I decided to rewind a burned-out 40-watt soldering iron. And why not, if all the materials are there?

But rewound to 220v. burned out when first turned on from the released burning at a voltage of 150 V. Since when rewinding I used adhesive tape made of fiberglass. Therefore, it is necessary to use insulating materials that are free from combustible substances or anneal them.

And first turn on at low voltages, increasing to 220 V. as the smoke stops. For example, for a soldering iron 40W. through light bulbs 15,25,40 watts.

To suffer again, winding a winding for 220v with a thin wire. I got sick.

I took nichrome from a hair dryer and wound two layers. It turned out at 30v., 1.1A.

Then I got an electronic transformer for 12v, which, perhaps, would fit

To power the soldering iron in one layer, but the soldering iron was already ready.

Main materials for rewinding:

Mica. Taken from a large mica capacitor type KCO13.

Nichrome. From a hair dryer.

Step-down transformer and graphite rod from a battery for welding nichrome with copper wire.

Asbestos cord for thermal insulation.

Black auto seal. Withstands temperatures up to 300 degrees.

Metal braid. For small soldering irons, a braid from connecting hoses for toilet bowls, boilers, ... But it is very soft, maybe in two layers.

For 40w. a tighter braid is better. From high pressure hoses, brake hoses, etc.

MGTF wire. For rewinding the transformer and for the soldering iron, I used it with an outer insulation diameter of 0.7 mm. For welding to nichrome two pieces of wire with a diameter of 2 mm in insulation.

We wrap the place of winding with mica and fix it with several turns of a thin thread.

Before winding, we weld one piece with nichrome (for those who have no experience, read it on the Internet, then practice), isolate the junction and insert the handles into the tube. I fix the first turn by winding the next two turns on it. Do not forget that after the inserted leads, you need a place for attaching the outer braid, about 1 cm. and from the end as well. I fix the last turn by wrapping it several times with thin nichrome. We put the second piece of thick wire into the handle, sweaty twist it with nichrome, weld it, isolate it. The conclusions of the wire segments from the handle must be well fixed so as not to accidentally pull out the turns. At least firmly insert a piece of wood on the glue into the handle.

You can now connect it to a step down transformer or to a suitably sized power supply with regulated output voltage to check that the heating coil is working properly and to get a rough idea of ​​the voltage and current at which it will operate.

After cooling, we wind a layer of mica and then an asbestos cord. The cord, unlike the sheet, does not crumble and lies more densely. Those who are embarrassed by asbestos can look for a replacement. Some kind of fiberglass cord or cloth.

Check that the tightened braid will fit over the cord. Lubricate with auto-sealant and put on a braid. With the same nichrome we wind the edge of the braid from the side of the handle, after which we pull it, seal the braid and wind it to the tube in front. We untwist and cut off the unnecessary part of the braid with wire cutters. While the sealant hardens, we collect a soft cord that does not melt from the soldering iron tip. Since there was a wire in fluoroplastic insulation with a diameter of about 0.7 mm over the insulation, I used it. I took 6 wires, weaved them with a pigtail - we got a soft, strong cable. We solder it to the leads from the soldering iron, and attach the joints with electrical tape to the handle. This makes it easy to resolder the cable if it breaks at the handle.

Lightweight and small-sized electronic transformers for halogen lamps gave rise to their use for powering low-voltage soldering irons.

I got 160w. with punched 12-amp transistors 13009. Since this power is superfluous, I replaced them with the existing 4-amp 13005. Instead of 8 turns of the busbar for 12v., I wound 45 turns with a tap from 39. The installed switch connects the soldering iron

To 39 turns - for soldering small things without overheating or to 45 turns. The output transformer is mounted on the board on silicone with a gap of about 1mm to the board. If necessary, extra coils can be easily removed. If you install the soldering iron power switch inside the case, you may have to install the transformer by sliding it to one side. An LED indicator with a diode and a resistor is installed in the center of the output. transformer by connecting it to the last turns.

The mains plug can be attached to the case by cutting it off from similar devices, such as wall power supplies, cell phone chargers. You can also connect the plug on a short cable, it is more convenient to connect to tees.

When first turned on, the electronic transformer did not work. Small load. Since the load is constant and k. it is not foreseen that without bothering with alteration to the voltage OS, I added a turn to the existing turn of the current winding on a small ring, and it worked.

What is written here is a general direction. Everyone will have their own path, depending on the components they have.

As is known, the only available high-temperature insulating material with high thermal conductivity is mica. To solve the problem of attaching mica to the surface of the mandrel, I was "helped" by an ordinary collet pencil. So, all I had to do was choose the appropriate size of the pencil and remove the slotted tube from it.

