How to fasten wooden parts without nails, glue and screws. Connections of wooden structures: general information

The tree is widely used in various areas of human household activities. Especially widely wooden structures are used in construction. However, any wooden structures consist of separate parts that must be connected together in one way or another.

There are several types of connections. But you need to learn one rule: before starting work, you need to carefully mark out future cuts and always follow the markup. In the final product, the parts must fit exactly and tightly.

Methods for connecting boards and bars of small length: 1 - "butt" (butt); 2 - "in the groove and crest"; 3 - "on the mustache"; 4, 6 - "toothed" adhesive; 5 - "half a tree"; 7 - "on the rail"; 8 - "direct lock" overhead; 9 - "oblique lock" overhead; 10 - "straight" and "oblique" tension locks.

The simplest and relatively fragile is the "butt" connection. For this connection, the ends of the fastened parts are made clearly rectangular, and the ends are processed with a planer.

The mustache connection is similar to the butt joint, but here the ends of the parts are beveled at an angle of 45o. For accurate marking, a device called a yarunok is used. Such a connection is strengthened with a plywood lining or a metal square. Strengthen the connection "with a mustache" by fastening on the inside of a square or triangular beam.

More durable connections include “overlay” connections by making saw cuts. If the parts to be joined are of the same thickness, then cuts are made on both parts for half of their thickness. In the case when one part is thicker than the other, then the cut is made only in a thicker part. To enhance the strength, the parts are glued and additionally fastened with wooden dowels or screws.

If it is necessary to obtain a T-shaped connection, a half-tree overlay is used. In this case, both parts are cut if they are of the same thickness, or a thicker part is cut off with different thicknesses of the fastened elements.

The most durable connections that have come down to the present time from ancient times are connections with through spikes, on two plug-in round spikes and in the middle knitting method with a single spike. Details connected by a straight through spike are additionally fastened with dowels and glued. To make a connection on two round plug-in spikes, use a template pad made of plywood or thick cardboard to accurately drill the holes for the spikes. The median knitting with a single spike is deaf, if you need to hide the end of the spike on the front side, and through, which is much stronger than deaf.

For box joints, spiked joints with straight and oblique ("dovetail") spikes are used. Despite the higher labor intensity, the connection with oblique spikes is more durable and reliable.

For reliability, all joints can be strengthened with dowels, gluing, nails, screws, bolts, and a combination of these joint strengthening techniques.

Nagel is made in the form of a wooden rod with slightly pointed ends from hardwood. If the product will subsequently be painted or varnished, then the outer end of the dowel is recessed and puttied or a blind hole is drilled for the dowel.

Before gluing, the parts are thoroughly dried, the surface is cleaned of dirt, grease and oil stains, dust and roughened with a rasp for better adhesion. Moreover, hardwood parts are glued with a more liquid composition, and soft wood is thicker because it absorbs moisture much better. The surfaces to be glued must be carefully smeared with glue, which significantly increases the strength of the connection. The adhesive layer should not be too thick or too thin. This will significantly degrade the quality of the connection. The adhesive is applied in a uniform, dense, non-breaking layer. For reliable bonding, the product must be kept for at least a day before being subjected to further processing.

For gluing, carpentry or casein glue is used. Joiner's glue is not waterproof and at high humidity, finished products can stick out. Therefore, it is recommended to use casein glue, devoid of this drawback. In addition, casein glue is somewhat cheaper, and the bonding strength is slightly superior to carpentry.

To achieve special strength, the joints of wooden structures are strengthened with nails, screws and bolts. The length of the nail or screw is selected 3–5 mm shorter than the total thickness of the parts to be joined, and when connecting parts of different thicknesses, the length of the fasteners should be 2–4 times the thickness of the thinnest part.

It should be borne in mind that screws and nails screwed or hammered across the fibers hold the parts better.

The part of the bolt that extends beyond the parts to be joined should be slightly larger than the thickness of the nut. Washers are placed under the bolt heads to protect the wood from crushing. The slots of the screw heads are parallel to the wood fibers. It is desirable to place the slots of all screws on one straight line or parallel to each other. Before screwing in thin screws or driving in thin nails, it is recommended to make signal holes with a smaller diameter.

Screw connections are considered the strongest. You need to be careful not to split the tree. For this purpose, screws and nails should not be driven in and driven close to the edge and to each other.

K category: wood carving

Joining wood parts

Joining wooden parts with nails

Nails are enough to connect the parts of a simple product. The nomenclature of nails is very large, there are, for example, wallpaper, with a reduced head, and box (Fig. 3). The length of the nail should be equal to three times the thickness of the part to be joined. The extreme nails are hammered in at a certain angle so that they do not crawl out (Fig. 4), with a carpenter's hammer, slightly different from a locksmith's hammer (Fig. 5). For a better entry into wood nails are smeared with soap.

