It is believed that the castle "in dovetail"has maritime roots; the dovetail was used to fasten ships with a wooden hull. This connection turned out to be the most resistant to wet wood and multidirectional loads caused by rough seas. The main advantage of the technology is reliable docking wooden parts without the use of additional fasteners, the reliability of fastening is ensured by the original lock trapezoidal shape. The tools of ship carpenters included a special saw called a “dovetail.”

Traditionally in Rus', the crowns of a log house were placed “in a bowl”; such coupling was cut out with an ax. With the advent of good carpentry tools, the log house began to be laid “in the paw”, the connection had a rectangular tenon. A further improvement to this lock was the use of a dovetail tenon with a trapezoidal profile.

Dovetail technology for fastening beams has become the main one in industrial housing construction; standard sizes and connection features are determined by GOST 30974-2002. The introduction of the standard created favorable conditions for the development of low-rise housing construction, domestic wooden houses industrial production The quality is not inferior to Finnish samples.

The standard establishes the types of dovetail joinery:

Connection "in the paw";
Deaf “frying pan”;
Open “frying pan”;
Fastening with a trapezoidal key.

A distinctive feature of these types of fastenings is the tongue-and-groove design, which has a trapezoidal shape with a straight base.

Fastening the timber “into the paw” is the simplest way to build a log house; reliable grip is provided by a trapezoidal tenon, which is cut out at the end of each row of the crown. A properly made and assembled lock reliably secures the crowns of the log house in all planes. The fastening is universal, it is used for the construction of a log house from timber and rounded logs; the “claw” connection is most often used in shrinkage construction.

The design is distinguished by the absence of ends protruding beyond the corners of the building; such a lock is called a “clean corner”. The spike in this design is load-bearing element and bears the main load. To build a log house in a “clean corner”, it is recommended to use timber of the maximum standard sizes, with a side of at least 250 mm.

Making dovetail fasteners with your own hands is quite difficult; to avoid mistakes, use a full-size dovetail tenon template for timber; the sample can be cut from tin or thick paper. The template is applied to the end and outlined, the boundaries of the cuts are marked with a hammer and chisel. The cuts are made by hand circular saw. The easiest way is to make inclined cuts every 10-15 mm, press out the trim with an ax and clean it with a chisel.

The advantage of the technology is the ability to work with lumber natural humidity, in this case the tenon is made with an allowance of 5-7%. The allowance will lead to the formation of gaps between the crowns, which will be eliminated naturally during the shrinkage process.

Disadvantages and features of dovetail joints:

A “clean corner” has through gaps that can expand over time;
The log house does not have closed crowns, the masonry on each wall is shifted by half a beam, the structure must be reinforced with dowels;
The corners of the building have an unpresentable appearance and do not decorate the facade;
The developer is limited in choosing the standard size of lumber.

According to the technology, a dovetail log house is built country houses economy class, bathhouses and outbuildings, such construction is low-cost and accessible to mass developers.

Blind frying pan

This method in construction practice makes it possible to fully use the advantages of trapezoidal fastening; a special feature is the hidden T-shaped groove-tenon connection. The size of the tenon does not exceed half a beam and is completely recessed into the body of the beam. The corner of the house assembled using this technology was called “ warm corner" The lock provides reliable grip into the crown without through gaps during processing construction sealant creates a completely sealed space. The beam is built up in the same way if its length is less than the length of the wall.

Sawing of the profile is carried out according to the drawing using a circular and axing saw. A rectangular blank for a tenon and groove is cut out using a circular saw, and the given shape is given with a special hand saw. You can use a hand cutter to cut the groove, workplace easy to equip yourself.

Advantages of the blind “frying pan” fastening technology:

Improved thermal insulation of the building;
You can use lumber of any size;
The castle is “hidden”, the facade takes on an attractive appearance;
During construction, you can use timber with a smaller profile;
Ensures economical use of building materials.

The main feature is the increased requirement for wood moisture content - lumber should have a moisture content of no more than 20%. The technology is widely used by manufacturers finished houses"turnkey".