In order not to wrinkle a thin-walled tube, when installing a drill in a chuck, I picked up a steel rod of a suitable diameter and drowned out the edge of the tube with it.

Now you can safely wind the coil of the heating element.

I think you have already guessed that if you insert the edge of the mica gasket into the slot of this tube, then, when winding, the turns of wire will securely fix the gasket. After winding, the heating element can be easily removed from the tube by moving along the slot.

This is how the finished heating element, made by hand, looks like. You can see all the subtleties of this technology in the attached video.

An electric soldering iron is a hand tool designed to fasten parts together using soft solders, by heating the solder to a liquid state and filling the gap between the soldered parts with it.

As you can see in the drawing, the electrical circuit of the soldering iron is very simple, and consists of only three elements: a plug, a flexible electrical wire and a nichrome spiral.

As can be seen from the diagram, the soldering iron does not have the ability to adjust the tip heating temperature. And even if the power of the soldering iron is chosen correctly, it is still not a fact that the temperature of the tip will be required for soldering, since the length of the tip decreases over time due to its constant refilling, solders also have different melting temperatures. Therefore, to maintain the optimum temperature of the soldering tip, it is necessary to connect it through thyristor power controllers with manual adjustment and automatic maintenance of the set temperature of the soldering tip.

Soldering iron device

The soldering iron is a red copper rod that is heated by a nichrome spiral to the melting temperature of the solder. The soldering iron rod is made of copper due to its high thermal conductivity. After all, when soldering, you need to quickly transfer heat to the soldering iron tip from the heating element. The end of the rod has a wedge shape, is the working part of the soldering iron and is called a sting. The rod is inserted into a steel tube wrapped in mica or fiberglass. Mica is wound with nichrome wire, which serves as a heating element.

A layer of mica or asbestos is wound over the nichrome, which serves to reduce heat loss and electrical insulation of the nichrome spiral from the metal body of the soldering iron.

The ends of the nichrome spiral are connected to the copper conductors of an electric cord with a plug at the end. To ensure the reliability of this connection, the ends of the nichrome spiral are bent and folded in half, which reduces heating at the junction with the copper wire. In addition, the connection is crimped with a metal plate, it is best to crimp with an aluminum plate, which has a high thermal conductivity and will more effectively remove heat from the junction. For electrical insulation, tubes made of heat-resistant insulating material, fiberglass or mica are put on the junction.

The copper rod and the nichrome spiral are closed by a metal case consisting of two halves or a solid tube, as in the photo. The body of the soldering iron on the tube is fixed with cap rings. To protect a person's hand from burns, a handle made of a material that does not see heat well, wood or heat-resistant plastic is mounted on the tube.

When the soldering iron plug is inserted into the socket, electric current flows to the nichrome heating element, which heats up and transfers heat to the copper rod. The soldering iron is ready for soldering.

Low-power transistors, diodes, resistors, capacitors, microcircuits and thin wires are soldered with a 12 W soldering iron. Soldering irons 40 and 60 W are used for soldering powerful and large radio components, thick wires and small parts. For soldering large parts, for example, gas column heat exchangers, you will need a soldering iron with a power of one hundred or more watts.

Soldering iron supply voltage

Electric soldering irons are available for 12, 24, 36, 42 and 220 V mains voltage, and there are reasons for this. The main thing is human safety, the second is the mains voltage in place soldering work is done. In production, where all equipment is grounded and there is high humidity, it is allowed to use soldering irons with a voltage of not more than 36 V, while the body of the soldering iron must be grounded. The on-board network of a motorcycle has a DC voltage of 6 V, a car - 12 V, a truck - 24 V. In aviation, a network with a frequency of 400 Hz and a voltage of 27 V is used.

There are also design limitations, for example, it is difficult to make a 12 W soldering iron for a supply voltage of 220 V, since the spiral will need to be wound from a very thin wire and therefore many layers will be wound, the soldering iron will turn out to be large, not convenient for small work. Since the winding of the soldering iron is wound from nichrome wire, it can be powered by both alternating and constant voltage. The main thing is that the supply voltage matches the voltage for which the soldering iron is designed.

Heating power of soldering irons

Power electric soldering irons are 12, 20, 40, 60, 100 W and more. And this is not accidental either. In order for the solder to spread well over the surfaces of the soldered parts during soldering, they need to be heated to a temperature slightly higher than the melting point of the solder. Upon contact with the part, heat is transferred from the tip to the part and the temperature of the tip drops. If the diameter of the soldering iron tip is not sufficient or the power of the heating element is low, then having given off heat, the tip will not be able to heat up to the set temperature, and it will be impossible to solder. At best, you get a loose and not strong solder.

