home · electrical safety · News: Japanese mahogany bearings have worked for the benefit of the Russian city for half a century! What's new, bearing? What kind of wood are sliding bearings made from?

News: Japanese mahogany bearings have worked for the benefit of the Russian city for half a century! What's new, bearing? What kind of wood are sliding bearings made from?

Publication date: 08/21/2009

According to the State Television Company Tomsk, during the reconstruction of the local GRES-2 (located in the Siberian city of Tomsk, owned by OJSC "TGC-11") when disassembling the old one steam turbine made in Japan, it was discovered that all turbine bearings were made of... mahogany. Turbine with a capacity of 30,000 hp. (29 MW) was installed back in 1948 and operated until 2001.

The turbine was originally installed on one of the ships of the Japanese Imperial Navy. However, after World War II, when some of the Japanese ships were transferred to the USSR and then scrapped, the steam installation from one of these ships was removed and brought to Tomsk to GRES-2, which was then being completed. After the war, the recovering Soviet economy required more and more energy, but many machine-building plants at the beginning of the peace period were still unable to produce much, as the post-war devastation and the need to switch to the production of civilian products were taking their toll. Therefore, in the then USSR they were forced to install machines from former fascist countries (Germany, Japan and their allies) received as trophies and under reparation agreements at power plants. Often the equipment was already worn out, technical documentation did not exist at all; significant adaptation to local conditions was required. But, despite everything, Tomsk power engineers managed to put into operation the second stage of GRES-2 in 1952, on which a turbine was installed that had once worked on a warship from the distant land of the rising sun. For almost half a century, the Japanese turbine served Tomsk residents faithfully, and only at the beginning of the 21st century was it finally stopped.

In the photo: the beginning of construction of Tomsk State District Power Plant-2 (1943-1945)

Photo: TGK-11

At the Tomsk State District Power Plant No. 2, which was under construction, immediately after the war, they were forced to use captured equipment. This is how a turbine with mahogany bearings from a Japanese warship ended up there.


Currently, the old turbine has been completely dismantled, and a modern Russian one - T-50 with a capacity of 50 MW produced by the concern - is being installed in its place. « Power machines» . Its launch is scheduled for September 30 this year. The service life of a new turbine should be 30-40 years.

Brief information


Due to the harsh operating conditions, sleeve bearings are often used in power turbines. Sliding bearings made of wood materials can be found in installations of outdated design. Hardwoods (for example, boxwood and buckout) and wood plastics were used as the main structural materials for such bearings. Modern turbines use plain bearings made of metal and synthetic alloys. Both rolling bearings and progressive magnetic bearings are used. More details about these types of bearings can be found in the article .

Usage: mechanical engineering. The essence of the invention: plates into liners for sliding bearings are molded in two stages using a stepped cone-cylindrical receiver, first to half their thickness, then until they are in full contact with each other, while the humidity of the initial plates is 8 -12% and molding is carried out until the density of the liners is the intermediate cage is no more than 1350 kg/m 3 on the inner surface and no less than 800 kg/m 3 on the outer surface, and the receiver is made of two conical and one cylindrical parts. 2 s. and 1 salary f-ly, 7 ill.

