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. Skate run can also be evaluated 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
In addition to accurately determining the location for pairing 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 at a calculated 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 butt 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, which is 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 another 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.
Due to the limited size of the tree, creating from it building structures large spans or heights is impossible without connecting individual elements. Connections wooden elements to increase the cross section of the structure is called rallying, and to increase their longitudinal length - splicing, at an angle and attaching to the supports - anchoring.
Increasing the workpieces in length is called splicing. The increase in blanks along the section is called rallying. Connections wooden structures classified according to various features. For example, by the type of work of the element and the work of the connection itself (connections on stretched bonds, connections on pliable bonds).
By the nature of the work, all the main connections are divided into:
- without special connections (frontal stops, cuts);
- with compressive bonds (shoe keys);
- with bonds working in bending (bolts, rods, nails, screws, plates);
- with ties working in tension (bolts, screws, clamps);
- with shear-shear bonds (adhesive joints).
According to the nature of the work of the joints of wooden structures, they are divided into pliable and rigid. Compliant are made without the use of adhesives. Deformations in them are formed as a result of leaks.
It is customary to distinguish between three groups of joints of wooden structures:
- Contact connections (without the use of working mechanical connections: notches and other "end-to-end" connections)
- Connections using mechanical connections (dowel: bolted, nailed; keyed, connections on washers, dowel plates, etc.)
- Adhesive and combined type joints
Connection Requirements
1. Reliability. In particular, it is recommended to minimize unfavorable (unreliable) types of work of wood in joints (work of wood for chipping, crushing across the fibers, stretching across the fibers). The so-called principle of fragmentation is closely related to the concept of reliability: "the smaller the connections and the more of them, the higher the reliability of the connection." In other words, ten bolts small diameter it is preferable to use one bolt at the same cost of metal, since in the first case the wood works mainly on crushing (“reliable” type of wood work), and in the second case - on shear (“unreliable” type of wood work)
2. Strength. In particular, the desire for equal strength with the main part of the structure, the absence of weakening (holes) in the section.
3. Reduced labor intensity in the manufacture and installation of structures (manufacturability)
4. Deformability. For example, in contact joints, the value of the ultimate deformation of the collapse is limited
The work of wood in joints. Types of wood work for crushing across and at an angle to the fibers, as well as for chipping, are unfavorable. It is these types of wood work that accompany the work of joints, and it is they that are most often a direct or indirect cause of structural failure.
Collapse. The work of wood on crushing across and at an angle to the fibers is characterized by increased deformability and low strength. The “force-strain” diagram during the collapse of wood across the fibers reflects the effect of flattening of tubular wood cells. There are three types of crush:
- n collapse over the entire surface (R cm = 1.8 MPa, the most unfavorable type of collapse)
- n collapse into parts of length
- n collapse on part of the surface (under the washers) (R cm = 4 MPa)
The increase in strength in the latter case is explained by the reinforcing effect of the wood fibers surrounding the crushing area.
Main empirical dependences at crushing.
Dependence of resistance on the angle between the direction of the force and the direction of the wood fibers
R cm, a \u003d R cm, 0 / (1 + (R cm, 0 / R cm, 90 - 1) sin 3 a
Dependence of resistance on the length of the crush area
R cm, L = R cm (1 + 8 / (L cm + 1.2);[cm]
chipping. The work of wood for shearing (shear) is characterized by low strength and brittle fracture. In a "pure" form, chipping practically does not occur. Usually this type of stress state is combined with others (tension and compression across the fibers).
There are two types of chipping: one-sided chipping and two-sided chipping. In the first case, the strength is less, since the degree of uneven distribution of stresses is higher. In the calculations, a uniform distribution of stresses along the length of the shear area is conditionally assumed. Therefore, the concept of "average shear resistance" is introduced.
R sk,av = R sk,av / (1+ bL/e)
The formula reflects the physical essence of the shearing phenomenon: coefficient b takes into account the type of shearing, and the L/e ratio takes into account the effect of normal stresses accompanying shearing. R sk, sr- resistance to chipping with a uniform distribution of shear stresses.
