How to bend a wooden board at home. How to bend a wooden beam. Gluing with simultaneous bending

Bending wood using steam. Or how to bend strong, unbending oak into the shape you need without any problems.

I have been working with flexible wood for 13 years now and during this time I have built many steaming chambers and tested them in action. different systems steam generation. What you are reading now is based on reading literature and personal practical experience. Even mostly from experience. I usually worked with oak and mahogany (mahogany). I had to deal a little with thin birch veneer. I haven’t tried other breeds because I build and repair boats. Therefore, I cannot judge with authority the work with other species such as cedar, pine, poplar, etc. And since I haven’t done this myself, I can’t judge it. I write here only about what I experienced personally, and not just what I read in a book.

After this introduction, let's get down to business...

To begin with, there are a few basic rules that are always followed.

By steaming wood to bend it, you soften the hemicellulose. Cellulose is a polymer that behaves like thermoplastic resins. (Thanks to John MacKenzie for the last two suggestions).

To do this, you need heat and steam at the same time. I know that in Asia people bend wood over a fire, but that wood is definitely quite wet - usually freshly cut. Shipbuilders in ancient Scandinavia prepared hull materials for their ships and placed them in a saltwater swamp so that they would remain flexible until they were ready for use. However, we are not always able to obtain freshly harvested wood for these purposes, and excellent results can be achieved by using conventional air-dried wood. It would be very good if, a few days before the operation itself, you immerse the workpieces in water so that they gain moisture - those Vikings knew what they were doing. You need warmth and you need moisture.

The main rule concerns steaming time: one hour for every inch of wood thickness.

As I discovered, along with the probability of understeaming the workpiece, there is also the probability of oversteaming it. If you hovered an inch board for an hour and when you tried to bend it, it cracked, do not conclude that the time was not enough. There are other influencing factors that explain this, but we'll get to those later. Steaming the same workpiece for a longer time will not give a positive result. In such a situation, it’s a good idea to have a workpiece of the same thickness as that intended for bending and which you don’t mind. Preferably from the same board. They need to be steamed together and after the presumably required time, take out a test sample and try to bend it into shape. If it cracks, then let the main workpiece steam for another ten minutes. But no more.

Wood:

Usually, the best option it will if you can find freshly cut wood. I understand that the cabinet makers will shudder at these words. But the fact remains that fresh wood bends better than dry wood. I can take a two meter inch board from white oak, clamp one end of it in a workbench and bend it along any curvature I need - fresh wood is so pliable. However, naturally, it will not remain in this state and you will still have to float it.

In shipbuilding, the main evil is rot. If you are concerned about this issue, then please note that the very fact of steaming fresh wood eliminates its tendency to rot. Therefore, you don’t have to worry - the frames of boats are usually made from fresh steam-bent oak and do not rot if it is taken care of. This also means that in this way it is possible to make at least blanks for the Windsor Chair. However, I also worked a lot with air-dried oak and the result was also excellent.

When selecting wood for bending, one thing to avoid is cross-layering. When trying to bend such a workpiece may burst.

Therefore, regarding wood moisture content, the rules are as follows:

• Fresh wood is best.
• Air-dried wood is a second good option.
• Wood after drying is the third and very far from the first two option.

If all you have is from the dryer and you can’t get anything else - well, then you have no choice. I dealt with this too. But still, if you can get air-dried wood, it will be much better. Just last week I bent 20mm thick walnut boards for the transom of my yacht. The blanks were dried for several years and their bending went completely smoothly.

Steaming chambers.

It is absolutely useless, and even harmful for the bending result, to strive to make an absolutely sealed chamber. The steam must leave it. If you do not provide steam flow through the chamber, you will not be able to bend the workpiece and the result will be as if you steamed it for only five minutes. After all my experiences, this is familiar to me.

Cameras can be the most different forms and sizes. It should be large enough so that the workpiece seems to be suspended and steam flows around all sides of it. A good result will come from pine boards with a cross section of about 50 x 200. One way to ensure that the workpiece is “suspended” is to drill through holes in the side walls of the chamber and drive round wooden rods from hardwood. With their help, the workpiece will not touch the bottom and the area of ​​​​closed wood will be minimal. However, you should not make the chamber so large that the amount of steam generated is not enough to fill its volume. The chamber should be such that it is humid inside and the steam rolls in waves. This means that the dimensions of the chamber must correspond to the capabilities of the steam generator (or vice versa).