Open frying pan

This method is used when constructing internal partitions from timber, laying floor joists and ceilings. The groove is cut across the entire width of the beam. The lock resembles a “claw” connection in the T-shaped version and ensures fixation of the structure in the horizontal plane. This mount is simple and can be cut with a circular saw and processed with a chisel.

A simplified version of a frying pan lock is a profile in the shape rectangular trapezoid, the fastener is called a half-frying pan. This fastening is designed for damper wood and is popular with individual developers.

Fastening with trapezoidal key

The dovetail connection scheme was further developed in a keyed connection. A butterfly key formed by two trapezoidal shapes is made from wood hard rocks. The groove is cut on modern milling machines. With a dovetail keyway, the fastening dimensions are minimized, but this design ensures reliable fastening of wooden structures of any complexity and allows the production of wood products to be streamlined.

Features of keyway technology:

Requires precise wood processing using modern technology and devices;
Minimizes resource and material consumption;
Maintains an attractive appearance of wood texture;
Allows you to make wooden structures of any complexity.

Dowel fastening is used by manufacturers of ready-made wooden houses made of expensive laminated veneer lumber and allows you to implement the most complex house designs.

Conclusion

Dovetail joints of timber in house construction are a reliable way of fastening wooden parts. With the advent of modern carpentry tools, this technology has become available for mass use. This type of fastening is widely used in interior design and the manufacture of small architectural forms. In a miniature version, such fasteners are used in furniture production.

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DOVE-TAIL JOINTS

Dovetail joints are not only visually attractive, but also very durable. The ability to cut such tenons correctly is a sign of skill that comes with experience.

When assembling furniture, fasteners are now widely used - screws, dowels, and various ties. However, tenon joints, including those on dovetail tenons, do not completely give up their positions. They are quite reliable and at the same time beautiful. On such connections it is possible to fasten, for example, side walls cabinet furniture with covers. It is not easy to break a dovetail joint by tension. Therefore, it is often used in the manufacture of drawers. But we should not forget that the dovetail connection is resistant to such a load only in one direction.

Chipboard parts are not suitable for dovetail joints: this material is too loose. To one degree or another, plywood, boards or furniture panels are suitable here.

Dovetail spike shape

If you look at the connection from above, you can clearly see that the “dovetails” are fan-shaped spikes at the end of one of the parts. The sides of the tenons are beveled inward with a slope ranging from 1:5 - for “rough” but strong connections used when joining parts made of soft wood and furniture panels, up to 1:8 - for parts made of hard wood. The connection on the latter looks more attractive. And you need to know that with a smaller slope, the connection may come apart under load, and with a larger slope, the tenons may break.

In the finished connection, the “teeth” that engage with the spikes are clearly visible. The slope of the spikes must exactly match the slope of the “teeth”.

The joint should always have “teeth” at the edges (not halves of tenons) -

this prevents bulging of the parts being connected.

Another factor influencing appearance connections, - the distance between the dovetails. In principle, the following rule applies: the wider the dovetails (spikes) or the greater the distance between them, the better. However, there is a limit to everything, besides, products come in different sizes (for example, a chest and a casket), and we should not forget about the strength of the connection.

Marking the studs

The preparation of parts begins with trimming (in this case, their thickness does not have to match), and then marking
position of the spines and “teeth”. It is better for a novice master to give a small (1-2 mm) allowance in length.

For marking, use a small marker. To adjust it to a stud angle, for example 1:6, draw two mutually perpendicular lines on paper and divide them from the intersection point into six equal parts. Connect the sixth mark on one line with the first mark on the other. The slope of the resulting diagonal will be equal to 1:6. Based on this sketch, the fry is displayed.

At both edges, parts with spikes mark the width of the outer “teeth” and draw lines parallel to the edges through these points. Further onto the part diagonally
Apply a tape measure or ruler and turn it until the size between the lines is divided without a remainder by the desired number of spikes. These points are marked on the diagonal, and then, using a thicknesser, they are transferred to the end of the part. As a result of these simple constructions, the positions of the centers of the spaces between the spikes were determined.

