El viernes me animé a abrir mi soldadora eléctrica de 150 Amperes, y descubrí que el bobinado primario tenía lugar como para agregarle algunas vueltas de cable grueso.
Some time ago I'm warming for spot welding projects made with microwave transformers. I searched in my small town and there is no way to get one of those, except buying it new, and rather expensive.
On Friday I dared to open my 150 amperes electric welder, and discovered that the primary winding have place as to add a few turns of thick wire.
Step 1: The wire (el cable)
I bought 1.5 m cable 16 mm2 in section (5 mm diameter). The next highest , 25 mm2, is too thick to pass through the gap of the primary winding.
Step 2: Bobinando (winding)
I could fit only two laps, and with some difficulty (I used soap as a lubricant). By my calculations, each lap provides approximately 0.89 volts. The idea is only to do a test.
Step 3: Terminales (terminals)
Cable terminals were a point to be solved: it's no good having a 16 mm2 section wire, if the terminals don't pass every amp transported. So I used a copper pipe, copper section of which was slightly greater than 19 mm2, crushed, folded U-shaped and made it holes, allowing cramp strongly the cable with hex head screws and nuts. It would have been better to solder the terminals, from the electrical standpoint, but that would have prevented me disassemble the monster to leave the welder in its original state.
Step 4: Saliendo al mundo exterior (Exiting the outside world)
I pierced the front plate of the welder to pass the cables. For that before I had to make holes with a 2.5 mm bit, since I had no way of striking with a punch to mark the starting point of the holes. By the way, the large holes get out better if they are doing in successive steps, with smaller bits up to the final size.
Para atravesar la chapa con los cables necesitaba tapones de goma perforados, pero no pude conseguirlos. Así que compré un trozo de manguera de pvc blando transparente de diámetro interior igual al exterior del cable. La corté en dos trozos de unos 6 cm de largo, y los atravesé en los agujeros de 12 mm. Tuve que usar jabón como lubricante, otra vez. Fijé los trozos de manguera en sus lugares con precintos de plástico, y los cables también. Coloqué los terminales en sus lugares, y armé nuevamente la soldadora.
To cross the plate with the wires needed rubber plugs, but could not get them. So I bought a piece of transparent soft pvc hose, whose inside diameter is equal to the outer of the cable. I cut two pieces of about 6 cm long, and crossed them into the 12 mm holes. I had to use soap as a lubricant, again. I fixed the hose pieces in their places with plastic seals, and the cables too.
Step 5: Prueba (test)
The test was moderately satisfactory. Easily welded thin iron sheet, which is used in food cans. I tried welding galvanized sheets, but there was no way to do it. The cables are a bit thin, after two or three welds begin to warm. I suppose the next step is to replace cables by strips of copper or bronze sheet, larger section. Once the machine capacity is satisfactory, I will build the jaws to allow use with ease, alternating between electrode tip as the current sheet welding and soldering wires flat electrode. I'll have you informed.
Step 6: Metiendo violin en bolsa (putting fiddler in bag)
To hang up the welder, it is imperative to isolate the new electrodes, which is not going to touch and cause a disaster at using. I cut two pieces of bike innertube, and two small rubber bands from the same innertube. I put them as a condom and well assured them.
Step 7: Mejoras previstas (planned improvements)
2) Hacer las mandíbulas.
3) Hacer buenos electrodos, más gruesos.
1) Test with thicker conductors: copper strips or copper wire bundles wrapped in plastic tape.
2) Make the jaws.
3) Make good electrodes, thicker.
Step 8: Update feb 28, 2010 (actualizado 28/02/10)
Como mencioné antes, una de las alternativas de mejora era duplicar el amperaje que circula por los cables de salida, simplemente agregando un conductor igual. Eso hice.
Compré 1.5 m adicionales del mismo cable de 16 mm2, y dado que era imposible poner ambos cables dentro del escaso hueco disponible, lo primero fue eliminar la aislación de ambos. Una vez desnudo el cobre de ambos, tuve que resistir la tentación de retorcerlos para hacer un único conductor cilíndrico, porque no hubiera entrado en el transformador. Primero los envolví con cinta de pintor, tratando de que quedaran lo más planos y paralelos posible. Cuando empecé a enrorrarlos en su lugar, me di cuenta de que la cinta de pintor se arrancaba en todos los lugares donde razaba con el núcleo de hierro. Así que los saqué y los recubrí con cinta de embalaje, que es muy delgada, bastante resistente y más resbalosa. Me dio bastante trabajo bobinar el conjunto, de todas maneras.
As I mentioned earlier, one of the alternatives for improvement was to double the amperage that
flows through the output wires, as simply adding a new cable. I did. I bought an additional 1.5 m of the cable 16 mm2, and since it was impossible to wind both cables into the little hole available, the first thing was to remove the insulation from both. Once both bare copper, I had to resist the temptation to twist them to make a single cylindrical conductor, because it had not fit into the transformer. First I wrapped them with masking tape, trying to stay flat and parallel as possible. When I started to wind it in place, I realized that the masking tape was peeled in all places where touch the iron core. So I took the cables out and covered them with duct tape, which is very thin, very resistant and more slippery. It gave me enough work winding the assembling, anyway.
Step 9: Cortocircuito! (short circuit!)
Once the winding of the two laps finished, with the tester I checked if there were short the new cable and the core, which indeed they had. Since there was not much place to introduce insulation separator, cut some small pieces of PET bottle of soda. Conveniently tucked under pressure between wire and core, as well as time to replace the PVC hose pieces into holes on the front panel, the problem disappeared. I had to enlarge the holes on the front panel of the welder.
Step 10: Nuevos terminales (new terminals)
The terminals also were replaced by other similar, but doubling the section. Before crushing the copper pipe, I was careful to clean the oxide to improve the contact. Once installed terminals, I lined with PVC insulation tape the exposed wires.