When I needed to bend a five-meter mahogany board with a cross-section of about 200 x 20 for the new deckhouse of my yacht, I made a chamber from pine boards with a cross-section of 50 x 300. A 20-liter metal tank acted as a steam generator. The energy source was a propane torch. The thing is absolutely wonderful because it is convenient and mobile. Capacity 45000 BTU (1 BTU ~ 1 kJ). This is an aluminum cylinder with three legs and one burner with a diameter of 200 mm.

I recently found a 160,000 BTU propane burner in the West Marine catalog for $50 and purchased that as well. With its help I can bend frames even for "Constitution".

When I say one hour of steaming per inch of thickness, I mean one hour of SERIOUS CONTINUOUS steaming. Therefore, the boiler must be designed to provide steam for the required time. I used a new 20-liter fuel container for these purposes. You can put workpieces into the chamber only when the installation has reached full power and the chamber is completely filled with steam. We must absolutely ensure that the water does not run out prematurely. If this happens and you have to add water, it is better to give it up. Adding cold water will slow down steam generation.

One way to make the most of the water is to position the chamber at a slight angle so that the condensed water inside flows back into the boiler. But at the same time, it is necessary that the fitting through which the steam enters inside is closer to the far wall. Another way is to do siphon system, ensuring that its level is replenished as the water boils away.

Here's what a photo of such a system looks like:

In the picture you see a wooden camera located slightly at an angle. Directly below it is the steam generator boiler. They are connected to each other via a hose from the radiator. If you look closely, you can see an L-shaped pipe coming out of the base of the boiler on the left. It’s hard to see in the photo, but its vertical part is actually translucent and this way we will know about the water level inside the boiler. To the left of the boiler you can see a white bucket containing water for make-up. Take a closer look and you will notice a brown tube connecting the bucket to the vertical part of the pipe - the level gauge. Since the bucket is located on a hill, a siphon effect is observed: as the water level in the main boiler drops, water enters it from the bucket. You can add it from time to time, but do this extremely carefully so that it does not rush quickly into the boiler and cool it too much.

To minimize the need to add water during the steaming process, it is better to start work with a bucket filled to the top. I myself prefer to leave a small air gap in the boiler.

Many chambers have a door at the end through which workpieces can be moved if necessary and removed if necessary. For example, if you are engaged in the manufacture of bent frames and you would like to complete this as much as possible in a day, you melt the boiler and (when reaching full power) put the first workpiece inside. After 15 minutes, add the second one. After another 15 - the third and so on. When it's time for the first one, you take it out and bend it. I'm assuming this procedure will take less than 15 minutes. When she sits still, the second one is already on the way... etc. This allows you to get a lot of work done and avoid over-steaming.

The door has another important function. It doesn't even have to be made of hard material - on my small camera, just a hanging rag serves for this purpose. I say "hanging" because the steam must emanate outward from the end (since a stream of steam is needed). We must not allow what will happen in the cell overpressure, making it difficult for steam to enter. And besides, the picture itself wooden box, from which steam pours out in clouds, looks quite cool - passers-by are simply dumbfounded. The second purpose of the door is to prevent cold air from entering the chamber from below the workpieces.

So, we will assume that our wood is boiling (with a pleasant smell) and the templates are ready. Try to organize everything in such a way that the operation of removing the workpiece from the chamber and bending it goes quickly and smoothly. Time is of the essence here. You have only a few seconds to do this. As soon as wood is ready, quickly take it out and immediately bend it. As fast as human dexterity allows. If pressing to the template takes time, just bend by hand (if possible). For the frames of my yacht (which have a double curvature), I took the blanks out of the chamber, stuck one end into the clamp and bent this end and then the other just by hand. Try to provide more bend than is necessary for the template, but not much. And only then attach it to the template.

But I repeat once again - the wood must be given curvature immediately - within the first five seconds. With every second the wood cools, it becomes less pliable.

The length of the blanks and the curvature at the ends.

It is practically impossible to produce blanks of exact length and expect to be able to achieve a bend at the ends. You simply don't have the strength to do it. For this reason, if you need a piece one meter long, but its thickness is more than 6 mm, you are better off cutting a piece about two meters long and bending it. I'm just going by the assumption that you're not in the workshop. hydraulic press- I definitely don’t have one myself. When cutting out a workpiece with a margin, remember that the shorter it is, the more difficult it will be to bend.
And if it is with a reserve, then the end of the real part will have a large curvature - with an inch oak board, the last 150 mm are absolutely straight. Depending on the radius required at the end, it may be necessary to resort to wood carving in such areas and to take into account the required thickness when choosing the material.