The dependence of chipping resistance on the angle between the direction of the force and the direction of the wood fibers has the form:
R sc, a = R sc, 0 / (1 + (R sc, 0 / R sc, 90 - 1) sin 3 a
| Purpose of connections |
In designs manufactured in the factory |
In structures manufactured using lightweight means of mechanization. |
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dried lumber |
from beams and boards |
from local roundwood |
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| Rallying | With waterproof adhesive | On oak or birch Derevyagin plates; on nails and dowel pins made of round steel, of plastics | On pads, bolts, brackets |
| Building | |||
| In a tight joint |
frontal stop |
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| In a stretched joint | Serrated joint on waterproof glue | Wooden slips and spacers on dowels made of round steel, on bolts, nails | Wooden plates on round steel dowels, bolted |
| Overlays with glued washers | Overlays with washers on deaf dowels and screws | Steel overlays with washers on deaf dowels and capercaillie | |
| Nodal adjunctions | |||
| Compressed rods | Frontal and three-frontal emphasis | Frontal notch; frontal and three-frontal emphasis | |
| tension rods | Steel bands or clamps through linings and gaskets on glue or dowels and bolts | Steel bands or clamps through linings and gaskets on nails or dowels and bolts | Steel strands or clamps through the lining on the dowels and bolts; cross profile brackets |
| Rods that perceive alternating forces | Center bolt through glue washers | Pins, cross profile pins, nails | Nagels, pins of a cross profile |
| Center bolt, through claw washers, washers on blind dowels, screws, cross pins or nails | Center bolt through washers on deaf dowels, capercaillie or cross profile pins | ||
The main types of connections (when rallying)
1. Connections on cuts working without special working connections. Connections are thrustless; only auxiliary cross ties are required (obsolete type of rallying)
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| Connection diagram on cuts | |
| The main area of application of cuts is the nodal connections in block and log trusses, including in the support nodes of the junction of the compressed upper chord to the stretched lower chord.
The elements of wooden structures (d.c.) connected by a notch must be fastened with auxiliary connections - bolts, clamps, brackets, etc., which should be calculated mainly for mounting loads |
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2. Connections doweled working mainly for compression(c), similar to the compressed braces of the truss (c). Spacer Q w is perceived by working cross-links (p) - bolts, clamps, etc., working on stretching similar to stretched truss posts (p)
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Dowel connection diagram |
3. Connections on dowels working mainly for bend(and), similarly to the racks (and) of a diagonal truss. Connections are non-expansion, only auxiliary cross braces are required
4. Connections on glue working mainly on shift(τ), similar to a weld in metal beams. Cross-linking is usually provided by the adhesive line itself.
Width Connections
When joining narrow boards, shields of the required dimensions are obtained.
There are several ways to connect.
1)Connection on a smooth fugue;
With this connection method, each rail or board is called a plot, and the seam that is formed as a result of the connection is called a fugue. The quality of the jointing is indicated by the absence of gaps between the joints of the edges of adjacent plots.
2)Rail connection;
Along the edges of the plots, grooves are selected and inserted into their rails, fastening the plots together. The thickness of the lath and the width of the groove should not exceed 1/3 of the thickness of the board.
3) Connection in a quarter;
In fastened plots, quarters are selected along the entire length. In this case, the dimensions of the quarter, as a rule, do not exceed half the thickness of the plot.
3) Tongue and groove connection (rectangular and triangular);
This type of connection provides the plot with a groove on one side and a ridge on the other. The comb can be either rectangular or triangular, but the latter is rarely used because its strength is slightly worse. The tongue and groove connection is quite popular and is often used by parquet manufacturers. The disadvantage of such a connection is considered to be less economical, since more boards are used.
4) Dovetail connection;
This type of fastening is a bit similar to the previous one, only the comb has a trapezoidal shape. Well, hence the name.
Connection of boards into shields: a - on a smooth fugue, b - in a quarter, c - on a rail, d - in a groove and a rectangular comb, e - in a groove and a triangular comb, e - in a dovetail
Also, when assembling the shields, dowels, tips in the groove and a comb with the rail pasted into the end are used. Among the glued rails, there are triangular, rectangular and glued ones, and when using the dowel, the dovetail groove is mainly chosen. All this is necessary for reliable fastening of the shield.
Shields: a - with dowels, 6 - with a tip in the groove and comb, c - with a glued rail in the end, d - with a glued triangular rail, e - with a glued triangular rail.
Length connection
Among popular types connections along the length can be distinguished: end-to-end, on the "mustache", in the groove and comb, on the toothed adhesive connection, in a quarter and on the rail. The most popular gear connection, because it has the best strength.
The connection of the bars along the length: a - end-to-end, b - in the groove and ridge, c - on the mustache, d, d - on the toothed adhesive connection, e - in a quarter, g - on the rail
There is also splicing, when longer segments are joined together. This can happen in several ways. For example, half a tree, oblique cut, oblique and straight overhead lock, oblique and straight tension lock and end-to-end. When choosing half-wood splicing, the required joint length should be 2 or 2.5 times the thickness of the timber. For greater reliability, dowels are used, for example, this can be found in the construction of cobbled houses.
When using an oblique cut with end trimming, the dimensions are 2.5 - 3 of the thickness of the beam and are also fastened with dowels.
The connection with a straight or oblique overhead lock is used in structures in which tensile forces are present. A straight overhead lock is located on a support, and an oblique one can be placed at the supports.
If you decide to use a bevel cut with end trimming, then the connection should have 2.5 or 3 bar thicknesses. In this case, the same dowels are used.
When docking with a straight or oblique tension lock, you don’t have to worry about strength, but such a connection is difficult to manufacture, and when the wood dries out, the wedges are weakened, so this connection method is not suitable for serious structures.
