home Auditorium 8 Circular saw for longitudinal cutting. Circular saws for longitudinal sawing on wood. Sawing with a carpenter's hacksaw

Circular saw for longitudinal cutting. Circular saws for longitudinal sawing on wood. Sawing with a carpenter's hacksaw

The main cutting element of any hand saw is a series of teeth cut on the blade and representing wedge-shaped cutters. Wood, in the manufacture of all kinds of products from it, is sawn along, across and at an angle Θ to its fibers, in this regard, transverse, longitudinal sawing and sawing at an angle to its fibers are distinguished and in each case they use the appropriate type of saw, which differs from others in shape teeth

a - cross cutting; b - longitudinal sawing; 1 - wood; 2 - cut; 3 - marking line for sawing; Θ - angle of inclination of the marking to the wood fibers during mixed sawing.

At cross sawing cross-cut saws are used, the cutting edges of the teeth of which, when moving in the wood, cut its fibers like a knife and form a cut. Longitudinal sawing differs from cross-cutting in that the direction of movement of the saw is parallel to the grain of the wood. The leading edges of the teeth of rip saws plan wood, like knives in planes, and, going deeper, form a cut. When sawing wood at an angle Θ, universal (mixed) saws with teeth that are an intermediate form of teeth for transverse and longitudinal saws are used to its fibers.

Sharpening the saw

During operation, the saw teeth become dull, the cutting front and side edges become rounded, the saw stroke becomes heavy and you have to put a lot of pressure on it. Experienced craftsmen can easily determine its sharpness by the shine of the cutting edges and tops of the teeth and by the sound of the saw. To restore the cutting ability of the teeth, they are sharpened with files or needle files, giving them sharpness and maintaining their parameters: angles, pitches and heights.

Sharpening saw teeth is an art of its own, requiring faithful hands, a good eye, and attention. It is not difficult to learn this business, you must have the desire and strictly adhere to the following rules:

Crosscut saws. The teeth of cross-cut saws are sharpened using a finely cut triangular file with an apex angle of 60°.

To sharpen the teeth, the saw is clamped into a special device that allows you to set its blade at an angle of 45-50° to the plane of the work table. The file is parallel to the work table at an angle of 60-75° to the saw blade and thus the left edge A 1 A 2 B 2 B 1 is sharpened in the first tooth.

1 - saw blade; 2 - sharpened tooth; 4 - sharpening device; 5 - work table for sharpening saws; 6, 8 - directions of file 7 in relation to the work table and the saw teeth being sharpened; 9 - bending line of the teeth when they are set apart

The saw teeth are sharpened in several stages. First, a file is passed along the left edges of the odd teeth located in the far row, tuning the hands for the same movement. Then they pass the file along the right edges of the same odd teeth, finishing sharpening the main cutting edges with very sharp tips. After sharpening the odd teeth is completed, the saw blade in the sharpening device is turned over and thus the even teeth that are in the far row are sharpened. When sharpening the teeth of cross-cut saws, it is necessary to carefully ensure that each tooth has sharp main cutting edges with a dihedral angle φ = 60-75°, a short cutting edge and a sharp tip.

Rip saws. The teeth of longitudinal saws, in which the angle is π To sharpen the teeth, the saw blade is installed vertically in a clamping device, which, in turn, is fixed on the work table. Below are two methods of sharpening the teeth of longitudinal saws, differing from each other only in the sharpening angle φ, i.e., in the directions of the file in relation to the saw blade.

The first method is direct, in which a file or needle file is directed horizontally at an angle φ = 90° to the saw blade and a small layer of metal is removed from the front and rear edges of the tooth, sharpening the cutting edges.

7 - direction of file movement

In this way, all the teeth located in the far row are sharpened. Then the saw blade in the clamping device is turned over and the teeth of another row, which are in the far row, are sharpened. This method is used by most modern carpenters and hobbyists when sharpening the teeth of rip saws.

