Products under this name are produced in different modifications and are characterized by specific application. Some hair dryers are designed for drying hair, others are used in construction or renovation. Yes, and they are of interest to radio amateurs.
For example, when soldering microcircuits, given the number of their pins, working with such a device is much more convenient than the most advanced soldering iron. In principle, you can buy such a hair dryer for soldering microcircuits. The cost ranges from 2,000 to 10,500 rubles.
For those who are used to doing everything with their own hands, this article will tell you how and what to use to assemble a hairdryer for soldering at home, without wasting money and time on shopping trips.
Someone will think that it is inappropriate to engage in such construction if it is easier to acquire miniature soldering skills. Still, a self-made hairdryer is a fairly universal device. In everyday life, they can be used to burn materials, removing old paintwork from them, and to heat something before further processing. In skillful hands, it will become an indispensable assistant.
It is almost identical to the design of analogues intended for other purposes. The fundamental difference is in the power of the heating element and especially some of its components.
It is necessary to expect that the temperature inside the product rises to +780 ±50 ºС. Therefore, the materials must be heat resistant. In principle, you can use a used hair dryer that is faulty, but you will have to improve something.
It must be isolated as much as possible. There are recommendations that you can use a canvas mitten or a thick mitten when soldering microcircuits. Although this prospect is unlikely to suit anyone. How to proceed?
But using tubes made of different metals is not recommended for two reasons. Firstly, any “iron” is characterized by high thermal conductivity. This handle will get hot very quickly. Secondly, we must not forget that the device is being assembled electrically. Therefore, the fewer metal parts, the safer the operation of the hair dryer.
How to prevent it from overheating will become clearer below.
Considering the high temperature and the fact that the hair dryer will have to be held in different positions during operation, the best solution is a steel tube. Copper is not only more expensive, but also heavier. It is unlikely that you will be able to hold such a hair dryer motionless for any long period. Aluminum doesn’t count – it won’t last long and will start to deform. To reduce the heating time of the “working” section of the board, one end can be slightly flattened. In principle, if you understand the essence of the entire technological operation of soldering microcircuits, it is not difficult to determine the optimal shape of the nozzle. Especially for yourself.
Which wire should I use – fechral or ? The first option is eliminated due to the rigidity of the material. It is unrealistic to wind a spiral out of it, and with a small radius, with your own hands.
For a homemade hair dryer, you can adapt a miniature fan that is mounted on the back of the case. Some people use a small aquarium compressor.
Everything else - a switch, a stand for a hair dryer - is not directly related to the topic. Everyone will decide for themselves whether they need these “services” and how best to organize them.
There is no point in assembling a device with your own hands without knowing what power it should be designed for. If the board is not heated enough, it will be impossible to install (replace) the microcircuit. The result of overheating is the melting of the housings of all radio components located in the working area. Therefore, it is advisable to focus on industrial production models.
The author will not provide mathematical calculations. It is enough to point out that with such a hair dryer power (and it is quite enough to regulate the temperature within 100 - 500 ºС), the resistance of the coil should be at the level of 100 Ohms. All that remains is to find nichrome wire. Its cross-section in this case is unimportant. The main thing is to measure the part that, when measured, “shows” R of the order of 100 Ohms. It is from this piece that the spiral should be wound. For those who do not like this option, they can make other calculations by analogy, reducing/increasing the power and accordingly changing the length of the wire.
Reader, do not be confused by the fact that the author uses such terms as “about”, “approximately”, “within” and so on. You won’t be able to do everything with your own hands with maximum precision. Therefore, a homemade hair dryer will have to be powered through a device (or from a power supply) with adjustable output voltage. If anyone is lucky enough to find a LATR (laboratory transformer), even better. Before using a hair dryer, you should practice a little on used circuit boards (you can always find them on the farm). This is the only way, through experimentation, that you can determine the optimal operating mode of a hairdryer assembled with your own hands. And any miscalculations made are precisely leveled out by the voltage regulator.
A completely logical question - why not use a household hair dryer for soldering, especially since almost every family has one? And many inexperienced radio amateurs who do not quite understand the design features of various models ask themselves this question. The answer can be given immediately, and unequivocally - no, it’s impossible.