Joining wooden parts with screws

Screw connection - more durable, collapsible. Screws (Fig. 39) are steel, brass, from 11 different alloys. Their designation is similar to the designation of screws (screw 2 X 20 means a screw with a diameter of 2 mm and a length of 20 mm).

Rice. 1. Rasp: a - flat; b - semicircular; 1 - rasp body; 2 - handle; 3 - notch; 4 - shank

Rice. 2. Bar for sanding wood: 1 - glass skin; 2 - wooden block; 3 - cork

Rice. 3. Nails: a - wallpaper; b - with a reduced head; in - box

Rice. 4. Joining wooden parts with nails

Rice. 6. Hammers: a - joiner's; 1 - handle; 2 - striker; h - auxiliary striker; 4 - wedge; b - locksmith

Rice. 7. Screws: a - with a countersunk head; b - with a semicircular head; in - with a semi-secret head; g - with a hexagonal head; d - with square head

Rice. 8. Tools for preparing for drilling: 1 - awl; 2 - drill

Rice. 9. Phillips head screw (and screw) and appropriate screwdriver

Before screwing in a screw, it is enough to make a small hole in soft wood with an awl, and in hard wood with a drill (Fig. 8).

The threads of large screws are lubricated with soap. Screws are screwed in with a screwdriver with a spatula in the form of a groove in the screw. Even with the most careful attitude, the bladed screwdriver often breaks off the head (especially with alloy screws) and scratches the part. In this regard, it is more expedient to use screws with a cross slot (Fig. 9).

Joining wooden parts by splicing

If it is necessary to connect the planks into a solid frame, cut off four planed parts and lay them in the form of a rectangle according to the sketch drawn. On the upper and lower sides of the planks, the width of the adjacent parts is marked with a pencil, and then the mark is transferred to the entire contour with a square. After that, with the help of a thickness gauge (Fig. 11), risks are applied to remove the material. When cutting, the thickness of the saw blade must be taken into account (Fig. 10). After that, the frame is assembled, smearing with glue, sometimes connecting with pins.

Rice. 10. Corner step connection

Rice. 11. Planer

Rice. 12. Details of the spike connection: 1 - eye; 2 - spike

Stud connection of wooden parts

For the manufacture of a frame, which should be stronger than a spliced ​​frame, a single tenon joint is used. The two opposite frame pieces (called the strapping) have lugs or spikes (Figure 12). If a part of the bark is preserved on a harness of a greater length, a spike is made in it, on a shorter one - eyes. The ends of the strappings are marked into three equal parts and cuts are cut out: for the spike - on the outside, the risks, for the eye - on the inside. The eye is hollowed out with a chisel to the middle, then the harness is turned over and the eye is completed to the end. After that, the eyes and spikes are cleaned with a rasp or glass skin and the frame is assembled (Fig. 13).

An even stronger connection with multiple spikes is used to connect the corners of the frames of the supporting structures of tables, chairs, drawers, etc. Manually, such spikes are made as follows: precise marking is applied with a pencil, cuts are made with a saw on both sides, first with a narrow chisel on one side, and then, on the other hand, the material is cut down, cleaned with a rasp or glass skin. Finished strappings are connected, defects are eliminated and the dimensions and squareness of the connection are checked. After that, epoxy or other glue is prepared, gently applied with a brush or a sliver to all mating surfaces and, tapping lightly, assemble the product. After that, the protruding adhesive is cleaned off, the squareness is measured, tightened under load and kept in air for drying. Even more difficult is the dovetail connection (Fig. 14).

Rice. 13. Spike connection: 1 - eye; 2 - spike

Rice. 14. Dovetail connection

Adhesive connection

To connect wooden parts, carpentry glue, casein, epoxy glue of various brands are used. When using synthetic adhesives, follow the instructions for their use.

Joiner's glue. Glue is sold in the form of tiles, granules or powder. The tiles are crushed, filled with water (in a mass ratio of 1: 1) and kept for 12-24 hours: crumbs - 90 minutes, and powder - 20 minutes. After the glue swells, it is heated in a water bath (Fig. 15) to 60°C, stirring continuously. In no case should glue be brought to a boil. Properly prepared glue flows slowly and evenly from a stick or chip.

Rice. 15. Water bath for wood glue

The glue is applied to the surfaces to be joined (before joining, they must be heated to at least room temperature so that the glue does not cool too quickly, does not harden and does not lose its properties) and the product is clamped with clamps. After holding for 24 hours, the adhesive dries and the joint becomes strong. Bonding must be carried out indoors at a temperature not lower than 20 °C. Glue is prepared in the amount necessary to connect the parts.