Templates.

After steaming the workpiece and clamping it onto the template, you must wait a day for complete cooling. When the clamps are removed from the workpiece, it straightens somewhat. The extent of this depends on the structure and type of wood - it is difficult to say in advance. If the workpiece already has some natural bend in the desired direction, which can be taken advantage of (I try to do so whenever possible), the degree of straightening will be less. Therefore, if you require a certain curvature in the final product, the template must have more curvature.

How much bigger?

Here we are dealing with pure black magic and I personally cannot give you any numbers. One thing I know for sure: it is incomparably easier to straighten an excessively bent workpiece than to bend a cold, unbent one (provided that you do not have a giant lever).

Warning. If you bend workpieces for lamination, the template must be exactly the shape of the workpiece in the laminate - I have rarely had cases of large bending of well-bent laminated wood.

Exists infinite set options for bending templates. And it doesn’t matter at all which one you choose if you happen to be the owner of a clamp factory - you can never have too many of them. If wood with a thickness of more than 12 mm is bent, the template must have significant mechanical strength - it will experience quite high loads. You can see what it looks like in the photo at the beginning of the article.
Quite often, when bending, people use a metal strip on the outside of the bend. This helps to evenly distribute stress along the length of the workpiece and avoid cracks. This is especially true if the outside fibers are located at an angle to the surface.

Well, that’s probably all my thoughts for now.

Traditionally, Advent wreaths appear in homes in the run-up to Christmas. Most often they decorate doors and fireplaces, and any interior is filled with anticipation of the holiday. You can also decorate with a wreath on a satin ribbon large mirror in a wide frame, attach to a cornice and decorate curtains, or even use it to decorate a Christmas table by placing candles inside the wreath.

I have already talked many times about how you can doChristmas wreath with my own hands, because this topic is relevant for me - there are no Christmas trees here. And that’s why the wreath is a real lifesaver.

So today I will tell you how to make a Christmas wreath from twigs. Make one like this wreath very simple. It does not require any special decorations. All necessary elements can be found in the park while walking. The basis of the Christmas wreath is flexible birch branches, and the decoration is various cones, nuts, and twigs. These branches are thin, flexible, roll well into a circle and do not break. Additionally, you can decorate with small Christmas balls for contrast.

So, let's go to the park (or forest) and collect branches. You can collect everything “that is bad”: birch, willow, any shrubs and trees even unknown to you: o). Of course, you don’t need to pick a bush clean, a couple of branches from one tree and to the next. We love nature! Take branches that are not thick, but not too thin.

Before you start creating, you need to keep in mind that cut rods dry out quite quickly and become unplastic, so if you decide to make a wreath with your own hands, you should not put it off for long.
At home, we collect all the branches into one neat bundle and tie them up. We place our creation in the bathtub or wherever you don’t mind (what if you have a gold-plated bathtub: o), fill hot water. And let's go have tea... For about an hour.

After this you need to twist the wreath. There are several options here:

Method 1. Make a wire frame and wrap it with rods. However, we still need to find the wire :o)

Method 2. If you did not pre-soak the branches, then before forming a circle from the twigs, each branch must be bent over every 5 cm, otherwise it may break during work.

We form a circle from one long branch.

Then, holding the woven ends of the first branch and the beginning of the second in one hand, we braid the first circle with the other. And so on, branch by branch. Gradually the branches begin to hold on to each other.

After the branches are all twisted, take water-based paint(for example, matte for interior works, almost no smell and dries quickly) or acrylic paint. When painting the wreath, use a dry brush with a small amount of paint on the tip.

We cover our wreath with paint. Let it dry. Then, for added beauty, we spray it with gold paint from a spray can (in hardware store sold or in a car).

That's it - the hardest part is over! You can decorate the finished wreath with satin ribbons, beads, Christmas decorations, bells, felt figures, birds, decorative flowers and even gingerbread cookies.

You can hang it from ribbons from the ceiling (if you have something to tie it to), on a nail to the wall or on the door.

The wreath, of course, doesn’t have to be painted.