And that's why. A household hair dryer, even with high power, is not able to heat the solder to such an extent that it melts (about +250 ºС). The device will have to be upgraded.
Possible options:
To increase the temperature of the air flow, you can reduce the fan motor speed. But the spiral is designed for a certain operating mode. The result of such a modification (modification) of the hair dryer is easily predicted - the wire will overheat and the circuit will break.
Reduce the nozzle cross-section. The bodies of all household hair dryers are made of plastic. An increase in temperature inside the device can lead to softening (melting) of the polymers. Consequently, soldering the microcircuits will turn out to be very short-term, and then the hairdryer will go to the garbage chute and to the store for a new one.
Any other options (for example, shortening the spiral) also “do not work.” Tested many times. Many have tried in different ways, but the result is always the same – negative.
If it is clear what needs to be done and how, then making a hair dryer for soldering microcircuits with your own hands is a completely doable task. And if you carry out a complete inspection of the garage (shed, storage room, mezzanine), then you will definitely find everything you need.
Good luck with your design!
Sometimes it is simply irreplaceable in the household. Using a hot air gun, you can perform a number of necessary works in different sectors of human activity. It allows you to solder films, linoleum; solder microcircuits; turns out to be indispensable for other work.
A hot air gun can be useful in circumstances that require hot air to change the structure of a material.
Currently, many models are offered that meet high requirements. Such professional devices are capable of much. However, their cost is significant, and therefore a DIY hot air gun for soldering looks preferable for many.
A hot air gun can be classified as a device for soldering low-melting materials using a heated air jet. In addition to the main function of soldering materials, such a device can be used for heat treatment of the surface of materials for another purpose, for example, to remove paint or warm up a product, for example, a pipe during bending.
The hot air gun consists of a body with increased heat resistance, a heating element and a device for pumping air flow. The air in the device heats up to 650-700ºС. To ensure such heating, the power of the heating element must be more than 1.6 kW. An important element of industrial hair dryers is temperature control, usually in steps, 300 and 500ºС. The temperature that is achieved on the surface of the materials being soldered is also regulated by the distance from the device nozzle to the workpiece. Most hot air guns are set so that when the nozzle moves 7-8 cm away from the workpiece, the air flow reduces the temperature by half.
Hot air guns are widely used for removing old paint from the surface of materials, especially wooden surfaces. In this case, you need a maximum air flow temperature of at least 500ºС. With this heating, the paint softens and peels off the wood. Recently, artificial aging of wooden coverings has found demand. A heat hair dryer copes well with this task at a temperature of 500ºC and the device nozzle is 1 cm or more away from the surface. Hot air (at the lower control stage) is used when drying coatings.
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The main initial requirement for a hot air gun for do-it-yourself soldering can be formulated as follows: the device must create a flow of hot air with a temperature of up to 800ºC with a heating element power of at least 2.5 kW. In addition, all parts of such a hair dryer should be accessible and inexpensive. Ordinary household hair dryers do not meet this requirement in terms of both temperature and power.
The heating coil for a hot air gun should not be too long, otherwise it will heat up slowly.
The design, as a rule, can be of two types: stationary and manual. It’s easier to make a stationary hot air gun, since the dimensions of the device are not limited and you don’t have to think about the temperature on the handle. However, in this case, the hair dryer (in this case, as a type of soldering iron) is fixed motionless, and the part needs to be moved. This circumstance makes the work much more difficult. More promising, although more complicated, is a hand-held portable design, which should be small-sized and be able to be held by unprotected hands.
One of the main problems is the heating element. Heaters in household appliances (hair dryers, soldering irons) are not suitable in terms of power. The required heating element will have to be made independently from nichrome wire with a diameter of 0.3-0.7 mm. Wire with a larger diameter can provide more power, but it will be much more difficult to achieve the desired temperature. To compactly lay a heating element made of wire, it will have to be wound in the form of a spiral with a diameter of 5-7 mm.
The spiral of the heating element should be located on some kind of cylindrical base (in the form of a tube or a hollow cone) made of a material with high thermal resistance. It is difficult to do without porcelain or quartz elements here. Such a base can be removed from inactive household hair dryers, but it is recommended to use a quartz insulator of a tubular halogen lamp for spotlights with a power of 2.2-2.5 kW. If you take a burnt-out lamp, then this part of a homemade hot air gun can cost free.
