SPOT WELDINGI made welding machine is a well-proven in practice a modernized version of the device description and drawings of which are published in the journal “modelist-Konstruktor” No. 3, 1966. Most importantly — new “svarochnik” significantly more powerful than its predecessor, easier to manufacture and operate. In the absence of the kind of “bells and whistles” it allows you to securely connect steel sheet with thickness up to 3 mm. However, the mode of operation is one of the most necessary most homebrew spot welding.

Adjusting the amount of current is not provided. The welding is determined by the heating time (that is passage of current) and is controlled either visually (by color), or by using a time relay, the range of shutter speed which is 0.5—5 s.
As the basic transformer use serial OSM-1.0 power 1 kV*a Primary winding it is desirable to leave without changes because (although if required, and rewinding is available here for only 200 turns ПЭВ2-1.9). But the secondary better be replaced by a more “productive” performed by wire THP-50 — trehmetrovye two parts connected in parallel to the total cross-section was 100 mm2.
Holders recommend electrodes made of duralumin, isolated from cheeks textolite washers and mounting bolts M8 — varnished cloth or protective adhesive tape on cotton basis. The electrodes themselves are advised to use copper with a diameter of 12 mm, fixing them in the holders with rectangular brass washers and two M6 screws for which the special steel inserts prudently made appropriate thread.
In the initial position holders with electrodes divorced a spring with suitable dimensions (for example, from old beds-Raspadsky). But we must make sure that the spring did not create a short circuit on the terminals of the secondary winding during operation of the welding transformer. One of the acceptable technical solutions is, in particular, the variant with application of the separation of the plastic sleeve, secured in the fixed end of the electrode holder screw M6. The lower end of the spring is electrically isolated from all other parts “svarochnik” under any, even the most incredible situations.
Apparatus for spot welding sheet steel
Apparatus for spot welding sheet steel:
1 — transformer OSM-1,0 finalized; 2 — conductor (aluminum rod Ø30, L 300, 2); 3 — liner (steel rod Ø10, L30, 2pcs); 4 — electrode (copper rod Ø12, L50, 2pcs); 5 — puck brass (2 PCs); 6,12 – M6 screws; 7 — handle; 8 – eccentric; 9 — cheek (2 PCs); 10 — spring; 11 — the withdrawal of half of the secondary winding (4 PCs.); 13 — textolite bushing (with groove under the end loop of the spring); 14 — bolt M8 (6 PCs); 15 — the textolite washer (4 PCs); 16 — insulating coating (varnished cloth or protective adhesive tape on fabric base, 2); 17 — a casing of the transformer.
The scheme of connection of the apparatus to a household outlet

Wiring diagram of the apparatus to a household outlet.
Connect the welding machine to the network, preferably by the well-proven wiring diagram (see Fig.) through the automatic 20-amp breaker. On a similar (at least!) current must be calculated and the meter. Well, direct control of “svarochnik” — with the help of magnetic starter K1, turn on the pedal with the button S2 of the type “fungus”. The housing and the secondary winding of the transformer must be grounded.
To turn on and off a “svarochnik” it is only necessary to tight the electrodes. Failure to observe this simple rule can lead to the occurrence of intense sparking, which leads to burning of the electrodes with highly undesirable consequences.
And one more, verified by practice, the Board. Since forced cooling is not provided to the transformer or conductors and electrodes during the welding should continuously monitor temperature. As necessary to do breaks in work, but in any case, to prevent overheating of the equipment.
GAVRILOV, G. G mistletoe, Republic of Belarus

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