Often, during the construction of frames for roofs of complex configuration, there is a need to use elements custom size. Typical examples include hip and half-hip structures, the diagonal ribs of which are significantly longer than ordinary rafter legs.

Similar situations arise in the construction of systems with valleys. So that the created connections do not become the cause of the weakening of the structures, you need to know how the rafters are spliced ​​along the length, in what way their strength is ensured.

Splicing the rafter legs allows you to unify the lumber purchased for the construction of the roof. Knowledge of the intricacies of the process makes it possible to almost completely build a truss frame from a bar or board of one section. The construction of a system of materials of the same size has a positive effect on the total cost.

In addition, a board and a bar of increased length, as a rule, are produced with a larger cross section than that of the material standard sizes. Along with the cross section, the cost also increases. Such a margin of safety when constructing hip and valley ribs is most often not needed. But with proper splicing of the rafters, the elements of the system are provided with sufficient rigidity and reliability at the lowest cost.

Without knowledge technological nuances it is quite difficult to make truly bending lumber joints. Rafter junctions belong to the category of plastic hinges that have only one degree of freedom - the ability to rotate in the connecting node when a vertical and compressive load is applied along the length.

In order to provide uniform stiffness when a bending force is applied over the entire length of the element, the mating of the two parts rafter leg located in places with the smallest bending moment. On diagrams showing the magnitude of the bending moment, they are clearly visible. These are the points of intersection of the curve with the longitudinal axis of the rafter, at which the bending moment approaches zero values.

We take into account that during the construction of the truss frame, it is required to ensure that bending resistance is equal over the entire length of the element, and not the same opportunities to bend. Therefore, the junction points are arranged next to the supports.

As a support, both an intermediate rack installed in the span, and directly a Mauerlat or a trussed truss are taken. The ridge run can also be assessed as a possible support, but it is better to place the rafter legs joining areas lower along the slope, i.e. where the minimum load is placed on the system.

Splicing options for rafters

Except exact definition places to pair the two parts of the system element, you need to know how the rafters are properly extended. The method of forming the connection depends on the lumber chosen for the construction:

• Bars or log. They are built up with an oblique cut formed in the connection zone. For reinforcement and to prevent rotation, the edges of both parts of the rafters cut at an angle are fastened with a bolt.
• Boards sewn in pairs. They are spliced ​​with the location of the docking lines apart. The connection of two parts superimposed on each other is made with nails.
• Single board. The priority is splicing with a frontal stop - by joining the trimmed parts of the rafter leg with the imposition of one or a pair of wooden or metal linings. Less commonly, due to the insufficient thickness of the material, an oblique cut is used with fastening with metal clamps or a traditional nail fight.

Let us consider in detail these methods in order to understand in depth the process of increasing the length of the rafters.

Option 1: Bevel cut method

The method involves the formation of two inclined cuts or cuts, arranged from the side of the pairing of parts of the rafter leg. The cutting planes to be joined must be perfectly aligned without the slightest gaps, regardless of their size. In the connection area, the possibility of deformation must be excluded.

It is forbidden to fill cracks and leaks with wedges made of wood, plywood or metal plates. It will not work to fit and correct flaws. It is better to accurately measure and draw cutting lines in advance, according to the following standards:

• The depth is determined by the formula 0.15 × h, where h is the height of the beam. This is the size of the area perpendicular to the longitudinal axis of the beam.
• The interval within which the inclined sections of the cut are located is determined by the formula 2 × h.

The location for the docking area is found according to the formula 0.15 × L, which is valid for all types of truss frames, in which the value of L displays the size of the span covered by the rafters. The distance is measured from the center of the support.

Details from a bar, when making an oblique cut, are additionally fastened with a bolt passing through the center of the connection. The hole for its installation is drilled in advance, its Ø is equal to the Ø of the fastener rod. To prevent the wood from being crushed at the place where the fastener is installed, wide metal washers are placed under the nuts.

If a board is connected using an oblique cut, then additional fixation is carried out using clamps or nails.

Option 2: Rallying the boards

In the case of using rallying technology, the center of the connected section is located directly above the support. The joining lines of the trimmed boards are located on both sides of the center of the support on estimated distance, equal to 0.21 × L, where L denotes the length of the overlapped span. Fixation is carried out with nails installed in a checkerboard pattern.