A standard small-sized fan is needed as a blower element. When making a hot air gun with your own hands, this element will be the most expensive. The blower can be taken from any powerful household hair dryer. Among the standard fans, we can recommend the BAKU8032 model with a capacity of 30 l/min. This fan operates from a 220 V network and has a power of about 400 W. The simplest and cheapest option that can meet the requirements is a small aquarium compressor. It must be installed with the receiver, i.e. with air accumulator. Any small plastic bottle is suitable for this, since there is no heating at the place where it is installed, and the flow of hot air is directed in the opposite direction. And the air blower itself is not subject to thermal effects.
There are two options for designing the body of a hot air gun. You can use a material with very high thermal insulation, such as porcelain or ceramics, but this will complicate the design and significantly increase the cost. The most rational is the second option, which consists in reliable thermal insulation of the hot flow distribution channel and the heating element. In this case, the housing material is not exposed to thermal effects, except for the area adjacent to the nozzle of the device.
For the handle of the tool, you can use the body of any old household hair dryer.
As the main part of the body (including the handle), you can use the body from any old large-sized household hair dryer (the older the year of manufacture, the better). The nose of the body, i.e. the nozzle section must be made of thermal insulation material, which itself can withstand temperatures up to 800ºС and at the same time insulate the rest of the body from the effects of such temperatures. The hot air gun nozzle itself must be made metal to take into account possible contact with the melt during soldering. Thermal insulation is well provided by quartz elements (plates, tubes), mica, glass or fiberglass, ceramics, porcelain, etc. When assembling the device, you will need special heat-resistant glue.
In the design of a homemade hot air gun for soldering, it is necessary to provide, firstly, a start switch, and secondly, a mechanism for regulating the power (temperature) of the heating element and the air flow rate. For this purpose, smooth regulators - rheostats - must be provided. The adjustment system can be used from old household appliances if these elements are in good condition. A push-button or key mechanism can be used as a start switch.
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The main purpose of a hot air gun is soldering materials. Materials such as PVC film, linoleum, rubber are welded by filling the weld with a melt of the filler tow, which is achieved by a stream of hot air. Melting of the rope is carried out by heating to 350ºС. This method is considered the main one when joining linoleum when laying it on the floor. A hot air gun greatly simplifies the task of bending plastic pipes, profiles, and sheets. Heating when bending plastic is provided within the range of 300-400ºС at a reduced speed (power) of air flow. Warming up the plastic should be done slowly, gradually.
The production of a hot air gun begins with winding the heating element spiral. The spiral is wound onto a steel wire with a diameter of 5-6 mm with tension. It is better to wind it with nichrome or fechral wire with a diameter of 0.4-0.5 mm. The length of the spiral is determined from the condition that its electrical resistance should be 70-90 Ohms.
The spiral is wound onto a tubular base from a soldering iron (for example, type EPSN-100) or a halogen spotlight lamp. The spiral turns are superimposed evenly over the area of the cylinder with a gap (the turns touching each other is unacceptable). A layer of fiberglass is forcefully wound over the laid spiral or a layer of asbestos is fixed. It is advisable to seal this layer with a heat-resistant adhesive. Then a thermal insulating tube (porcelain, ceramics, quartz glass, etc.) is put on the adhesive layer. The ends of the spiral are brought out.
It is advisable to coat the outlets and ends of the heating element with heat-resistant glue.
The manufactured heating element is inserted into the internal channel of the housing. The installation site must first be paved with asbestos, mica or quartz plates as additional thermal insulation. The spiral leads are connected to the power supply wire using a screw connection. This wire must have heat-resistant insulation - fluoroplastic or fiber insulation. The wire must pass through the start switch and rheostat to regulate the current supplied to the coil.
