheet plastic. All elements are fixed on the basis, as shown in the following photo.

Used as primary wire guide axially drilled bolt. The result is something like a wire extruder. At the inlet of the fitting, a cambric reinforced with a spring is put on (for rigidity).

The rods on which the rollers are fixed are also spring-loaded. The clamping force is set using a bolt located below, to which the spring is attached.

Advice! If for some reason you do not have the opportunity to make a wire pulling mechanism with your own hands, then you can buy it in China. There are 12 V and 24 V mechanisms on sale. In this case, since a PSU is used from a computer, a device powered by 12 V is required.

The basis for fixing the bobbin can be made from a small piece of plywood or textolite and trimmed plastic pipe suitable diameter.

Mechanics control scheme

To achieve good quality seam when welding, it is necessary to ensure that the wire is fed at a certain and constant speed. Since the motor from the wiper is responsible for the feed rate of the equipment, a device is needed that can change the speed of rotation of its armature. Suitable for this turnkey solution, which is also available in China and is called

Below is a diagram from which it becomes clear how the speed controller is connected to the engine. The regulator of the controller with a digital display is displayed on the front panel of the case.

Next, you need to install relay controlling the gas valve. It will also control the start of the engine. All of these elements must be activated by pressing the start button located on the burner handle. In this case, the gas supply to the place of welding should be ahead (by about 2-3 seconds) of the start of the wire feed. Otherwise, the arc will ignite in the environment atmospheric air, and not in a shielding gas environment, as a result of which the electrode wire will melt.

Delay relay for homemade semi-automatic can be assembled on the basis of the 815th transistor and capacitor. To get a pause of 2 seconds, a 200-2500 uF capacitor will be enough.

Advice! Since the power comes from a computer PSU that outputs 12 V, instead of self-manufacturing module, you can use an automotive relay.

It is placed in any place where it will not interfere with the operation of moving parts, and is connected to the circuit according to the diagram. You can use an air valve from GAZ 24 or buy a special one designed for semiautomatic devices. The valve is responsible for the automatic supply of shielding gas to the burner. It turns on after pressing the start button located on the semi-automatic burner. The presence of this element significantly saves gas consumption.

But as already noted, the current-voltage characteristics (CVC) of the inverter are not suitable for the full operation of the semiautomatic device. Therefore, in order for the semi-automatic prefix to work in tandem with an inverter, small changes are required to be made to its electrical circuit.

Changing the I-V characteristic of the inverter

There are many schemes to change the I-V characteristic of an inverter, but the easiest way to do this is as follows:

• assemble the device using throttle from fluorescent lamp according to the scheme below;

• to connect the assembled device, you will need to assemble another block according to the following scheme;

• In order to prevent the inverter from triggering the overheating sensor, an optocoupler must be soldered (in parallel) to it, as shown in the following diagram.

But if the welding current is controlled in the inverter with a shunt, then you can assemble a simple circuit of three resistors and a mode switch, as shown below.

As a result, the conversion of a welding inverter into a semiautomatic device will cost 3 times cheaper than an already finished unit. But of course, for self-assembly of the device, you will need to have certain knowledge in the radio business.

A semi-automatic welding machine is a functional device that can be purchased ready-made or made from. It should be noted that the manufacture of a semi-automatic apparatus from an inverter device is not an easy task, but it can be solved if desired. Those who set themselves such a goal should study the principle of operation of a semiautomatic device well, look thematic photos and video, prepare everything necessary equipment and accessories.

What is required to convert the inverter into a semi-automatic

To remake the inverter, making it a functional semi-automatic welding machine, you must find the following equipment and additional components:

• inverter machine capable of generating a welding current of 150 A;
• a mechanism that will be responsible for feeding the welding wire;
• the main working element is a burner;
• hose through which welding wire;
• hose for supplying shielding gas to the welding area;
• a coil with welding wire (such a coil will need to be subjected to some alterations);
• an electronic unit that controls the operation of your homemade semi-automatic device.

Special attention should be devoted to the alteration of the feeder, due to which the welding wire is fed into the welding zone, moving along a flexible hose. In order for the weld to be of high quality, reliable and accurate, the speed of wire feed through the flexible hose must match the speed of its melting.

Since when welding using a semiautomatic device, wire from different materials and different diameters, its feed rate must be regulated. It is this function - the regulation of the welding wire feed speed - that the feed mechanism of the semiautomatic device should perform.

Internal layout Wire spool Wire feeder (view 1)
Wire feeder (view 2) Attaching the welding sleeve to the feeder Construction of a homemade torch

The most common wire diameters used in semi-automatic welding are 0.8; one; 1.2 and 1.6 mm. Before welding, the wire is wound on special coils, which are prefixes of semi-automatic devices, fixed on them with the help of simple structural elements. During the welding process, the wire is fed automatically, which significantly reduces the time spent on such technological operation simplifies it and makes it more efficient.

The main element of the electronic circuit of the semi-automatic control unit is a microcontroller, which is responsible for regulating and stabilizing the welding current. It is from this element of the electronic circuit of the semi-automatic welding machine that the operating current parameters and the possibility of their regulation depend.

How to remake an inverter transformer

In order for the inverter to be used for a homemade semiautomatic device, its transformer must be subjected to some alterations. It is not difficult to do such an alteration with your own hands, you just need to follow certain rules.

In order to bring the characteristics of the inverter transformer in line with those required for a semiautomatic device, it should be wrapped with a copper strip, on which a thermal paper winding is applied. It must be borne in mind that for these purposes it is impossible to use an ordinary thick wire, which will be very hot.

The secondary winding of the inverter transformer also needs to be redone. To do this, do the following: wind a winding consisting of three layers of tin, each of which must be insulated with a fluoroplastic tape; solder the ends of the existing winding and do-it-yourself winding to each other, which will increase the conductivity of the currents.

The design used to include it in a semi-automatic welding machine must necessarily provide for the presence of a fan, which is necessary for effective cooling of the device.