Method 3. And if you also managed to collect pine cones in the forest, then you can decorate a wreath like this in an interesting way.

For this we need: birch branches; various buds: Pine cones, larch cones (you can also use medium-sized spruce cones, acorns), walnuts, dried cracker branches ; glue gun or some silicone glue in a tube; silver paint in a cylinder; small Christmas balls; satin ribbon; two bells.
The cones must be dried on a radiator so that they open.

Take several branches, form a circle and tie their ends. We fold the birch branches into a bunch, such a thickness that the bunch is completely covered by the palm. We fasten the bundle in the middle with a strong thread. Then we fasten again after 10-15 cm - and so on in a circle. At the end, we overlap the branches over each other and fasten them with thread.
Wind the remaining branches from above. Those. wrap around an already made frame of branches in a circle. We tuck the ends into the branches themselves (like the end of a thread in a ball). It turns out like this rim from birch branches.

We distribute decorative elements based on the basis and compose a composition. There is no need to glue it yet, as you may want to change the order decorative ornaments

Once you are finally sure that the composition is finished, you can start gluing.

One of the ways to process carpentry blanks is bending. Treated with hot steam wooden blanks are able to bend and retain their shape after drying. Such technological process is not particularly difficult, but some features of how to bend wood should be taken into account. You may also be interested in pine stairs, which you can order on the website http://mirdereva.ru/.

Wood fibers are held together by a special substance - lignin, which, under the influence high temperature softens, and after cooling again binds the fibers. The process of bending blanks is based on this. Please note that wood different breeds bendable in its own way. For bent products, it is best to use oak, beech, birch, yew, cherry, and elm. But pine, spruce, cedar, and alder should not be used for these purposes.

Work on bent parts begins with the choice of material. The workpieces must be straight-grained; the use of wood with curved fibers is not allowed. The prepared material is dried in natural conditions, under canopies, to a moisture content of no more than 20%. But artificially dried wood should not be used for bending, since it is less amenable to such processing. If you have to use such material, then before bending it must be soaked in water (at least a week). Soaking is also necessary for hard wood such as oak, ash, and beech.

To heat the workpieces before bending, it is best to use a steam chamber. It is easy to make such a camera at home using plastic pipe suitable sizes and regular kettle. The parts are placed in a pipe, and steam is supplied from the kettle. The exposure time in the chamber depends on the size of the part and is determined empirically. In this case, you can be guided by the fact that for 1 cm of the thickness of the workpiece, 30-40 minutes of steaming the wood are required.

In places of bending on parts, if the design of the product allows it, you can slightly reduce the thickness of the material and remove the chamfers. This will make the bending process easier. Thin workpieces, in the absence of a steam chamber, can be heated over an electric or gas stove.

Before you start bending wood, you need to prepare a form on which the part will be fixed, and clamps for fixation. It should be borne in mind that after heating the wood, there will be very little time to fix the workpiece, no more than 5 minutes. Therefore, everything needs to be done quickly, but if the part begins to cool, then it should be heated again. Otherwise, the workpiece may break.

Therefore, it is important to provide a design of molds and clamps that would allow the workpiece to be quickly fixed in in the right position. If the molds are made of wood, they should not be covered with any protective compounds, paint, varnish. Firstly, they deteriorate from heating, and secondly, they will interfere with the drying of the workpieces.

Short blanks are bent on mandrels of a larger radius, and then secured in a mold. This pre-bending reduces the likelihood that the part will break as the bend is formed. It is necessary to keep the parts in shape until completely dry so that they do not bend back. This usually takes 6 to 9 days and is determined empirically.

After freeing the workpiece from the clamps, it must be put aside for a day, and only then begin processing and finishing. This is necessary in order to relieve residual extension stresses. The tips are simple, but they will allow you to easily master the process of bending wood.

Often during the process repair work There is a need to obtain curved surfaces of products made from wood. How to bend a board so that the bend is strong and does not crack during the bending process? Well, if you have already decided to do major renovation with your own hands, then you should not retreat in the face of such difficulties. In this article we will talk in detail about how to give wood material curved shape.

How to bend a tree?