An air blower is mounted in the rear part of the housing strictly coaxially with the heating element channel. If the discharge element (compressor) does not fit into the housing, then it can be fixed from the end of the housing to the outside. In this case, a guide tube for air flow must be attached to it. This tube must fit the heating element inside the housing and be positioned coaxially with its channel. Wires for power supply come from the blower and are connected to the wire for the heater so that the switch simultaneously controls the power supply to both elements. The air flow control rheostat must be inserted into the wire circuit for the supercharger - its operation does not depend on the operation of the heater.
The power supply wire is brought out from the bottom of the housing handle, and the switch button (key) and rheostat levers are fixed in a convenient place on the outside of the housing. Then the halves of the body are combined and connected to each other. An end element made of thermal insulating material in the form of a cylinder or cone is installed. The metal nozzle is screwed on. It is advisable to provide a set of nozzles with different outlet diameters in the design.
High-quality professional equipment for soldering microcomponents costs a lot of money, and inexpensive hot air guns are not suitable for most tasks. Many repairmen and radio amateurs from time to time encounter low-quality hot air guns for soldering.
To avoid such misunderstandings, it makes sense to make a soldering gun with your own hands. This option is perfect for repairmen and radio amateurs who have specific equipment requirements and a very limited budget.
Before you start designing a homemade soldering gun, you should familiarize yourself with the basic methods of using this tool.
Soldering gun drawing.
A hot air gun for soldering, as a rule, may be needed in the following cases:
Control of temperature and air flow density is usually carried out using buttons on the heat gun.
Using a soldering hot air gun involves the following steps:
In order to protect nearby components from heat, special screens made of aluminum foil should be placed on them.
After carrying out the work, you should check the quality of soldering of all contacts using a needle.
Removing the element using a hair dryer is even easier. To remove a faulty microcircuit you must:
When heating the surface with a hot air gun, it is necessary to make circular movements. This technique allows you to avoid local overheating of the board and disruption of its geometry.
Electrical circuit of a soldering gun.
The basic requirements for a hot air gun for soldering microcircuits with your own hands are:
The device must contain exclusively safe elements. When making a homemade compressor power supply, special attention should be paid to the reliability of the design and its safety for others.
Experience shows that many craftsmen manage to make full-fledged working thermal tools from a hair dryer, a household hair dryer, or even an ordinary soldering iron.
Soldering gun diagram.
Before you make a soldering gun with your own hands, you should:
When considering how to make a soldering iron from a regular soldering iron, you should take into account all the subtle points so as not to expose yourself to excessive risk.
The main criteria that a soldering iron-based thermal device must meet are:
It is recommended to install a supercharger for a DIY soldering station in accordance with current electrical safety regulations. Connecting the equipment in this way will ensure that there is no interference in the electrical network.
When creating a hair dryer for soldering with your own hands, you should prepare:
Schematic diagram of a soldering gun.
All equipment must be connected to specially prepared connectors, the pinout of which depends on the manufacturer of the soldering equipment.
A homemade microcircuit hair dryer from an old soldering iron is assembled in several stages:
It is better to place the temperature regulator of the heating source on the body of the hot air gun.
The operating principle of a hot air gun based on a soldering iron is as follows:
A small current is applied to the nichrome thread, causing it to become hot. The air coming from the compressor is collected in a special insulated chamber and heated under the action of a spiral and insulating foil. After this, the air leaves the heating chamber and goes directly to the printed circuit board.
Soldering gun - drawing for manufacturing.
Unfortunately, this method of making a thermal hair dryer has a lot of disadvantages.
The disadvantages of a hot air gun made from a conventional soldering iron include:
In most cases, making a heat gun from a soldering iron is not justified. Remaking an inexpensive construction hot air gun is a much more efficient method of making a hot air gun for soldering micro components.
There are a huge number of instructions on the Internet on how to make a hair dryer. Most methods for making a thermal hair dryer are based on modifying existing equipment, for example, a construction hot air gun, a household hair dryer, or a regular soldering iron with a metal tip.
In many cases, if you need to use a soldering hot air gun, you should think about purchasing the appropriate station. A hot air gun connected to the soldering station provides data on the current temperature of the air flow and allows you to calibrate the thermocouple.
The idea to make a hot air gun was born when I needed to remove mounting fasteners from the surface. The time to make a hairdryer for soldering microcircuits with your own hands took about two hours, including photography.