The second method is oblique, differing from the first only in the direction of the file in relation to the saw blade, that is, the sharpening angle, which is chosen within the range φ = 75-80°.

8 - direction of file movement

The front and rear edges of the teeth are also sharpened, first of one row and then of the other. With this method of sharpening the teeth, side edges are obtained, and it is used by cabinetmakers when sharpening bow swing saws.

Mixed cutting saws. To restore the cutting qualities of the teeth, they are sharpened, like the teeth of a rip saw, using fine diamond files or coarser needle files. As with sharpening rip saws, two methods are used: straight and oblique, differing from each other in the sharpening angle φ, which are equal to 90° and 75-80°.

The sharpening angle φ = 75-80° is used by cabinetmakers when sharpening the teeth of tenon and fine-toothed bow saws. After sharpening the teeth, remove burrs from the cutting edges and check the sharpness of the teeth in the light.

Saw sharpening devices. To sharpen the teeth, the saw blade is installed in a clamping device, which, in turn, is fixed to the work table. The figure below shows a clamping device used for sharpening the teeth of bow saws and hacksaws and allowing them to be installed at an angle of 45° and 90° relative to the work table.

Clamping device for sharpening hacksaw saws: a - general view; b - details; 1 - desktop; 2 - base of the clamping device; 3 - hacksaw; 4 - wing nut; 5 - clamp; 6, 10 - clamping and support strips connected on hinges 7; 8 - guide triangle; 9 - M6 pin.

The device consists of a base measuring 550x200 mm, made of plywood about 20 mm thick. Two guides are installed on the base right triangle with equal legs, welded from steel strip with a section of 20x3 mm. To install the guide triangles, four M6 studs are provided at the base of the device, screwed with PVA glue. In turn, support and clamping strips are attached to the guide triangles using M6 bolts with wing nuts, connected to each other on hinges measuring 400x150 mm, made of plywood 15 mm thick. The sharpening saw is placed between the slats with the teeth facing up. Its blade is set so that the teeth protrude 15-20 mm above the pressure bar. This clamping device allows you to set saws to be sharpened at an angle of 45° (this position is shown in the picture) and at an angle of 90°. To do this, it is necessary to change the positions of the guide triangles based on the device, which is clearly visible in the figure. When sharpening the teeth of cross-cut saws, the support-clamping bars are set at an angle of 45°, and when sharpening the teeth of longitudinal and mixed saws - at an angle of 90°.

The device, when positioning the slats at an angle of 90°, can be used both to level the height of the teeth and to set them apart.

The figure below shows a clamping device for sharpening the teeth of two-handed saws and large hacksaws.

Clamping device for sharpening two-handed saws and large hacksaws: a - general view; b - details; 1 - saw (hacksaw); 2 - clamping bar; 3 - stand; 4 - crossbar; 5 - wing nut.

The device consists of two racks 1100 mm long with a cross-section of 60x40 mm, two transverse strips about 550 mm long with a cross-section of 40x30 mm and two clamping strips with dimensions of 450x150 mm, made of plywood 15 mm thick. The posts and crossbar are connected to each other with screws. The assembly of the device is carried out in the following sequence: the lower crossbar is screwed to the racks at a small height from the floor, then the right leg is placed on it and the place of attachment of the second crossbar is marked so that the knee right leg rested on the second crossbar. This ensures the rigidity of the stand leaning against a table or workbench. The saw blades for sharpening are placed between the clamping bars with their teeth facing up and clamped with M8 bolts and wing nuts. Having finished sharpening on one side, without removing the saw from the clamping bars, turn the device over and continue sharpening on the other side.

Saw layout

To allow the saw to move freely in the wood and to avoid pinching it in the cut, as it deepens, its teeth are spread apart, that is, they are bent alternately in different directions by the same amount. As a result, the width of the cut becomes greater than the thickness of the saw blade, free gaps are formed on both sides, and the saw moves back and forth, almost without its blade in contact with the surface of the cut, and only its cutting edges gradually remove the wood layer by layer.

