Semi-automatic welding machine: do it yourself at home

The welding machine is in demand among metal workers. It is used for joining, fusing, repairing metal/metal alloy surfaces. Welding is not cheap, so not everyone can afford it.

In this article we will look at how to make a semi-automatic welding machine with your own hands, what you will need to create a welding machine at home, and what are the features of making homemade welding.

Peculiarities

To make semi-automatic welding at home, you need basic knowledge of electronics. The easiest way to do welding is to remake the inverter or transformer. The inverter power must be 150 Amperes or more.

To make homemade welding you will need the following materials:

• Electrical control system.
• Gas supply hose/guide hose.
• Cylinder with protective gas (argon, carbon dioxide).
• Bobbin/reel.
• Filler wire and a device for feeding it (a window regulator from a car will do, it will need to be adjusted).
• Transformer or inverter (power more than 150 A).
• Burner.

You will also need a housing. You can do without it, but it is inconvenient and unsafe both for you and for the device itself. You can use a microwave or a computer system unit as a case.

The entire process of manufacturing a semi-automatic machine is to connect ready-made elements.There is no need to change them, except for the mechanism for feeding wire and gas; the rest work as is. The wire feeder must be adjusted so that the wire is fed at the melting speed. The wire feed speed is affected by its diameter, material of manufacture (copper, steel), as well as the material being welded (metal, alloy). Take this into account when making adjustments. We recommend adjusting the speed before each welding job.

How to do welding at home. Tips for making a semi-automatic machine

First you need a diagram/drawing. They are freely available on the Internet. They may differ depending on the welding model, but there are no differences in the main components, so you can use generalized drawings.

Next, if you use a window lifter to feed the wire, it needs to be adjusted, because the quality of welding directly depends on this - the wire must feed smoothly, evenly and at the welding speed. To adjust the window regulator, use a PWM controller. Feed delay can be done using a relay. The relay can also be taken from the car. Instead of a relay, you can use an electric valve; such valves are installed on cylinder reducers.

Adjust the gas supply mechanism. If gas is supplied too late, the electrode may catch fire - the seam will be of poor quality, weak and uneven, and the surface may be damaged. In a properly configured semi-automatic device, it is protected by a “bathtub” of protective gas.

To regulate the gas supply, open/close the gas valve. The correct setting is that the gas is supplied a few milliseconds/seconds earlier than the circuit closes/welding begins.

Preparation

The transformer is the most important element in the welding machine. It changes the voltage and powers the working part.The household voltage is too high for welding to work, so the transformer steps down the voltage. You can take a transformer for homemade welding from a regular microwave.

Transformers from step-up microwave ovens increase the voltage from the network. For welding, you need a step-down type, so the transformer from the microwave must be converted before using it in welding. To do this, change the number of turns on the primary and secondary windings. This will change the transformation coefficient.

For a standard transformer, 100 turns are suitable for the primary circuit, 5 for the secondary circuit. At the output you will receive a voltage twenty times less than in the network (11 V).

The number of turns is written without taking into account the base ones - that is, there should be a total of one hundred turns on the primary circuit, and only five on the secondary circuit. Most of the problems arise at this stage - users remove too much wire, there is high voltage in the network, the wire cannot withstand it, and the wiring catches fire. Or, on the contrary, they removed few turns - the voltage does not decrease enough, the current is weak, the welding simply cannot weld.

Take your time, accurately calculate the number of windings and wire cross-section.

Frame

There are few requirements for the housing for a homemade welding machine - it does not affect the performance of the device. The welding itself consists of many parts, wires, and elements. To use the device conveniently and safely, you need to assemble them into a housing. A microwave oven, a system unit from a personal computer, or you can make it yourself are suitable as a basis. If you decide to make the body yourself, then use thin sheet metal. Make a drawing in advance taking into account all the sizes of the parts.

When making calculations and installing elements, set aside space for cooling.For cooling, use two through fans/coolers from the computer. They should only work for blowing. Do not place parts close to each other, they may overheat.

Two coils must be connected in parallel, the other two in series. This method will provide high DC current.

Control system

To make a control system for a homemade welding machine you need:

• Generator (defining type).
• Relay.
• Feedback.
• Overload protection.
• Control board.

Connect the control board to the transformer block. Connect the remaining elements to it - generator, relay, protection, fan/cooler. Connect the homemade welding device to the power supply via the board. Before performing such welding, you need to check the operation of the control system and working units. Use an oscilloscope, connect it to the outputs.

How to use homemade welding

As usual:

• Insert the wire spool and inspect/check the device. Also check how the gas supply hoses are connected and open the cylinder.
• Clean the work area and the mass, install the mass.
• Connect the welder to the mains and wait.
• Turn on the wire feed and start cooking as with a regular semi-automatic machine.