The same length is laid on both sides of the found centers (in our example - 3 mm). The distance between the ends of the segments will be equal to the minimum gap between the tenons. From these points, with the help of a small mark, the spikes themselves are finally marked. The height of the spikes is marked with a surface planer placed on a thick

the part with the “teeth”. Markings are made on both sides of the part.

If the part has an allowance in length, it should be taken into account when marking. In this case, the length of the spikes will be slightly longer than required. Later, when the parts are connected, the excess is removed with an end plane.

When marking, all parts with spikes are marked with some symbols to avoid confusion.

Tenon cutting

Special tenon saws are used to cut tenons and “teeth”. When using a regular fine-tooth saw to rip sawing it will need to be additionally prepared, in particular, to reduce the spread of the teeth (especially if the saw is new). To do this, the saw blade is placed with its entire surface on the whetstone and easily passed along it once or twice. The same thing is repeated, turning the canvas over to the other side.

When cutting dovetail tenons, the part is clamped in a vice. If there are two such parts (for example, the side walls of a drawer), tenons can be cut on both at once.

Start cutting along the marking lines by tilting the saw back and simultaneously guiding it with your thumbnail. When the cutting line is “caught”, the saw is leveled and work continues until the part is cut to the full height of the tenon (to the horizontal mark). Under no circumstances should you cross this mark.

Now you can remove the material between the cuts that form the tenons. This operation is performed with a chisel. Having selected the wood from one side to half the thickness of the part, it is turned over and processed in the same way on the other side.

Next, they begin cutting the “teeth”. The part with the “teeth” is clamped in a vice, the part with sawn tenons is placed on the end and fixed. Then the saw is inserted into the cuts and the end part of the part with the “teeth” is cut. Finally, the “teeth” are cut in the same way as the “dovetails”. And in this case, you should not cut along the marked line, but so that the saw teeth lightly touch it from the outside. Finally, the material between the “teeth” is removed with a chisel.

Before joining the parts, it is necessary to remove any possible irregularities and carefully chamfer the inner edge on both sides of each tenon (especially on the outer ones). This will make it easier to connect the parts, and finished product such a bevel will not be noticeable.

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FINGER CONNECTIONS

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Dovetail, detachable tenon joint (trapezoidal grooves), used in mechanical engineering and carpentry for reliable fastening of parts to each other. In this material we will consider the manufacture of devices that facilitate the production of grooves in wood using hand router.

DIY accessories for a wood router

The machine itself is a very ancient invention of mankind; descriptions of the principles of milling appeared in the 16th century, and the prototype of the machine was the invention of Leonardo da Vinci, who proposed rotating a round file to increase the processing of the product, which can be considered the first analogue of a milling cutter.

And already the American inventor Eli Whitney, over the years of his life from 1765 to 1825, brought to fruition all the scattered attempts to create a full-fledged machine, for which he is rightfully considered the creator of the first milling machine, although not all scientists agree with this statement.

And since the machine has such ancient roots, there are a great many adaptations for the manufacture of various parts, it is not possible to describe them all in the light of this material, and therefore we will consider only some of them, in my opinion, the most important and useful.

Universal device for tongue and groove connection

factory plate for making a tongue and groove connection

Used with a router to cut the corresponding grooves and tenons, it is installed in a vice and the part is pressed against the device with a clamp. Typically sold in stores.

connection appearance

Consider devices for milling grooves

Cut out the top part - a tabletop from 18 mm plywood, 40 cm long and sufficiently wide to process the thickest workpiece that you plan to join with a tenon.

Cut two 5x10 cm bars, sawing them to the same length as the top. The bars will subsequently play the role of pressing the workpiece and centering it relative to the groove in the tabletop. To prepare the top, draw a line down the center of the top, then rout a mortise along the line at one end.

schematic representation of equipment

Please note

The notch should be the same width as the copy ring you will use with your router bit. The notch should be long enough to match the length of the longest groove you will be cutting.