You will need:
Silicone tubing is often used for fuel delivery in aircraft modeling and is inexpensive and easy to purchase at a hobby store or online.
When you take your soldering iron apart, you will have the following components: a handle, a resistive heater, and a heater guard. The tip is not shown in the photo; the nut that holds it in place is shown in the lower right corner.
To effectively heat the air flow, you need to increase the heat exchange area. I wanted to make a heat exchanger out of copper because it would be more efficient, but the only commercially available ones are stainless steel steel wool. You just need to push a few metal strips inside the heating element. There is no need to pack the strips too tightly; air should pass through them relatively unhindered; be sure to blow to check.
Note: Stainless steel may catch fire, use copper strips if possible.
Simply push the end of the silicone tube into the end of the heating element. It's not visible in the photo, but I sealed the connection between the tube and the heater using a piece of the same tube and superglue. This had to be done because air and smoke were coming out through the gap (although I understood that there was smoke there).
Use an engraver to make a hole near the top of the handle.
The photo shows how I inserted the tube into the hole I made. The air pressure can be reduced by simply squeezing the tube a little.
The photo shows how the connection between the silicone tube and the tube from the aquarium pump is made. I simply removed the cap from the ballpoint pen, put the wide end of it on the aquarium tube, and put the silicone tube on the narrow end, securing it with superglue. The used pen cap has a wide enough hole for the refill. If your cap's hole is too narrow, you can widen it with an engraver.
The photo shows the result after assembly, now your hot air soldering iron is only missing a nozzle. We make it from another pen cap using a cutting disc for an engraver.
The photo shows a pen cap cut into two parts. The idea is to make the larger hole of the cap slightly larger than the hole of the nut securing the tip. Thus, the nozzle will be placed on the tip of the soldering iron and secured with a nut screwed onto its narrow end.
The photo shows the result of an assembled homemade soldering gun. The nozzle from the cut-off cap fit just fine (I recommend taking the cap from a pen, since mechanical pencil caps have too small a hole for the refill).
The diagrams show diodes removed from a damaged network card. The air soldering iron worked great. This soldering iron can also be used as a regular one. Turn it on, let it warm up, turn on the pump and bring it to the part you want to remove. With a little help from wire cutters, this part will practically fall off on its own.
I have long wanted to make a soldering gun for myself. I'm not interested in ready-made ones. Since I started converting ATX power supplies into laboratory ones, it became possible to get 24-25 volts at currents up to 8 amperes. In reality, my hair dryer works up to 5 amperes. As a compressor, I used a hybrid of an axial fan, designed in a casing (volute) according to the principles of a centrifugal fan. There were also simply centrifugal ones, but I’m curious to try this option. The idea turned out to be quite workable. It blows no worse than my other centrifugal fans, even in the presence of aerodynamic resistance (the main problem of axial fans). I recommend it if you don’t find a suitable turbine.
It takes mosfets from boards with lead-free solder quite well. Small things even more so. I also took the composite video output connector from the same board. The video processor is no longer there.
Small things can be removed from boards with regular solder already at 75 watts of power quite comfortably. It can be lower if you reduce the fan speed. At full power, forty-legged microcircuits are completely removable. Phone payments are easy.
Decide on the power you can and want to receive. Less than 100 watts doesn't make much sense. It's enough for the little things, however, if you do the rest correctly. I came out at 100-110 watts. It's not enough to fix video processors.
Second. The current you can get from the power supply. The choice of nichrome for the spiral depends on it. I have nichrome 0.4 mm. If sclerosis does not change, it was sold on the market as a 1.5 kW tile spiral. I found it optimal. Thin wire does not hold its shape well, thick wire requires a large current to obtain sufficient temperature. For a 0.4 mm wire, a current of about 3.5 - 5.5 amperes is needed. So that the wire heats up to a yellow glow approximately. With intense airflow, its temperature will decrease. Let us remember that the diameter of the wire uniquely determines the current. But the power will have to be gained by voltage. Since my power supply supplies 24 volts for this purpose, I stopped there. The resistance of the cold spiral turned out to be around 3 ohms. In a heated form, according to calculations - about 4. The spiral does not care what kind of current, constant or alternating. You can power it directly from the transformer through a dimmer for adjustment. True, the trance will then buzz. And it must have sufficient power and a winding made of thick enough wire to hold the selected current.
