A simple home-made welding machine from LATR

When designing or repairing appliances, household equipment, the problem often arises: how to weld certain parts. Buying a welding machine is not easy, but making it yourself ...

In this article you can get acquainted with a simple home-made welding machine, made according to the original scheme.

The welding machine operates on a 220 V network and has high electrical characteristics. Thanks to the use of the new form of the magnetic circuit, the weight of the device is only 9 kg with overall dimensions of 125 x 150 mm. This is achieved by using a tape transformer iron rolled into a torus shape, instead of the traditional package of W-shaped plates. The electrical characteristics of the transformer on the magnetic pipe are about 5 times higher than that of the W-shaped, and the electric losses are minimal.

To get rid of the search for scarce transformer iron, you can buy a ready-made LATR for 9 A or use a magnetic pipe from a burned-out laboratory transformer. To do this, remove the fence, reinforcement and remove the burnt winding. The freed magnetic circuit must be isolated from future layers of the winding with an electric cardboard or two layers of varnish.

The welding transformer has two independent windings. In the primary one, a PEV-2 wire of 1.2 mm and a length of 170 m was used. For convenience, you can use a shuttle (wooden rail 50 x 50 mm with slots at the ends), on which the entire wire is pre-wound. An insulation layer is placed between the windings. The secondary winding - a copper wire in cotton or glassy insulation - has 45 turns on top of the primary. Inside, the wire is arranged round to round, and from the outside with a small gap - for uniform arrangement and better cooling.

The work is more convenient to carry out together: one carefully, without touching the adjacent turns, so as not to damage the insulation, stretches and stacks the wire, and the assistant holds the free end, preventing it from twisting. A welding transformer made in this way will produce a current of 50 - 185 A.

If you purchased Latr at 9 A and upon inspection it turned out that its winding was intact, then the matter is greatly simplified. Using the finished winding as the primary one, it is possible to assemble a welding transformer in 1 hour, giving a current of 70 - 150 A. For this, it is necessary to remove the fence, slip ring slider and mounting fittings. Then identify and mark the findings at 220 V, and the remaining ends, having been securely insulated, temporarily pressed to the magnetic circuit so as not to damage them when working with the secondary winding. Installation of the latter is carried out in the same way as in the previous version, with the use of a copper wire of the same cross section and length.

Transformer of a home-made welding machine: 1 - primary winding, 2 - secondary winding, 3 - wire coil, 4 - yoke.

Electric circuit of the welding machine

The assembled transformer is placed on an isolated site in the previous casing, after having previously drilled holes for ventilation in it. The wires of the primary winding are connected to the 220 V network with a SHRPS or GRP cable. A circuit breaker must be provided in the circuit.

The leads of the secondary winding are connected to flexible insulated wires of the PRG, an electrode holder is attached to one of them, and a welded part to the other. The same wire is grounded for the safety of the welder.

The current adjustment is provided by including in series with the ballast electrode holder wire - a nichrome or constantan wire with a diameter of 3 mm and a length of 5 m, rolled up by a snake, which is attached to an asbestos-cement sheet. All wire and ballast connections are made using M10 bolts.By the selection method, moving the wire attachment point along the snake, the required current is set. An option for adjusting the current using electrodes of various diameters. For welding electrodes of type 1 to 3 mm in diameter are used.

All necessary materials for the welding transformer can be purchased at the distribution network. And for a person familiar with electrical engineering, making such an apparatus is not difficult.

When working in order to avoid burns, it is necessary to use a fiber protective shield equipped with an E-1, E-2 light filter. Headdress, overalls and mittens are also required. The welding machine should be protected from moisture and prevent its overheating. The approximate mode of operation with an electrode with a diameter of 3 mm: for a transformer with a current of 50 - 185 A - 10 electrodes, and with a current of 70 - 150 A - 3 electrodes, after which the device must be disconnected from the mains for at least 5 minutes.

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