Butt splicing is when the two ends of the beam are placed on a support and securely connected with staples.
Splicing: a - half-tree, b - oblique cut, c - straight overhead lock, d - oblique overhead lock, d - straight tension lock, e - oblique tension lock, g - end-to-end
The connection of beams or logs can be found when building walls or in the upper or lower trim in frame houses. The main types of compounds are half a tree, half-paw, spiked and corner frying pan.
A half-tree cut is considered to be a cutting or cutting of half the thickness at the ends of the bars, after which they are connected at an angle of 90 degrees.
The half-lap connection is formed when cutting at the ends of the bars of inclined planes, due to which the bars are tightly connected. The slope size is determined by the formula.
Cutting with a corner frying pan is very similar to cutting in half a tree, but hallmark is that with such a connection, one of the bars loses a small part in width.
Building
The extension of beams and logs is the connection of elements in height, which is often used in the construction of poles or a match.
There are several types of extensions:
1) butt with a hidden spike;
2) end-to-end with a through comb;
3) half-wood with bolting;
4)half a tree with fastening with clamps;
5) half-tree with fastening with strip steel;
6) oblique cut with fastening with clamps;
7) butt with overlays;
8) bolting;
The length of the joints is usually 2-3 of the thickness of the joined beams or 2-3 of the diameter of the logs.
Connection of logs during extension: a - end-to-end with a hidden spike, b - end-to-end with a through ridge, c - half-tree with fastening with bolts, d - half-tree with fastening with strip steel, e - half-tree with fastening with clamps, e - oblique cut with fastening with clamps, g - end-to-end with overlays and fastening by bolts
spike connection
When spike knitting bars, a spike is cut on one, and an eye or nest is made on the other. Spike knitting of bars is often used to create joinery, doors, windows or transoms. All connections are made with glue. You can use not only one, but two or more spikes. The more spikes, the larger the bonding area. This type of connection can be divided into corner end, corner middle and corner box.
At the corner end connection, an open through spike is used (one, two or three), a spike with a dark through and blind, plug-in dowels. Angular middle connections can be found on the doors. Angled middle and end can additionally use nails, screws, dowels or bolts.
corner spike connections: a - open through single spike UK-1, b - open through double spike UK-2, c - open through triple spike UK-3, d - blind spike with semi-darkness UK-4, e - through spike with semi-darkness UK-5 , e - blind spike with darkness UK-6; with a plug-in flat stud UK-10, l - through on the mustache with a plug-in flat stud UK-11
Angled middle joints on the spike: a - blind type US-1, b through US-2, c - double through US-3, d - blind into the groove and crest US-4, e - blind into the groove US-5, e - blind on round dowels US-6
The toughest joiners and carpenters are said to be able to build a house without a single nail. Japanese artisans, even amateurs, are just one of those.
A few years ago, a young automotive industry worker, enthusiastic, fell into the hands of 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 schemes for making fasteners in the book. Then the guy decided to draw them himself.
To model and animate details, he used free service Fusion-360. 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 of detachable connections.
The variety of fasteners is really 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 an electric tool.
But even if manual labor doesn't inspire you at all, you'll probably enjoy watching GIFs. The way the details interlock with each other is mesmerizing.
If you take a closer look at the massive antique furniture or doors, a beautiful and uniform texture catches the eye: the product seems to be carved from one large piece of wood. Only upon closer examination, it is possible to single out individual planks, which make up the overall surface.
Previously, furniture was not made, as it is done today, from thick boards. It's just that the carpenters were more skilled. From many thin boards they could make large panel with perfect smooth surface. Although the tree is known to live its contented turbulent life even when it is no longer rooted to the ground. It is exposed to temperature and humidity, as well as mechanical stress, as a result of which it can unexpectedly show its “character”.
The technique of joining boards so that they remain even and smooth for a long time is called butt-to-length joining.
It is necessary to carefully consider each plank and compare its texture with the texture of neighboring parts: the wood fibers of each part must pass into reverse direction compared to the fibers of neighboring boards. So one board "locks" the other.
The nature of the texture depends on which part of the trunk the board is cut from - from the middle or the extreme. The boards can be laid out in different ways: in one case, so that the surface will seem like a cut of one trunk, in the other, by mixing the boards, create an unusual pattern.
But in any case, when fitting, the boards should be placed against each other so that a wavy pattern is obtained. Therefore, it is very difficult to achieve the effect of a “whole tree” and at the same time “lock” the tree. After all, alternately the front (facing the core of the tree), then the wrong side (facing the bark) side of the boards are visible.
In order for the boards to fit snugly together along the length, the edges must be absolutely straight. It is necessary to vertically fix the board between two guide boards and process the surface with a planer. Treat the wood immediately, without delay - when the humidity changes, it can deform again.
On the tabletop, assembled from boards, they used to judge the skill of the carpenter. The ability to connect boards end-to-end along the length can come in handy today. We will show and tell you how it's done.
