If you have a welding machine at hand, you can do not everything, but a lot. And if you decide to get into car body repair, then having a large set of tools will come in handy.
In the article we will talk about how to make spot welding with your own hands. This is a device that is useful for repairing car bodies, as well as for other daily needs. With this tool, you can quickly connect several metal elements.
Working principle
Before considering how to make a mini spot welding with your own hands, you need to know how this device even works. The demand for such products is extremely high: welding will be indispensable when working with metal - such a connection is much more reliable than bolted.
The welding machine works quite simply - due to the energy of the electric current, metal parts are heated. Due to this, a weld is formed. The quality of the final joint depends on the type of material used and its density.
Features of working with welding
Be sure to pay attention to the following points when welding:
- Welding should be done with low voltage. Often, voltages up to 10-12 volts are enough for normal operation of the equipment.
- The process of connecting elements takes a few seconds.
- The current in the circuit is very high.
- The smaller the melting area, the better the welding quality.
- It is imperative that the seam withstand high loads.
If you follow all the rules, the end result will please you - the seam will be not only beautiful, but also durable.
It is worth noting that before you make mini-spot welding with your own hands, you should consider several designs. To make even the simplest is quite difficult. It is extremely important to strictly adhere to the instructions during manufacturing - this directly affects how the device will work in the future.
The simplest designs work by changing the pulse duration manually. In other words, the person working with welding regulates the time for the pulse to flow. In more complex designs, a time relay is installed. The duration is set in advance. The operator only has to press the electrodes to start the process.
Important Design Features
The main element of the welding machine is a transformer. Homemade oftenuse devices from microwave ovens, old TVs, etc. First you need to calculate the current required for the normal operation of the device. Then, leaving the primary winding on the core (note that this is not always possible - we will tell you why later), completely get rid of the secondary. It is simply not needed when operating the welding machine.
When winding the secondary winding, a thick copper insulated wire is used. The larger the cross section of it, the higher the current in the circuit will be. Please note that for normal use of the welding machine, you need to use not one, but two microwave transformers connected in parallel. This will increase the current output, therefore, it will be possible to work with thicker metal elements.
Features of the welding scheme
Before you make a spot welding machine with your own hands, it is recommended to study in detail all possible schemes. This will allow you to answer many questions, and first of all, the following one: what metal are you planning to weld with the machine? Welders are used for both joining sheet metal and wiring cables.
Be sure to consider the following points:
- All equipment must operate on 220 Volt AC power.
- At the output of the transformer, the voltage must be up to 12 volts. Usually 3-7 V is enough.
- Welding current reaches 1500 amps - twice as much as short-circuit consumptionclosing the car starter.
Be sure to draw up a detailed circuit diagram, on which you indicate all the elements: circuit breakers, thyristors, etc.
In the event that dangerous situations may occur during welding, it is necessary to provide for a switch to turn off the device. It is allowed to use non-contact thyristor single-phase switches included in the power supply circuit of the primary winding of the transformer.
Control schemes
Industry produces MTT4-K systems, in which a thyristor key is installed. It is with its help that the supply voltage is switched. Moreover, the protection unit can operate under voltage up to 800 Volts and a current of 80 A. The circuit contains the following components:
- Power supply.
- Electromagnetic relay.
- Chain for setting up the device.
Together with such a device, you can use transformers whose power does not exceed 20 watts. Please note that the device is installed in the primary power circuit. In the secondary, the voltage is not very high, it can be rectified if necessary using semiconductor diodes.
Transformer features
Today, you can find the implementation of various functions of control circuits. In the event that it becomes necessary to turn on the device for a certain period of time, it is enough to correctly set the value. And specify it in the system logic settings. In the manufacture of the device, electrolyticcapacitors, it is advisable to use devices with a voltage margin of up to 50-100 volts.
In the manufacture of a transformer, special attention is paid to its windings. Actually, you need to completely get rid of them and leave only the core.