The invention relates to the technology of producing pressed wood products and can be used in mechanical engineering in the design of various friction units for machines and mechanisms. There is a known method for producing wood-metal products such as bushings, which involves manufacturing rectangular plates from pressed wood, installing them in a boundary contour, followed by molding them in the bushing using a conical receiver with a taper angle of 3-5° and a height twice the height of the boundary contour. The disadvantage of this method is that it does not ensure the production of bushings with a high final density, nor does it exclude defects due to significant compressive and bending stresses that arise at the transition boundary from the conical receiver to the cylindrical cage. Further reduction of the cone angle and multiple increases in the height of the receiver complicate the technical process and reduce its productivity. There is a known method for producing wood-metal bushings, adopted as a prototype, including additional operations: drying, impregnation with anti-friction lubricants, followed by final pressing of the liners into the cage (bearing housing) with a given interference along the contact surface. Despite the fact that this method, although it improves the quality of finished products, as it gives them dimensional stability, anti-friction properties, and expands the range of operating temperatures, however, like the first method, it does not provide a high percentage of yield of high-quality liners after molding in one step with using a similar type of cone receiver for the same reasons. The objective of the invention is to improve the quality of products and save raw materials. This is achieved by the fact that the molding of the plates into liners is carried out in two stages using a stepped cone-cylindrical receiver, first to a degree of compression up to half their thickness, then until they are in full contact with each other, while the moisture content of the initial plates is taken within the range of 8-12% and molding lead to a density of liners in the intermediate cage of no more than 1350 kg/m 3 on the inner surface and no less than 800 kg/m 3 on the outer surface, and the conical receiver is made stepped, consisting of two conical and one cylindrical parts, each of which is equal to the height of the original plates. In this case, the diameter of the cylindrical part of the receiver is less than the diameter of the limiting contour by one plate thickness, and the diameter of the exiting conical hole and the diameter of the intermediate cage are less than the diameter of the limiting contour by two plate thicknesses. The closest to the proposed device is a device in the form of an adapter with a conical hole and a cone angle of 3-5°, and the height of the conical part is at least two times the height of the boundary contour. However, it does not provide a significant increase in the percentage of yield of high-quality bushings or liners after they are molded through a conical receiver with a 2-fold height and a taper angle of 5 degrees. At a cone angle of 3°, the height of the cone increases sharply, which complicates the technical process, reduces its productivity and insignificantly reduces the rejects of finished products. When manufacturing bearings using a known conical receiver, the plates move into the intermediate cage all the time along an inclined plane, and therefore their compression by the side surfaces and the increase in density increases unevenly in height. So, for example, when the plates enter the intermediate cage, they reach maximum density with their lower parts , while the upper parts have half the density, which often leads for this reason to their destruction or the formation of cracks. In order to eliminate these disadvantages, a device is proposed for producing sliding bearings with inserts made of wood, including a limiting contour, a conical receiver and an intermediate cage, in which the conical receiver is stepped, consisting of two conical and one cylindrical parts, each of which is equal to the height of the original plate, in this case, the diameter of the cylindrical part of the receiver is less than the diameter of the limiting contour by one plate thickness, and the diameter of the exit hole of the cone and the diameter of the intermediate cage are less than the diameter of the limiting contour by two plate thicknesses. Figure 1 shows the proposed device, section; Figures 2-4 show the stages of molding plates into liners; in Figs. 5 and 7 the final pressing of the liners with the calculated interference into the bearing housing; Figure 6 shows shrinkage and impregnation of the liner. The device has a limiting contour 2, a conical receiver consisting of three parts: upper cone 4, lower cone 6, articulated with each other by a cylindrical sleeve 5, intermediate cage 7, auxiliary cone 8, bearing housing 9. The device is used as follows. The limiting contour 2 is installed on a conical-cylindrical receiver 4, 5, 6 articulated with each other, which, in turn, is installed on the intermediate clip 7. After which a package with end plates 1 made of wood is installed in the limiting contour 2 (Fig. 1-2 ), which are then pressed under the washer 3, first into the cylindrical part of the receiver 5 until the plates are incompletely compressed by their side surfaces (Fig. 3), and then into the intermediate cage 7 until they are completely compressed (Fig. 1-4). The intermediate clips 7 with the liners 1 pressed into them are removed for drying (Fig. 5) after each cycle and replaced with new ones. All main parts of the cone-cylindrical receiver 4, 5, 6 as well as auxiliary parts 2, 7 are equal in height to the original plates (blanks), while the diameter of the cylindrical part of the receiver 5 is less than the diameter of the limiting contour 2 by the thickness of one plate, and the diameter of the exiting conical hole and the diameter of the intermediate cage 7 is less than the diameter of the limiting contour 2 by two plate thicknesses. Using the proposed device, the method is carried out in the following sequence. Rectangular end plates 1 with a certain thickness are made from natural or pressed wood with a density of at least 800-1000 kg/m 3 and a humidity of 8-12%, installed in the limiting contour 2 in the form of a polyhedron, from which they are pressed with a washer 3 through a cone-cylindrical