Then mill two adjustment slots perpendicular to the center line. Finally, drill an inspection hole between these two slots. To assemble the entire structure, screw the bolts into the jaws and secure the top to the bars with wing nuts and washers.

To use our equipment, draw a groove on the workpiece and mark the center line on it. Loosen the screws and place the workpieces between the bars so that the center line connects with the top line of the jig, making sure that the edge of the workpiece is opposite the edge of the top.

Pinch the lambs. Align the router bit to one end of the mortise drawing, then mark guide lines on the top surface of the table along the edge of the router base.

How to work correctly with tongue and groove equipment

Repeat this again to mark the lines of the other end. Route the slot by starting the cut at the bottom by aligning the router base with the first construction line, and stop routing when the insert reaches the second construction line.

Let's make a device for making spikes with our own hands

Product for making spikes

The wood and plywood jig shown above allows you to cut rectangular tenons with two shoulders. The object being processed is located with its front surface underneath the jig, while the router moves along the stop from above, removing excess material in two passes.

The piece consists of two parallel base bars, a stopper and a stop - all made from wood of the same thickness as the piece, in this case from 25x75mm bars, and a top surface and support made from 18mm plywood.

The base bars should be approximately 400 mm long; cut out the top surface of approximately 200 by 250 mm from plywood and screw it to the bars as shown in the figure. Screw the stopper onto the ends of the base bars along with the support. Place the stop approximately 25mm from the end of the top surface.

cut out the tenon using the device

Countersink holes for all screw heads and make sure all corners are square. Drill an inspection hole in the top surface to accurately position the workpiece exactly according to the markings.

Detachable fastening of parts using the dovetail method is carried out by installing a trapezoidal tenon, cut into the edges of the other element, into a groove located on one side of the workpiece. The type of connection of parts is used in many structures that require the creation of a rigid one-piece frame: small arms, furniture production, mechanical engineering, wooden capital construction.

After the drawing is drawn up, the dimensions of the dovetail are selected individually. The master begins to carry out preparatory operations, during which the bed and slide take part. The material used in the process of solving a problem with loaded nodes can be steel, cast iron, bronze. In other cases, connection types can be made of light non-ferrous metals and plastics. The surface of the product is processed with a profile cutter and finished with a scraper or polishing disc.

Before you make a dovetail with your own hands, you should create a drawing, the dimensions of which must withstand permissible operating loads. When making a cut, it is necessary to correctly select the angle of inclination of the sides of the trapezoid, the standard value of which is 45 0, 55 0 and 60 0. The connection according to the selected method is used in the system:

small arms canopy;
metalworking machine;
optical device;
“in the paw” and “squawk” in wooden housing construction.

The positive properties of the technology include high structural strength. The use of the method allows you to fasten elements without nails, screws, self-tapping screws and chops.

Application of the method with wood

The wooden tenon and fastening groove must have an identical shape and be connected into a tight, sealed unit. The dovetail connection, the drawing of which is intended for different products, helps to form T-shaped and corner fastenings of boards, beams or logs without overlaps in places where internal partitions are installed. Assembly technology wooden structures allows you to use for interior partitions building material smaller diameter. If protection from wind and drafts is necessary, the corner joints of the structure of a capital structure are sealed with jute fibers.

A classic example of the use of connecting elements is the drawer of a furniture set. The electric joinery equipment used in the construction of a tenon and groove system for a hand router allows interlacing of tenon elements using the natural resistance of the joint to the force applied to the face of the product during extension.

The connection, the drawing of which is drawn up for each item individually, can be made in different ways.

Most craftsmen working in furniture production and house construction prefer the method of end-to-end connection of joints due to the decorative nature of the repeating pattern. The elements are prepared on a milling machine using a special device.

Marking of connecting tenons

Preparing the material for connecting the tongue and groove with your own hands according to the template is carried out after marking the “tails” with a thicknesser, pencil or marker along the sides and edges of the part with sockets or partitions. The dimensions and number of elements depend on the type of material, the width of the board and the method of placing the tenons. To give decorative look connection lines, the spikes must have the same dimensions and be located at the same distance from each other.