The wider the tooth spread, the wider the cut and, accordingly, the less likely the saw to jam in it. However, a cut that is too wide due to the large tooth set requires great effort to move the saw through the wood.

When using an unset or slightly set saw, which happens after its repair or long work, when the spread of the teeth is greatly reduced, the width of the cut turns out to be close to the thickness of its blade, and the friction that arises between the walls of the cut and the blade causes its heating and expansion and, ultimately In other words, the saw gets stuck in the cut, which will require incredible effort to move. Probably, each of us has experienced this trouble when sawing raw wood with a thin saw. And yet, if there is no free gap in the cut for the saw blade, then it is difficult to control and it is pulled away from the intended direction.

The saw teeth are set using a special tool called a set. Some of its designs allow you to select the amount of spread to one side using an adjusting screw, which ensures the same bend of the teeth.

The saw teeth are set in a special wooden clamping device, in which the saw blade is installed so that only the teeth protrude slightly from it, and the device itself is mounted on the work table. The set of teeth is formed by bending them alternately in different directions along the break line, located approximately at half of their heights, but the entire tooth cannot be set back - it will break at the base. It may turn out that when bending, some teeth protrude to the side more than others, and during sawing they will slow down, reduce the quality of the cut surface and quickly become dull. To avoid this, the teeth are aligned by pulling them between the jaws of a hand vice, opened to the amount of spread. As a result, all teeth are aligned and their spread becomes uniform.

The amount of saw tooth set is determined by the elastic recovery of the wood in the cut, which is greater the softer and wetter it is. Therefore, for such wood the spread should be greater than for hard and dry wood. The amount of teeth set to one side and the amount of cut in wood are determined by the formulas:

Δ=k a and b=a+2 Δ

where a is the thickness of the saw blade (mm), k is a coefficient depending on the condition of the wood, k = 0.25-0.4 - for hard and dry and k Example. Determine the amount of spread on one side for a bow saw and a hacksaw with blade thicknesses of 0.6 and 0.9. Wood to be cut: dry and hard for a bow saw and wet for a hacksaw. We select the coefficient for the bow saw k=0.35 and k=0.5 for the hacksaw. Then for a bow saw the size of the spread on one side and the size of the cut are equal:

Δ=0.35 0.6≈0.2;
b=0.6+2 0.2=1 mm;
and, accordingly, for a hacksaw:
Δ=0.5 0.6=0.3;
b=0.9+2 0.3=1.5 mm.

You should not choose any amount of set for the saw teeth, without taking into account the condition of the wood being cut, as this affects the quality of the cut and the force of saw advancement. It is difficult to saw hard wood with a saw with a large offset - you get a wide, uneven, ragged cut of poor quality, the saw stroke is heavy, you have to put a lot of pressure on it, and as a result, its teeth quickly become dull. Therefore, the master must have several saws on his farm with different saw values: for dry and wet wood. And if he has one saw with a small gap and it is necessary to saw wet wood along the grain, then in this case, during the sawing process, a wooden wedge is inserted into the cut, which is moved behind the saw so that it does not pinch, and additionally lubricate its surface with laundry soap.

Saw routing devices. The saws are set using a special tool called a set. The figure shows common types simple wiring and wiring with emphasis.

Tools for setting saw teeth: a - slotted simple setting; b - wiring with a stop; 1 - slot; 2 - handle; 3 - stop with a wing nut (4) and a screw (5) for fixing the amount of spread.

A simple wiring is made in the form of a small steel die of any shape with a wooden or metal handle. The die has several slots of different widths.

The use of such a layout is very simple: select a slot in the layout that corresponds to the thickness of the saw blade, and, having grabbed half of the saw tooth with it, carefully bend it in one direction or another. When bending the teeth, you must strive to ensure that their inclination is the same along the entire length of the saw.