An important element is the fan. Axial ones can be used as a last resort, but they do not cope well with pushing air through labyrinths. Their path is to blow in a straight line. Therefore, a centrifugal fan is preferable for a hair dryer. It is precisely designed to push air through significant aerodynamic resistance. It so happened that some time ago I visited a friend and he showed me a heating system of his design. Where there is also a centrifugal fan. Homemade too. It turned out that he made both possible mistakes there for fans of this kind. I incorrectly chose the direction of rotation for the impeller from the vacuum cleaner and incorrectly made the snail for it. I’m not a fan designer at all, but I studied physics at school, so I have an idea of how it works. Well, it seems like a well-worn topic, so while preparing the article I went to Google. And, to my surprise, I discovered that almost a third of the pictures on this topic contain one of two or both errors at once. Therefore, I will give my diagrams so that no one gets confused. Moreover, this makes direct sense for beginners.
This is the general principle for constructing centrifugal fans. Three different possible impeller options are shown. There are actually more options, but that's enough for us. Please note that these are three different versions of impellers. Just partially shown. This is by no means one. As you can understand from the diagram, the impeller should “push” the air to the sides, thereby creating pressure. (Oh, those “painters” from Google, they draw what they themselves do not understand).
Red option number 1 is the best. Green (2) is worse. Blue (3) is worse than the previous two, but it will work. If your impeller rotation direction is different, just mirror the diagram.
I did almost the same thing, only I installed the impeller from an axial fan.
The impeller, naturally, works to “blow” air inside. The difference from a simple axial fan is that the energy for swirling the air flow is not wasted, but is used according to centrifugal principles. In theory, such things should be patented.
The resulting hybrid works quite adequately. It's noisy, but that depends on your luck. The fact is that with a small impeller diameter (either axial or centrifugal), in order to ensure sufficient air flow, you will have to give high engine speeds. With all the ensuing consequences. With a large impeller it could be quieter, but the convenience of a hairdryer will be lower.
If you create a turbine, as I suggested, when choosing a base for a fan, preference should be given to small-sized blades with a high rotation speed, preferably straight blades (saber-shaped blades will work worse). The more blades the better. The steeper their inclination (angle of attack), the better. I used an impeller from a very old video card. 12 volts, about 1.5 watts. Impeller diameter 37 mm. Use what you find. Experiment.
Suitable centrifugal fans in almost finished form, or as donor impellers with an engine for my snail. You can put it not “flat” like mine, but perpendicular to the hairdryer. In my first attempts I did just that. And the turbine from the laptop showed itself very well. And quieter too. But it was already very worn out and was designed for 3.5 volts, so I went a different route.
My hybrid compressor is larger.
The main body of the snail is made of polystyrene foam. It doesn’t matter what it’s made of, even wood. The structure is clearly visible. By the way, if you are planning to make protection for the impeller, I highly recommend not drilling small holes in the top cover. If you want to know why, google the device of a mechanical hand-held siren from the war. The noise level will be three times higher than with the shown option.
I used a case from an 18650 battery as a sleeve for a hair dryer. The extraction technology is similar to that shown in this video (from someone else’s YouTube channel):
Only I didn’t bother with drilling, as the author suggests, through the bushings. Drilled it with a small drill. Drilled out 4 mm. Use a needle file to correct it if the center of the hole has shifted. I drilled further with a step drill, adjusting with a file at each step, if necessary. I also made the bushing differently. From some kind of chandelier there is a threaded tube with two thin nuts. I riveted one nut at the end so that it would no longer rotate, and I tighten the second one. I insert the fixed nut from the inside of the battery cup. I ground off the excess part of the thread for beauty. You can do without a bushing, but the flow will be worse. Not a jet, but a diverging torch. I don't recommend very thin ones. An internal diameter of 7-10 millimeters, I think, will be more convenient. And there is no need to create unnecessary air resistance.