Setting the inverter used for semi-automatic welding

If you decide to make a semi-automatic welding machine with your own hands, using an inverter for this, you must first de-energize this equipment. To prevent such a device from overheating, its rectifiers (input and output) and power switches should be placed on radiators.

In addition, in that part of the inverter housing where the radiator is located, which heats up more, it is best to mount a temperature sensor, which will be responsible for turning off the device if it overheats.

After all the above procedures are completed, you can connect the power part of the device to its control unit and connect it to electrical network. When the mains indicator lights up, connect an oscilloscope to the outputs of the inverter. Using this device, it is necessary to find electrical impulses with a frequency of 40–50 kHz. The time between the formation of such pulses should be 1.5 μs, which is regulated by changing the voltage value supplied to the input of the device.

It is also necessary to check that the pulses reflected on the oscilloscope screen have a rectangular shape, and their front is no more than 500 ns. If all checked parameters correspond to the required values, then the inverter can be connected to the electrical network. The current coming from the output of the semiautomatic device must have a strength of at least 120 A. If the current strength is less, this may mean that a voltage is supplied to the equipment wires, the value of which does not exceed 100 V. In the event of such a situation, the following must be done: test the equipment by changing the current (in this case, it is necessary to constantly monitor the voltage on the capacitor). In addition, the temperature inside the device should be constantly monitored.

After the semi-automatic has been tested, it is necessary to check it under load. To make such a check, a rheostat is connected to the welding wires, the resistance of which is at least 0.5 ohms. Such a rheostat must withstand a current of 60 A. The current supplied to the welding torch in this situation is controlled using an ammeter. If the current strength when using a load rheostat does not correspond to the required parameters, then the resistance value of this device is selected empirically.

How to use a welding inverter

After starting the semi-automatic device that you assembled with your own hands, the current value of 120 A should appear on the inverter indicator. If everything is done correctly, then it will happen. However, the inverter display may show eights. The reason for this is most often insufficient voltage in the welding wires. It is better to immediately find the cause of such a malfunction and promptly eliminate it.

If everything is done correctly, then the indicator will correctly show the strength of the welding current, which is regulated using special buttons. The adjustment interval for the operating current, which is provided, is in the range of 20–160 A.

How to control the correct operation of the equipment

So that the semi-automatic welding machine that you assembled with your own hands serves you long time, it is better to constantly monitor temperature regime inverter operation. To implement such control, it is necessary to press two buttons simultaneously, after which the temperature of the hottest radiator of the inverter will be displayed on the indicator. The normal operating temperature is the one whose value does not exceed 75 degrees Celsius.

If this value is exceeded, then, in addition to the information displayed on the indicator, the inverter will start emitting intermittent sound signal which you should pay attention to right away. In this case (as well as in the event of a breakdown or short circuit of the temperature sensor), the electronic circuit of the device will automatically reduce the operating current to a value of 20A, and an audible signal will be emitted until the equipment returns to normal. In addition, a malfunction of DIY equipment may be indicated by an error code (Err) displayed on the inverter indicator.

I bought myself a welding inverter GYS IMS 1300
Thing is awesome.
Lightweight, small, take it with you.
Cooks with a 2 mm electrode - anything.
But they can't weld the car
the metal of the car is thin - it burns holes.
We were looking for 1.6 mm electrodes, but not in Chernihiv, maybe in Kyiv, but they haven’t called yet (I ordered to find it)
We suffered at home, but we could not weld the metal in the Zhiguli.

I went to a friend, he has a SEMI-AUTO, with CO2 which.
I cooked them - I really liked it.
Thin metal is also easy to cook, just pours neatly.
I found a wire that cooks without gas - POWDER WIRE, it seems that's what it's called.
Brought it, tried to cook it, without gas - COOK.
I immediately had an idea - what if you make such an installation at home?

I bought a wiper motor in the market.
I ordered a toothy gear cut at the factory, hardened - done.
Assembled the installation that feeds the wire.
I bought a real nose, like a semi-automatic.

I connected the wire feeder to the Inverter and started testing.
TOTAL:
Sometimes it is possible to catch a constant arc, somewhere at 20 Amperes, or at 30 A.
But thin metal is weeded, and on thick drops of "CPET9 but the welding quality is terrible.
It was possible to weld metal to metal. but TERRIBLY ugly, the Electrode would have turned out more accurately.

Further nuances: the wire is fed normally.
1. The first option was - the feed was fast, set 60-70 A - it managed to both supply and burn, and the arc is constant, but it cuts the metal, too much current.
2. The second option - the speed is reduced by 2 times - the optimal feed rate is at 15-20 Amps.
- tried to weld thin metal (from the body of the Zhiguli) to 3 mm - barely welded. Looks terrible. A bunch of drops, garbage, but holding on tight)))
=====================================================================
Now for the experts:
1. If I did something UNEARTHLY - do not scold, I just did not know.
2. Should such a monster work.
3. maybe something in the feeder is wrong?
4. Maybe welding of this type cannot weld with such a wire (cored wire 0.9 mm)?
5. Sometimes I can’t create an arc, what is the reason for this. (the feed is on, but the wire rested and does not burn, you have to strike like an electrode)

ASYA - 422458106 (for those who are interested in talking with such "unique"9)))

Easier - buy ready-made.
Cooking semi-automatically from a source intended for welding with a stick electrode (MMA mode, external current-voltage static characteristic - VAC - steeply falling - 15-20V / 100A, or “bayonet9 - current source), in principle, is possible. But this requires a feed mechanism with a feed rate dependent on the arc voltage. By the way, self-shielded wire is good, but expensive, so shielding gas (at least carbon dioxide, by no means food!) Doesn't hurt!

