The coolest joiners and carpenters are said to be able to build a house without a single nail. Japanese artisans, even amateurs, are just that.
Some years ago young worker In the automotive industry, an enthusiastic man came across a book describing traditional Japanese woodworking techniques. He was very fascinated by the descriptions of the connections of parts without the use of nails, screws and glue. He wanted to learn how to do the same. But there were no diagrams for making fasteners in the book. Then the guy decided to draw them himself.
He used the free service Fusion-360 to model and animate the parts. The Japanese translated the resulting result into GIFs and posted it on a Twitter account called The joinery... In almost a year, the young carpenter visualized 85 different ways detachable connections.
The variety of mounts is truly amazing. With their help, you can make basically anything - a stool, a sofa, a table, and so on. The main thing is to have straight arms and a good, preferably electric tool.
But even if the manual labor does not inspire you at all, you will probably enjoy watching GIFs. The grace with which the details mesh with each other is mesmerizing.
It will be useful for novice home craftsmen to learn about the methods of joining wooden parts. We devote a short educational program to this topic, which will describe the main types of joinery joints and rallies with the use of glue, nails, screws or dowels, or without them at all.
Rules for choosing a connection depending on the type of load
The most simple end connections, they are used when it is necessary to build up a part. These joints are best suited to withstand compressive loads, but good resistance to twisting, stretching and bending can be achieved by cutting down specially shaped locks. Standard Option end connection - with undercut to half the thickness of both parts. The cut can be straight or oblique, if necessary, to prevent bending, stretching or twisting, a thorn or an obtuse angle is cut at the end of each cut, or the cut is made stepwise, forming a kind of "lock".
1 - a straight overlay in a half-tree; 2 - oblique pad; 3 - straight strip with a stepped joint; 4 - half-wood overlay with an oblique joint; 5 - oblique patch lock; 6 - half-wood connection with an oblique thorn
Corner and side joints are used to connect straight parts into a truss or frame. Usually, this part of the structure is a supporting one, so the main loads fall on displacement and compression. If the structure is subjected to the stipulated static load, a rectangular tenon is cut on one of the parts, and a groove or eyelet of appropriate dimensions is cut on the other. If action to break the structure is possible, the tenon and groove are cut in the form of a trapezoid.
Corner joints: 1 - with an open through thorn; 2 - with a deaf closed thorn; 3 - with a through oblique thorn
Overhead cross and T-shaped connections are used, as a rule, for additional connections between critical structural parts. The main load in them is on compression, displacement and rupture. The first two types of loads are eliminated by cutting half a tree or less, followed by aligning the parts. The shoulders of the notches take the main load on themselves, it remains only to secure the connection with screws or overhead brackets. In some cases, a dowel is used to strengthen the connection or a thorn with a wedge is cut out.
1 - cross connection with a half-wood overlay; 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 plate
A separate type of connections is box-type. They are intended for joining boards at right angles. Usually, for a box connection, 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 angle from the planks looks like one whole. The teeth can also be wedge-shaped, which prevents the angle from breaking in one direction, or they are additionally fastened with glue or nails.
Box corner joints: 1 - with straight through thorns; 2 - with oblique through thorns
How to make a spike connection
To make a spike connection, you need to circle both parts with a marking line on all faces at a distance from the end equal to the width of the connection. On two opposite sides and the end, the body of the thorn is marked with lines, the markings on both parts are completely identical.
The thorn is trimmed from the sides with a hacksaw for a cross-cut and the wood is chipped with a chisel. The width of the stud is made 2-3 mm larger for subsequent precise processing with a knife or chisel. The groove is cut with a hacksaw for longitudinal cutting and chipped with a chisel, also leaving a small allowance for processing. This is followed by fitting, in the process of 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 eyelet is hollowed out on the other or two side cuts are made, depending on the type of the first part. To make the eyelet, a chisel is used, turning the inclined part of the blade into the hole. If the eyelet is not solid, I make the spike 8-10 mm more depth and cut off its end in the form of a deployed wedge. So, when hammering, the spike will open itself, and the part will be firmly seated.
To connect wide parts, you can use box connection by cutting several thorns and grooves. The easiest way to secure a tenon joint is to drill through the tenons and hammer a wooden dowel into the hole (window gusset).