The process of setting saw teeth is greatly simplified by using a setting with a stop, which ensures an equal bend of the teeth. Before starting work, the tool is adjusted to a certain amount of spread, and then the stop is secured in the desired position with a wing nut and screw. The saw teeth are set in a wooden (carpentry) and bench vice or in special clamping devices in which the teeth are sharpened. When using a bench vice, plywood strips corresponding to the size of the saw blade are laid between their jaws. The saw is clamped in a vice so that its teeth are very close to their jaws.

Alignment of teeth in height

To align the saw teeth in height, apply to a sheet of paper laid on a flat and smooth surface, press the saw blade with teeth. If the tops of all the teeth are imprinted evenly on the paper, then they have the same heights and such a saw cuts efficiently. If not all the teeth are printed evenly on the paper, then they are leveled in height using a file. When sawing wood, saw teeth with different heights are in different conditions: they cut differently and are also loaded differently. The unevenness of their heights ultimately affects their wear resistance and the quality of the cut surface. Teeth that differ from others by a significant height bear the maximum load, and as a result they wear out quickly. And teeth that are inferior to others in height are not involved in sawing wood at all. The operation of leveling the teeth is performed after they have been set, before sharpening.

Saw tooth shape

Crosscut saws. Cross-cut saws are a very widely used tool in the construction of all kinds of wooden structures, furniture making, etc. household. As the name suggests, they are used for sawing wood across the grain. The teeth in them are a series of isosceles triangles or rectangular ones, hypotenuses facing each other. The picture below shows the various tooth shapes most commonly used in crosscut saws.

Types of saw teeth for cross-cutting: a, b - simple triangular; c, d - triangular, sparse and with wolf teeth; d, f - rectangular, hypotenuses facing each other and sparse.

Each tooth can be imagined as an acute-angled knife with an apex angle β, sharpened from the sides with a one-sided edge with a sharpening angle φ = 60-75° (sharpening is shaded), and each of them contains two front and two side edges.

1 - saw blade; 2 - sharpened tooth.

For example, in a drawn tooth, the front faces are A 1 B 1 B 2 A 2 and A 1 B 3 B 4 A 2, the lateral ones are A 1 B 1 B 3 and A 2 B 2 B 4. Edges A 1 B 1 and A 1 B 3 are the main cutting edges, and edge A 1 A 2, resulting from sharpening the two front edges, is called a short cutting edge. Each tooth, having the above cutting edges, saws the wood when it moves in both directions, that is, away from itself and towards itself. For example, in a drawn tooth, the cutting edge A 1 B 1 cuts the wood fibers when the saw moves to the left, and the cutting edge A 1 B 3 - when the saw moves to the right, and the short cutting edge A 1 A 2 stratifies the cut fibers and removes them in the form of sawdust from the resulting cut.

Cross saw teeth, which are isosceles triangles, are characterized by a sharpening angle β, a rake angle γ, a cutting angle δ, a pitch t and a height h. Points A 1, A 4, A 5 are the tops of the teeth. The sharpening angle β characterizes the ability of the saw to cut a particular wood. Typically, in cross-cut saws for soft and green wood, the angle β is taken equal to 40°, and for dry and hard wood - 50-60°. The angles in the tooth triangle depend on each other:

γ=β/2 and δ=90°+γ

Rip saws. In rip saws, the teeth are cutters in the form of inclined wedges. The figure below shows two types of teeth, the first is the most common in saws, and the second is with a deep cavity, used in saws for sawing soft wood (linden, aspen, alder), which produces sawdust abundantly.

1 - saw blade; 2 - tooth; 3 - line of tooth apexes; 4 - dog tooth cavity.

Each tooth in a rip saw, like a wedge, has four edges: front A 1 A 2 B 2 B 1, rear A 1 A 2 B 4 B 3 and side ones B 1 A 1 B 3 and B 2 A 2 B 4.