receiver 4, 5, 6 into intermediate clip 7. In this case, after the passage of the cone 4 and their entry into the cylindrical part of the receiver 5, the plates occupy vertical position and are compressed by their internal surfaces only to half their thickness (Fig. 3), and after pressing through the cone 6 into the intermediate cage 7, they are compacted without destruction to the maximum possible density (1350 kg/m 3) due to full contact with each other. After these operations, the liners located in the intermediate holders 7 are dried in chambers or in mineral liquids until moisture is completely removed from them, while the liners are separated from the holder to the extent of complete drying (Fig. 6). Then the liners located in the same cages are impregnated with water-repellent and antifriction substances according to known conditions and, using an auxiliary cone 8, are finally pressed into the bearing housing 9 with the calculated interference (Figs. 5 and 7). PRI me R 1. End plates 1 in the amount of 8 pieces were cut from bars of pressed wood brand DMTM-OX according to GOST 9629-81 with an initial density of 950 kg/m 3. 5.0 mm thick, 13-13.5 mm wide, 30 mm high and installed them in a boundary contour with an internal diameter of 44 mm in the form of a closed polyhedron. Then, using a washer 3 under a press, the plates were repressed using a cone-cylindrical receiver 4, 5, 6, first into the cylindrical part of the receiver 5 with an internal diameter of 39 mm, and then through the cone 6 into an intermediate cage 7 with an internal diameter of 34 mm. In the cylindrical part of the receiver 5, the plates are closed to each other by half their thickness in Fig.3. The density on the inner surface of the curved plates in this case increased to 1280 kg/m 3, and after pressing them into the intermediate cage 7, the plates completely closed their side surfaces with each other (Fig. 4). Their density on the inner surface reached almost a maximum of 1346 kg/m 3 without any noticeable damage or cracks. The density on the inner surface was determined from the following ratio: o D n to d in, where o the initial density of the plates (950 kg/m 3); Dn is the diameter of the inner intermediate race (34 mm), which is also the outer diameter of the curved plates; d external diameter of the internal plates after molding them into an insert in the intermediate cage (24 mm); k - final (specified) density on the inner surface of the plates after molding them into the liner. Substituting the values ​​into the formula, we get: 950 x 34 k x 24 k = = 1345.83 1346 kg/m 3. After that, the liners, pressed into intermediate clips 7, were dried in molten ceresin according to known conditions until moisture was completely removed (Fig. 6), impregnated under pressure with the same melt and finally pressed using an auxiliary cone 8 into steel housings 9 with a given interference along the contact surface . Example 2. From blocks of natural ash wood with a density of 800 kg/m 3 and a moisture content of 10%, end plates of 5 mm thickness, 10.5-11.0 mm wide, 60 mm high, in the amount of 8 pieces were cut and they were installed in limiting contour 2 with an internal diameter of 37 mm in the form of a closed polyhedron. After this, the plates, similar to example 1, were repressed using a cone-cylindrical receiver 4, 5, 6, first into the cylindrical part of the receiver 5 with an internal diameter of 32 mm, and then through cone 6 into an intermediate cage 7 with an internal diameter of 27 mm. In the cylindrical part of the receiver 5, the plates are closed to each other by half their thickness (Fig. 3). The density on the inner surface in this case increased to 1163 kg/m 3, and after pressing the plates into the intermediate cage 7, the plates completely closed (Fig. 4) without any destruction. Their density on the inner surface reached 1270 kg/m3. All other operations are similar and described in the first example. Forming end rectangular plates into bushings or liners in two stages ensures a significant reduction in rejects due to the fact that during the first stage the compression of the plates on the inner surface does not occur immediately to the maximum density (1350 kg/m 3), but to medium density 1100-1250 kg/m3, at the same time the density is outer surface plates remains unchanged (800-1000 kg/m3). The bending of the plates at the moment of passage through the conical part of the receiver into the cylindrical part occurs insignificantly, i.e. up to half their thickness. However, after this they significantly increase their strength on the inner surface and acquire a more rigid structure, which more easily withstands further compression of the plates to the maximum possible density of 1350 kg/m 3 and their repeated bending without any damage or cracks when pressed into the intermediate cage. An important role in implementing this method is played by the initial moisture content of the end plates, which should be in the range of 8-12%. At the same time, the moisture content of the plates has good elasticity and flexibility. Plates with a moisture content below 8% are noticeably brittle and are destroyed when they are pressed in at the first stage. Although plates with a moisture content of more than 12% have high elasticity, they shrink greatly and warp significantly. The use of wood with a density below 800 kg/m3 as a starting material also negatively affects the quality of finished products due to the large difference in density on the outside and internal surfaces liners or bushings. In the mass production of sliding bearings, the plates are pre-glued onto gummed paper tape, which is then cut into bags of a certain length and thus quickly and accurately place the bag in the restrictive contour 2. The production of pilot batches of sliding bearings with wood inserts using the proposed method showed that defects finished products are reduced from 25-30% to known method up to 5-10% Bearings manufactured according to new technology, have undergone successful production tests at a number of enterprises in the electrical, electronic, radio engineering industries, etc. in highly precise precision equipment instead of steel ball and bronze guides. In terms of wear resistance, such bearings are superior to steel, bronze, and plastic, both when operating in normal conditions, and in aqueous, abrasive and dusty environments. In addition, they can operate for a long time using self-lubrication.