Marking and gluing
How to properly connect the boards along the length of the insert strip
The plank reinforces the joint along its entire length, while performing two functions: it doubles the area of the joint areas covered with glue, as it penetrates inside both boards, which gives the joint additional strength, and due to the opposite direction of the fibers in the plank in relation to the fibers in the main parts connection is more resistant to stress.
Use of plywood
For a plank that must be very thin, the most suitable material- plywood. If, for example, you take a plank of solid wood, then the arrangement of the fibers in the plank and the boards will be parallel. In this case, high bond strength will be achieved, but the bar itself will not withstand the load and will break if the boards begin to sag. You can use a bar with a transverse direction of the fibers. It well withstands the load during the deflection of the boards and gives greater strength to the connection, but such strips are limited in length and extremely unreliable under longitudinal loads. The multi-layered plywood compensates for the shortcomings of the solid wood planks, providing strength to the joint.
An alternative to the rail is plug-in spikes, which are placed with a landing on glue at a distance of 10-20 cm from each other. First, a hole for the spikes is drilled in one board, then the location of the spikes on the other board is marked with special markers.
The left bar is longer, the middle one is thicker than necessary, the right one is done correctly. It should be shorter than the overall height of the grooves to leave room for the adhesive.
Blind connection using a plywood plank. The bar is completely hidden, and the boards at the ends remain intact.
A myriad of connections can be used to connect wooden parts. The names and classifications of joinery-carpentry joints tend to vary considerably by country, region, and even school of woodworking. The craftsmanship lies in the fact that the precision of execution provides a correctly functioning connection that is able to withstand the loads intended for it.
Initial information
Connection categories
All connections (in carpentry they are called bindings) of wooden parts according to the scope can be divided into three categories (foreign version of the classification):
- box;
- frame (frame);
- for splicing/splicing.
Box connections are used, for example, in the manufacture drawers and arrangement of cabinets, frame are used in window frames and doors, and rallying / splicing serves to obtain parts of an increased size in width / length.
Many joints can be used in different categories, for example, butt joints are used in all three categories.
Material preparation
Even planed lumber may need some preparation.
- Trim the material with a margin in width and thickness for further planing. Don't cut to length yet.
- Choose the best quality layer - the front side. Plane it along the entire length. Check with a straightedge.
After the final alignment, make a mark on the front side with a pencil. - Plane the front - clean - edge. Check with a straightedge, as well as a square against the front side. Smooth out warp by planing. Mark a clean edge.
- Use a thickness gauge to mark the required thickness along all edges of the part contour. Plan up to this risk. Check with a straightedge.
- Repeat the operation for the width.
- Now mark up the length and actual connections. Mark from the front side and a clean edge.
Lumber marking
Be careful when marking lumber. Make sufficient allowances for kerf width, planing thickness and joining.
All readings are taken from the front side and the clean edge, on which put the appropriate marks. In frame and cabinet designs, these marks should face inward to improve manufacturing accuracy. For ease of sorting and assembly, number the parts as they are manufactured on the front side so that, for example, it indicates that side 1 is connected to end 1.
When marking identical parts, carefully align them and make markings on all workpieces at once. This will ensure that the markup is identical. When marking profile elements note that there may be "right" and "left" parts.
Butt joints
These are the simplest of joinery and carpentry joints. They can be included in all three categories of compounds.
Assembly
The butt joint can be reinforced with nails hammered at an angle. Drive the nails in randomly.
Trim the ends of the two pieces evenly and join them. Secure with nails or screws. Before this, glue can be applied to the parts to enhance fixation. Butt joints in frame structures can be reinforced with a steel plate or corrugated key with outer side or a wooden block fixed from the inside.
Nail / dowel connections
Wooden dowels - today they are increasingly called dowels - can be used to strengthen the connection. These plug-in round spikes increase shear (shear) strength and, with adhesive, hold the assembly in place more securely. Dowel joints can be used as frame joints (furniture), drawer joints (cabinets) or for splicing/joining (panels).
Assembling the dowel joint
1. Carefully cut out all the components to exactly the right dimensions. Mark the position of the crossbar on the face and clean edge of the upright.
2. Mark the center lines for the dowels at the end of the crossbar. The distance from each end must be at least half the thickness of the material. A wide bar may require more than two dowels.
Mark the center lines for the pins on the end of the crossbar and transfer them to the rack using the square.
3. Lay the upright and bar face up. On the square, transfer the center lines to the rack. Number and label all connections if there are more than one pair of uprights and crossbars.
4. Transfer this marking to the clean edge of the post and the ends of the crossbar.
5. From the front side with a thickness gauge, draw a risk in the center of the material, crossing the marking lines. This will mark the centers of the holes for the dowels.
With a thickness gauge, draw a center line, crossing the marking lines, which will show the centers of the dowel holes.