A more powerful soldering iron can solder small parts, but there is a problem of inaccessibility to the soldering point. How, for example, to solder a microcircuit with a leg pitch of 1.25 mm into a printed circuit board with a 5 mm soldering iron tip? True, there is a way out, several turns of copper wire with a diameter of 1 mm are wound onto such a sting and soldered with the end of this wire. But the bulkiness of the soldering iron makes the job almost impossible. There is one more limitation. With high power, the soldering iron will quickly warm up the element, and many radio components do not allow heating above 70 ° C, and therefore, the allowable soldering time is no more than 3 seconds. These are diodes, transistors, microcircuits.

Do-it-yourself soldering iron repair

The soldering iron stops heating for one of two reasons. This is due to rubbing of the power cord or burnout of the heating coil. Most often the cord frays.

Checking the health of the power cord and soldering iron spiral

When soldering, the power cord of the soldering iron is constantly bent, especially strongly at the exit from it and the plug. Usually in these places, especially if the power cord is hard, it frays. First, such a malfunction manifests itself by insufficient heating of the soldering iron or its periodic cooling. Eventually, the soldering iron stops heating up.

Therefore, before repairing the soldering iron, you need to check the presence of supply voltage in the outlet. If there is power at the outlet, check the power cord. Sometimes a cord malfunction can be determined by gently bending it at the exit from the plug and soldering iron. If the soldering iron at the same time became a little warmer, then the cord is definitely faulty.

You can check the serviceability of the cord by connecting the probes of a multimeter to the pins of the plug, which is included in the resistance measurement mode. If the reading changes when the cord is bent, the cord has frayed.

If it is found that the cord break is located at the exit point of the plug, then to repair the soldering iron it will be enough to cut off part of the cord along with the plug and install a collapsible cord on the cord.

If the cord is frayed at the point of exit from the soldering iron handle or the multimeter connected to the pins of the plug does not show resistance when the cord is bent, then you will have to disassemble the soldering iron. To gain access to the place of attachment of the spiral to the wires of the cord, it will be enough to remove only the handle. Next, sequentially touch the probes of the multimeter to the contacts and pins of the plug. If the resistance is zero, then the spiral is broken or it has poor contact with the wires of the cord.

Calculation and repair of the heating winding of the soldering iron

When repairing or when making an electric soldering iron or any other heating device on your own, you have to wind the heating winding from nichrome wire. The initial data for the calculation and selection of wire is the resistance of the winding of the soldering iron or heater, which is determined based on its power and supply voltage. You can calculate what the resistance of the winding of a soldering iron or heater should be using the table.

Knowing the supply voltage and measuring the resistance of any heating appliance, such as a soldering iron, electric kettle, electric heater or electric iron, you can find out the power consumed by this household appliance. For example, the resistance of a 1.5 kW electric kettle will be 32.2 ohms.

Table for determining the resistance of a nichrome spiral depending on the power and supply voltage of electrical appliances, Ohm
Power consumption soldering iron, W	Soldering iron supply voltage, V
	12	24	36	127	220
12	12	48,0	108	1344	4033
24	6,0	24,0	54	672	2016
36	4,0	16,0	36	448	1344
42	3,4	13,7	31	384	1152
60	2,4	9,6	22	269	806
75	1.9	7.7	17	215	645
100	1,4	5,7	13	161	484
150	0,96	3,84	8,6	107	332
200	0,72	2,88	6,5	80,6	242
300	0,48	1,92	4,3	53,8	161
400	0,36	1,44	3,2	40,3	121
500	0,29	1,15	2,6	32,3	96,8
700	0,21	0,83	1,85	23,0	69,1
900	0,16	0,64	1,44	17,9	53,8
1000	0,14	0,57	1,30	16,1	48,4
1500	0,10	0,38	0,86	10,8	32,3
2000	0,07	0,29	0,65	8,06	24,2
2500	0,06	0,23	0,52	6,45	19,4
3000	0,05	0,19	0,43	5,38	16,1

Let's look at an example of how to use the table. Let's say you need to rewind a 60 W soldering iron designed for a supply voltage of 220 V. Select 60 W from the leftmost column of the table. On the upper horizontal line, select 220 V. As a result of the calculation, it turns out that the resistance of the soldering iron winding, regardless of the material of the winding, should be equal to 806 ohms.