Ribs A 1 A 2, A 3 A 4 are the main cutting edges, and ribs A 1 B 1, A 2 B 2, A 3 B 3, A 4 B 4 are the side cutting edges. The teeth in rip saws, like cutters on planing machines, cut wood when moving only in the direction of the inclination of the teeth, in which the main cutting edges, when performing cutting, form the bottom of the cut, and the side edges form its walls, and when moving back they make an idle motion, sliding along the cut without sawing the wood.

The positions of the cutting edges of the tooth form angles between themselves: α is the rear angle formed between the rear edge and the cutting plane; β is the sharpening angle between the front and rear edges; γ - rake angle between the front edge and the perpendicular to the cutting plane; δ - cutting angle; π is the angle between the front and rear edges of adjacent teeth. Considering the triangle of the rip saw tooth, we find the relationships between the angles:

α + β + γ = 90°; α + β = δ; π The quality of the cut surface and the performance of the sawing process depend on the right choice angular values of the cutting saw tooth. The most important of all angles is the sharpening angle β; when its value is small, sawing wood occurs with less effort, but the strength of the tooth decreases, it chips, quickly becomes dull, and it has to be sharpened frequently. At great importance At this angle, the tooth strength increases, but the sawing force increases. Typically the taper angle should be at least 20°.

With an increase in cutting angle δ, the quality of the cutting surface increases, but the sawing force increases, the cutting angle can be reduced due to the relief angle, but at the same time the friction between the tooth and the wood increases and the tooth heats up excessively, releases, and its strength decreases, so the cutting angle δ is taken within 40-75°.

The angle γ determines the inclination of the tooth; its value is taken within the range of 10-20°.

Thus, the values of the angles α, β, γ for the teeth of longitudinal saws are interrelated, and they are determined by practice - for example, the teeth of beam longitudinal (swing) saws are determined by the angles α = 20-30°, β = 50-60°, γ = 8- 10°, and the teeth of the rip saws are at angles α=20-40°, β= 40-50°, γ=10-20°.

Mixed cutting saws. In hand saws, tooth designs are widely used, which can be used for both longitudinal and cross cutting of wood. The figure below shows some of the tooth shapes used in compound saws.

If the teeth of rip saws can be characterized as acute-angled wedges, then the teeth of saws for mixed sawing can be represented as rectangular or obtuse-angled wedges with a cutting angle δ=90°+γ. Angle γ - front, equal to zero or a negative value within 10-15°. They cut wood with these saws in the same way as with longitudinal saws, when moving only from themselves, and when moving towards themselves they make an idling motion.

Each tooth in a mixed saw has four edges: front A 1 A 2 B 2 B 1, rear A 1 A 2 B 4 B 3 and side ones B 1 A 1 B 3 and B 2 A 2 B 4.

Ribs A 1 A 2, A 3 A 4 are the main cutting edges, and ribs A 1 B 1, A 2 B 2, A 3 B 3, A 4 B 4 are the side cutting edges. When sawing wood along the grain, the main cutting edges form the bottom of the cut, and the side edges form its wall, and when sawing wood across the grain, the side edges A 2 B 2, A 3 B 3, A 6 B 6 cut the wood fibers from the sides of the cut, and the main cutting edges A 1 A 2, A 3 A 4 stratify the cut fibers and remove them in the form of sawdust from the cut.

The teeth of saws for mixed sawing are determined by the point angle β, the cutting angle δ and the rake angle γ. Angles δ and γ are related by the dependence δ= 90°+γ. The quality of the cut surface and the performance of the sawing process depend on the correct choice of angular values of the teeth. In practice, the following angle values are chosen: in bow saws β=60°, γ=-10°, hacksaws β=45-50°, γ=0° or -(10-15°). Saws with teeth with a rake angle γ = -10° are widely used in bow saws (tenon, circular) as universal ones for sawing wood in any direction.

