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It is important for motorists and homeowners to have a device for welding metal parts on hand. Industrial in the distribution network is not cheap – from 3 rubles. Do-it-yourself welding from the microwave will completely replace it.
How to do this, we will tell further.
The main element of the welding machine
The basis of homemade products will be a transformer from an old microwave oven.
It provided power to the magnetron in it and generated up to 4 kilowatts due to the high transformation ratio. In large ovens, its power is 700–800 watts. The unit created on it will be able to connect thin metal.
You will need:
- Transformer (if you need a larger unit, you will need two).
- Installation platform.
- Large copper wire.
- Long lever.
- Clamp.
- Cable and insulating material.
- Electrodes.
- Chisel or hacksaw.
- Ammeter.
Removing the microwave oven
The electromagnetic emitter and the inverter in it required high voltage. Therefore, the converter has a smaller number of turns on the primary winding and more on the secondary. At the latter, a voltage of 2 kilovolts is formed, which then increases with the help of a doubler.
To make a spot welder from a transformer:
- Carefully remove it by removing the case and disconnecting the fasteners.
- We remove the secondary winding without damaging the primary.
- Shunts that limit the current strength are removed.
- With a stranded wire with a cross section of 1 cm or assembled into a bundle of several thin ones up to the same diameter, we wind two or three turns of a new winding.
So that the thick insulation does not impede the winding operation, we remove it and wrap it with electrical tape from the fabric. In order not to increase the resistance and not decrease the current strength, the wire must be as short as possible.
Redesign
The converted converter will provide the desired output voltage and current up to 1 amperes, which will allow micro-spot resistance welding of thin sheet metal.
For a more powerful unit, you will need two upgraded, as described above, parts tied in series into a chain. Such a welding machine will be able to weld five-millimeter metal fragments.
The same windings of both converters and their correct combination will avoid the formation of an antiphase, as well as a short circuit!
Check the accuracy of the assembly, mark the conclusions. The serial connection is shown in the diagram.
Measure the values uXNUMXbuXNUMXbof the “spark” indicators with an ammeter.
If the original devices had a power of 0,5 kilowatts, then at the input voltage they gave 2 kilovolts at the output and 250 amperes. In a pair, the latter will increase to 500. In order not to create interruptions in the power grid, it should be no higher than 2 amperes.
The same process occurs in welding. But due to the increasing resistance, when the ends of the secondary winding with a large cross section are connected to the electrodes, significant losses are created.
Electrode preparation
For them, use copper rods or soldering iron tips.
Their diameters strictly correspond to the cross section of the wires, which should be as short as possible in order to avoid power losses. It is more efficient to solder the electrodes to reduce the resistance at the crimp point on the contacts.
To make them replaceable, do not solder on the wire-to-lug connections themselves. Connect them with a bolt method by drilling holes of the same size. It is better to use copper nuts and bolts, which have less resistance.
Management
It is enough to make a switch and levers that provide a sufficient fit for the parts to be welded. To increase the pressing force, complete the mechanism with screws. For convenience, equip the clamping lever with a length of 60 cm with a durable rubber ring. It will ease the load force, and the elastic band will fix it.
For work in the home workshop, this is usually enough. So that when pressed, the apparatus does not move along the desktop, its platform is fixed with a clamp.
The switch is connected to the primary winding so that additional resistance and overheating do not appear on the contacts. For convenience, it is better to place it on the upper arm.
Attention! Turn on the equipment only when the electrodes are compressed, otherwise a strong spark will appear and the contacts will burn!
During operation of the transformer installation, wires and lugs become hot. Therefore, think about how to arrange their cooling. A household fan will do. Take breaks while you work.
Work principles
They are almost no different from the processes when using an industrial welding machine. After the workpieces are compressed and the electrodes touch them, voltage is applied, an electric arc occurs at the welding site. Its plasma melts the metal, connecting the parts.
At the bonding site, a residual voltage is kept for some time, which can be reduced by not immediately disconnecting the contacts after the process is completed.
Using the above recommendations, you can also assemble an arc welding machine on your own.
As you can see, with the necessary skills, the availability of initial elements and tools, it is quite possible to make a welder on your own. It will be a great help in the household and save you money.