Claim

1. A method for producing sliding bearings with inserts made of wood, including cutting rectangular plates and molding them into inserts using a receiver and intermediate cages, drying and impregnation with anti-friction lubricants, followed by final pressing into the bearing housing, characterized in that the molding of the plates is carried out in two stages using a cone-cylindrical receiver, first to a degree of compression to half their thickness, then until they come into complete contact. 2. The method according to claim 1, characterized in that the humidity of the initial plates is 8-12% and molding is carried out until the density of the liners in the intermediate cage is no more than 1350 kg/m 3 on the inner surface and no less than 800 kg/m 3 on the outer surface. 3. A device for producing sliding bearings with inserts made of wood, including a limiting contour, a conical receiver and an intermediate cage, characterized in that the conical receiver is made stepped, consisting of two conical and one cylindrical parts, each of which is equal to the height of the original plate, while the diameter of the cylindrical part of the receiver is less than the diameter of the limiting contour by the thickness of the plate, and the diameter of the exiting conical hole and the diameter of the intermediate cage are less than the diameter of the limiting contour by two thicknesses of the plate.

Stacked wood-polymer plain bearing

wood in such an installation is made twice as dense, three times stronger, four times harder!

There is another interesting option machines for impregnation and pressing of wood (see figure). To reduce friction forces, rotating rollers are installed around the perimeter of the channel inlet, the axis of which is perpendicular to the action of friction forces.

Of course, it is difficult to imagine that a “piece of wood” can replace a bearing with hardened steel balls rolling along a precisely ground treadmill. But this is true. Let's take, for example, conveyors transporting ore, molding soil, foundry waste - in a word, very abrasive bulk materials. They mix with industrial dust, lubricating oil, vapors of process fluids and form a “paste”, which can be nothing more dangerous for rolling bearings, these aristocrats of mechanical engineering. Such an abrasive paste even penetrates through the seals of bearing units and, like sandpaper, abrades the running grooves of the bearings, or even completely, becoming hard and monolithic, jams the balls. At least two or three times a year, conveyor belts have to be stopped and rollers replaced. But wooden bearings, as tests have shown, can withstand a year to a year and a half without replacement. And the roller itself, equipped with them, costs 3-4 rubles less, since there is several kilograms less metal in it. And according to engineering estimates, 5 million rollers are needed per year - just for replacement!

Even greater benefits are provided by large-sized wooden bearings - those in which, for example, augers with the diameter of a carriage wheel rotate, transporting cement in concrete plants. The loads on the bearings are so great and the cement so abrasive that the metal plain bearings have to be replaced every two days.

three months, stopping production. And wooden bearings last here for more than a year!

Wooden bearings in machines for producing artificial fiber last twice as long as metal bearings, although they “bathe” in hot alkalis and acids. Modified wood simply does not react with these metal enemies.

The technology and equipment developed at the Institute of Mechanics of Metal-Polymer Systems makes it possible to produce compacted modified wood not only for bearings. Bushings for auxiliary mechanisms of rolling mills, flanges, covers, levers, pulleys of metal-cutting machines, parts of mine cars and hoisting and transport machines, parts and assemblies electric forklifts, forage harvesters, sleeper tamping machines and subway cars - these are far from full list mechanical engineering parts made of wood.