Before starting work on the machine, the material is equipped with markings across the workpiece with a deviation of 6 mm from the edges. The remaining part of the board must be divided into an even number of tenons, measure 3 mm on each side of the marks, and draw a marking line perpendicular to the end. Using a stencil or chalkboard, draw the contours of the slope of the tenons for the dovetail joints.

Cutting trapezoidal tenons

To form the connecting elements, the box blank is placed in a vice so that one side of the tenons is vertical. On the side edge of each tenon, cuts are made that do not reach the line of the shoulders, the workpiece is reinstalled, and others are processed in a similar way. side faces. After this, the part is fixed horizontally, the side waste is cut off at the level of the shoulder pads. Excess wood between the tenons must be removed with an openwork saw.

Marking and sawing out the landing nest

To accurately mark the seat, the workpiece is placed on carpenter's table in a vice in a vertical position, the end of the board is rubbed with chalk to obtain an imprint on parts with already cut tenons. Using a special device, the edges, the line of the side shoulder pads are aligned with the shape of the tenons and the end of the workpieces with sockets.

After completion preparatory work you can begin to form grooves at the corners of the workpiece next to the shoulder line in accordance with the tenon markings. The cut, for which a tenon and groove cutter is used for a manual router, should be made in the waste part of the board so that the groove is parallel to the marking line. Excess wood between the partitions of the nest is removed with an openwork saw, and cleaned with a chisel or chisel with a beveled edge. The movement of the tool should be directed from the edges to the center.

Assembly of connecting joints

For the production of products whose parts are connected using the dovetail method, almost all types of wood, plywood, and plastic are used. A special feature of the method is its non-separable technology using fastening agents (wood glue). Accuracy check and fitting of parts is carried out after:

preliminary “dry” assembly of the final product;
removing excess material;
stripping or sanding tight areas.

The adhesive is applied to the contacting sides of two pieces of wood. To tightly connect the parts of the structure, a hammer and a wooden spacer are used, which protects the product from accidental damage.

After tapping the joint along the entire line, it is necessary to remove excess glue, the product is sent for drying, followed by cleaning with a jointer in the direction from the edge to the middle.

Shape and angle of cut

Standard bonding angles should not be sharp or obtuse. The large slope of the milling cut promotes the formation of short fibers in the corner part. Insufficient groove inclination reduces the strength of the connection between the elements. To solve the problem, experts recommend using bevel markings, templates or stencils. For hard wood, it is necessary to select the optimal cutting slope, which should be 1/8; for soft wood, the slope is milled to 1/6.

Decorative connection of elements

A carefully executed grooved dovetail can serve as an additional decoration for household and office furniture. Design options for furniture designs allow you to highlight the beauty of wood and appreciate the skill of a specialist. The selected type of product assembly corresponds to the standard design proportions.

A feature of the “dovetail” is the possibility of cutting a log or beam into half a tree in the shape of a trapezoid with angular fastening of parts. IN wood construction The method of connecting beams using the “root tenon” method is often used, when two elements are joined with a rectangular tenon and a groove of a similar shape. Cutting out parts for connection is carried out using a milling cutter according to drawings, diagrams and dimensions.

Wooden and veneered furniture, as well as other furniture assembled from individual structural elements made from solid wood, unfortunately, cannot last indefinitely. And this is quite understandable. In addition to natural aging and various “diseases” of wood, there are loose adhesive joints, traces of careless storage, unskilled repairs, restoration, and others. Furniture with weakened strength is most often received for restoration. structural connections individual elements, in particular tenon joints.

1.1. Strengthening socket-tenon and dovetail joints

It should be noted that over the past two centuries, furniture has been assembled using various tenon joints. The most commonly used joints were socket-tenon joints or similar hidden joints that used wooden dowels (rods). Such joints hold the base of the frame of many tables, armchairs, chairs, sofas and other furniture products. This position remains unchanged in the practice of restoration of structural elements made from solid wood even today.