Backlash and gaps are also unacceptable, but they are easier to avoid by carefully trimming the board. This method is much simpler than the previous method in execution, but in order not to waste hardware and not to weaken the wood with extra holes, the number of points of fasteners to be installed should be calculated with accuracy.

Nails with a stem section up to 6 mm are installed without pre-drilling the corresponding holes. For fasteners larger than the specified size, it is necessary to drill so that when connecting, the board does not split along the fibers. An exception is cross-section hardware, which, regardless of size, can simply be hammered into wooden parts.

To ensure sufficient strength in the rally zone, the following conditions must be observed:

• Fasteners are placed every 50 cm along both edges of the boards to be joined.
• Nails are placed along the end joints in increments of 15 × d, where d is the diameter of the nail.
• For rallying the board at the interface, smooth round, screw and threaded nails are suitable. However, threaded and screw versions are preferred because they have much higher pull-out strength.

Note that the connection of rafters by rallying is acceptable in the case of an element of two sewn boards. As a result, both joints are overlapped with a solid piece of lumber. The advantages of the method include the size of the overlapped span, which is impressive for private construction. Similarly, rafter legs can be increased if the distance from the top to the bottom support reaches 6.5 m.

Option 3: Frontal stop

The method of frontal extension of the rafters consists in the end joining of the connected parts of the rafter leg with the fixation of the section with nails, dowels or bolts through the lining installed on both side planes.

To exclude backlash and deformation of the extended rafter leg, the following rules must be followed:

• The edges of the board to be joined must be perfectly trimmed. Gaps of any size along the connection line must be excluded.
• The length of the overlays is determined by the formula l = 3 × h, i.e. they must be no less than three board widths. Usually the length is calculated and selected based on the number of nails, the formula is given to determine the minimum length.
• Overlays are made of material, the thickness of which is not less than 1/3 of the same size of the main board.

Nails are hammered into the overlays in two parallel rows with a checkerboard "scatter" of fixing points. In order not to damage the overlay thin in relation to the main lumber, the number of attachment points is calculated based on the resistance of the nails to the transverse force acting on the legs of the hardware.

When the junction of the rafter parts is located directly above the support, there is no need for nailing calculations to fix the overlays. True, in this case, the docked leg will work as two separate beams for both deflection and compression, i.e. according to the normal scheme, it will be necessary to calculate the bearing capacity for each of the constituent parts.

If steel rod bolts or rods without thread, dowels are used as fasteners, when joining a thick board or beam, then the threat of deformation will be completely eliminated. In fact, even some gaps in the joining of the ends can be ignored, although such flaws are still best avoided.

When using screws or screws, holes are pre-drilled for their installation, the Ø of the holes is 2-3 mm less than the same size of the fastener leg.

In the production of frontal joints of rafters, it is necessary to strictly observe the estimated installation step, the number and diameter of fasteners. If the distance between fixing points is shortened, splitting of the wood may occur. If the holes for the fasteners are larger than the prescribed dimensions, the rafter will be deformed, and if less, the lumber will crack during the installation of the fasteners.

Extension with composite rafters

To connect and increase the length of the rafters, there is still a very interesting way: building with two boards. They are sewn to the side planes of the single element being extended. Between the extended parts there is a gap equal to the width of the top board.

The clearance is filled with trimmings of equal thickness, set at intervals of not more than 7 × h, where h is the thickness of the board being extended. The length of the distance bars inserted into the clearance is at least 2 × h.

Extension using two stackable boards is suitable for the following situations:

• The device of a layered system along two side runs, which serve as a support for the location of the docking area of ​​the main board with the attached elements.
• Installation of a diagonal rafter that defines an inclined edge of hip and half-hip structures.
• Construction broken roofs. As a support for the connection, the strapping of the lower tier of rafters is used.

Calculation of fasteners, fixation of remote bars and connection of boards is carried out by analogy with the methods described above. For the manufacture of remote bars, trimming of the main lumber is suitable. As a result of the installation of these liners, the strength of the prefabricated rafters significantly increases. Despite significant material savings, it works like a solid beam.

Video about how to build rafters

Demonstration of basic splicing techniques structural elements truss system:

A video with a step-by-step process for connecting rafter parts:

Video example of one of the ways to connect lumber:

Compliance with technological requirements, according to which the rafters are spliced ​​along the length, guarantees trouble-free operation of the structure. Elongation methods allow you to reduce the cost of building roofs. You should not forget about preliminary calculations and about preparing to make connections so that the result of the effort becomes perfect.