Mica is placed inside the 18650 cup. The spiral was wound on a glass fiber laminate plate 14 mm wide. Nichrome with a diameter of 0.4 mm. I wound 16 turns. If you use a different supply voltage, you will have to select the number of turns. The ends were bent at 90 degrees. Leave the ends longer, then cut them in place. And this spiral must be placed on a ceramic tube. I bought it at the Mitinsky radio market at one time. Diameter 4 mm. In principle, almost any one will do, but if the diameter is very different, you may have to experiment with the width of the winding plate. One end of the spiral is passed through a ceramic tube. The spiral placed on a ceramic tube must be “twisted”, shifting each subsequent turn relative to the previous one. If you can unwind these 16 turns a couple of turns, that’s not bad. Since the length of the spiral is short, we must strive to position it more evenly. To enhance the heating of the air, I additionally inserted an impeller made of galvanized iron (or tin), which additionally rotates the air flow against the rotation of the spiral, improving heat transfer. And at the same time it serves for some kind of centering of the ceramic tube inside the glass. The resulting spiral should be freely inserted inside the cup with mica. But it is advisable that it does not flop around there too much. I insert it tightly enough.
The picture shows the same impeller for twisting the air flow and you can see how I finished it with nichrome. I bent it in half, twisted it a little, put on and flattened the brass tubes from the NShvi 0.7-8 tips (you can use a tube from an antenna, for example). I wrapped the ends with a thin copper wire, soldered them, soldered silicone wires from some kind of heater (in principle, you can use ordinary ones), and also crimped the soldering area with brass tubes. All this is needed to reduce the heating of nichrome in the area of contact with the wire. On top there are fiberglass tubes. Can be found in dead energy savings, for example. Instead of soldering, you can use mechanical clamps. Which ones will you find? Keep in mind that the spiral and impeller for swirling air must be insulated to prevent short circuits to the housing and to each other.
The further “body” was assembled from a pipe (used in furniture and design) and a housing from a car cigarette lighter (it fits well on a battery cup), fortunately I had several of them accumulated after experiments with an infrared soldering iron. Use what you find, it doesn't matter. The tube was connected to the cigarette lighter body by soldering. There is no special heat, it will hold up. The ends of the body were cut crosswise to get something like a collet, for clamping a cup from 18650 through a piece of glass insulating tape, or just fiberglass for thermal insulation.
I made the duct shell from tin and soldered it. A plate is soldered to it on top (I used foil fiberglass) to which the fan is attached with screws. I cut the threads for the fastening screws directly into it.
In the picture the spiral is not yet completely twisted.
In the final form it looks something like this. This photo more or less shows how the rest of the wire was designed. This is not the final version, without the impeller yet.
At the exit.
The fan is powered from the duty room. It's three amp. I installed a 12 volt Chinese boost converter. The fan turns on together with the power supply fan. And the heating is turned on with the Ps-On key (upper right corner of the power supply). And first we turn off the heating with this key after work, and after the hair dryer has cooled down, we turn off the power (at the back). The toggle switch is designed to switch the fan speed. Until I implemented it, there was no need to overheat the air flow. I plan to simply power the fan through a diode or two (I’ll have to try), and the toggle switch would simply send the voltage past the diodes, short-circuiting them. The lower the flow rate, the more the air will heat up.
I used COM dad-mom. From somewhere on the boards. I wired it like this: two groups of three contacts each for heating (more than enough for 5 amperes), one for the fan. Then I fixed it with hot glue and insulated it.
Thus, the power supply is stabilized (if it is not operating at maximum voltage), the fan power supply is stabilized, and therefore the outlet air temperature is stabilized.
I'm happy with the design. For amateur purposes it is quite enough. At maximum heating, the metal pipe in the area of the handle heats up quite noticeably, but the hand is quite tolerable. During normal operation, the pipe is simply warm. Those. nothing will melt there. The air flow through the tube does a good job of cooling. And it is advisable to place the air duct like mine, closer to the handle. To prevent backflow of air from the hot zone. The hairdryer was tested by turning off after maximum heating. I was simply deprived of power. Along with a fan. Nothing melted.
For beginners: to start constructions of this kind, you need to get into bins, stashes, etc. and contemplation of previously accumulated wealth. And with a high degree of probability you will find something that can be used quite easily. What I mean is that the design does not have to completely replicate mine.