I got a question.
Purely in theory, it should be cooked from an inverter, transformer, etc.
Question:
How is wire contact made?
My wire is in contact only with the COPPER tube at the outlet. That is, I attach power from welding to copper tube, through which the wire climbs.
And how is it necessary?
Can contact also be made on rollers, feeders?
Or should the contact be in general along the entire length, even in the spring along which the wire goes?

The fact is that sometimes the wire rests on the metal and creeps further, without combustion, rested and crawls, but there is no arc.
That's what I suspect.
Maybe this is due to the fact that I have contact only when I exit?
maybe you need to make contact with the power supply, if possible, make 100%, along the entire length of the wire advance?

How to make a semi-automatic device from an inverter with your own hands

A good owner must have a semi-automatic welding machine, especially for owners of cars and private property. You can always do small things with him. If you need to weld a part of the machine, make a greenhouse or create some kind of metal structure, then such a device will become an indispensable assistant in the personal household. Here the dilemma arises: buy or make yourself. If there is an inverter available, then it is easier to do it yourself. It will cost much less than buying trading network. True, you need at least basic knowledge on the basics of electronics, the availability of the necessary tools and desire.

Creating a semiautomatic device from an inverter with your own hands

Converting an inverter into a semi-automatic welding machine for welding thin steel (low-alloy and corrosion-resistant) and aluminum alloys with your own hands is not difficult. It is only necessary to understand well the intricacies of the upcoming work and delve into the nuances of manufacturing. An inverter is a device used to lower the electrical voltage to the required level to power the welding arc.

The essence of the semi-automatic welding process in a protective gas environment is as follows. The electrode wire is fed at a constant speed into the arc burning zone. Shielding gas is supplied to the same area. Most often it is carbon dioxide. This ensures that a high-quality weld is obtained, which is not inferior in strength to the metal being joined, while there are no slags in the joint, since the weld pool is protected from the negative effects of air components (oxygen and nitrogen) by protective gas.

The kit of such a semi-automatic device should include the following elements:

• current source;
• welding process control unit;
• wire feed mechanism;
• shielding gas sleeve;
• carbon dioxide cylinder;
• torch gun:
• wire spool.

Welding post device

Principle of operation

When connecting the device to network converts alternating current to direct current. This requires a special electronic module, a high-frequency transformer and rectifiers.

For high-quality welding work, it is necessary that the future device has such parameters as voltage, current strength and welding wire feed speed in a certain balance. This is facilitated by the use of an arc power source having a rigid current-voltage characteristic. The length of the arc is determined by a fixed voltage. The wire feed speed controls the welding current. This must be remembered in order to achieve the best welding results from the device.

Easiest to use circuit diagram from Sanych, who has long made such a semi-automatic device from an inverter and successfully uses it. It can be found on the Internet. Many home craftsmen not only made a semi-automatic welding machine with their own hands according to this scheme, but also improved it. Here is the original source:

Scheme of a semi-automatic welding machine from Sanych

Semiautomatic Sanych

For the manufacture of the transformer, Sanych used 4 cores from the TS-720. The primary winding was wound with copper wire Ø 1.2 mm (number of turns 180 + 25 + 25 + 25 + 25), for the secondary winding I used an 8 mm 2 bus (number of turns 35 + 35). The rectifier was assembled according to a full-wave circuit. For the switch, I chose a paired biscuit. I installed the diodes on the radiator so that they do not overheat during operation. The capacitor was placed in a device with a capacity of 30,000 microfarads. The filter inductor was made on the core from the TC-180. The power part is put into operation with the help of the TKD511-DOD contactor. The power transformer is installed TS-40, rewound to 15V. The roller of the broaching mechanism in this semi-automatic machine has a diameter of 26 mm. It has a guide groove 1 mm deep and 0.5 mm wide. The regulator circuit operates on a voltage of 6V. It is sufficient to ensure optimum welding wire feed.

How other craftsmen improved it, you can read messages on various forums devoted to this issue and delve into the nuances of manufacturing.

Inverter setting

To ensure high-quality operation of the semiautomatic device with small dimensions, it is best to use toroidal type transformers. They have the highest efficiency.

The transformer for the operation of the inverter is prepared as follows: it must be wrapped with a copper strip (40 mm wide, 30 mm thick), protected by thermal paper, of the required length. The secondary winding is made of 3 layers of sheet metal, isolated from each other. To do this, you can use fluoroplastic tape. The ends of the secondary winding at the output must be soldered. In order for such a transformer to work smoothly and at the same time not overheat, it is necessary to install a fan.

Transformer winding diagram

Work on setting up the inverter begins with a de-energization of the power unit. Rectifiers (input and output) and power switches must have heatsinks for cooling. Where the radiator is located, which heats up the most during operation, it is necessary to provide a temperature sensor (its readings during operation should not exceed 75 0 С). After these changes, the power section is connected to the control unit. When included in the email the network indicator should light up. Using an oscilloscope, you need to check the pulses. They must be rectangular.

Their repetition rate should be in the range of 40 ÷ 50 kHz, and they should have a time interval of 1.5 µs (the time is corrected by changing the input voltage). The indicator should show at least 120A. It will not be superfluous to check the device under load. This is done by including a 0.5 ohm load rheostat in the welding leads. It must withstand a current of 60A. This is checked with a voltmeter.

A correctly assembled inverter during welding makes it possible to regulate the current in a wide range: from 20 to 160A, and the choice of the operating current depends on the metal to be welded.

For making an inverter with my own hands you can take a computer unit, which must be in working condition. The body needs to be reinforced by adding stiffeners. An electronic part is mounted in it, made according to the Sanych scheme.

Wire feed

Most often, in such home-made semi-automatic devices, it is possible to feed a welding wire Ø 0.8; 1.0; 1.2 and 1.6 mm. The feed rate must be adjustable. The feeder together with the welding torch can be purchased from the distribution network. If desired and the availability of the necessary details, it is quite possible to do it yourself. Savvy innovators for this use an electric motor from car wipers, 2 bearings, 2 plates and a Ø 25 mm roller. The roller is mounted on the motor shaft. Bearings are fixed on the plates. They stick to the roller. Compression is carried out using a spring. The wire, passing along special guides between the bearings and the roller, is pulled.