How to splice boards with glue
A very popular method of joining boards and bars is longitudinal and transverse gluing. When joining the boards with the wide side, the end can be even, although in most cases a tongue-and-groove profile is used. A tight fit of the parts is very important so that the adhesive layer is as thin as possible, this is the only way to achieve maximum strength. Sometimes a small amount of cotton fiber is applied to the butt, greased with glue, this improves the quality of the adhesion.
The boards can also be connected in profile, but this will require wedge-shaped toothed cutting of both ends with an offset to the floor of the tooth for different parts... At home, such an operation can be performed using a hand-held router.
For gluing parts use casein glue or PVA of high concentration, sifted wood flour is added to the adhesive to impart 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 wood itself and never breaks at the joint.
How to weld structural members
For load-bearing structures use two types of connections - extension and articulation. The easiest way to fuse two pieces together is to make a half-thickness cut with a hacksaw at the same distance from the ends, and then chop off the 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 with a tight fit of the parts.
The ends cut into half a tree can be brought together at almost any angle, this is the main method of connecting roof trusses. For fastening the parts, an additional tightening bond is required: the bar is applied to the connected parts from the side at a distance of 30-50 cm from the corner and cut in 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 a rafter system to floor beams. In this case, a notch is made of the landing nests on the horizontal beam, into which the racks will be inserted. It is very important to observe the angle of inclination and make the undercut by no more than a third of the thickness of the timber.
Connections with ad hoc links
Almost all joinery joints are made with additional reinforcing ties. In the very simple example the role of such is played by nails or screws.
When building up parts, the unit can be strengthened with a through bolt connection, clamps, brackets and wood grouses, or it is simply wrapped with cold-rolled wire. Spliced vertical supports it is enough to fasten it 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 small mobility of the connection, one through bolt is used, which either stitches across the place of the overlay of the parts, or pulls them in the longitudinal direction with a minimum offset from the overlay.
The attachment point of the special connection must be at least 10 diameters of the fastening element from the edge and must not have any 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 load.
Often during the construction of roof frames complex configuration there is a need to use elements of non-standard size. Typical examples include hip and semi-hip structures, the diagonal ribs of which are significantly longer than ordinary rafter legs.
Similar situations arise when constructing systems with valleys. So that the created connections do not cause weakening of the structures, you need to know how the rafters are spliced along the length, in what way their strength is ensured.
The splicing of 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 rafter frame from a bar or board of the same section. The construction of a system of materials of the same size is beneficially reflected in the total cost.
In addition, a board and a bar of increased length, as a rule, are produced with a cross section larger than that of the material. standard sizes... Together with the cross-section, the cost also increases. Such a margin of safety is most often not needed when constructing hip and end ribs. But with the correct implementation of the splicing of the rafters, the elements of the system are provided with sufficient rigidity and reliability at the lowest cost.
Without knowledge of technological nuances, it is quite difficult to make really bending-stiff lumber joints. The rafter mating units belong to the category of plastic hinges that have only one degree of freedom - the ability to rotate in the connecting unit when a vertical and compressive load is applied along the length.
In order to ensure uniform stiffness when a bending force is applied along the entire length of the element, the pairing of the two parts rafter leg located in places with the least bending moment. On the 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.
Let us take into account that during the construction of the rafter frame, it is required to ensure equal resistance to bending over the entire length of the element, and not the same ability to bend. Therefore, the mating points are arranged next to the supports.
As a support, both an intermediate rack installed in the span and a Mauerlat or truss truss are taken directly. Ridge run can also be assessed as a possible support, but the areas of joining of the rafter legs are better placed lower along the slope, i.e. where the minimum load is imposed on the system.
Splice options for rafters
except precise definition places for mating two parts of a system element, you need to know how the rafters are properly lengthened. The method of forming the connection depends on the lumber selected for the construction:
- Bars or log. Build up with an oblique cut formed in the joint zone. For reinforcement and to prevent rotation, the edges of both rafters cut at an angle are bolted together.
- Planks sewn in pairs. They are spliced with the arrangement of the docking lines at random. The connection of two superimposed parts is made with nails.