The socket-tenon connection is a rectangular version of the structural furniture assembly and has two main connection methods. First, when the socket is with a ledge and the spike is at the same end wooden element cut and adjusted to fit into a slot cut into another element. In another method, the tenon is located at the same level on one side of the flat frame of a furniture part, for example a table drawer.

Rice. 1. Dovetail connection

The dovetail connection (Fig. 1) is a complicated version of the socket-tenon connection. The spikes should fit tightly into swallow-tail shaped sockets, which enhance the strength of the connection; They are separated only in one direction.

“Dovetail”, as well as “tenon”, are used to connect two wooden flat elements converging at right angles, for example in drawers tables, cabinets and other products.

Rice. 2. Strengthening the dovetail joint with inserts

Rice. 3. Strengthening the “socket-tenon” connection with inserts

With a rod (initial) connection, one structural element (part) of furniture, with a dowel glued into the socket, is inserted into the socket on the second element with pre-applied wood glue.

Strengthening the dovetail and socket-tenon joints is shown in Fig. 2 and 3 respectively.

IN wooden chairs, armchairs, sofas have many joints, more than in other types of furniture. The connections discussed above must withstand significant loads, although sooner or later in any furniture they weaken or completely collapse. One weakened connection leads to an increase in the load on healthy connections, so the weakened one must be strengthened - and the sooner the better.

In cases where disassembling the furniture is undesirable, and its tenon joints are greatly weakened, the adhesive joints are strengthened by injecting liquid fresh wood glue using a medical syringe and left until the glue dries completely. The gluing area is fixed with clamps.

If it is necessary to ensure increased strength of the joints, then the structure of the furniture frame is strengthened with additional parts: cut plates from ordinary multi-layer birch plywood, glued with hot wood glue inside the frame and secured with screws; wooden bosses, also glued in internal corners tsar belt of chairs, armchairs, tables; wooden dowels, which are driven with tension and glue into the holes drilled in the tenon joints.

During restoration work, when the tenon joints are disassembled, the tenons are cleaned of old glue. To remove glue from the surface of the tenon, use a knife, scraper, or coarse sandpaper. You need to hold the knife almost perpendicular to the wood of the tenon, applying force on the blade so as to remove the dried glue without pressing the knife into the wood. The socket is cleared of old glue using a chisel by scraping, while it is slightly expanded to create space for an expanded tenon due to an additional lining of a thin veneer sheet. This will provide increased strength to the connection when new gluing occurs. In addition, if there is a gap in the socket-tenon connection, then a wedge is sometimes added to make a tight connection, and in some cases, for greater fastening, a beveled key is driven into the edge of the connection.

If the tenon has a crack, then it is sawed through with a tenon saw and a slightly beveled wedge is inserted into the cut.

If a spike is destroyed, it is replaced with a new one. To do this, in place of the old tenon, use a chisel to make a nest 2-3 cm deep, into which a new tenon is glued.

After eliminating all defects on the parts and checking the fit of the tenons and sockets, the tenon joints are again glued together with wood glue. To do this, glue is applied to the tenons, dowels and spacers, as well as into the sockets. After assembly, placing the tenon in the socket, tighten the tenon joints with a clamping device and hold them until the glue dries completely.

1.2. Strengthening tongue and tongue joints

A “tongue and tongue” connection (Fig. 4) is used in the case when the connected places of structural elements have rectangular shape, for example, two folding boards.

Rice. 4. Tongue and tongue connection

This connection is weakened as a result of the simultaneous shrinkage of the tongue of the furniture element and the tongue in thickness. The thickness of the ridge is restored on both sides with thin veneer spacers. If the ridge has cracks or is broken, then it is cut off with a plane. In its place, a recess is made, that is, a tongue of the same width and depth as the board being attached. The boards are held together on a tenon. The insert tenon is glued into the groove, and the direction of its fibers should be perpendicular to the direction of the fibers of the parts being connected. The tongue-and-groove can be made from plain birch plywood with a thickness of at least 5 mm, if the connecting ribs of the tongue are of sufficient thickness.