All photos from the article

Sometimes, when carrying out construction and other work using wood, it is required to make elements longer or wider, and very few people know how to do this correctly. That is why we will consider how to splice the board yourself and what methods and techniques exist. It is important to choose the option that is best suited in a given situation and will require minimal time and money.

Basic workflow requirements

Before we begin to consider specific options for carrying out work, it is necessary to understand what factors are observed to ensure that the result that is expected is obtained:

Material quality	Everything is simple here: it is impossible to make durable structures out of low-quality wood, especially when it comes to joints, if they have knots, damage by woodworms, mold and other problems, then there can be no question of any reliability and durability. Pick the most best elements so as not to waste energy and money in vain
Humidity	Another most important parameter that should always be taken into account. Only dry elements are suitable for work, since high humidity, firstly, reduces strength, and secondly, reduces adhesion adhesive composition when using it, and thirdly, after the completion of work, no one will guarantee that in a week or a month the structure will not lead or it will not crack
Connection loads	It is on this indicator that the choice of one or another connection option largely depends, the greater the load, the higher the requirements for the quality of the interface and the harder process. Therefore, decide in advance which option will be used in order to guarantee a high result.
Using a quality tool	A lot also depends on this, especially when it comes to complex options when the connection is cut special devices. They must provide maximum cutting quality and maximum docking accuracy, since reliability largely depends on this.

Important!
Remember one simple rule that experts always use: to obtain the best result, it is necessary that the parameters of the connected elements be similar, in other words, one type of wood should be used.

Work options

All events of this kind can be divided into two large groups - rallying boards in width and length, we will consider them separately and tell you which methods are the most popular and how to implement them correctly.

Width connection

Of course, the simplest solution would be a shield splicing option, so we will start with it, first we will present a diagram of the main options, and below we will describe them in detail:

• The first method involves cutting a cavity with a milling machine, which has a trapezoidal shape and allows the use of a key as a retainer.. The advantage of this solution can be called reliability, and the disadvantage is the need for milling machine or presence manual router for work, hand tool you won't get around here;
• Rallying using an end bar, which is connected to the ends of the board using the tongue-and-groove method, is used for elements of small length, since this option provides high reliability precisely small structures. Again, you will need to work. With his help, it will be carried out quickly and efficiently;
• You can make a cutout on the end, fit the rail under it and put it on wood glue, this is also a rather interesting option that is suitable for small structures;
• The last two options involve gluing a triangular rail, only one of them cuts into the end, and the second option involves cutting the end at an angle, you need to choose what is best suited in a given situation.

But if you want to connect the board more securely, then one of the following methods will do:

• The first option is called the connection to a smooth fugue, when it is performed, very careful grinding of the ends is required for a snug fit, after which they are lubricated with glue and connected under pressure or using special ties. This solution is suitable in cases where high bearing capacity is not needed;

• The traditional groove-ridge option is often used, here it is important to ensure the optimal connection configuration, so the width of the groove and, accordingly, the tongue should not be more than a third of the total thickness of the board, it is important to cut very accurately so that the elements match perfectly, this will significantly increase the strength of the connection;

Important!
When working, a milling cutter is most often used, but the cutters can have a different configuration, you should monitor the condition of their cutting edges and sharpen or replace them in a timely manner, since the quality of the connection largely depends on the cleanliness of the processing.

• You can use the option of cutting at an angle, it is well suited where special strength is not required, but you need to connect elements that can be used for finishing, etc .;
• The triangular thorn-groove in many respects resembles the usual one, only the configuration of the ends differs. It is also important here that the elements fit perfectly with each other, as this will ensure both the accuracy of the pairing and its maximum reliability;
• A quarter connection is simple - cuts are made for half the thickness, the length of the protrusions should not greatly exceed the thickness, the elements are lubricated with glue and compressed until the composition dries, this is a standard procedure for almost all options;
• The last type is key rallying, it does not differ from the above option when working in width, the requirements are the same.

Conclusion

Correctly and reliably connecting the board means ensuring its maximum strength, it is important to follow all the recommendations and use only high-quality materials. The video in this article will show some of the options for carrying out the work clearly, and if you have questions or an addition, unsubscribe in the comments.

Making tight joints from wood

Professional layout with precision tools

Tight joints of wood products start with neat and precise markings. This is especially important if you are making connections by hand and marking lines serve as guides for tools. Machining accuracy depends on careful adjustment of stops, stops, reach and tilt saw blades and cutters. The steps below will help you achieve great results. This does not require unique equipment, but should choose tools that guarantee accuracy and efficiency. Also, develop the habit of following rules when measuring and marking.