All components of the mechanism are installed on a plate with a thickness of at least 8-10 mm, made of textolite, while the wire should come out at the place where the connector connecting to the welding sleeve is installed. A coil with the necessary Ø and brand of wire is also installed here.

Broaching mechanism assy

A homemade burner can also be made with your own hands, using the figure below, where its components are shown clearly in disassembled form. Its purpose is to close the circuit, to provide the supply of shielding gas and welding wire.

Homemade burner device

However, those who want to quickly make a semi-automatic can buy a ready-made gun in the distribution network, along with sleeves for supplying shielding gas and welding wire.

To supply shielding gas to the welding arc, it is best to purchase a cylinder standard type. If you use carbon dioxide as a protective gas, you can use a fire extinguisher cylinder by removing the mouthpiece from it. It must be remembered that it requires a special adapter, which is needed to install the reducer, since the thread on the cylinder does not match the thread on the fire extinguisher neck.

Semiautomatic do-it-yourself. Video

You can learn about the layout, assembly, testing of a home-made semiautomatic device from this video.

Do-it-yourself inverter welding semiautomatic device has undoubted advantages:

• cheaper than store counterparts;
• compact dimensions;
• the ability to cook thin metal even in hard-to-reach places;
• will become the pride of the person who created it with his own hands.

We make a semi-automatic welding machine with our own hands

A unit designed for welding products is considered to be a semi-automatic welding machine. Such devices can be various kinds and forms. But the most important is the inverter mechanism. It is necessary that it be of high quality, multifunctional and safe for the consumer. Most professional welders do not trust Chinese products, making devices on their own. The manufacturing scheme for homemade inverters is quite simple. It is important to consider for what purposes the device will be manufactured.

There are inverters for:

• Welding with flux-cored wire;
• Welding on various gases;
• Welding under a thick layer of flux;

Sometimes, for a high-quality result and obtaining an even weld, the interaction of two devices is necessary.

Also inverter devices are divided into:

• Single-hull;
• double-hull;
• pushing;
• Pulling;
• Stationary;
• Mobile, which includes a trolley;
• Portable;
• Designed for beginner welders;
• Designed for semi-professional welders;
• Designed for professional craftsmen;

What will be required?

A home-made apparatus, the scheme of which is very simple, includes several main elements:

• Mechanism with main function, responsible for controlling the welding current;
• Mains power supply;
• Special burners;
• Convenient clips;
• Sleeves;
• Cart;

Scheme of welding using a semiautomatic device in a protective gas environment:

The master will also need:

• The mechanism that provides the wire feed;
• Flexible hose, through which the wire or powder will flow to the weld under pressure;
• Bobbin with wire;
• Special control device;

Principle of operation

The principle of operation of the inverter includes:

• Adjustment and movement of the burner;
• Control and monitoring of the welding process;

When the unit is connected to the mains, an alternating current is converted to direct current. For this procedure, you will need an electronic module, special rectifiers and a transformer with a high frequency. For high-quality welding, it is necessary for the future unit to have such parameters as the feed rate of a special wire, current strength and voltage be in identical balance. For these characteristics, you will need an arc power source that has current-voltage readings. The length of the arc must be determined by the given voltage. The wire feed speed is directly related to the welding current.

Diagram of a homemade device:

The electrical circuit of the device provides for the fact that the type of welding strongly affects the progressive performance of the apparatus as a whole.

Wiring diagram of a homemade device:

Do-it-yourself semiautomatic device - detailed video

Created plan

Any scheme of a home-made device provides for a separate sequence of work:

• On the entry level it is necessary to provide a preparatory purge of the system. She will perceive the subsequent supply of gas;
• Then you need to start the arc power supply;
• Feed the wire;
• Only after all actions are completed, the inverter will start moving at a given speed.
• At the final stage, the seam should be protected and the crater should be filled;

An example of the implementation of a homemade device:

A home-made device should work on the principle of converting high-frequency currents. In this case, the EMF conversion is excluded. Due to this, the Device can be significantly reduced in size and weight. But to pass quality repair devices, it is necessary to understand electrical engineering.

A story about a homemade semi-automatic

Transformer preparation

Your attention must be paid to the feed mechanism. Using this device, the electrode wire must be fed. Due to the fact that this mechanism breaks down most often, qualitative calculations should be made. It is important to consider that an increase in current in most cases leads to ignition of the electrode. This results in severe damage to the product. But if the current is very weak, then it will not work to make a full-fledged unit. The resulting weld will be unreliable. Therefore, on this stage preparation, it is necessary to correctly perform all the calculations.

Source of power

Repair or fabrication of the structure includes a power source. Such a device can be a rectifier, inverter or transformer. It is this detail that affects the volume and cost of the welder. Inverter power supplies are considered to be the most professional and high-quality devices.

Power supply circuit:

Control board

To create an inverter, a special control board is required. On the this device the units of the device must be mounted:

• Master oscillator, including a galvanic isolation transformer;
• The node by which the relay is controlled;
• Blocks feedback, responsible for the mains voltage and supply current;
• Thermal protection block;
• Block "antistic";

Control unit printed circuit board:

Enclosure selection

Before assembling the unit, you need to select the case. You can choose a box or box with suitable dimensions. It is recommended to choose plastic or thin sheet material. Transformers are mounted into the housing, which are connected to the secondary and primary reels.

Coil Matching

Primary windings are carried out according to parallel circuit. Secondary reels are connected in series. According to a similar scheme, the device is capable of accepting a current of up to 60 A. In this case, the output voltage will be 40 V. These characteristics are perfect for welding small structures at home.