First, wind the primary winding - for this, use a copper wire in varnish insulation. Be sure to securely separate the primary winding from the secondary - for this, lay 3-5 layers of varnished fabric. For the manufacture of the primary winding, you need to use a wire with a thickness of 1.5 mm - only this can withstand high current consumption.
The secondary winding is a few turns of thick wire (approximately 20 mm, maybe even more - depending on the specific case).
Experts recommend making intermediate conclusions when winding the primary winding - this will allow you to get the most out of the device.
Pliers for welding machine
Before you do your own spot welding, you need to decide what it will be used for. After all, what pliers are needed directly depends on this:
- Portable.
- Stationary.
The latter are easy to use and have good insulation, but you need to apply force to get good downforce.
As for portable devices, they are easy to use, and most importantly, they have small dimensions. To control the effort, you just need to changelength of removal of pincers for the body of the device. For the manufacture of pliers, copper rods are used. Please note that the diameter of the electrode must be the same as the secondary wire of the transformer. It is impossible for the electrode to be thicker. To improve the quality of the weld, the ends of the electrodes are sharpened.
Microwave transformers
And now consider a small instruction on how to make spot welding with your own hands from a transformer that can be found in simple microwave ovens. Of course, it will have to be slightly modernized - to completely get rid of the windings. Note that if you use 2, 3, or 4 of the same transformers, then it is likely that you will not have to destroy the primary coils. Such an approach is possible. In fact, if you connect 4 identical windings in parallel, then we can assume (conditionally) that the wire is used to wind it 4 times thicker. In other words, these four transformers will be able to handle 4 times more current than one.
By the way, about which microwave to take. Of course you don't need a new one. It is quite possible that you, your friends or neighbors have one that has become unusable. Usually, in such devices, it is not the transformer that breaks, but the magnetron - a special emitter of microwaves, which, in fact, warm up the food. Also, one of the cases can be adapted for the installation of a transformer and all other devices.
A little about windings
Now let's start creating the transformer. Let's say you decide not to experiencefate and just make a welder out of 2 transformers. A good solution - you do not need to deal with the calculation of the primary winding. And this is the most difficult. The secondary winding data is much easier to calculate - this can even be done empirically. To do this, wind several turns (for example, 10) over the primary winding and turn on the transformer in the network. By measuring the voltage at the terminals of the secondary winding, you can calculate how many volts one turn produces.
But this will not be useful to you in the case of the manufacture of a welding transformer - here you need to use the maximum thickness of the wire. And how much it will fit in a free place, so much will be. Therefore, the voltage fluctuates up to 12 V. By the way, two transformers connected in parallel can be used to increase the current strength. Actually, this is what we plan to do.
Transformer assembly: step by step guide
Before you do spot welding with your own hands from the microwave, you need to correctly calculate all the elements. And first of all it concerns the transformer. To make it, perform the following manipulations:
- Using a hacksaw or grinder, cut the core in half - otherwise you won't be able to disassemble it.
- Get rid of windings.
- Make a frame from dense textolite. The cross section of the frame must be the same as that of the transformer core. This is the inner clip, over which you will wind the wire.
- Wind the primary winding.
- Install the frame and assemble the core. Use a conductive wire to connectadhesive compound. Outside, it is necessary to tighten the core with metal plates.
- It is recommended to use a wire for the secondary winding, which will fit tightly into the transformer window. This will allow you to get the maximum current. Stack as many turns as you can.
Please note: if you leave the primary winding native, then you do not need to cut the core. Our guide is given only for the most difficult option. Before you do a quick spot welding with your own hands, make sure that all the necessary materials are at hand.
Final stage
Perhaps now you know how to do spot welding with your own hands. It will not be possible to use it for the battery (its charging) - the voltage is low. But for connecting sheet metal, it will be just right. Please note that all connections must be made as reliable as possible. All wires must be as short as possible. Moreover, it is important that they are designed to work with the maximum possible current.
Before you make do-it-yourself spot welding for a car, you need to consider the design of the pliers. It depends on them how convenient it will be to use the device in the future. And most importantly - a reliable case. It should not be flimsy - keep this in mind. After all, the welding machine can be subjected to heavy loads.