In construction, wood also seemed to be losing ground. Brick, reinforced concrete, aluminum - what can be opposed to them? But in Lately inventions and developments have appeared that make it possible to assess the prospects of wood in a different, much more optimistic way in this area.

Let's think about it, we spend almost half of all harvested wood on repairs, restoration and replacement of wood cracked by the sun, swollen by water, corroded by insects and simply rotten. wooden structures and structures. A quarter of all wood harvested per year is used for parts of windows and doors, skirting boards, stadium stands, garden benches, country houses. We paint them, often varnish them, but time passes and we throw our forest, our work, into a landfill. Wood processed according to the method proposed by Moscow inventors is a different matter. A vertical pipe is mounted into the bottom of the bath with molten tin, through which compressed air. The upper cut of the pipe is located just below the melt level, so a wave appears on the surface, which washes the processed wooden parts. The hot wave makes the surface of the wood absolutely smooth and reveals the texture. The temperature of the molten metal is almost 232°C, and the wood is not charred, since the process takes place without access to air, but it acquires decorative, antiseptic and other beneficial features. The workpiece passes quickly through the wave - it turns out golden, at medium speed - brown, slowly - black, like bog oak. Regular construction details- skirting boards, window frames, window sills - acquire a sum of new valuable qualities in this font.

The Belarusian Institute of Technology has developed a technology that allows you to make stained oak from freshly cut oak in just a minute! A sheet is placed at the bottom of the steel mold

light oak veneer, coat it with resin, add a layer of birch sawdust, cover the whole thing with a second sheet of veneer and, finally, a polished sheet of stainless steel. The mold is placed under a press and heated to 200°C. At a pressure of 200-250 atm, birch sawdust “let out the sap.” Part of the sap penetrates through the gaps between the walls and the lid of the mold, solidifies, seals it and turns it into a kind of chemical reactor, where hydrolysis occurs sawdust, sugars are formed, acetic, oxalic and other acids, furfural are released. In the presence of acids, a binding resin is formed, holding the sawdust together into a monolithic, strong and hard slab, lined with oak veneer. Simultaneously with this process, diffusion of hydrolysis products occurs into both the oak veneers and they darken. After about a minute, the bog oak is pulled out of the mold, no less beautiful and durable than one that has lain in water, as it should be, for more than a century.

But the giant hyperboloid of the cooling tower - wooden structure for cooling waste water at thermal power plants. This wooden skyscraper has not been in operation for three years, but has already lost a third of its mass. Hot water washed resinous and minerals. Another year or two, and the cooling tower will have to be stopped for repairs, hundreds of cubic meters of first-class timber will have to be spent... Or - forty meters -

Design of an installation for compacting and modifying wood in an ultrasonic field: 1 - casing, 2 - workpiece in the contour compaction zone, 3 - magnetostrictive plates, 4 - rubber gaskets, 5 - waveguide, 6 - impregnation zone.

1. GOALS AND OBJECTIVES.
The main purpose of this article is detailed description handmade manufacturing process cutting tool from bearing races according to Viktor Ivanovich’s method. A description of this method is available on the forum in the topic “My favorite homemade instrument“, in this article, based on the available material, I decided to show the production of flat collectors of various widths.

2. SOURCE MATERIALS AND TOOLS.
As starting materials Bearing races with outer diameters of 95, 65 and 65 mm were used, their width was 25, 12 and 7 mm, respectively; in the following text I will call them 1, 2 and 3. The dimensions given here may differ slightly from the true ones, since measurements must be taken immediately I didn’t bother, and then to determine the diameters I had to “draw and trace” circles, but if I was wrong, it wasn’t by much.
The largest clip (number 1) was especially noteworthy; it had a strictly rectangular cross-section. Probably the bearing was a roller bearing, and the rollers had a slight taper. Next in the photo you will see a shiny stripe work surface, along which they, the rollers, “ran.” Both other bearings were conventional single row ball bearings.
The tools used were: emery (sharpener), drilling machine, gas torch, pliers, hammer, coarse file, sandpaper (sandpaper), cylindrical cutter (?), vice.