Cooling system

During continuous operation, a homemade inverter can overheat greatly. Therefore, such a device needs special system cooling. by the most simple method creating cooling is the installation of fans. These devices must be attached to the sides of the case. The fans must be installed opposite the transformer device. Mechanisms are attached so that they can work on the hood.

Cooling to be used in homemade device, can be taken out of outdated computer equipment. In order to make not only the removal of warm air, but also the supply of fresh oxygen, 20-50 holes are drilled in the mechanism case. The diameter of such holes must correspond to the diameter of the drill and be at least 5 mm.

Repair / modification of the electrode wire feed speed device

Inverters are considered reliable devices. But with careless care, the devices can fail. Devices may need to be repaired. In most cases main reason is a regulator failure. If the first problems occur, the breakdown affects the further operation of the device. Therefore, in order to avoid future repairs, you should devote as much time as possible to the high-quality assembly of the device.

The scheme of the unit includes a pressure roller. It is equipped with a special wire pressure level regulator. Also in the unit there is a wire feed roller, in which there are two small recesses. Welding wire should come out of them. The use of wire with a diameter of up to 1 mm is allowed. Immediately after the regulator is a solenoid that controls the gas supply.

The regulator is considered a large element. It is fixed with small screws. Therefore, the fastening is extremely unreliable. The unit may tilt, which may cause a malfunction. It is because of this reason that the device often breaks down and requires additional repairs.

Throttle do-it-yourself

In order to make a choke, you will need a transformer, an enamel wire with a diameter of more than 1.5 mm. Insulation is wound between the layers. With the help of an aluminum tire with dimensions of at least 2.5x4.5 mm, 24 turns are wound. The remaining ends of the tire remain 30 cm each. The core is laid using pieces of textolite with a gap of at least 1 mm. It is also allowed to wind a choke on iron from an old tube color TV. But only one coil can be put on such a device. Such a device can stabilize the welding current. The finished product must provide a minimum of 24V at 6A.

welding torch

This device is designed to supply electrode wire, carbon dioxide and arc voltage to the desired welding area. The purpose of the device is to close the circuit, which ensures the supply of the welding wire to the shielding gas.

The cylinder is recommended to buy a standard type. If carbon dioxide is used, the use of a fire extinguisher cylinder is allowed. Previously, the horn is removed from the device. To install the reducer, a special adapter is required, since the cylinder thread does not match the fire extinguisher neck. You will need a trolley to move the cylinders.

The trolley can be made by yourself. The use of ready-made structures is also allowed. You can make single-level, two-level and three-level products. For convenience, the top level stores tools and materials that will be needed for work. For convenient movement, the trolley includes wheels with a diameter of at least 5 cm.

Homemade cart with several variations:

Welding modes in carbon dioxide:

A semi-automatic device differs from a conventional device in a wire feed mechanism. Therefore, such a unit is considered the most complex device. Repair will be necessary in the event of a feeder failure.

Another useful option manufacturing

Alteration of the welding inverter into a semiautomatic device

To make a semiautomatic device from a welding inverter, it is necessary to subject the device to some manipulations. The device is wrapped with a copper strip wrapped with thermal paper. It is important to note that an ordinary thick wire will not work. It will get very hot. The cooling system may not be able to cope with the set load, which will lead to severe overheating of the device.

The secondary winding should consist of three layers of tin. Each layer should be carefully isolated. To do this, use fluoroplastic tape. The ends of the winding must be made soldered together. This procedure allows you to increase the conductivity of currents.

Oscillogram of welding voltage and current on reverse and direct polarity:

Any homemade apparatus poorly perceives the presence of dirt and dust. Therefore, such devices should be cleaned at least once every 4-6 months. The intensity of cleaning should depend on the number of applications. Otherwise, the device will have to be repaired annually.

Approximate modes of welding butt welds using a semiautomatic device:

The main advantage of such devices is little weight. It is also possible to use both AC and DC. Units can weld non-ferrous metals, as well as cast iron. The disadvantages include the low temperature range. Do-it-yourself semi-automatic welding cannot be used at temperatures below 15 ° C. Therefore, for cold regions and for winter period time such devices will not work. Basically, such inverters are used outdoors in summer period or indoors. Homemade designs perfect for welding small structures at home. For professional welding and for wide production, it is recommended to buy ready-made inverters.

How to convert a welding inverter into a semiautomatic device for almost free

Inverters are widely used by home and garage craftsmen. However, welding with such an apparatus requires certain skills from the operator. You need the ability to "hold the arc."

In addition, the arc resistance is a variable value, so the quality of the seam directly depends on the qualifications of the welder.

All these problems fade into the background if you work with a semi-automatic welding machine.

Design features and principle of operation of the semiautomatic device

A distinctive feature of this welder is that instead of replaceable electrodes, a wire is continuously fed into the welding zone.

It provides constant contact and has less resistance than arc welding.

Due to this, a zone of molten metal is instantly formed at the point of contact with the workpiece. The liquid mass glues the surfaces, forming a high-quality and durable seam.

With the help of a semi-automatic device, any metals are easily boiled, including non-ferrous and stainless steel. You can learn the welding technique on your own, there is no need to sign up for courses. The device is very easy to operate, even for a novice welder.


In addition to the electrical part - a high-power current source, the semi-automatic device has a continuous welding wire feed mechanism and a torch equipped with a nozzle to create a gaseous medium.

They work with ordinary copper-plated wire in a protective inert gas (usually carbon dioxide). To do this, a cylinder with a gearbox is connected to a special inlet fitting on the body of the semiautomatic device.

In addition, semi-automatic welding can be done in a self-protective environment, which is created using a special coating on the welding wire. In this case, inert gas is not used.

It is the ease of operation and versatility of the semiautomatic device that makes the unit so popular among amateur welders.

In many kits, the two-in-one function is implemented - a welding inverter and a semiautomatic device in a common housing. An additional tap is made from the inverter - a terminal for connecting the holder of replaceable electrodes.