The disadvantage of wood glue is that in a humid environment, the connection loses its strength, so it is unsuitable for moisture-resistant joints.

casein glue. Casein is a white powder that is dissolved in water in a glass or ceramic container in the ratio indicated in the instructions for use. The disadvantage of casein glue is the need to use it immediately after baking, as it quickly loses its properties. However, glue is cheap and moisture resistant. The powder is slowly poured into water with continuous stirring until a slurry is obtained; after 30 minutes, the glue is stirred, and it is ready for use. Thick glue is applied in a larger layer than carpentry. The parts to be glued are clamped with a clamp and held for at least 8 hours. The next day, the glue hardens and the joint is ready for further processing.

synthetic adhesives. In specialized stores, you can purchase various synthetic adhesives based on phenol-formaldehyde, urea-formaldehyde, epoxy and other resins.

The adhesive selected depending on the purpose is prepared in a room with a temperature of approximately 20 ° C, equipped with supply and exhaust ventilation.
Glue is mixed in glass, porcelain, ceramic or enameled dishes. It is impossible to prepare glue in stock, since the viability of synthetic adhesives usually does not exceed 4-6, rarely - 20 hours.

The adhesive is applied with a brush or spatula to one of the surfaces to be joined. Glue consumption is 0.15-0.2 kg/m2. With hot gluing, the consumption of glue is somewhat less; at the same time it hardens faster - in a few minutes. The surfaces to be glued are compressed with a force of 0.2-1 MPa until the adhesive is completely cured and a strong connection is formed.

By adding pigments (in the amount of 3-10% of the resin mass) or dyes soluble in alcohol and acetone, the adhesive can be dyed in the desired color.
For the preparation of glue based on urea-formaldehyde resins (M-60, M-70, SFC-70), ammonium chloride, 40% lactic or oxalic acid are used as a hardener.

Polyvinyl acetate (PVA) dispersion is successfully used to join wood, celluloid, cork, leather, paper, fabrics, PVC, expanded polystyrene, laminated plastics. After curing, the compound has moisture resistance, though short-term. The dispersion gives a colorless film, invisible when the adhesive flows out in the gaps. If necessary, the dispersion can be colored with pigments.

Epoxy adhesives are sold as a two-component kit - resin and hardener (diethylenetriamine). These adhesives are highly durable. Immediately after mixing both components, i.e. 100 mass parts of resin and 6-9 mass parts of hardener, the liquid mixture should be used to obtain the connection. At room temperature, bonding should be carried out no later than 90 minutes after mixing the adhesive. Epoxy adhesives of the VK type (for example, VK-3, VK-13, etc.) are used for bonding wood, glass, porcelain, polyester fiberglass, and also not very soft plastics.

For gluing ceramic and plastic facing tiles to concrete, plaster, asbestos cement, adhesives of the Bustilat, Stylit brands, as well as various mastics (for example, PS-B, Gumilaks) are used.

Adhesives based on polyester resins (usually used for fiberglass laminates) are also suitable for gluing wood, especially when moisture-resistant joints are required. The strength of these adhesives is lower than those based on epoxy resins.

In order to avoid leakage of glue from vertical joints, it can be thickened with elutriated chalk, cement, kaolin, more expediently - with colloidal silica. Such additives simultaneously somewhat reduce shrinkage.

In the manufacture of the adhesive, the resin and accelerator are thoroughly mixed, and then the catalyst is added with continuous stirring. At room temperature, the adhesive cures after 2 hours. Adhesives based on polyester resins are moisture, oil, gasoline and acid resistant, even at a temperature of 80 °C.

For gluing rubber and rubber with each other and with metals, glass, rubber glue of the 88NP brand is used, which is a solution of the 31-NP rubber mixture and butylphenol-formaldehyde resin. The adhesive is water resistant, does not cause corrosion of some non-ferrous metals (aluminum, magnesium, copper). Adhesives "Thermo-pren", "Leikonat", VKR-15 have a similar purpose and properties.

Adhesives BF-2, BF-b, which provide tight and durable joints between metals and non-metals, are very popular. Glue BF-b is used in medicine for gluing cuts, scratches, small wounds.

For joining products made of organic glass, adhesives V31-F9, BC-1GTM, VK-14 are used.

Nitrocellulose glue AK-20 is designed for joining fabrics together and gluing them to wood and metals.

- Connection of wood parts

"Types and methods of connections

parts in wood products»

technology lesson

7th grade

2016

Subject: Types and methods of joining parts in wood products.

Lesson Objectives: to form knowledge about the types and methods of joining parts in wood products; to promote the development of students' ability to choose ways to connect; generate the need for work.