3. PROGRESS OF WORK.
The essence of the method is to attach part of the bearing race a certain shape with subsequent “unforging - straightening” of the so-called shank while maintaining the factory hardening of the working part. How bent! In other words, the clip must first be cut, then the future shank must be turned and by heating it red-hot, hammer it into the required straight shape at the desired angle to the blade. When heated, the future blade should be in a tin can with wet sand so as not to lose its hardening. Photo 1 shows a diagram of the “cutting” of the bearing race.
Photo 1.

As shown in the diagram, the clip must be cut in two places. In this case, the number of blanks obtained from one holder depends on its size. From clips 1 and 3 we got two blanks each, and from clip 2 only one. All three clips were cut on the edge of the grinding wheel. The first “cut” was performed gently, with frequent cooling and not completely. And with the second, the frequency of cooling was to ensure comfort for the hands and only... The goal was to save time. After this, the clip was carefully clamped in a vice through aluminum or wooden jaws and broken even more carefully. BEWARE OF FRAGMENTS! The resulting pieces were naturally fried on one side. It was from this fried side that the shank was turned.

Photo 2.

Photo 3.

Photo 4.

Large blanks from holder 1 were given a wedge-shaped shape, photo 3. This will increase the “maneuverability” of the future tool and facilitate the process of straightening or “forging-bending” the shank. To carry out this process, as already reported above, a jar of wet sand, a gas burner and pliers were used, photo 5.

Photo 5.

The results of the process are presented in photos 6, 7 and 8.

Photo 6.

Photo 7.

Photo 8.

A total of five blanks were obtained, three of which had an internal groove. Since the goal of this work was to obtain flat collectors, we need to get rid of these grooves. The process of “disposal - withdrawal” was carried out using a cylindrical cutter Ø 16 mm and height 24 mm and drilling machine, Photos 9 and 10.

Photo 9.

Photo 10.

As it turned out, this is quite a labor-intensive task. It took more than 3 hours to remove the groove of the workpiece from holder 2 (width 12 mm). And it took about an hour to make two blanks from clip 3 (width 7 mm). In all of the above cases, it was not possible to completely remove the groove at the very tip of the future blade; the missing ends had to be cut off, photo 11. The temperature of the workpieces being processed was controlled “manually”, cooling was frequent.

Photo 11.

So, the blade blanks are ready. Now it's time to think about pens. In this story I wanted to give them Special attention. Lately I've been making handles with safety metal rings, I like it better. I won’t argue that a blade glued to epoxy will serve for a long time and reliably until the very end, but you will agree, comrades, that the ring gives the chisel a more “aesthetic” appearance. It to some extent protects the handle from accidental “knocks” on the stone when sharpening or straightening, and plus a general increase in strength .
So, the rings, I made them from the inner races of the bearings, turning them on a grinder along the entire outer surface into a cone. In order for the turning process to proceed accurately and the surface of the ring to be ground evenly, it is necessary to select a suitable mandrel. A simple bolt was usually used as a mandrel, but its diameter should be close to the inner diameter of the ring so that it rotates freely on it, but without “bumpiness”, Photo 12.

Photo 12.

Photo 13.

During the turning process, the ring rotates on a mandrel so that it does not “run away”; it must be held with something, but not with your hands. In photo 13, in the left hand there is a bolt with a mandrel, and in the right hand there is a short rod flattened at the end (a screwdriver would also work), limiting the movement of the ring. It is necessary to sharpen until the central groove completely disappears. When working, STRICTLY MONITOR THE GAP between the stone and the sharpener stop! Photo 14 shows the final result.

Photo 14.

The material for handles was usually various elements“recycled” furniture, most often legs from chairs and cabinets. Material: oak, beech and some kind of mahogany. In the state At one time, this stuff could be found in large quantities in institutions, the main thing is that the household did not object to the transformation of the living space into a storage area. Photo 15 shows former leg from the closet. Marked on the end surface inner diameter push-on ring. We process the “seating” area with a file evenly on all sides with a slight taper, the main thing is not to overdo it. The ring should fit snugly enough.

Photo 15.

Photo 16.