The only serious drawback is that a high-quality semi-automatic is much more expensive. simple inverter. With similar characteristics, the cost differs by 3-4 times.

Therefore, home craftsmen seek, if possible, to convert the welding inverter into a semi-automatic device. How to do this - we will tell in the next article.

Do-it-yourself welding semiautomatic device from an inverter

The basis of the future unit is a factory welding inverter with output current parameters of at least 150A. Some "kulibins" recommend making changes to the inverter control module, since the nominal current-voltage characteristic is falling, and a different I-V curve is needed for a semiautomatic device.

To do this, you need to have a good understanding of how the device works. If the intervention is incorrect, the inverter will simply stop working. Therefore, the issue of upgrading the scheme is a separate conversation. Let's look at the mechanical part first.

To convert (more precisely, refine) a welding inverter into a semiautomatic device, we need the following elements:

• wire feeder
• the main tool is a burner (gun)
• abrasion resistant hose (internal) for welding wire feed
• sealed hose for supplying inert gas to the welding zone
• bobbin (coil) with welding wire
• control unit for your semi-automatic.

The best solution would be to place the mechanical unit in a separate housing. A full-sized box from a computer system unit is well suited. Moreover, the power supply is used for the wire feed mechanism.

We try on the size of the bobbin with wire. There should be enough space for the stock PSU and hose connector.


The roller feed mechanism is designed based on the existing motor. A good donor is a wiper motor with a standard gearbox.

Under it, we design the frame of the mechanism. The layout is drawn on cardboard, for fitting in real scale.


You can make your own connector and hose with a torch, but for safety, it is better to purchase a ready-made kit. The wire feeder is configured with the intended placement of the connector.


All components must be level, opposite each other, for even wire feed. Therefore, the rollers are carefully centered relative to the inlet fitting of the connector. We use conventional ball bearings as guides for the feed mechanism.


We carry out a preliminary assembly of the feed mechanism in metal. We make fine adjustment and adjustment of the relative position.

Important! With any distortions, the wire will wedge. This is very distracting during welding, and you can "screw up" the seam.

Since the welding wire will be energized, the entire module, including the connector, must be insulated from the housing.

You can use textolite, durable plastic or just a sheet of plywood with a thickness of at least 6 mm. We fix the structure on the body, check the absence of mutual contact metal parts.


The primary guide is made from a conventional bolt, in which a longitudinal hole is drilled (with a conventional electric drill).

It turns out something like a wire extruder, only with free running. A fluoroplastic cambric reinforced with a spring is put on the inlet fitting.

The pressure roller bars also need to be spring-loaded in tension. The tension force is adjustable with a bolt.


We make a console for hanging a bobbin with wire from a plastic pipe (drainage system) and thick plywood.

Provides sufficient strength and (which is especially important!) Electrical isolation from the metal case.

We try on the coil, we thread the wire into the feed mechanism. At this stage, we finally adjust the gaps, mutual arrangement elements, free running wire.


After fine finishing, it is necessary to ensure that the nuts are locked. There are many ways - paint, locknuts, metal sealant.

Semi-automatic control scheme

The motor speed is controlled by a PWM controller. When welding, it is important to accurately set the intensity of the wire feed into the welding zone. Otherwise, you will not be able to ensure a uniform melt of the weld metal.

The variable resistor of the controller is mounted on the front panel of the inverter. The next important part of the circuit is the control relay for the inert gas supply valve and engine start. contact groups should be triggered by pressing the button on the burner.

Moreover, the gas should be supplied two to three seconds earlier than the wire goes into the welding zone.

Otherwise, the ignition of the arc will occur in the atmospheric environment, and the wire will simply burn out, instead of melting.

For this, a simple delay relay is assembled on an 815 transistor and a capacitor. For a pause of a couple of seconds, 200-250 microfarads is enough.

The relay will fit the usual car. Our power supply is 12 volts (computer PSU), so it is convenient to select components.

The valve itself is installed in a free place in the body. Any locking device from the car will do. In our case, an air valve from GAZ 24.

final assembly

We assemble all the controls on the front panel, assemble the case.


PWM feed rate controller can be equipped with a digital indicator. By setting the speed, you can calibrate the readings, or simply remember the numbers for certain operating conditions. In any case, it will add comfort when using.


The semiautomatic welding inverter is ready. However, the falling current-voltage characteristic makes operation inconvenient. There is no that vaunted smoothness of welding, characteristic of a semiautomatic device.

The task is to make the output parameters stable in voltage, and not in current.

Many schemes have been developed for this. Look at the structural solution - the selection of elements occurs for various inverter circuits individually.


Another problem is the operation of the overheating protection temperature sensor on the inverter. This is solved by installing an optocoupler. The temperature sensor is now used as a controller for the modified circuit.


Outcome:
A semi-automatic welding inverter will cost you three times less than a factory copy. The main thing is to study the scheme of your regular welder, and not be afraid to do the work yourself.

How to convert a semi-automatic welding machine from an inverter with your own hands - video instruction

Communities › Homemade (garage car industry) › Blog › Overview of a semi-automatic welding machine With your own hands. The final.

I present to you final version your semi-automatic welding machine or how to make a semi-automatic machine from an MMA welding inverter (stick electrode welding).

At the moment, MMA inverter welding machines (for welding with stick electrodes) are very common, they give out direct current, weigh little and have good efficiency, compared to transformers, and have quite affordable prices. There are also MIG / MAG inverter semi-automatic machines, they have the same advantages, except for one thing - the price, based on this, I thought about how to make a semi-automatic machine from a conventional inverter welder.
The beginning of the project for the construction of a semi-automatic welding machine, or rather a prefix to the inverter, so that the inverter can be used in semi-automatic mode.
In our case, a good welding inverter BRIMA ARC-250

The goal is to make it possible to use the MMA inverter in semi-automatic mode using improvised materials with a minimum budget.
1) For starters, without reinventing the wheel, we purchased a sleeve with a euro connector: Burner EURO MB15AK Jingweitip 180A 3m CYCLONE.