Lesson objectives:

1. Give students an idea about the types and methods of joining wood parts. Corner, middle and box stud joints, their elements and design features;

2. Demonstrate the types and methods of connection;

3. Teach how to correctly calculate the connection.

Lesson equipment:

1. Material and technical base: Samples of connecting wood parts.

2. Didactic support of the lesson:

Technology grade 7. Edited by V. M. Kazakevich, G. A. Molevoy;

Presentation.

Teaching methods:

1. verbal methods (explanation, conversation);

2. visual methods (demonstration of visual aids).

Lesson type: lesson explaining new material.

During the classes

Organizing time

Updating of basic knowledge

As soon as the ancient man came up with a tool, he almost immediately set about building a dwelling made of wood. Many millennia have passed, but he continues to improve his home. Modern technology makes this process much easier, but the foundations laid down by our ancestors are passed down from generation to generation (Slide 3)

Who knows how to build a house?
So that we feel comfortable in it,
To keep it warm and durable.
The builder knows this for sure.

Do you know what houses can be built? (Brick, panel, wooden, etc.)

Message about the topic and purpose of the lesson.

Today we will talk about building a wooden house.

What material is the wooden house made of?

What are the types and methods of connecting wooden parts - we will study with you today.

Let's remember in what ways you can connect wood parts (screws, nails, bolts, gluing).

Where can these types of compounds be found?

Learning new material

1. Teacher's story

Let's take a look at how to connect wooden parts with you. Basically, these are carpentry joints that have been passed down from generation to generation for many centuries.

All wood products consist of several parts that can be connected in various ways. The process of connecting parts into a whole product is calledassembly .

Starting to combine wood, we must process it and prepare it for use.

One of the basic rules that you should know and follow is the attachment of thin parts to thicker ones.

There are several types of wood joining:

End connection

Invoice connection

Half tree connection

Cleat

Connection "nest - spike"

Splicing in length (Slide 4)

Depending on the location of the parts in the products, end (Fig. a) and middle (Fig. b) connections are distinguished.

They can be made with nails, screws or glue.

(Slide 5)

End connection (splice) considered the simplest way to connect. With this method, the surfaces of the two parts to be joined are tightly fitted to each other using nails or screws. The length of the nail (screw) should go through the first part and enter the second part by 1/3 of the length of the nail. The thickness of the nail must match the size of the wood so that cracks do not appear when hammering. There must be at least 2 nails and they must not be located on the same line. (Slide 6)

Invoice connection - two parts are superimposed one on top of the other and connected with nails, screws or bolts. Workpieces can be placed in one line or at a certain angle.

Splicing in length. Splicing is simple for vertical supports. (Slide 8)

Cleat used when laying the floor or sheathing boards. With this connection, the gaps between the boards are excluded. (Slide 9)

Connection "nest - spike" the most common among the joints of wooden parts. (Slide 10)

A spike connection consists of a groove hollowed out or drilled in one of the wooden parts, as well as a spike made at the end of another attached element. The parts must have the same thickness, but if the thickness is different, then the socket is made in the thicker part, and the spike is made in the second, thinner part.

The elements of a stud connection are a stud connected to a socket or eye. (Slide 11, 12)

Spike connection of parts: a - single spike; b - double spike

Thorn called the protrusion at the end of a wooden part.

nest call a hole in another part that connects to a spike.

eyelet call the groove at the end of the part, connected to the spike.

The profiles and dimensions of the stud and eye must match. The length of the spike should be equal to the width of the attached bar.

Depending on the thickness of the parts, spikes are used: single, double, triple, etc. With a workpiece thickness of up to 40 mm, single spikes are usually used, from 40 to 80 mm - double, over 80 mm - triple and multiple. "Spike" - from the German "middle". Eye - the gap between the ears (cheeks, spikes).

The connection is carried out on glue with additional fastening with nails, screws.

1. Conversation on the studied material.

1. What types of connections exist?

2. What connections are called spiked?

3. Where are they used?

4. How are they different?

5. Name the types of spiked joints.

Practical work of students "Connecting wood parts"

1.TB students at work

2. Making models of spiked joints.

3. Evaluation of student work, error analysis.

Summing up the lesson

Workplace cleaning

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 can be divided into three categories according to the field of application (foreign version of the classification):

• box;
• frame (frame);
• for splicing/splicing.

Drawer connections are used, for example, in the manufacture of drawers and cabinets, frame connections are used in window frames and doors, and rallying / splicing is used to obtain parts with an increased 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 as to indicate, for example, 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, keep in mind that there can 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 a corrugated key on the outside, or with a wooden block fixed on 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 connections can be used as frame connections (furniture), drawer connections (cabinets) or for splicing (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. Using an electric drill with a twist drill or a hand drill with a spade bit, 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 joint.

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, a quarter corner (corner joint) and a dark/semi-dark corner joint. 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 the workpiece 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.