6. An electric drill with a twist drill or hand drill with a spatula drill, drill holes in all parts. The drill must have a center point and cutters. The hole across the fibers should be about 2.5 times the diameter of the dowel, and the hole at the end should be about 3 times the depth. For each hole, make an allowance of 2 mm, at this distance the dowel should not reach the bottom.
7. Remove excess fibers from the top of the holes with a countersink. This will also make it easier to install the dowel and create space for the adhesive to secure the connection.
Nagels
The dowel must have a longitudinal groove (now standard dowels are made with longitudinal ribs), through which excess glue will be removed when assembling the joint. If the dowel does not have a groove, then cut it flat on one side, which will give the same result. The ends should be chamfered to facilitate assembly and prevent damage to the hole by the dowel. And here, if the dowels do not have a chamfer, make it with a file or grind the edges of their ends.
Use of pins for marking dowels
Mark and drill the crossbars. Insert special dowel pins into the pin holes. Align the crossbar with the markings of the rack and squeeze the parts together. The tips of the teats will make marks on the rack. Drill holes through them. Alternatively, you can make a template out of a wooden block, drill holes in it, fix the template on the part and drill holes for the dowels through the holes in it.
Using a jig for a dowel connection
The metal jig for dowel connections greatly facilitates the marking and drilling of holes for dowels. In box joints, the jig can be used at the ends, but it will not work on the face of wide panels.
conductor for nail joints
1. Mark center lines on the front of the material where the dowel holes are to be. Select a suitable drill guide bushing and insert it into the jig.
2. Align the alignment marks on the side of the jig and secure the slide bearing of the guide bush.
3. Install the jig on the part. Align the center notch with the center line of the dowel hole. Tighten.
4. Install the drilling depth gauge on the drill at the desired location.
Rallying
To obtain a wider wooden part, you can use dowels to connect two parts of the same thickness along the edge. Place two boards with the wide sides together, line up the ends exactly, and clamp the pair in a vise. On a clean edge, draw perpendicular lines indicating the center lines of each dowel. In the middle of the edge of each board, with a thickness gauge, make risks across each previously marked center line. The intersection points will be the centers of the dowel holes.
The pin connection is neat and strong.
Flange / mortise connections
A notch, tie-in or groove connection is called a corner or middle connection, when the end of one part is attached to the layer and another part. It is based on a butt joint with an end cut made in the face. It is used in frame (house frames) or box (cabinets) connections.
Types of mortise / mortise connections
The main types of butt joints are the dark/semi-dark T-joint (often this term is replaced by the term "flush/semi-flush"), which looks like a butt joint, but is stronger, corner cut(corner connection) in a quarter and a corner cut in the dark / semi-dark. A corner cut into a rebate and a corner cut into a rebate with darkness / semi-darkness are made in the same way, but the rebate is made deeper - two-thirds of the material is selected.
Making a cut
1. Mark a groove on the face of the material. The distance between the two lines is equal to the thickness of the second part. Continue the lines on both edges.
2. Use a thickness gauge to mark the depth of the groove between the marking lines on the edges. The depth is usually made from one quarter to one third of the thickness of the part. Mark the waste part of the material.
3. C-clamp fasten the item securely. Saw through the shoulders on the waste side of the marking lines to the desired depth. If the groove is wide, make additional cuts in the waste to make it easier to remove the material with a chisel.
Saw close to the marking line on the return side, making intermediate cuts with a wide groove.
4. Working with a chisel on both sides, remove excess material and check the flatness of the bottom. To level the bottom, you can use a primer.
With a chisel, remove the waste, working from both sides, and level the bottom of the groove.
5. Check the fit, if the piece is too tight it may need to be trimmed. Check for perpendicularity.
6. The notch connection can be strengthened by one of the following methods or a combination of them:
- gluing and clamping until the adhesive sets;
- screwing with screws through the face of the outer part;
- nailing at an angle through the face of the outer part;
- nailing obliquely through the corner.
The notch connection is strong enough
Tongue and groove connections
This is a combination of a quarter cut and a rebate cut. It is used in the manufacture of furniture and the installation of slopes of window openings.
Making a connection
1. Make the ends perpendicular to the longitudinal axes of both parts. On one part, mark the shoulder by measuring the thickness of the material from the end. Continue marking on both edges and front side.
2. Mark the second shoulder from the end, it should be at a distance of one third of the thickness of the material. Continue on both edges.
3. Use a thickness gauge to mark the depth of the groove (one third of the thickness of the material) on the edges between the shoulder lines.
4. With a hacksaw with a butt, saw through the shoulders to the risks of the thicknesser. Remove waste with a chisel and check for evenness.
5. Using a thickness gauge with the same setting, mark a line on the back and on the edges of the second part.
Tips:
- Tongue and groove type joints can be easily made with a router and an appropriate guide, either for the groove only or for both the groove and rebate. Recommendations for correct work with a cutter, see p. 35.
- If the comb is too tight in the groove, trim the front (smooth) side of the comb or sand with sandpaper.