• Use precise tools. For example, try, if possible, to use an accurate steel ruler instead of a tape measure with a flexible tape in most cases. good tools are more expensive, but they will last you a lifetime.
• Consistency is the key to success. Use the same measurement tools throughout your project to avoid small inaccuracies that affect the quality of your connections. For example, the 300 mm marks on the two rulers may not match.
• The main thing is the result, not the measurements. In most cases, measurements should be avoided when you can use an already finished part with connection elements to mark an adjacent part. For example, having made spikes on the front wall of the box, use them to mark the “dovetails” on the blanks of the side walls.
• Apply right tricks markings and the right tools. With good marking and measuring tools, it is easier to achieve the required accuracy.

It is not always possible to accurately align the end of the ruler with the end of the workpiece, so in such a situation it is better, as they say, to sacrifice zero. Align the next ordinal division with the end and mark the size in accordance with it.

To draw a thin line parallel to the edge of the workpiece, use a thickness gauge. Shows the outline of the nest on the post after determining the position of the end of the crossbar

Sharp knife leaves thinnest line, providing high marking accuracy. In some cases, the recessed line also becomes the starting position for the chisel.

Fine-tuning of machines for precise machining of parts

Machine tools and power tools will provide excellent results only if they are correct setting and adjustments. This page shows the main features of setting up three machines that are essential for most workshops: a saw and planer, as well as milling table. Having prepared them for work, remember the following rules.

• First of all, make blanks of the same thickness. Start any project by cutting all pieces to the same thickness. Any differences in thickness make it difficult to obtain accurate joints and necessitate additional adjustments in grinding and sanding.
• Reasonable approach. Long boards are inconvenient to process, so it is better to immediately cut them into blanks with a small allowance, which are easier to handle, achieving the necessary accuracy.
• Double check the dimensions. The actual thickness of slabs and sheet materials, as a rule, differs from the nominal, therefore, a caliper should be used to measure them. Only after that, cut the grooves, tongues and folds of the appropriate width.

Before cutting anything, check that the blade is parallel to the slots in the table, adjust the cross (corner) stop to 90°, and then set longitudinal stop parallel to the disk. At longitudinal sawing use a clamping comb to hold the work piece firmly against the rip fence.

Align the rear table with the highest point of the cutting edge path of the knives as shown in the figure on the right. Then, using a checked square, make sure that the rip fence is set exactly at right angles to the back table. To achieve excellent result, always press the workpiece against the fence when planing. Slowly feed the board onto the rotating cutterhead. When the front end of the board passes over the knives, move the downforce forward so that the board is pressed against the back table. For getting good result adjust the rear table and rip fence.

Plan to do the most milling work over multiple passes, setting the fence to the final height or width for the last pass. Fix the position of the router after each change in the overhang of the cutter. When selecting grooves, tongues, folds and other elements of connections, use clamps similar to the clamping comb shown here. It is easy to do it yourself, it does not require a lot of material.

The final fit guarantees success

No matter how many connections you want to make on the machine, after each change in settings, always make test passes and connection samples using offcuts. Adjustment should be continued until a tight assembly of the test joint is achieved, and only then proceed to processing the details of the project. But despite all your efforts, sometimes you can find imperfections in the connections. Chips on the saw table or subtle warping of a previously planed workpiece can ruin the job and make assembly impossible. If the piece is too thick or too wide, resist the temptation to adjust the size with the help of lathes. Precise fitting is best left to hand tools.

• Little zenzubel. With its help, it is possible to quickly remove a layer with a thickness of 0.5 mm or more from a wide spike or comb. The low angle zener is especially effective when working across the fibers. Side protruding cutting edge allows processing inner corner close to the shoulder of the spike.
• Rasp or file. A flat rasp with a coarse cut quickly removes material, but leaves a rougher surface than a planer. A flat file is slower, but it works well for smoothing the surface.
• Sandpaper. If you need to remove very little material from a tenon or other wide surface, glue a piece of 100 grit sandpaper to a suitable piece of board or cork block. Use self-adhesive sandpaper or stick a regular one with spray adhesive or double sided tape. This method allows you to process only one plane without affecting the adjacent ones, as happens if you just wrap the bar with sandpaper.
• Chisel. Various widths blades will allow you to remove material from any hard-to-reach places. When scraping a flat surface, hold the chisel with the bevel up, pressing its flat front edge against the wood.