Adviсe:

• 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. 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 a bevel of the ends in a corner joint, 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 unevenness, 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 reinforce the corner joint on the mustache, you can glue a wooden block inside the corner if it is not visible. If appearance is important, 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 an edge 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 a corner or in the middle (for example, the corner of a window frame or where a table leg meets a 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 socket. 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 nest. 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 bias.

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.
• Spike in the dark (steps of the stud on its two sides) - for relatively wide details, such as the lower trim (bar) of the door.

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. In addition, 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 sawing methods into one panel.
• Never join boards of different types of wood unless they are properly dried. 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 a 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, or for large areas dilute with water and apply with a paint roller. Since PVA glue has a water base, it shrinks when setting.

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 overall 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 a flat surface, use a mallet to tap the protruding sections through a piece 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.

At the heart of all connections is the knot - the place of attachment. Depending on what shape the connected parts resemble and how the node is located, there are several types of connections. Among them are end, side, corner, T‑shaped and cruciform.

The main types of connections and their requirements

The emergence of new types and methods of manufacturing joints of wooden elements has led to significant progress in the development of wooden structures in recent decades. In modern wooden structures, along with traditional, hand-made connections, new connections of an improved type are used.
The timber used for construction needs in the form of logs and lumber has a maximum cross-sectional dimension of 25-28 cm and a maximum length of 6.5 m. Due to the limited size of the tree, the creation of building structures of large spans or heights from it is impossible without connecting individual elements.
Connections of wooden elements to increase the cross section of the structure are called rallying, and to increase their longitudinal length - splicing. Along with rallying and splicing, wooden elements can be connected at structural nodes at various angles.
The need for the correct solution of the connections of individual wooden elements for the operation of the structure as a whole is also explained by the fact that the anisotropic structure manifests its negative qualities to a greater extent at the joints.
The development of connections of wooden structures traces its history back to ancient wooden structures. One of the first to be used were joints in which forces were transferred from one element to another directly through the contact surfaces and caused mainly crushing stresses (front cuts, stop, etc.). The use of such compounds led to a large waste of wood. Later, thanks to the use of working connections in the joints, it was possible to transfer large tensile forces. Finally, an important step in the development of individual elements and wooden structures as a whole was the emergence of adhesive joints. This was facilitated by the creation of new branches of the chemical industry for the production of synthetic polymeric materials and building adhesives based on them.

The use of one or another type of connection is determined by the type of the entire structure, in some cases it is possible to use different types of connections in one structure.
The advantage of solid wood in terms of cost compared to glued wood makes it advisable to use it in almost all cases where natural wood reserves allow or its use on conventional (non-glued) joints is possible. The use of glued board structures is rational in cases where a large cross-section of elements is required, when it is necessary to minimize the number of metal inserts, to increase fire resistance, reduce the impact of chemically aggressive environments, or when special requirements are placed on the architectural expressiveness of the structure. Plywood, chipboard and fiberboard and other sheet materials are used as sheathing and attached to the wooden frame with glue or various working bonds.

Wood fastening methods

Fastening wood with nails, screws and dowels.

In order for wood to hold nails, screws and dowels well, you need to learn the basic rules for their fastening.

A nail hammered along the grain holds less well than a nail hammered across the grain. Nails should be hammered in with some slope, but not parallel to each other.

On nails, you can put together a box for a parcel, a stretcher, but you should never fasten shelves, chairs, tables, etc. with nails. In addition to gluing, you need to use screws or dowels here.

Screws hold wood much stronger than nails. The heads of the screws are countersunk, semi-secret and semicircular. Before screwing a screw, a hole is drilled in the wood, equal to about a third, half of its length and less than the diameter of the unthreaded part of the screw. Under the countersunk head, the hole must be countersunk, after which the screw is screwed into the wood.

Nails are called wooden nails - planed, rectangular and round, turned on a lathe. Round dowels are usually machined from durable wood, while rectangular dowels are made from the same wood as the product. Examples of the use of dowels to secure knitting with and without spikes are shown in Figure 33.

Rice. 1. Fastening wood with nails: A - correct; B - wrong

Rice. 2. Knitting wood with round dowels: A and B - when knitting on spikes; C and G - with angular knitting without spikes

Wood connections. To obtain large surfaces, wood is made up of separate parts. The strength of the product often depends on the correctness and thoroughness of the joining of wood. Wood compounds are usually divided into three types. Splicing is used to lengthen pieces of wood. Examples of splicing are well-known butt and lap joints, as well as splicing wood on spikes. Increasing the width of wood (by layers) is called rallying. The connection of boards at an angle is called viscous.

Examples of rallying, splicing and knitting wood are shown in the figures.