If you needed to make a soldering iron with a power of 60 W, designed for a voltage of 220 V, a soldering iron for power from a 36 V network, then the resistance of the new winding should already be 22 ohms. You can independently calculate the winding resistance of any electric heater using an online calculator.

After determining the required resistance value of the soldering iron winding, from the table below, the appropriate diameter of the nichrome wire is selected based on the geometric dimensions of the winding. Nichrome wire is a chromium-nickel alloy that can withstand heating temperatures up to 1000 ° C and is marked Kh20N80. This means that the alloy contains 20% chromium and 80% nickel.

To wind a soldering iron spiral with a resistance of 806 ohms from the example above, you will need 5.75 meters of nichrome wire with a diameter of 0.1 mm (you need to divide 806 by 140), or 25.4 m of wire with a diameter of 0.2 mm, and so on.

I note that when heated for every 100 °, the resistance of nichrome increases by 2%. Therefore, the resistance of the 806 ohm spiral from the above example, when heated to 320˚С, will increase to 854 ohms, which will practically not affect the operation of the soldering iron.

When winding the soldering iron spiral, the turns are stacked close to each other. When heated, the red-hot surface of the nichrome wire oxidizes and forms an insulating surface. If the entire length of the wire does not fit on the sleeve in one layer, then the wound layer is covered with mica and the second one is wound.

For electrical and thermal insulation of the heating element winding, the best materials are mica, fiberglass cloth and asbestos. Asbestos has an interesting property, it can be soaked with water and it becomes soft, allows you to give it any shape, and after drying it has sufficient mechanical strength. When insulating the winding of the soldering iron with wet asbestos, it should be taken into account that wet asbestos conducts eclectic current well and it will be possible to turn on the soldering iron in the mains only after the asbestos has completely dried.

The press machine is placed on a wooden base 8.

Notes: 1. During any processing of plastics, and especially after their cutting (drilling, turning, etc.), it is necessary to remove residual stresses by boiling in water (for more than an hour). Otherwise, the part may crack at the processing points.

and split.

2. When using stockings made of kapron, nylon, etc. as raw materials, all seams must be removed, the toe and heel must be cut off, since

they are made from other materials.

3. When using kapron fabrics, you cannot use those in which the base is made of cotton or other thread.

To obtain various decorative edgings, it is necessary to make dies 9 desired configuration. The die is screwed onto the sprue. When extruded, the mass acquires the profile of the die hole; upon exiting the die, the mass must be cooled in

cold water.

It should be noted that with the help of this press machine (using dies) it is also possible to produce insulating gaskets from polyvinyl chloride (insulating edging for glass-to-metal television tubes, etc.). The softening temperature of polyvinylchloride is 80-100 ° C; when using other materials not listed here, to determine the softening temperature, you must use the data in Table 17, remembering that the softening start temperatures are given there.

Mica. Mica is a non-combustible, layered mineral with high dielectric properties.

There are two varieties of natural mica: muska-

vnt-with high electrical data and phlogopite-with reduced electrical data. The first is used mainly in radio engineering, the second in electrical engineering.

A number of materials based on mica are also used as thermal and electrical insulating materials. Milled mica - micanite dust - serves as a filler in refractory putties.

Varieties of mica and some materials based on it are given in Table. twenty.

Table 20

The most common types of mica are:

CO-mica exemplary (muscavite);

SF-mica filter (muscavite);

SLF-mica low-frequency (muscavite);

High-frequency microwave mica (muscavite);

SZ - protective mica (muscavite and hard phlogopite).

Note. In the manufacture and repair of various equipment, and especially soldering irons, it is sometimes necessary to bend mica with small bending radii. In order to prevent mica from crumbling and breaking, it must first be calcined to a light yellow color. Mica becomes more elastic and bends without cracking or breaking.

Rubber. Rubber is an elastic insulating material with low electrical data. Conventional rubber, which the industry produces, has three varieties: soft, medium hard and hard. In addition to indicating hardness, sometimes there are letters on the rubber: A - slightly swelling in gasoline;

B - swelling in gasoline. Most shock absorbers and shock absorber pads are made by radio amateurs.

they bark from rubber, although some plastics have recently begun to be used for this purpose.

Soft sheet rubber is used to make belts for amateur tape recorders.

Microporous rubber is used for various sound-absorbing coatings (for example, when creating high-quality sound units).

Paper. Paper - the cheapest insulating material, has low electrical data, but after appropriate processing (impregnation) can compete with the best insulating materials. It is mainly used in the manufacture of permanent capacitors and transformer windings.

Cardboard is used for the manufacture of insulating gaskets, transformer coil frames, etc.