When using a rasp, chisel, or any other tool to remove material, take your time and regularly check the result by joining the parts.

Plan your build sequence carefully

You have carefully cut out all the details, achieved tightness in all joints and are now ready to start assembling. But before you open the bottle of glue, be sure to do a trial dry assembly (without glue). When assembling the product, determine in what order it is better to connect the parts, how many clamps are required to tightly compress all the joints, and how best to place the clamps so that there are no distortions.

The assembly of large and complex projects is best divided into several simple steps, instead of fussing around trying to glue all the pieces together in one go. For example, when making a cabinet with paneled sides, first assemble the frames with panels, and then proceed with the main assembly. This approach gives you more time to check all connections and requires fewer clamps. Another way to buy time is to use glue with an extended setting time. For example, the usual yellow Titebond glue makes the entire assembly in 15 minutes, and variety Titebond Extend allows you to align the gluing within 25 minutes.

When installing clamps, make sure that their pressure is on the middle of the joint. An incorrectly installed clamp can deform the parts so that a gap forms between them. Sometimes, despite your best efforts, the connections don't come out neat. An accidentally slipped tool, inattention or unnoticed filings near the stop lead to the fact that the connection is loose or a noticeable gap appears in it.

Assemble the locker in stages, first gluing the small side paneled frames. Then you can pay more attention to each connection. Then proceed to assemble the body

How can a seemingly ruined job be salvaged?

The gap can be covered with a mixture of fast-setting epoxy adhesive with sanding dust from the same wood (the mixture should have the consistency of a thick paste). It is better to use epoxy glue instead of PVA, since the putty is inevitably smeared on the surfaces adjacent to the joint and the epoxy glue hardens without being absorbed into the wood. Excess of such a composition is easy to remove by grinding, so that there are no problems when applying the finish. Use this filling method when it comes first appearance connection, not its strength.

If, during trial assembly, the spike dangles in the socket, such a connection will not be strong. Filling the gaps with glue won't do any good, so don't be lazy to reinforce a piece that's too thin with wood. Cut out two overlays to make the spike a little thicker than required, and glue them on both sides. After drying, re-adjust the spike to the dimensions of the nest.

Turn a disadvantage into a virtue

Sometimes it is better not to hide the traces of repair, but to make them visible. In a too narrow ash thorn, two cuts were made and thin cherry wedges were inserted into them, which tightly pressed the narrow cheeks of the thorn to the edges of the socket. In other cases, such as countersunk joints, small chamfers or roundings along the ribs of the shoulders will make the loose seam less noticeable.

Replace Part

This can happen to any of us. Some mistakes do not make sense to fix for two reasons: (1) if no matter your skill and effort, the unsightly defect remains noticeable or (2) if it is faster and easier to make a new part to replace the damaged one.

In any carpentry or furniture, the most important node is corner connections. They provide quality and durability. wooden products. Compared to dowel mounting, the classic way - tenon connection on glue has greater durability and rigidity. Such connections are used in cases where the assembled frame must have a groove or fold for inserting a panel or glass.

In practice, they are represented by several options: two grooves and a spike inserted into them, one-sided or two-sided connection with a “mustache” and with a double spike. But most simple option for home master the use of an inserted (“foreign”) spike remains. Such a connection is nothing more than a tongue-and-groove connection.

The quality of the connection depends entirely on the exact correspondence of the groove and the tenon, which is achieved only by choosing a measuring tool and a well-ground saw and chisel.

In case of a corner joint with one tenon, the thickness of the bar is divided into three equal parts (on a bar less than 25 mm, the tenon should be somewhat thicker than the cheek of the groove).

When marking, the width of the frame is first transferred to the inner edge of the opposite part. The risks are applied using a square with an awl. Since the wood around the spike is selected, its marking is done from any side. For the groove, marking is done only on its narrow side. Then the details are marked. It is customary to make grooves in the vertical elements of the frames, and spikes in the horizontal elements. The grooves are marked with a thickness gauge. A spiked bow saw is sawn along the falling part (for a groove to the base, for a spike - to a ledge). Then a groove is hollowed out with a chisel. To do this, the sawn part is fixed on a workbench. The chisel is placed with a sharpening cut to the detachable part and is driven with a mallet exactly into the mark with light blows. First, a wedge-shaped hole is hollowed out. The detachable part of the wood is left in place so that when working with reverse side there was emphasis. The spike is cut at a right angle with a miter saw.