There are other ways to join wood. We talked about the most accessible ones that young masters can easily learn.

Gluing wood. When gluing boards or bars, it is necessary to take into account the location of the annual layers. The annual layers of adjacent boards should be facing in different directions. This greatly reduces wood warping.

The location of the annual layers should not be mutually perpendicular, because this also contributes to damage to the gluing, since the degree of drying and moistening along and across the fibers is so different that it can lead to the destruction of the gluing.

For gluing wood products, carpentry or casein glue is used.

Joiner's glue is prepared from the waste of tanneries and slaughterhouses, which, as a result of industrial processing, give a glue with a strong gluing ability. The more transparent and lighter the glue, the better it is in quality.

Wood glue works when it is in a hot, liquid state. To do this, having crushed the glue tiles into pieces, they are placed in a bowl and poured with water in a proportion by weight approximately: three to four parts of water are taken for one part of the glue. After 10-12 hours, when the glue swells, it is heated, stirring, but not boiling.

Compound

There are the following main types of interfaces of wood parts: rallying, splicing and building up elements: length, adjoining elements at an angle, intersection of elements. Figures 16, 17, 18 and 19 show the main types of carpentry joints most often found in the designs of young technicians.

The parts are usually connected with glue, nails and screws, less often with bolts.

Bonding parts. For gluing wood, carpentry or casein glue is used. With proper gluing, the strength of the seam is not inferior to the strength of the wood itself.

Only those parts that are made of dry wood can be glued, since its high humidity significantly reduces the strength of the joint. The surfaces to be glued must be carefully adjusted to each other so that the seam is thin and uniform in thickness throughout. The strength of the joint increases if the surfaces to be bonded are made rough (for example, using a rasp).

For the strength of gluing, the cleanliness of the surfaces to be glued is of great importance, "the absence of dust, dirt, grease, and remnants of old glue on them. For the same reasons, do not touch the surfaces prepared for gluing with your hands.

Joiner's glue on the surfaces to be glued must be applied in a heated state (at a temperature of 40-70 °), quickly and in a thin layer. The strength of the bond is increased if the surfaces to be bonded are slightly warmed up before the adhesive is applied to them. Such heating is especially recommended when gluing large surfaces.

After applying the adhesive solution, the parts to be glued are immediately connected and pressed tightly against each other in the clamps of the workbench or with the help of special devices (Fig. 20) - clamps, vim, sulag, screw presses, wedge clamps. Small parts can be tied with strong threads or compressed with spring-loaded laundry clips (pins). In many cases, some kind of weight is used to compress the glued parts. Under the press, the glued parts must remain in a dry and warm room for 12 to 24 hours, but not less than 6-8 hours. It is possible to process glued parts only after they are completely dry.
The density of the glue depends on the material from which the parts to be glued are made, and on the "mutual arrangement of the wood fibers. So, when gluing dense - oak, beech, maple - the glue must be diluted thinner than when gluing less dense species - linden, pine, spruce, To increase the strength of gluing parts in which the planes of the seams are located across the fibers of the wood, dry and heated ends should be glued with a liquid glue solution (the so-called gluing).Only after this layer of glue has dried, the parts are glued in the usual way.

In the manufacture of various models and devices, young technicians use casein glue to glue wood. Unlike wood glue, casein glue is not heated. Otherwise, all the basic rules - surface preparation, gluing procedure - when using casein glue are the same as for carpentry.

When assembling their models on glue, young aircraft modelers and ship modellers use special AK-20 glue and nitrocellulose glue - enamel. The latter is a light (i.e., unpainted) nitro lacquer used in production for applying the first lacquer coating to the product. The order of gluing remains the same.

Connection on nails and screws is the simplest and most affordable way to connect individual parts made of wood (Fig. 21). Nails and screws are also widely used for attaching various metal parts to wooden bases.

In order for the connections on the nails to be strong, you need to choose the right size of nails, their number and direction of driving. Nails hammered into the end of the part, that is, along the wood fibers, hold weaker than those hammered perpendicular to the wood fibers.

The leader of the circle should warn young technicians against hammering several nails along one layer of wood, as this may cause splitting of the wood. A too thick nail or a nail hammered too close to the end edge of the board, bar or lath can also split the wood.

A thinner part is always nailed to a thicker one: a board or a board to a bar, plywood to a board or a bar, etc. Nails are selected so that their length is 2.5-4 times the thickness of the nailed part (the thicker the nailed part , the smaller the relative length of the nails used for nailing it) .

The strength of the connection of parts increases if the nails are hammered in with a dovetail, that is, in different planes.

To increase the strength of the connection, nailing parts with nails is often combined with gluing.

If the length of the nails exceeds the total length of the parts to be joined and the nails pass through, the end of each nail is bent with a hook and hammered into the surface of the part (Fig. 21, c).