1.3. Strengthening connections on dowels

Dowels are widely used to connect individual elements round section(Fig. 5). For example, a dowel is used to connect two broken parts of a chair leg or armchair. The sockets for the dowel are drilled with a drill of the required diameter. The dowel is not necessarily made from the same material as the furniture. The best dowels are made from beech, which is less brittle than oak. The dowel should penetrate deeply (up to 5-6 cm) into the parts being connected.

Rice. 5. Dowel connection

1.4. Strengthening joints on a “smooth fugue”

The connection of boards to a smooth reveal (Fig. 6), weakened as a result of warping of the boards and shrinkage, is strengthened with transverse dowels of a trapezoidal or rectangular cross-section.

Rice. 6. Joint with a “smooth fugue”

They are inserted into grooves made on the inner (non-facial) side of the part. The dimensions of the dowel groove for thin boards should be at least half their thickness. Glue the boards along the edges and glue the dowels at the same time. To do this, after applying the glue, the bonded boards are placed face down on a dense and even backing board, the dowels are inserted and placed under the press. At the same time, use a clamp to compress the boards from the edges. This eliminates minor warping of the overall surface.

Strengthening joints on a smooth fugue can be done with inserts in the form of a dovetail tenon (Fig. 7) - this is a traditional method.

Rice. 7. Strengthening joints with a dovetail tenon

The “swallowtail,” sometimes called “butterflies” by restorers, is an insert in the shape of double spikes. After the parts of the boards are connected, grooves are cut into the wood about a third of its thickness according to the shape of the insert, into which they should fit tightly. Inserts are made from the same type of wood as the exhibit, or from durable wood (oak, beech); their fibers must be perpendicular to the direction of the fibers of the edges being joined. The dovetail should be wide enough at the bridge (in the center). Due to its shape, this insert provides a strong connection, but some restorers consider it insufficient.

1.5. Strengthening mustache connections

Restorers quite often encounter compounds furniture elements on the “whisker” (Fig. 8), which consist of superimposing one element on another in an oblique cut. The parts to be joined should, if possible, have the maximum contact surface, then the gluing reliability will be greatest. The glued place is reinforced with dowels or insert tenons.

Rice. 8. Strengthening “mustache” connections

1.6. Strengthening joints with “crackers”

This method of strengthening furniture structural elements and their connections is used in cases where the furniture cannot be dismantled. Strengthening can be done using connecting pads of any shape (Fig. 9).

To seal a crack from the inside and prevent it from spreading, you can use a pad to secure the connected area vertically and horizontally. The overlays are made from wood of the same species as the exhibit itself. When gluing them onto a crack, it is necessary that the fibers of the pads be perpendicular to the fibers of the parts being connected. Often the cracks being glued are not straight, then it is preferable to make not one overlay, but several smaller ones next to each other. After covering them with good wood glue, if possible, they are tightened with screws. The advantage of this strengthening of connections is that the pads can be removed if necessary.

One of the types of overlays are “crackers”, which strengthen the connections between the drawer and the leg. Some restorers object to the use of “crackers”, considering them irrational. They prefer to dismantle the furniture and redo the drawer with a new internal connection. In this case, the principle of maximum preservation of the original is violated. In addition, sometimes it is harmful to remove the upholstery and then dismantle the exhibit. “Rusks” compensate for the “fatigue” of the wood of the drawer, caused by numerous re-upholstery. “Rusks” are especially useful when the bars of the seat frame are curved and have longitudinal cracks.

“Crusks” are made from soft, well-adhesive wood (linden, poplar). Their height should be equal to the height of the king. They are given a concave line from the inside, because this shape facilitates upholstery and final fastening at the corners of the drawer-leg connection. The “crackers” are installed after the leg is secured. If they fit well and are glued, then there is no particular need to screw them in with screws. But some restorers, nevertheless, press the “crackers” with clamps during gluing, and after gluing, screw in screws. It is unacceptable to use nails.

Rice. 9. Strengthening joints with “crackers”

Dovetail, tenon groove and other accessories for a milling machine with your own hands. Chapter V. Restoration of structural elements of furniture Dovetail tenon joint