The data of some papers and cardboards are given in Table. 21.

Table 21

Fabrics. Widely used for decorative finishes of finished equipment. In combination with insulating varnishes and resins, they form the basis of some insulating materials.

The data of some fabric products are given in table. 22. Table 22

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Glass. The main material for various scales, protective glasses of instruments, the manufacture of optics, mirrors, etc. is glass. The main types of glass processing are cutting, drilling and gluing.

Cutting glass with a diamond or glass cutter is simple and doesn't require much explanation. But sometimes it becomes necessary to cut glass of a complex configuration. To do this, a pattern of the desired shape is applied to the glass, but in such a way that one side of this pattern falls on the edge of the workpiece. "At this point, they wash it down with a trihedral personal file. With a red-hot sharp object (a device for burning wood with full heat or a soldering iron for soldering with hard solders , described in one of the following sections) slowly circle the drawn contour. A crack will continuously form under the hot object, visible to the naked eye. Next, the excess glass is broken off in small sections (preferably in water). The finished part is boiled in water for an hour.

If desired, the edges can be filed with a medium-sized abrasive bar.

Holes in glass. Holes in glass can be made using one of the following methods.

1st way. A hole in the glass is drilled with an ordinary drill without much pressure. The glass must rest on a hard and level surface. Drilling should be done only through the conductor (a piece of metal sheet 5-8 mm with a hole equal to the diameter of the drill thickness), tightly pressed against the glass.

When drilling, the place of the future hole should be continuously moistened with the following composition (in parts by weight):

Camphor - 8;

turpentine - 12;

2nd way. Drilling is done with a flat drill (sharpened with a spatula) also through a jig. The drill should rotate alternately in one, then in

the other side.

The emulsion in this case is silicate glue (liquid glass); the emulsion is changed every time it becomes cloudy.

3rd joint venture The drill can be a copper (worse brass) tube of a suitable diameter; conductor

is also needed here.

A few drops of silicate glue with emery powder are applied to the place of the future hole (better

she corundum No. 000-240); during drilling, this mixture is continuously updated.

Holes in relatively thick glass (more than 4 mm) are drilled with a copper tube slightly expanded at the end (with a punch or other suitable tool), which facilitates the drilling process at the final stage and reduces the likelihood of glass damage.

Bonding of optical glass.

Optical glass is glued with special adhesives of high transparency, such as fir balsam and balsam.

Glass before gluing is thoroughly degreased with dichloroethane or acetone and wiped with clean suede. Glue is applied to both parts to be glued, after which they are clamped in a clamp. In this case, it is necessary to ensure that there are no air bubbles in the place of gluing.

Glass is glued to other materials with various adhesives, cements and putties, the recipes of which are given below,

IV. ADHESIVES, PASTES, PUTTY, VARNISHES. THINNERS.

Adhesives are widely used in amateur radio practice. The use of the right adhesive, combined with the right technology, makes it easy and secure to bond metal to glass, rubber, plastics, porcelain and much more. Below are the most common adhesives.

Starch paste - it is paper glue; his

starch - 60-80 g/l;

borax - 25 g / l.

Starch is dissolved in * / 5 parts of water (cold), thoroughly stirred, brewed with the rest of the water (boiling water) and, finally, borax is introduced into the paste. Flour paste- This is an adhesive for paper and cardboard;

its composition:

Flour - 200 g / l;

joiner's glue (dry) - 50 g/l.

Flour is kneaded with cold water to a doughy state and poured with hot wood glue (temperature 80 ° C). Be sure to strain the glue.

Binding glue. To diluted hot wood glue (directly in a water bath) add Vao part (from the total volume of glue) of glycerin.

gum arabic glue for paper and cardboard is produced from gum (hardened juice) of some fruits

Wheat flour is kneaded with cold water until a batter is formed. In the rest of the water (heated to 50 ° C), aluminum alum is dissolved; the dough is placed in the resulting solution and boiled until a transparent syrupy mass is formed.

Dextrin glue- common paper glue. The recipe is simple: dextrin at the rate of 400 g / l is diluted with cold water.

Glue for cardboard. In 100 c. hours of water dissolve 9 c. hours of office (silicate) glue, 6th c. hours of potato flour and 1 c. hours of sugar. The resulting slurry must be heated until a uniform mass is obtained.

Photoglue. The composition of the photo adhesive:

starch - 60 g/l;

aluminum alum - 40 g/l;

chalk (tooth powder) - 40 g / l;

dry blue - 1 g / l.