The width of the frame is transferred to the opposite part, maintaining perpendicularity. Add 2-3 mm to the width of the cut.	Mark the groove and spike with a thickness gauge. This is the simplest and most accurate markup method.	Sawing is always from the side of the detachable part in the middle of the markup. spiked bow saw designed specifically for this kind of work.
A self-made auxiliary stop template will help you make accurate cuts and on circular saw. At the same time, be safe.	The grooves are hollowed out with a chisel. To do this, the connection parts are tightened with a clamp or fixed on a workbench. They weakly hit the chisel with a mallet.	A miter saw with a fixed angle adjustment will allow precise tenon placement. This work can be done on a circular saw.

Special options for corner connections

Special forms of grooves and tenons - double tenon and grooves on the "mustache". Double studs are used in products subject to heavy loads and thick frames. If a frame structure at the end it will be profiled, then they make a connection on the “mustache”. There are one-way and bilateral grooves on the “mustache”, (due to the insufficient area of ​​the contact surfaces, they are less durable).

The groove should be located in the middle third of the thickness of the part. The sample around the spike is made less than the depth of the groove, otherwise there will be a gap in the connection. After assembly, the remaining cheeks of the groove are sawn off along the entire length. The reverse is also possible.

The rebate on the frame must be consistent with the division into three parts. This will save time on the spike. The width of the fold must be taken into account when marking out, otherwise gaps will occur here when milling.

After grinding the inner and outer surfaces of the groove and tenon, the frame is glued together. In this case, it is necessary to compress the gusset in two planes through the gaskets. The ends of the groove and tenon must be open for inspection and adjustment during assembly. The protruding adhesive is removed. When gluing, the right angle of the frame is controlled.

After the glue has dried, the clamps are removed and the protruding parts of the tongue or cheeks of the groove are ground down from the flanks to the level with outside products.

	Spike connection on the "mustache": one-sided and two-sided. The choice is determined by the design requirements for the product or its appearance.
	A double spike is made for especially loaded corners and thick frames. In this case, the thickness of the bar is divided into five equal parts.
	When selecting a longitudinal groove in the details of the frame, the spike is not affected. Otherwise, when gluing the knot, a hole will appear in its end face.
	The fold, even when marking, must have an appropriate increase, otherwise gaps will result. Depth is determined by dividing into three parts.
	The spikes and cheeks of the grooves protrude for an increase. When compressed, gaskets will be required. After that, the increase is sawn off.

It will be useful for novice home craftsmen to learn about connection methods wooden parts. We dedicate a brief educational program to this topic, which will describe the main types of carpentry joints and rallying using glue, nails, screws or dowels, or without them at all.

Connection selection rules depending on the type of load

End connections are the simplest; they are used if necessary to build up a part. These joints are best able to withstand compressive loads, however, when punching specially shaped locks, good resistance to twisting, stretching and bending can be achieved. Standard option end connection - with cutting by half the thickness of both parts. The cut can be straight or oblique, if necessary, to prevent bending, stretching or twisting, a spike or an obtuse angle is cut at the end of each cut, or the cut is made stepped, forming a kind of “lock”.

1 - direct overlay half a tree; 2 - oblique pad; 3 - straight overlay with a stepped joint; 4 - overlay half a tree with an oblique joint; 5 - oblique overhead lock; 6 - half-tree connection with an oblique spike

Angular and side connections are used to connect straight parts into a truss or frame. Usually this part of the structure is supporting, so the main loads fall on displacement and compression. If the structure experiences the static load provided, a rectangular spike is cut on one of the parts, and a groove or eyelet of the appropriate size is cut on the other. If it is possible to act on the break of the structure, the spike and groove are cut in the shape of a trapezoid.

Corner joints: 1 - with an open through spike; 2 - with a deaf closed spike; 3 - with a through oblique spike

Overhead cross and T-shaped connections are used, as a rule, for additional connections between critical structural details. The main load in them is compression, displacement and rupture. The first two types of load are eliminated by cutting half a tree or less, followed by matching the parts. The shoulders of the notches take the main load on themselves, it remains only to fix the connection with screws or overhead brackets. In some cases, a dowel is used to strengthen the connection or a spike with a wedge is cut down.