- Single board. The priority is splicing with a frontal stop - by joining the butt-cut parts of the rafter leg with the imposition of one or a pair of wooden or metal linings. Less often, due to the insufficient thickness of the material, an oblique cut is used with fastening with metal clamps or traditional nail striking.
Let us consider in detail the indicated methods in order to understand in depth the process of increasing the length of the rafters.
Option 1: Oblique cut method
The method involves the formation of two inclined cuts or cuts arranged on the side of the conjugation of the rafter leg parts. The planes of the cuttings 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 gaps and leaks with wood wedges, plywood or metal plates. It will not work to fit and correct the flaws. It is better to accurately measure and draw the cut lines in advance, according to the following standards:
- The depth is determined by the formula 0.15 × h, where h denotes the height of the bar. 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 place for placing the docking section is found according to the valid for all types rafter frames the formula 0.15 × L, in which the value of L represents the size of the span covered by the rafters. The distance is measured from the center of the support.
When making an oblique cut, parts from a bar 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 crumpling at the mounting location, wide metal washers are placed under the nuts.
If a board is connected using an oblique cut, then additional fixation is made using clamps or nails.
Option 2: Bundling the planks
In the case of using the joining 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 at an estimated distance of 0.21 × L, where L denotes the length of the span to be covered. Fixation is carried out with nails installed in a checkerboard pattern.
Backlash and gaps are also unacceptable, but it is easier to avoid them 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 unnecessary holes, the number of points of the fasteners to be installed should be accurately calculated.
Nails with a foot section of 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 the board does not split along the fibers when joining. The exception is hardware with a cruciform section, which, regardless of size, can be simply driven into wooden parts.
To ensure sufficient strength in the rallying zone, the following conditions must be met:
- Fasteners are placed every 50 cm along both edges of the spliced boards.
- Along the end connections, nails are placed in increments of 15 × d, where d is the diameter of the nail.
- Smooth round, screw and threaded nails are suitable for joining the board at the mating point. However, threaded and screw options in priority, because they have much higher pull-out strength.
Note that the joining of the rafters by rallying is acceptable in the case of an element made of two sewn boards. As a result, both joints are overlapped by a solid piece of lumber. The advantages of the method include the size of the span to be covered, which is impressive for private construction. Similarly, you can build rafter legs if the distance from the top to the bottom support reaches 6.5 m.
Option 3: Headrest
The method of frontal rafter extension consists in butt-joining of the connected parts of the rafter leg with fixing the section with nails, pins or bolts through the overlays installed on both side planes.
To eliminate backlash and deformation of the extended rafter leg, you must adhere to the following rules:
- The edges of the board to be joined must be flawlessly trimmed. Gaps of any size along the connection line must be eliminated.
- The length of the overlays is determined by the formula l = 3 × h, i.e. they must be at least three board widths. Usually the length is calculated and selected based on the number of nails, the formula is given to find out the minimum length.
- The 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 driven into the lining in two parallel rows with a staggered "spread" of fastening points. In order not to damage the lining thin in relation to the main lumber, the number of attachment points is calculated with a reference point for the resistance of the nails to the shear force acting on the legs of the hardware.
When the joint of the rafter parts is located directly above the support, there is no need for nail break calculations to fix the linings. True, in this case, the joined leg will work as two separate beams for both deflection and compression, i.e. according to the normal scheme, you will have to calculate bearing capacity for each of the constituent parts.
If steel rod bolts or non-threaded rods, pins, when joining a thick board or timber are used as fasteners, the threat of deformation will be completely eliminated. In fact, even some gaps in the joining of the ends can be ignored, although it is still better to avoid such flaws.
When using screws or screws, holes are pre-drilled for their installation, the diameter of the holes is 2 - 3 mm less than the same size of the fastener legs.
In the production of frontal rafter joints, it is necessary to strictly observe the calculated installation step, the number and diameter of the fasteners. Splitting of wood can occur if the distance between the anchoring points is reduced. If the holes for the fasteners are larger than the prescribed sizes, the rafters will be deformed, and if less, the lumber will split during the installation of the fasteners.