Nail head caps. usually spoil the appearance of the product. Therefore, they try to “drown” them a few millimeters under the surface of the part, and putty the resulting recesses. To do this, each nail, before driving it, “is laid flat on some massive metal object - an anvil, a slab or an ax butt - and its head is flattened with a hammer. Then the nail is hammered so that the plane of its flattened head coincides with the direction of the wood fibers. A hammered nail is driven a few more millimeters. To do this, the head of another nail is laid sideways on its head and the clogged nail is deepened with a hammer blow on the latter.

When it is necessary to nail thin laths, glazing beads and other details, or when these details are pre-glued, the nail heads are bitten off with wire cutters.

To extract hammered nails, they use tongs or a special hammer that has a grip for this purpose - a nail puller. To protect the surface of the product from damage, under the pincers and the hammer, when removing the nails, plywood trimmings or wooden blocks are placed.

The assembly of wooden structures of various models and devices, especially when individual parts of the structures must be removable, is often carried out using screws.

When assembling structures on screws (Fig. 22), they first make markings, that is, they establish the location of the screws. Then, in the upper part for each screw, a hole is drilled with an awl, gimlet or drill, the diameter of which should be equal to or slightly less than the diameter of the upper cylindrical part of the screw. Holes of half the diameter are drilled in the lower part for the screws. When screwing into wood, the screws cut a thread in it, thanks to which they tightly tighten the parts to be joined and hold well in them.

Sometimes, in order to achieve special structural strength, parts are assembled on glue and screws at the same time.

Adhesive wood joints

From boards of limited sizes, structures of any size and shape can be glued together. For gluing, small-sized wood and low-quality wood are used with the removal of knots and defects. Adhesive structures can be straight, curved, constant, variable, profile sections, up to tens of meters long and with a cross-sectional height measured in meters. Adhesive joints are strong and monolithic, their compliance is so small that it is not taken into account, therefore, glued elements are calculated as elements of a solid section (Fig. 18). These joints are waterproof, resistant to decay and chemically aggressive environments, which ensures their reliability and durability. For gluing, boards with a thickness of not more than 50 mm and a width of not more than 180 mm are used. Boards with large dimensions warp during shrinkage and swelling. In this case, tensile stresses occur across the fibers, which destroy the adhesive seams. Boards must have a moisture content of not more than 10±2%. Boards are sharpened before gluing. Moreover, the depth of the sharpening should be at least 3 mm so that the glue line is as thin as possible (no more than 0.1 mm).

When gluing joints, in order to avoid warping of the structure, the direction of the fibers and annual layers of wood of the parts to be glued is taken into account. By gluing blanks, edge to edge, the annual layers of adjacent bars and planks are arranged so that the core and sapwood of one plank adjoin the core and sapwood of another. When gluing with layers, the direction of annual layers in the edges of adjacent planks should be opposite. To make the glued seam less noticeable, mineral pigments of the corresponding one are added to the glue - from 8 to 10% (by volume).

For gluing boards, glues based on thermosetting resins are used. Epoxy glue EPTs-1 is used for gluing wood with metal.

Bonding technology consists of several processes. First, solid wood boards are sawn into bars, these bars are jointed so that the side edges adjoin each other without a gap. Then they are cut out from the bars with cross cuts. Next, the bars are collected in a package with the orientation of the annual layers. The package is disassembled, a jagged joint (comb) is made at the ends of the bars, the surfaces to be glued are smeared with glue, the package is reassembled and pressed with clamps.

Glue is applied evenly on both surfaces to be glued. Applying glue only on one side of the glue line does not ensure uniform wetting of the other side, which leads to non-glued spots and a decrease in the strength of the entire product. It is also not recommended, and through the chur, abundant application of glue. This leads to its extrusion during pressing and the time spent on its removal. After applying the adhesive, the items to be bonded are allowed to stand for some time, determined by the adhesive manufacturer. During this time, excess moisture evaporates from the adhesive, and the concentration of the adhesive increases. Especially exposure is necessary for liquid adhesives or at high temperatures of the adhesive and the room air. Rushed bonding will cause the adhesive to extrude excessively and form a "hungry" bond. Conversely, in a cold room or thick adhesive, the exposure time should be reduced, up to immediate gluing. In a cold room, it is recommended to heat the parts to be glued, but not more than 45 ° C, because the glue can dry quickly on overheated wood, forming dry spots. For the same reason, drafts and dust are not allowed in the room.

After applying the glue, the parts are connected, tightly pressed against each other and pulled together with clamps, a vice or placed under a press. The most primitive clamp is obtained from two boards with drilled holes and bolts inserted into them. For bone adhesives, it is recommended to maintain a pressure of 0.1 to 0.4 MPa, when gluing with skin glue, the pressure can be from 0.1 to 1.2 MPa. The amount of pressure largely depends on the density of the adhesive. A pressure of more than 1.2 MPa is not recommended, as it leads to wood shrinkage and requires sophisticated equipment.