1 - cross connection with an overlay in half a tree; 2 - cross connection with landing in one socket; 3 - T-shaped connection with a hidden oblique spike; 4 - T-shaped connection with a straight stepped overlay

A separate type of connections - box. They are designed to connect boards at right angles. Usually, for a box joint, teeth are cut on each board, the width of which is equal to the distance between them. On different boards, the teeth are cut with an offset, so when connected, the corner of the boards looks like one piece. The teeth can also be wedge-shaped, preventing the corner from breaking in one direction, or additionally fastened with glue or nails.

Box corner joints: 1 - with straight through spikes; 2 - with oblique through spikes

How to make a spike connection

To make a spiked joint, you need to circle both parts with a marking line along all faces at a distance from the end equal to the width of the joint. On two opposite sides and the end face, the body of the spike is marked with lines, the markings on both parts are completely identical.

The spike is cut from the sides with a hacksaw for a transverse cut and the wood is chipped with a chisel. The width of the spike is made 2-3 mm larger for subsequent precise processing with a knife or chisel. The groove is cut with a hacksaw for a longitudinal cut and chipped off with a chisel, also leaving a small allowance for processing. This is followed by an adjustment, during which the parts are combined and achieve the most snug fit.

With a T-shaped spike connection, a central spike or groove is cut on one of the parts, and an eye is hollowed out on the other or two side cuts are made, depending on the type of the first part. To make an eye, a chisel is used, turning the inclined part of the blade into the hole. If the eye is not solid, I make the spike 8-10 mm more depth and cut off its end in the form of a developed wedge. So when driving, the spike will open itself, and the part will be firmly planted.

To connect wide parts, you can use a box connection by cutting several spikes and grooves. The easiest way to fasten a stud joint is to drill it through and across the studs and drive a wooden dowel (window gusset) into the hole.

How to glue boards together

A very popular method of joining boards and bars is longitudinal and transverse gluing. When connecting boards with a wide side, the end can be even, although in most cases a tongue-and-groove profile is used. It is very important to fit the parts tightly so that the adhesive layer is as thin as possible, only in this way can maximum strength be achieved. Sometimes a small amount of cotton fiber is applied to the end smeared with glue, this improves the quality of the hitch.

The boards can also be connected in profile, but for this it will be necessary to perform a wedge-shaped gear cutting of both ends with a tooth offset to the floor for different parts. At home, such an operation can be performed using a manual milling cutter.

Used to glue parts casein glue or high concentration PVA, sifted wood flour is added to the adhesive to give strength. The surfaces are covered with glue and kept in air for 3-5 minutes, after which they are placed under oppression or squeezed with clamps. Such a connection is stronger than the tree itself and never breaks at the junction.

How to assemble elements of load-bearing structures

For load-bearing structures, two types of connections are used - extension and articulation. The easiest way to splice two parts is to make a cut with a hacksaw half the thickness at the same distance from the ends, and then chop off excess wood with an ax. After matching the two parts, the connection is usually fastened with two overhead strips nailed to the side of the cut. Bonding is also possible, but only if the parts are tightly fitted.

Half-cut ends can be brought together at almost any angle, this is the main method of connecting roof trusses. To fasten the parts, an additional tightening bond is required: the beam is applied to the connected parts on the side at a distance of 30-50 cm from the corner and cut to half the thickness at the points of contact, and then the structure is fastened with nails.

Often vertical and inclined structures need support, for example when connecting the truss system to floor beams. In this case, the landing slots on the horizontal beam are notched, into which the racks will be inserted. It is very important to observe the angle of inclination and make a hemming no more than a third of the thickness of the timber.

Connections with Special Links

Almost all carpentry connections are made with additional reinforcing ties. In the very simple example the role of such is performed by nails or self-tapping screws.

When building up parts, the assembly can be strengthened with a through bolted connection, clamps, staples and wood grouses, or it is simply wrapped with cold-rolled wire. It is enough to fasten the spliced ​​vertical supports with two overhead strips - wooden or metal.

Corner joints are most often fastened with staples, patch plates or corners. In cases where it is necessary to maintain a slight mobility of the connection, one through bolt is used, which either flashes across the place of the lining of the parts, or tightens them in the longitudinal direction with a minimum indent from the lining.

The place of fastening of the special connection must be removed from the edge by at least 10 diameters of the fastener and must not have defects. It is important to remember that often the bonds do not provide the overall strength of the connection, but only compensate for the unaccounted for load.