Starch is poured 10 c. hours of warm water, stir and add 30 c. hours of boiling water. Alum is separately dissolved in warm (remaining) water, the solution is poured into the paste and stirred well. After half an hour, chalk paste (tooth powder and blue) is also added and mixed thoroughly.

Glue to store in the closed glass ware. Adhesive for gluing fabric, leatherette and leather to wood. The composition of the adhesive is given in parts by weight:

wheat flour - 40;

rosin - 3;

aluminum alum - 1.5;

All dry ingredients are mixed, poured with water and stirred. The resulting pasty mass is put on low heat and stirred until the mass begins to thicken.

Bonding is done with hot glue.

casein glue. Bonds paper, wood, fabrics. leather and ceramics. Casein (powder) is diluted in cold water at the rate of 250 g / l, adding water in small portions and continuously stirring the adhesive mass.

Glue composition:

wood glue - 200 g/l;

sugar -200 g/l;

slaked lime - 70 G(l.

Dissolve sugar in water, then lime and heat over low heat until a clear liquid is obtained. The resulting solution is filtered and dry wood glue is lowered into it. Within 24 hour wood glue swells, and then it is dissolved in a glue pot.

In a closed glass container, the glue can be stored for a long time and does not lose its gluing ability.

Glue for glass. Dissolve gelatin in an equal amount (by weight) of a 5% solution of potassium dichromate (the solution is prepared in a darkened room). The resulting adhesive is insoluble in hot water. The parts are smeared, tightened with a clamp (or tightly wrapped with threads) and put on 5 ^ -8 hour into the world.

Adhesives for glass and ceramics.

1. Casein dissolved in liquid glass (silicate glue) of the consistency of sour cream.

2. Gypsum mixed with egg white to the consistency of sour cream.

3. Gypsum, soaked for a day in. saturated solution of aluminum alum. After soaking, the gypsum is dried, ground and kneaded in water to the consistency of sour cream. This glue adheres well to ceramics.

4. Dry finely ground chalk (tooth powder), diluted in liquid glass in the ratio G: 4.

Universal cement. In dentures, it is used as follows; called "cement-phosphate"; it glues ceramics very well, is not afraid of hot water.

Cement is diluted as follows. The required amount of cement (powder) is poured into glassware and poured with thinner. Everything is thoroughly mixed with a glass rod and immediately applied to previously degreased parts. Details must be pulled together with a clamp (or thread). Drying time 2 hour.

Skin adhesives.

1. Glue "Rapid"; its composition (in parts by weight):

celluloid -15;

acetone - 65;

solvent RDV (or No. 000) -20.

2. A solution of natural rubber (1-2 parts) in carbon disulfide (10 parts) with the addition of a small amount of turpentine.

5 L. A. Erlykni 65

3. Carpentry glue(bone) with the addition of tannin to it until the formation of stretching threads. Rubber adhesives.

1. Natural rubber (1 w.h.), dissolved in solvent gasoline (gasoline "Galosha") or in aviation gasoline B-15 c. h.).

2. High quality rubber adhesive; its composition is given in parts by weight):

carbon disulfide - 10;

gutta-percha - 1.3;

graphite - 10;

varnish No. 000 - 9.

Rubraks and bitumen No. 3 are melted and the remaining components are mixed with them. The resulting putty is thoroughly mixed. Glue parts with hot putty.

rubrax putty consists of the following components (in parts by weight):

rubraks - 2;

varnish No. 000 - 2.5.

Rubraks is melted at a temperature of 120 ° C. Chalk and varnish are added to it. Everything is thoroughly mixed. Glue with hot putty.

Paste for bonding glass to metal. This paste holds glass to metal quite firmly. The liquid consistency of the paste allows gluing large surfaces of these materials.

The composition of the paste (in parts by weight):

copper oxide - - 2;

emery powder No. 60-2;

liquid glass - 6.

All components are ground until a homogeneous paste is formed. The glued parts are heated to 100 ° C and kept at this temperature 2 hour, then cooled to room temperature. After 12-14 hour the paste is completely hardened.

Putty "glass - metal". This type of putty is characterized by increased hardness of the glued joint, which can bear medium mechanical loads.

Below are two putty recipes (in parts by weight).

1st recipe:

lead litharge - 2.5;

rosin - 3.5.

Thoroughly ground and dried components are mixed and diluted with natural drying oil to the density of the putty.

2nd recipe:

lead litharge - 7;

manganese borate - 1;

rosin - 20.

Everything is ground, dried and mixed with natural drying oil until the putty is thick.

Paste for coating vitrified resistances.