6. From the front side with a thickness gauge, make markings on the edges towards the end and on the end itself. Saw along the lines of the thickness gauge with a hacksaw with a butt. Do not cut too deep as this will weaken the connection.
7. Working with a chisel from the end, remove the waste. Check fit and adjust if necessary.
Half tree connections
Half-timber connections refer to frame connections, which are used to connect parts in layers or along an edge. The connection is made by taking the same amount of material from each part so that they are joined flush with each other.
Types of joins in half-tree
There are six main types of connections in the half-tree: transverse, angular, flush, angular mustache, dovetail and splicing.
Making a half-tree gusset
1. Align the ends of both parts. On the top side of one of the parts, draw a line perpendicular to the edges, stepping back from the end to the width of the second part. Repeat on the underside of the second piece.
2. Set the thicknesser at half the thickness of the parts and draw a line on the ends and edges of both parts. Mark the waste on the top side of one and the bottom side of the other part.
3. Clamp the part in a vise at an angle of 45° (face vertically). Carefully cut along the grain close to the thicknesser line on the back side until the saw is diagonal. Flip the piece over and continue sawing gently, gradually raising the saw handle until the saw lines up with the shoulder line on both edges.
4. Remove the part from the vise and place it on the face. Press it firmly against the hutch and clamp it with a clamp.
5. Saw through the shoulder to the previous cut and remove the waste. Align all irregularities in the sample with a chisel. Check the accuracy of the cut.
6. Repeat the process on the second part.
7. Check the fit of the parts and, if necessary, level with a chisel. The connection must be rectangular, flush, without gaps and backlashes.
8. The connection can be strengthened with nails, screws, glue.
Corner joints on the mustache
Corner joints on the mustache are made using the bevel of the ends and hide the end grain, and also aesthetically correspond more to the angular rotation of the decorative overlay.
Types of corner connections on the mustache
To perform bevel ends in corner connection the angle at which the parts meet is divided in half. In a traditional joint, this angle is 90°, so each end is cut at 45°, but the angle can be either obtuse or sharp. In uneven corner joints, parts with different widths are connected to the mustache.
Making a corner connection
1. Mark the length of the parts, keeping in mind that it should be measured on the long side, as the bevel will reduce the length inside the corner.
2. Having decided on the length, mark the line at 45° - on the edge or on the face, depending on where the bevel will be cut.
3. With a combination square, transfer the markup to all sides of the part.
4. When hand cutting use a miter box and a backed hacksaw or hand miter saw. Press the part firmly against the back of the miter box - if it moves, the bevel will turn out uneven and the joint will not fit well. If you are sawing freehand, be careful not to deviate from the marking lines on all sides of the part. A miter saw, if you have one, will make a very neat bevel.
5. Place the two pieces together and check the fit. You can correct it by trimming the surface of the bevel with a planer. Firmly fix the part and work with a sharp planer, setting a small overhang of the knife.
6. The connection should be knocked down with nails through both parts. To do this, first lay the parts on the face and drive nails into the outer side of the bevel so that their tips slightly show out of the bevels.
Start nails in both parts so that the tips protrude slightly from the surface of the bevel.
7. Apply glue and squeeze the joint tightly so that one part protrudes slightly - overlaps the other. First, drive nails into the protruding part. Under hammer blows when driving nails, the part will move slightly. Surfaces must be level. Nail the other side of the connection and sink the nail heads. Check squareness.
Drive the nails into the protruding piece first, and the impact of the hammer will move the joint into position.
8. If there is a small gap due to uneven workmanship, smooth the connection on both sides with a round screwdriver rod. This will move the fibers, which will close the gap. If the gap is too large, then you will either have to redo the connection, or close the gap with putty.
9. To strengthen the corner connection, the mustache can be glued inside the corner wooden block if it is not visible. If important appearance, then the connection can be made on a plug-in spike or secured with veneer dowels. Pins or lamellas (standard flat studs) can be used inside the flat joints.
Splicing on a mustache and connection with cutting
Splicing on a mustache connects the ends of parts located on the same straight line, and a connection with a cut is used when it is necessary to connect two profile parts at an angle to each other.
Mustache splicing
When splicing with a mustache, the parts are connected by the same bevels at the ends in such a way that the same thickness of the parts remains unchanged.
Cutting connection
Connection with cutting (cutting, fitting) is used when it is necessary to connect two parts with a profile in the corner, for example, two skirting boards or cornices. If the part moves during its fastening, then the gap will be less noticeable than with a corner joint.
1. Fix the first skirting board in place. Move the second plinth close to it, located along the wall.
Fasten the first skirting board in place and press the second skirting board against it, aligning it with the wall.
2. Swipe along the profiled surface of the fixed plinth with a small wooden block with a pencil pressed against it. The pencil will leave a marking line on the plinth to be marked.
With a bar with a pencil pressed against it, attached with a tip to the second plinth, draw along the relief of the first plinth, and the pencil will mark the line of the cut.