After gluing the boards, sags are formed on the side surfaces of the elements, which are removed by milling. The tensile strength of adhesive joints is low, it approximately corresponds to the tensile strength of wood across the fibers. Gluing technology must be carefully observed. In this case, adhesion (adhesion of glue to wood) will be sufficient and possible damage will occur not through the glue, but through the wood.

Types of adhesive wood joints

Among wood compounds, glue is the most widely used. This is due to the fact that with the help of glue it is possible to obtain products of almost any shape, large size, high quality, economical profile from small-sized and low-quality wood.

Glued wooden structures are less susceptible to warping than those made from a whole piece of wood, and their strength, as a rule, is higher due to the redistribution of defects and the presence of adhesive layers. The parts are connected along the length, width, thickness and angle.

Length connection

The gluing of wood at the end is very fragile, therefore, when joining segments along the length, it is necessary to replace it with gluing of a different type. For this purpose, the connection of parts on a mustache and on a toothed spike is used.

Connection on the mustache.

The strength of the connection depends on the length of the mustache: the longer the mustache, the more the connection approaches the formation type of bonding and the higher its strength. However, this increases. For products of increased strength, the length of the mustache is taken equal to 10 ... 12 thicknesses of the parts, in other cases, eight thicknesses. Tension or compression of the mustache joint induces normal and shear stresses.

Normal stresses, MPa: a = P sin α 102/F. Shear stresses, MPa: τ = P sin 2 α 102/2F, where P - tensile or compressive force, N; α - mustache bevel angle, deg; F - cross-sectional area of ​​glued elements, cm2. These equations can be used for calculation, provided that the thickness of the adhesive layer is not more than 0.01 of the thickness of the elements to be glued. If the thickness of the adhesive layer is 0.1 of the thickness of the element, the stress concentration in the adhesive layer reaches 1.5.

Toothed connection.

The consumption of material in the connection to the toothed spike is less than in the connection to the mustache, with the same strength. Shear stresses in the adhesive seams of serrated spikes in tension are determined in the same way as for the mustache joint. Due to the symmetry of the bevels, the stress concentration and the uneven thickness of the adhesive layer have little effect on the strength of the gear joint.

All connections, whether carpentry or joinery, are called landings, because they are based on the principle of fitting a part with a tenon onto a part with a groove. Depending on how tightly the parts in the mount are in contact ( connection types), all landings are divided into tense, tight, sliding, loose and very loose.

At the heart of all connections is the knot - the place of attachment. Depending on what shape and how the node is located, there are several types of connections. Among them are end, side, corner, T‑shaped and cruciform.
End connections

There is another definition of such a connection - extension. It is characterized by the fact that all parts are fastened together in the end part, while the length of the whole part increases. Depending on the type of fastening, these end connections withstand high loads in compression, tension and bending. An ordinary whole board is in many ways inferior to that obtained by building.

T the end connection of parts that resist compression can have a different design. The main feature of this connection is that each has both an overlay and a groove, which are most often made equal in both thickness and length. If there is no confidence in the strength of the future connection, you can further complicate it with spikes or various joints, for example, a joint in an obtuse corner. But this connection will require additional adhesive fastening or fastening with nails and screws.

The end connection of the parts, which resists stretching, at the heart of its design contains an overlay in the lock. First, an overlay is drawn, then a groove is made on one part, and a ledge on the other. It is this lock that allows both halves not to be separated. As well as a compression-resistant connection, this type of connection can be provided with a straight overlay. Lateral connections

Lateral connections are also called rallying. Most often, such a connection is used when constructing floors, doors or gates. This is a fairly strong connection. Large arrays that are obtained as a result of such a connection are additionally fastened with transverse boards or shields Corner joints

This type of fastening is most often used in fastening window, door blocks, greenhouse frames, elements of benches and swings. The corner connection differs from others in that the parts to be joined are placed at an angle of 90 ° to each other. Depending on the fasteners used, all corner joints are divided into tenon and mustache joints.

Corner joints can be T‑shaped and L‑shaped.

L-shaped corner joints (they are also called end) have many options: from a simple one - half a tree, to the most durable - a triple tenon T-shaped connection is named so because of its appearance. After fixing the parts, the inserted part, as it were, grows out of the array of the other. Most often, this type of connection is used when pairing a log of ceilings and partitions with a house harness.
The angle at which the parts are connected must be 90 °. At other angles, the connection is fragile and very quickly becomes unusable.

Among the many varieties of T-connection, two types are most common