When repairing vitrified resistances, and especially when installing taps, it is necessary to restore the coating of the resistance, otherwise the life of the resistance is sharply reduced. You can restore the broken resistance coating with a special paste (the recipe for which is given below).

Dried talc (6 wt. h.) is mixed with liquid glass (silicate glue), which is taken so much as to obtain a mass of sour cream consistency (about 8-12 wt. h.).

The damaged areas of the coating are smeared with paste and dried at room temperature for about an hour. Then the resistance is heated to 100-110 ° C and maintained at this temperature for 10-15 min.

Magnesite putty. This putty is used for bonding ceramic products and metal with ceramic parts. The glued seam withstands heavy loads.

magnesium oxide -4;

porcelain flour - 2;

magnesium chloride solution (sp. weight 1.25) - 5.

Magnesium oxide is calcined for an hour at a temperature of 400-500 ° C. Porcelain flour is dried for 30 min at a temperature of 100-120 ° C. Magnesium chloride is dissolved in water at the rate of two parts of magnesium chloride per one part of water.

After that, magnesium oxide and porcelain flour are mixed, the resulting mixture is poured with a solution of magnesium chloride and kneaded until a homogeneous mass is obtained.

Putty should be applied immediately after production. Full drying time - two days.

Note. Porcelain flour can be obtained by heating pieces of old (broken) chinaware and cooling them in water, repeating this process several times.

Gletglycine putty. This putty (in terms of application and quality of the seam) is similar to magnesite and is widely used in industry for joining ceramic parts to each other and to metals.

The composition of the putty (in parts by weight):

glycerin technical -1;

lead litharge - 8.

The litharge is dried for 2 hour at a temperature of 230-250 ° C, grind in a mortar and small doses (with stirring) add glycerin to it. Putty should be used immediately after production. The drying time of the putty is one day.

Note. Lead litharge can be prepared from red lead. For this, 100 G dry lead minium, you must take 1 g of carbon black, mix everything thoroughly and ignite at a temperature of 450-550 ° C for an hour.

Putty for filling cracks in iron and cast iron castings.

Putty composition (in kg):

iron filings - 1 ammonia - 0.02 slaked lime - 0.1 liquid glass - 0.1.

Dry components are mixed, poured with liquid glass and thoroughly mixed until

homogeneous mass. Putty should be applied immediately after production.

Putty for strengthening iron reinforcement in stone.

Putty composition (in g):

iron filings - 100;

ammonia - 5;

table vinegar - 40-60.

Dilute a mixture of the first three (dry) components with table vinegar to the desired consistency; the resulting putty should be used immediately.

Putty that eliminates the untwisting of nuts. In industrial radio equipment, locking putty is widely used, which successfully replaces various kinds of lock washers.

The composition of the putty (in%):

nitroenamel DM-75;

talc - 25.

The putty is diluted to the desired consistency with acetone or WFD solvent.

§ 8. PAINTS, VARNISHES, ENAMELS, PRIMERS AND PUTTY

For metals, paints, varnishes and enamels serve as both anti-corrosion and decorative coatings.

Fine wood details with a beautiful texture (color and pattern) are covered with transparent varnishes and varnishes. Wood of less valuable species is sometimes covered with opaque (opaque) varnishes and paints.

Finishing wood with various transparent coatings is discussed in section V.

Primer. The painting of metals with varnishes and paints is preceded by a priming process.

The primer is practically no different from the color. The primer is applied to the surface of the part with brushes of medium hardness (and very rarely with spray guns). After drying, the soil is leveled (polished) with sandpaper No. 000-180.

It should be noted that a certain soil corresponds to a certain rhodukra - i ski (lacquer, enamel). ^ Incorrect combination of primer and topcoat sometimes leads to the fact that the paint (lacquer, enamel) bubbles or crumbles after drying.

The appendix given at the end of the book lists a number of the most commonly used paints, varnishes and enamels. Putties, primers and varnishes are also given there, basic recommendations are given on thinning, drying mode, as well as the purpose of coatings and their properties.

Putty. Putty mass is applied to the primed surface of the part with a spatula. A spatula is a flat spatula made of metal, wood or hard rubber.

If there are various irregularities on the surface of the part (cracks, chips, shells, etc.), putty is applied in these places with a slight excess (margin for shrinkage when the putty dries). The main layer of putty should not exceed 0.2 mm.

After drying, the putty is leveled with sandpaper No. 80-100, gradually reducing the grain of the skin. Flat surfaces are well leveled with a flat wooden block; between the skin and the bar it is necessary to lay a layer of fabric 2-3 thick mm.