3. Cut along the marking line. Check fit and adjust if necessary.
Complex profiles
Lay the first plinth in place and, placing the second plinth in the miter box, make a bevel on it. The line formed by the profile side and the bevel will show the desired shape. Cut along this line with a jigsaw.
Eyelet connections
Eyelet connections are used when it is required to join intersecting parts located "on the edge", either in the corner or in the middle (for example, the corner of the window frame or where the leg of the table connects to the crossbar).
Eyelet connection types
The most common types of eye connections are angle and tee (T-shaped). For strength, the connection must be glued, but you can strengthen it with a dowel.
Making an eyelet connection
1. Mark out in the same way as for but divide the thickness of the material by three to determine one third. Mark the waste on both parts. On one part, you will need to choose the middle. This groove is called an eyelet. On the second part, both side parts of the material are removed, and the remaining middle part is called a spike.
2. Saw along the fibers to the line of the shoulders along the marking lines on the side of the waste. Cut out the shoulders with a hacksaw with a butt, and you get a spike.
3. Working on both sides, select the material from the eyelet with a chisel/grooving chisel or jigsaw.
4. Check the fit and fine-tune with a chisel if necessary. Apply adhesive to the joint surfaces. Check squareness. Use a C-clamp to clamp the joint while the adhesive cures.
Spike-to-socket connection
Stud-in-socket joints, or simply stud joints, are used when two pieces are joined at an angle or at an intersection. It is probably the strongest of all frame joints in carpentry and is used in the manufacture of doors, window frames and furniture.
Types of spike-to-socket connections
The two main types of stud joints are the usual stud-in-socket connection and the stepped stud-in-socket connection (semi-dark). The spike and socket are approximately two-thirds of the width of the material. The expansion of the nest is made on one side of the groove (semi-darkness), and a spike step is inserted into it from its corresponding side. Semi-darkness helps to prevent the thorn from turning out of the nest.
Standard spike-to-socket connection
1. Determine the connection position on both pieces and mark on all sides of the material. The markup shows the width of the intersecting part. The spike will be at the end of the crossbar, and the socket will go through the post. The spike should have a small allowance in length for further stripping of the connection.
2. Pick up a chisel as close as possible in size to a third of the thickness of the material. Set the thickness gauge to the size of the chisel and mark the nest in the middle of the rack between the previously marked marking lines. Work from the front. If desired, you can set the thickness solution to a third of the thickness of the material and work with it on both sides.
3. In the same way, mark the spike on the butt and both sides to mark the shoulders on the crossbar.
4. Clamp a piece of wood secondary support in a vise high enough to attach the edge-on stand to it. Fasten the post to the support by placing the clamp next to the marking of the nest.
5. Cut out the nest with a chisel, making an inward allowance of about 3 mm from each of its ends so as not to damage the edges when sampling waste. Hold the chisel straight and parallel
its edges are the plane of the rack. Make the first cut strictly vertically, placing the sharpening bevel towards the middle of the nest. Repeat from the other end.
6. Make a few intermediate cuts, holding the chisel at a slight angle and bevel down. Select the waste by using the chisel as a lever. Going deeper by 5 mm, make more cuts and select a waste. Continue until about half the thickness. Flip the part over and work the same way on the other side.
7. After removing the main part of the waste, clean the nest and cut off the allowance left earlier to the marking lines on each side.
8. Cut the spike along the fibers, leading a hacksaw with a butt along the marking line from the side of the waste, and cut out the shoulders.
9. Check fit and adjust if necessary. The shoulders of the cleat must fit snugly against the post, and the joint must be perpendicular and free from play.
10. Wedges can be inserted on both sides of the spike to secure. A gap for this is made in the socket. Working with a chisel from the outside of the nest, widen about two thirds of the depth with a 1:8 slope. Wedges are made with the same slope.
11. Apply glue and press firmly. Check squareness. Apply glue to the wedges and drive them into place. Saw off the tenon allowance and remove excess glue.
Other spike connections
Stud joints for window frames and doors are somewhat different from half-dark stud joints, although the technique is the same. Inside there is a fold and / or an overlay for glass or a panel (panel). When making a connection with a spike into a socket on a part with a seam, make the plane of the spike in line with the edge of the seam. One of the shoulders of the crossbar is made longer (to the depth of the fold), and the second is shorter so as not to block the fold.
Studded joints for parts with overlays have a cut-off shoulder to match the profile of the overlay. Alternatively, you can remove the trim from the edge of the socket and make a bevel or cut to match the counterpart.
Other types of spike-to-socket connections:
- Side spike - in the manufacture of doors.
- A hidden beveled spike in semi-darkness (with a beveled step) - to hide the spike.
- With a spike in the dark (steps of a spike on its two sides) - for relatively wide parts, such as bottom trim(bar) doors.
All these connections can be through, or they can be deaf, when the end of the spike is not visible from the back of the rack. They can be reinforced with wedges or dowels.