No, our task is not at all to bend an innocent plant. It's about about wood building materials. How to bend a tree so that it bends and does not break? Bending method wooden products known since ancient times: to give wood a shape, only heat and moisture are needed, under the influence of which the plasticity of the material increases with all the ensuing consequences. How to bend a tree? Hold it in hot water (the higher the temperature, the faster the processes occur) or steam ( a steam generator can be made from a kettle or use an iron). The higher the temperature, the faster the wood gives way and you can start bending it. Moistened and heated wood can be bent under the influence of a load (the ends of the board are placed on supports), and a load is placed in the place of the future bend. Dried wood perfectly retains the minimum radius of curvature that was achieved during the bending process. Now we know how to bend wood, we can dwell on this issue in more detail.

Wood reaction to external influences

The fact is that wood reacts differently to bending. The convex part is subject to tension, the concave part is subject to compression. Moreover, the material also reacts differently to steaming. For example, the ability to compress increases by as much as a third, but the ability to stretch - just a couple of percent. That’s why you shouldn’t think about how to bend a board more than two centimeters thick at home. It is also necessary to take into account that different types wood reacts differently to bending. For example, species such as oak, larch, and maple bend poorly, but beech, ash, and walnut bend well. So before you think about how to bend the board, decide on the type of wood from which it is made.

How to bend plywood, fiberboard, MDF

At home, plywood is bent by increasing its humidity, then ironing it (an iron is required), and fixing it in a template. Any template can be used frame element and it is not at all necessary that its shape should be curvilinear. The product is attached to the template using tape. You can clamp bent plywood between two spacers, give it a bent shape using ropes, tying them around the product in several places along the radius of curvature. Plywood can only be used after it has dried. It seems that we have figured out how to bend plywood - let's move on.

How to bend fiberboard? The technique is the same as in the previous case! How to bend MDF? In this case, you can go two ways: either bend thin sheets(no more than 5 mm) and glue them together, or use flexible MDF, in which there are transverse slots on one side. The thickness of such sheets is usually 8 mm. When bending, they are placed on top of each other with their milled sides, and then glued together. That's all!

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Instructions

For the manufacture of curved parts from wood, two main methods are used: sawing according to a template and bending pre-steamed wood using a template on special machine. The first method leads to cutting the fibers and reducing the strength of the parts. Bending provides a high percentage useful output details and significant strength. Bent parts can be finished with high quality and subject to various machining(profile, form spikes, eyes, etc.).

The ability of a wooden board to bend is determined by the plasticity of the wood and depends on the type of wood. Beech, birch, oak, pine and spruce have the greatest plasticity. But you can control the plastic properties of the workpiece by hydrolyzing it heat treatment.

At a temperature of 100°C and a humidity of 30%, part of the substances that make up the cells of the material goes into a gel state, while the cell walls and wood fibers become elastic and soft. This wood bends easily. After drying bent board retains its given shape as colloidal substances harden.

Processing the workpiece consists of boiling it in hot water or steaming it with saturated steam. low pressure. Steaming is more common, since with this treatment the wood is heated more evenly and the wood does not become excessively moistened.

When a board treated in this way is bent on a pattern or in a special clamping device, arise in the material internal stresses. Wood stretches on the convex side and contracts on the concave side. In the middle neutral layer the voltages are zero.

Outer layer under the influence of tensile stresses it will elongate, and the inner one will become shorter. The amount of deformation depends on the thickness of the dock and the bending radius. To limit the elongation of wood fibers and prevent them possible rupture, from the convex side bent part apply a special steel splint up to 2.5 mm thick. The workpiece is bent together with the tire. In this case, the neutral line extends towards the stretched fibers beyond the board, and bending occurs only due to compression.

When making a wide variety of joinery products, the craftsman often has to use curved parts. It is not always possible to obtain the required shape by sawing, since ensuring the strength of the material and its economy are important here. In such cases, it is necessary to bend the wood at different angles.

You will need

• - hot water;
• - open fire;
• - sample;
• - steel strip;
• - ammonia water.

Instructions

Use steaming or heat treatment for bending. If you stand it wood within several hours under the influence of high temperature and moisture, it is possible to change the plasticity of the material and bend the workpiece at the required angle.

Carefully select the ones you will subsequently bend. Use boards sawn lengthwise for this treatment. Avoid defective and twisted boards, as well as those workpieces that have knots. If you use materials with damaged fibers, the workpiece may crack at the location of the defect.

If the original workpiece is made of freshly cut material, heat it over an open fire or in closed oven. At the same time, do not allow the wood to dry out or become charred. To do this, it is enough to periodically moisten it generously. wood