Coloring. Painting is usually done in two layers. The second layer is placed with brush strokes perpendicular to the brush strokes when applying the first layer. Before applying the second layer, it is desirable to level the dried first layer of the coating with sandpaper No. 000-180.

The tool for painting is most often soft brushes, but sometimes sprayers (sprayers) are also used. The latter are used when painting large parts with nitro paints.

The air pressure when painting parts with nitro paints should be 1-2.5 atm. With thicker paint consistency, the air pressure should reach 3-6 atm.

That might be interesting. The ability to change the supply voltage of a soldering iron designed for 220 V, among other things, allows you to return an already burned out one to operation. And use it in the future, for example, with a switching power supply from an imported TV, which at the output gives exactly half of the network. Bringing these two products together results in an intermediate option between a soldering iron with a regulator and a full-fledged soldering station. This is within the power of any radio amateur. I will show how to do this using the example of changing the supply voltage of a Chinese-made soldering iron, which did not inspire confidence for use without modification.

We disassemble the soldering iron

To disassemble the soldering iron, it was necessary to completely unscrew the two screws connecting the protective casing to the heating element and holding the tip, and three self-tapping screws securing the working part to the handle. Move the insulation from the wires and unwind the connecting twists.

Mica with soldering iron spiral

Inside the protective casing is a heating element. They are to be dealt with. It is necessary to make a change in the amount of wound nichrome wire - change the resistance of the heating element. Now it is 1800 ohms, 400 ohms are needed. Why exactly so many? Currently working with a UPS, the soldering iron has a resistance of 347 Ohms, its power is from 19 to 28 W, the second there is a desire to make it less powerful, so Ohm was added.

Rewind soldering iron

Winding the tip of the soldering iron

The sting is inserted into the heater again, clamped with screws and into the drill chuck. If you disassemble and unwind excess nichrome while holding the heating element in your hands, then everything will be much more complicated. The binding wire is removed.

The released wrappers of fiberglass and mica are removed. There is a slot in the mica from the side of the sting, where the conductor is inserted, going from nichrome to the network wire - therefore, the weakened mica wrapper is not unwound, but removed from it. Mica is a very brittle material. The end of the nichrome wire attached to the conductor is disconnected. Its thickness is just over 4 microns.

Nichrome must be wound on something round, the ideal option is a spool of thread. Unscrewed - rewound and so on until the end. It is not necessary to disconnect the second end of the nichrome wire.

Soldering iron wire resistance

Now you need to wind a length of 400 ohms, and in centimeters it will be about 70 (the total length of a nichrome wire of 300 cm is 1800 ohms, hence 400 ohms will be 66.66 cm). A latch (clothespin) is placed on a length of 70 cm and in the hanging position of the coil, slightly guiding with your fingers, winding is performed with an interval that ensures its termination at the first conductor. The rate of attempts is not limited, the main thing is not to break the nichrome. At the end of the winding, a control measurement of the resistance is necessary.

As soon as it turned out to wind the required amount of nichrome, we cut off the wire with an allowance of 1 - 2 cm and attach it to the conductor. We put on the mica winding, passing the conductor into the slot in it and pressing it against it (of course, on top of it).

From above we install a winding made of fiberglass and seal it by pressing, we wind the tying wire. The heating element designed for power supply with a voltage of 85 - 106 V is assembled.

Soldering iron assembly

Since the working part was previously attached to the handle with unintelligibly clumsy and short self-tapping screws, they had to be replaced. To do this, holes for new self-tapping screws were deepened at the attachment points on the handle.

Before connecting the mains wire to the conductors going to the nichrome heater, a plastic clamp was installed and adjusted on it.

The casing of the heating element ends with a kind of cooling radiator, through the holes in it and is attached to the handle. Here, to increase the cooling effect, the gap between it and the handle was increased using metal washers.

Tests

Soldering iron current consumption 190 mA

The UPS with which the soldering iron will work at the output under load gives from 85 to 106 V. The current consumption is 190 mA, this is at a minimum voltage. Power 16 W.

Soldering iron current consumption 240 mA

At maximum voltage, the current consumption is 260 mA. Power 26 W. Wish received.

Heating rate

In conclusion, the test for the duration of heating. Up to 257 degrees in 2 minutes 20 seconds. An excellent result, if we take into account that from a network with a voltage of 225 V, it heated up to 250 degrees in 5 and a half minutes.

Table. The dependence of the resistance of the heating element on the power and voltage of the soldering iron

And here is a table that will help you navigate the required resistance of the heating element, depending on the desired power and the available supply voltage. Author - Babay iz Barnaula.