Elongation with compound rafters
To connect and increase the length of the rafters, there is still a very interesting way: build-up with two boards. They are sewn to the side planes of the single element being extended. A gap remains between the enlarged parts, equal to the width of the top board.
The gap is filled with scraps of equal thickness, set at intervals of not more than 7 × h, where h is the thickness of the board to be extended. The length of the spacer bars inserted into the lumen is at least 2 × h.
Extension with two stackable boards is suitable for the following situations:
- The device of a layered system along two side girders, 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 defining an inclined rib of hip and half-hip structures.
- Construction sloping roofs... The strapping of the lower tier of the rafters is used as a support for the connection.
The calculation of fasteners, fixing of spacer bars and connection of boards is carried out by analogy with the above methods. For the manufacture of spacer bars, trimming of the main lumber is suitable. As a result of the installation of these inserts, the strength of the prefabricated rafter increases significantly. Despite significant material savings, it works like a solid beam.
Video about the methods of building rafters
Demonstration of basic techniques for splicing structural elements rafter system:
A video with a step-by-step process for connecting the rafter parts:
Video example of one of the ways to connect sawn timber:
Compliance with the technological requirements, according to which the rafters are spliced along the length, guarantees the trouble-free operation of the structure. Extension methods reduce roof construction costs. One should not forget about preliminary calculations and preparation for making connections so that the result of the effort becomes perfect.
All photos from the article
In this article, we will give an overview of what are possible options for connecting wood products. And there are a great many such ways, from simple connection end-to-end to the most complex connection " dovetail". It is important to remember that not all of them can be done independently, but the information below will definitely not be superfluous.
Reliable coupling is a guarantee of strength and reliability for any structure
We list the acceptable options
All of them are distinguished by their strength and complexity, for example, the cabinet body is assembled with a seam or butt joint, less often they use a "groove" or "mustache" alignment. But for the manufacture of a door frame or panel, the skill of the spike joint is useful.
Listed below are the ways to join wooden parts.
Butt joint of parts
Butt registration is called edge pinning. For this, fasteners and glue are usually used. But the butt joint is not very reliable, so it should be strengthened, which is not so difficult to do.
It is desirable to strengthen the fastening "end-to-end" metal mount: corners and screws
This method is commonly used when assembling a cabinet front frame, where strength is not important because the frame parts are securely attached to the cabinet itself. Compound wooden structures“End-to-end” is usually reinforced with lamellas or dowels, which are able to combine separate parts during gluing.
Fastening of parts "in a mustache"
This combination has some differences from the previous one. When gluing the surface, the parts are beveled at an angle of 45 ° with respect to the axis. The connection of wooden parts "in a mustache" must also be strengthened with additional fasteners.
For your information! Usually, this method of joining is used when it is necessary to join two pieces of molding in a corner.
Strengthening the connection of wood parts
As mentioned above, you can strengthen it with ordinary wooden dowels. Peg fortifications are usually made with the help of two pegs glued into one and the other end of the crossbar, in vertical posts, into their corresponding slots. There is a specific instruction for making such connections:
We mark the nests for the dowels:
- For clear marking, it is necessary to attach the parts to be fastened to each other.
- Draw a line with a pencil, marking the places for the dowels.
- Extend a line to the edge of each of the blanks using a square.
- We drill out the nests for the dowels:
- In order for the nest to be located exactly in the middle wooden parts, you must use a jig for drilling.
- In order for the socket to have the required depth, it is necessary to use a stopper sleeve.
Advice! If you do not have a locking collar, you can replace it by slipping a small piece of plastic over the drill bit.
- We collect the details:
- It is necessary to apply glue to the dowel and insert it into the corresponding slot of the first part.
- We connect the parts together.
- Clamp.
- We leave for a while to allow the glue to dry.
Strengthening the connection with lamellas
When comparing the types of joints of wooden structures, lamellar joining certainly wins. Let the price of such connections be a little higher, but they are very easy and convenient to work with.
Lamellas are compressed wood in the form of flattened balls. The nests for such balls are cut out using a special lamellar machine. In this case, the hole turns out perfect shape... And due to the fact that the lamellas are slightly shorter than the nest, the alignment of parts during gluing is more accurate. It is very uncomfortable.