Burner EURO MB15AK Jingweitip 180A 3m CYCLONE

2) One of the main elements of the PA is a tape drive, for the basics we took a motor from the wipers from some kind of bucket, we also needed a bearing time and a euro connector to connect the sleeve.

after I assembled my tape drive, I accidentally stumbled upon aliexpress for a ready-made version and not very expensive.

3) As a case for our prefix to the inverter, we took the case from an ancient computer and safely stuffed everything into it.

Scheme of the prefix PA

That's all the prefix for the inverter is ready!)))
Then the most interesting begins. As you know, the current-voltage characteristic (CVC) for MMA and PA (MIG / MAG) devices is different, for MMA manual welding machines, the CVC has a falling form, i.e. the device maintains a constant current. and for PA devices (MIG / MAG) the CVC has a hard form, i.e. the device maintains a constant voltage. No matter how much I searched, there is no information anywhere on the Internet on how to convert a conventional stick electrode welding machine into PA, but after understanding this issue a little, it turned out to be not so difficult ...

alteration of the CVC on the inverter

now our inverter has the ability to switch from stick electrode welding mode to PA mode.
In the end it turned out something like this:

Since I am a "certified9" welder; in short, I ask you not to judge strictly for the seam and the quality of welding, but nevertheless the device copes with its task and cooks even thin (falge) even thick metal.

You can also watch the video:

TOTAL: We have assembled a prefix and an MMA inverter to work in PA mode.
APPROXIMATE PRICE OF THE QUESTION:
Burner - 2500 rubles
Euro connector - 1000 rubles
PWM controller - 500 rubles
Bearings - 100 rubles
Electrical connector - 300 rubles
Little things - 100 rubles
Old junk - for free)))
TOTAL approx. 4500 rub.

7 months Tags: inverter semi-automatic

A do-it-yourself semiautomatic device from an inverter can be made without much difficulty if you have the appropriate technical knowledge. To make a semiautomatic device with your own hands, you will need to prepare a certain list of mechanisms, devices, tools and materials that are part of the unit.

The semiautomatic device from the inverter includes an inverter and a welding torch.

Preparation for manufacturing and design features

Home craftsmen have developed various schemes for designing semiautomatic devices from an inverter.

The most common device scheme involves required list tools and materials:

• welding inverter, which has the ability to deliver a working current of about 150 A;
• a feed mechanism that feeds the electrode wire into the welding zone;
• burner;
• flexible hose;
• working bobbin with electrode wire, which has changes in the device;
• device control unit.

The inverter should be about 150 A.

Particular attention should be paid to the feed mechanism. Using this structural element, the electrode wire is fed to the burner through a flexible hose. The ideal wire feed speed corresponds to the rate of wire melting. The indicator of the wire feed speed, which is provided by the feeder, has a significant impact on the process of work and the quality of the welding seam using a semi-automatic welding machine.

When designing a semiautomatic device, it is necessary to provide for the possibility of changing the speed of feeding the electrode wire into the welding zone. The ability to change the feed rate of the electrode material allows you to work with consumables of various diameters and from different materials. Most often, when operating semi-automatic welding machines, wire with dimensions of 0.8 mm, 1 mm, 1.2 mm and 1.6 mm is used. The wire is wound on special coils installed in the welding device.

If the wire feed is carried out fully automatically, this significantly reduces the time required for welding workpieces.

The semi-automatic control unit is equipped with a channel for adjusting and stabilizing the working current. Operating current parameters are controlled by the microcontroller in pulse-width mode. The voltage on the capacitor largely depends on the pulse-width parameter of the current. The voltage on the latter directly affects the strength of the working welding current.

Choosing a transformer for the inverter and assembling the unit

Before self-designing a semiautomatic device, you need to decide on the type and power welding transformer, which is planned to be installed in a semiautomatic device. It should be remembered that when using a minimum wire size of 0.8 mm for the welding process, the working welding current should be 160 A. The power of the welding transformer to obtain this current should be 3 kW. When choosing a transformer, you should pay attention to the fact that the toroidal core transformer has a lower weight compared to other types of devices.

When manufacturing a transformer, several subtleties must be taken into account. The transformer must be wrapped with a copper strip with dimensions (40 mm - width and 30 mm - thickness). Before using the copper strip, it is first wrapped with thermal paper. Use for winding ordinary copper wire not possible, because it is very hot.

The secondary winding of the transformer is made of three layers of tin. The layers of tin are isolated from each other with the help of a fluoroplastic tape. At the exit, the ends are soldered together to increase conductivity. In the case where the transformer is installed, a fan is mounted for blowing in order to increase the cooling of the system components during the operation of the device.

Adjustment of the current in the device can be carried out in two ways: on the primary and secondary windings. The implementation of the adjustment in the first way requires the use of a thyristor adjustment circuit. This method of regulation has certain disadvantages, which are eliminated by including a relay and some switching elements in the circuit.

When applying current regulation in the secondary winding, a high ripple occurs, to reduce which a thyristor circuit is used. The use of switching circuits leads to an increase in the weight of the structure and the cost of the installation. For this reason, the use of primary current regulation is considered more acceptable.

To smooth out ripples, a smoothing inductor and a capacitor with a capacity of about 50,000 uF are built into the secondary winding circuit. This configuration of the device allows you to smooth out voltage ripples when choosing any current control scheme.

As a gearbox for wire feed, you can use a gearbox from a VAZ windshield wiper.

Setting up a semi-automatic inverter

When assembling a semi-automatic inverter with your own hands, it is required for power switches, input and output rectifiers to ensure good cooling by using radiators. A thermal sensor is also required in the housing. After the installation of the power part of the device, it is connected to the control unit of the device.

The finished device can be connected to the network. After the indicator lights up, an oscilloscope is connected to the device and the correct operation is checked. Bipolar pulses should have a frequency of 40-50 Hz, and the time between them is corrected by changing the input voltage. The normal time interval between pulses should be 1.5 µs.