Rallying
Wide, high-quality wood is becoming increasingly difficult to find and very expensive. Moreover, such wide boards are subject to very large shrinkage deformations, which makes it difficult to work with them. To connect narrow boards along the edge into wide panels for worktops or workbench covers, rallying is used.
Training
Before starting the actual rallying, you must do the following:
- If possible, select radial sawn boards. They are less susceptible to shrinkage than tangential sawn timber. If boards of tangential sawing are used, then lay their sound side alternately in one and the other side.
- Try not to bundle materials with different ways sawing into one panel.
- In no case do not rally the boards from different breeds wood if not dried properly. They will shrink and crack.
- If possible, arrange the boards with the fibers in one direction.
- Be sure to cut the material to size before stapling.
- Use only good quality glue.
- If the wood will be polished, adjust the texture or color.
Rallying for a smooth fugue
1. Lay all boards face up. To facilitate subsequent assembly, mark the edges with a continuous pencil line drawn at an angle along the joints.
2. Plan straight edges and check the fit to the corresponding adjacent boards. Align the ends or pencil lines each time.
3. Make sure that there are no gaps and that the entire surface is flat. If you squeeze the gap with a clamp or putty it, the connection will subsequently crack.
4. When planing short pieces, clamp the two right sides together in a vise and plan both edges at the same time. It is not necessary to maintain the squareness of the edges, since when docking they will mutually compensate for their possible inclination.
5. Prepare as for a butt joint and apply adhesive. Squeeze with lapping to connect the two surfaces, squeezing out excess glue and helping the surfaces to “stick” to each other.
Other payment methods
Other fusion joints with different amplifications are prepared in the same way. These include:
- with pins (dowels);
- in a groove and a comb;
- in a quarter.
Bonding and clamping
Gluing and fixing glued parts is an important part of woodworking, without which many products will lose strength.
Adhesives
The adhesive reinforces the connection, holding the parts together so that they cannot be easily pulled apart. Be sure to wear protective gloves when handling adhesives and follow the safety instructions on the packaging. Clean the product of excess glue before it sets, as it can dull the planer knife and clog the abrasive of the skin.
PVA (polyvinyl acetate)
PVA glue is universal glue for wood. When still wet, it can be wiped off with a cloth dampened with water. It perfectly sticks together loose surfaces, does not require long-term fixation for setting and sets in about an hour. PVA gives a fairly strong bond and sticks to almost any porous surface. Gives a permanent bond, but is not heat and moisture resistant. Apply with a brush, and on large surfaces, dilute with water and apply paint roller. Since PVA glue has water base, then shrinks when set.
contact adhesive
Contact adhesive sticks together immediately after application and connection of parts. Apply it to both surfaces and when the glue is dry to the touch, join them. It is used for laminate (laminate) or veneer to chipboard. Fixing is not required. Cleaned with solvent. Contact adhesive is flammable. Work with it in a well ventilated area to reduce the concentration of fumes. Not recommended for outdoor use, as it is not moisture and heat resistant.
Epoxy adhesive
Epoxy is the strongest adhesive used in woodworking and the most expensive. It is a two-component resin-based adhesive that does not shrink on setting and softens when heated and does not creep under load. Water-resistant and bonds almost all materials, both porous and smooth, with the exception of thermoplastics such as polyvinyl chloride (PVC) or plexiglass (organic glass). Suitable for outdoor work. In the uncured form, it can be removed with a solvent.
hot glue
Hot melt adhesive bonds almost everything, including many plastics. Usually sold in the form of glue sticks that are inserted into a special electric glue gun for gluing. Apply glue, join surfaces and squeeze for 30 seconds. Fixing is not required. Cleaned with solvents.
Clips for fixation
Clamps come in a variety of designs and sizes, most of which are called clamps, but usually only a couple of varieties are needed. Be sure to place a piece of wood waste between the clamp and the product to avoid denting from applied pressure.
Gluing and fixing technique
Before gluing, be sure to assemble the product “dry” - without glue. Lock if necessary to check connections and dimensions. If everything is fine, disassemble the product, placing the parts in a convenient order. Mark the areas to be glued and prepare the clamps with the jaws/stops set apart to the desired distance.
Frame assembly
Spread the adhesive evenly with a brush on all surfaces to be glued and quickly assemble the product. Remove excess adhesive and secure assembly with clips. Compress the connections with even pressure. The clamps must be perpendicular and parallel to the surfaces of the product.
Position the clamps as close as possible to the connection. Check the parallelism of the crossbars and align if necessary. Measure the diagonals - if they are the same, then the rectangularity of the product is maintained. If not, then a slight but sharp blow to one end of the rack can even out the shape. Adjust clamps if necessary.
If the frame does not lie flat on flat surface, then tap the protruding areas with a mallet through a block of wood as a spacer. If that doesn't work, you may need to loosen the clamps or clamp the wood block across the frame.
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