Then, using a vice as a screw press, we finally put on the ring, act carefully without sudden movements, Photo 16. The ring should move evenly without distortions. In this case, it is allowed to grind the seating surface not to the entire depth of the ring, the main thing is that there is no gap between it bottom edge and the surface of the wood. All the same, when gluing the blade, the end surface will be flooded with epoxy. By the way, beech, according to my observations, during the “pressing” procedure behaves more plastically than oak or mahogany, which allows you to press the ring deeper and remove possible cracks caused by uneven grooves. After processing with a file, the result looked something like in photo 17.

Photo 17.

Thus, each blade had its own handle; as a rule, their length did not exceed 110 mm. Each handle had a hole drilled for its own shank. And, naturally, the “pasting” operation was carried out.
When gluing large blades obtained from clip 1, foreign epoxy was used adhesive composition DoneDeaL DD6573, and in other cases our classic EAF. I didn’t like the foreign glue, despite the convenience of dosing - there are two syringes with one piston. It separated too easily from the walls of the metal (!) container in which I mixed it. Time will tell how it will work... The results of my labors, after giving the handles their final shape using a file and sandpaper, are shown in photos 18 and 19. Here are 4 of 5 future collections, the photo of one wide one has not survived, sorry...

Photo 18.

Photo 19.

To finalize the handles, I decided to use the method described on the pages of this site by Viktor Ivanovich, namely firing ().
The result made me think about the frailty of everything in this world, photo 20.

Photo 20.

As you can see in the photo, significant cracks appeared on the handles. Until this moment, such a misfortune had never happened to me, and I had already burned more than twenty of them, and the processed handles were made of different types of wood and had different thickness. Here, out of four handles fired at a time, three cracked (the handles of two wide chisels from clip 1 were fired separately and without “adventures”, and the lower chisel in Photo 20 relates to the topic only regarding firing, the handle of a 12 mm chisel from clip 2 was the only one "survivor")
Reflecting on the cause of the trouble that befell me, I came to the conclusion that the firing mode was most likely to blame. Gas-burner clogged, and the flame was much smaller than last time (this is a fact). I'll have to check it out sometime...
After some thought, I decided not to redo the handles; the pasting turned out to be quite reliable. Photo 21 shows the final results after sanding and polishing the handles.

Photo 21.

I understand that for most of the audience it is most interesting practical use of this instrument. Well, comrades, I will try to cover this topic over time. Thank you for your attention.

The main shaft of the Project 636 boat rotates not on metal bearings, but on... wooden bushings made from special durable wood lignum vitae.

Backout - valuable wood trees of the genus Guaiacum. This wood was used in the past where its strength, weight and hardness were extremely important. All species of this genus are currently listed in Appendix II of CITES as potentially endangered species. Buckout is obtained mainly from Guaiacum officinale and Guaiacum sanctum, both of which are small, slow-growing trees.

In English and other European languages, the phrase lignum vitae is often used to refer to this wood, which means Latin"tree of life", and comes from her medical use: The tree's resin has been used to treat a range of ailments from coughs to arthritis; the shavings can be used to brew tea. Other names are palo santo (Spanish holy tree), greenheart (English green heart) and ironwood (one of many).

It is a hard, dense and stable wood, the heaviest one sold on the market, and sinks easily in water. The density of wood ranges from 1.1 to 1.4 grams per cubic centimeter. Backout hardness on the Janka scale, which measures the hardness of wood, is 4500 (for comparison: hickory - 1820, red oak - 1290, pine - 1225). Heartwood green with red and black streaks, which is where the English common name greenheart comes from. In shipbuilding, luxury furniture, and woodworking, the term greenheart is used to refer to the green heartwood of the Chlorocardium rodiei tree.

Watchmaker John Garrison used backout for the most stressed parts of his watches, which were made entirely of wood, since this wood produces a natural lubricant in the form of non-drying oil.

For the same reason, this wood was widely used for wheel hubs and bearings, e.g. propeller shafts. According to the San Francisco Maritime National Park Association website, the propeller bearings of the World War II submarine USS Pampanito (SS-383) were assembled from this wood. Turbine bearings for the Conowingo hydroelectric power plant on the Susquehanna River were also made from this wood.

One of the tallest free-standing wooden Christian churches in the world is built from bakout wood - St. George's Cathedral in Georgetown, Guyana.

On the Project 636 Varshavyanka submarine, the main shaft rotates along wooden guides made of this wood. Natural lubrication allocated by the tree allows you to use this technology within 20 years