The pulses that the oscilloscope registers must have rectangular fronts with a duration of no more than 500 ns.

After checking the inverter, it is connected to the household electrical network. When connecting the device, the indicator should show 120 A. If this indicator is not reached, it is necessary to check the correct assembly of the device.

After testing the device at idle, the device is tested under load. For this purpose, it is required to include a load in the form of a 0.5 Ohm rheostat in the welding wire circuit, which is capable of withstanding a current of more than 60 A. With this load, the current is controlled using a voltmeter.

After assembling the unit, its performance is checked. To do this, click on the start button. Immediately after this, carbon dioxide begins to flow, after a few seconds the current is turned on, the supply of the electrode wire begins. When the device is turned off, the supply of the operating current and the electrode wire is first stopped, and only after a few seconds the electrovalve is closed, which ensures the supply of carbon dioxide to the welding area. As a valve to ensure the supply of carbon dioxide, you can use the valve for supplying water to the rear window of a VAZ car.

Rules for using the welding inverter and the use of the unit

After starting the inverter, the current required for operation is set using the controller. When correct setting at the output of the device, the electric current is 120 A. Using the control unit, if necessary, the current strength can be changed in the range from 20 to 160 A. When using the unit, its heating temperature should be controlled. The heating temperature should not exceed 75º C. To control it, a temperature sensor should be installed in the device. If the temperature rises above the set maximum, the device should be switched off and allowed to cool down. To improve cooling, the unit provides for the installation of several fans.

Semi-automatic welding, made on the basis of an inverter, is used to carry out the procedure for precise welding of products from various types become. In addition, the device is used for welding thin metal blanks. The use of a semi-automatic device is common during automotive repair work body.

After the manufacture of semi-automatic welding from an inverter for the home, this unit becomes an indispensable device used in household for execution a large number various welding jobs.

The advantages of DC welding machines over their "alternating current counterparts" are well known. This includes soft arc ignition, the ability to connect thin-walled parts, less metal spatter, and the absence of non-welding areas. There is not even an annoying (and, as it turned out, harmful to people) cod. And all because there is no main feature inherent in AC welding machines - intermittent burning of the arc when the sinusoid of the supply voltage flows through zero

Rice. 1. Graphs explaining the process of welding on alternating (a) and direct (b) current.

Turning from graphs to real designs, it should also be noted: in AC machines, powerful transformers are used to improve and facilitate welding (the magnetic circuit is made from a special electrical iron with a steeply falling characteristic) and a deliberately overestimated voltage in the secondary winding, reaching up to 80 V, although 25-36 V is enough to support the burning of the arc and the deposition of metal in the welding zone. By reducing the voltage transformed into the secondary circuit to 36 V, it is possible to lighten the weight of the “welder” by 5-6 times, bring its dimensions to the size of a portable TV while improving other performance characteristics.

But how to ignite an arc with a low-voltage winding?

The solution was to introduce a diode bridge with a capacitor into the secondary circuit. As a result, the output voltage of the modernized "welder" was increased by almost 1.5 times. The opinion of experts is confirmed in practice: when the 40-volt DC barrier is exceeded, the arc easily ignites and burns steadily, allowing even thin body metal to be welded.

Rice. 2. Fundamental circuit diagram DC welding machine.

The latter, however, is easily explained. With the introduction of a large capacity into the circuit, the characteristic of the welding machine also turns out to be steeply falling (Fig. 3). The initial increased voltage created by the capacitor facilitates the ignition of the arc. And when the potential on the welding electrode drops to U2 of the transformer (working point "A"), a process of stable arc burning with metal deposition in the welding zone will occur.

Fig.3. Volt-ampere characteristic of the welding machine at direct current.

The "welder" recommended by the author can be assembled even at home, based on an industrial power transformer 220-36 / 42 V (these are usually used in systems for safe lighting and powering low-voltage factory equipment). After making sure that the primary winding, containing, as a rule, 250 turns of insulated wire with a cross section of 1.5 mm2, is intact, the secondary ones are checked. If their condition is not important, everything (with the exception of a working network winding) is deleted without regret. And in the vacated space, a new secondary winding is wound (until the “window” is filled). For the recommended 1.5 kVA transformer, this is 46 turns of a 20 mm2 copper or aluminum bus with good insulation. Moreover, a cable (or several insulated single-core wires twisted into a bundle) with a total cross section of 20 mm2 is quite suitable as a bus.

The choice of the cross section of the electrodes depending on the power of the transformer.

The rectifier bridge can be assembled from semiconductor diodes with an operating current of 120-160 A by installing them on heat sinks-radiators 100x100 mm. It is most convenient to place such a bridge in the same housing with a transformer and a capacitor, bringing to the front textolite panel a 16-ampere switch, an “On” signal light eye, as well as “plus” and “minus” terminals (Fig. 4). And to connect to the electrode holder and the "ground" use a segment single core cable of the corresponding length with a section for copper 20-25 mm2. As for the welding electrodes themselves, their diameter depends on the power of the transformer used.

Rice. 4. Homemade welding machine for DC welding.

And further. When testing, it is recommended, by disconnecting the device (10 minutes after welding) from the network, to check the thermal conditions of the transformer, diode bridge and capacitor. Only after making sure that everything is in order, you can continue to work. After all, an overheated "welder" is a source of increased danger!

Of the other requirements, it is worth noting, I think, that the welding machine must be equipped with a spark-protective mask, gloves and a rubber mat. The place where they are performed welding work, equipped according to the requirements fire safety. In addition, it is necessary to ensure that there are no rags or other combustible materials nearby, and the connection of the “welder” to the network must be carried out in compliance with electrical safety rules through a powerful plug connector of the electrical panel at the entrance to the building.

V.Konovalov, Irkutsk
Mk 04 1998