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Saws and sawing. Saws are made of high quality steel with cut teeth. For carpentry and joinery work, use a wide hacksaw, a hacksaw with a butt, or a narrow hacksaw; a saw with a cutting depth limiter (reward), a bow saw, and also a plywood file (knife) (Fig. 1).

A wide hacksaw is made from a steel strip 0.7 m long, 11 cm wide at the handle and 2...7 cm at the narrow end. The handle can be wooden, metal or plastic. A narrow hacksaw is used for cutting curved through holes in large-width parts. The jigsaw (Fig. 2) has a narrow and thin (0.3 mm thick, 1...2 mm wide) file with fine teeth. The file is fixed in an arched frame and can be easily removed. Thin parts (plywood) of a curved shape are cut out with a jigsaw. Before starting work, the end of the file is inserted into a pre-made hole, and the other end is secured in the frame. Sawing is carried out according to the markings. At the end of the work, release the end of the file and remove it from the hole in the part.

Hacksaws with a back are used for shallow sawing, for example, sawing grooves in wide workpieces, for fitting parts during their assembly. The top of the canvas is reinforced with a steel backing, which increases the rigidity of the canvas. Fine teeth have a shape isosceles triangle. Use a hacksaw to cut in both directions (Fig. 1, c).

Based on the shape of the teeth, saws for longitudinal, mixed and cross-cutting are distinguished (Fig. 3).

For sawing along the grain, saws with oblique teeth are used. They cut wood in one direction - away from themselves. The cavity between the teeth is called the sinus. The tooth pitch is the distance between the tips of adjacent teeth. The height of a tooth is equal to a perpendicular drawn from the top of the tooth to its base. There are three edges in the saw tooth (Fig. 3, a). In rip saws, the cutting is performed by a short cutting part - the front edge, and the side edge only separates the wood fibers.


Rice. 1. : a - wide hacksaw: b - the same, narrow; c - axing hacksaw; g - reward; d - plywood saw.

Rice. 2. Jigsaw.	Rice. 3. : a - saw elements; b - saw tooth angles; I - for longitudinal sawing; II - for mixed sawing; III - for cross cutting: 1 - side cutting edges; 2 - front edge; 3 - front cutting edge; 4 - step; 5 - top; 6 - sinus; 7 - height; 8 - line of the base of the teeth.

A bow saw is used for longitudinal and cross cutting. It consists of a beam frame with a tensioned saw blade. The latter is made of steel strip about 1 m long, 45...60 wide and 0.4...0.7 mm thick. The pitch of the teeth is 4...5 mm, the height of the teeth is 5...6 mm. The ends of the saw blade are fixed at the bottom of the beam frame posts. The canvas is stretched with a string of twine secured between the upper ends of the posts and twists. The saw blade is rotated using handles. This saw can be operated by one person. The cut is smooth and even. The teeth of crosscut saws cut the fibers, the side edges of the teeth, and the leading edge only separates them. In rip saws, the leading edge of the tooth cuts the wood. This is taken into account when determining the sharpening angles of saw teeth for transverse and longitudinal sawing.


Rice. 4. Sawing along the grain with a bow saw if the material is in horizontal position: to the right - the position of the worker’s feet while sawing.

Rice. 5. Stands: a - wooden with a movable support: b - metal with a roller; c - wooden with a roller.	Rice. 6. Sawing with a bow saw along the grain while securing the material vertically: a - the position of the worker’s hands during sawing; b - the same, feet.	Rice. 7. Cross cutting: a - sawing techniques; b - supporting the sawn part with your hand at the end of sawing.

In saws for longitudinal sawing of soft wood, the sharpening angle is 40...45°, in saws for hard wood - up to 70°, in cross-cut saws, the angle between the cutting edges of the teeth is 60...70°, and the sharpening angle is 45... 80°. Saws for mixed sawing have a sharpening angle of 50… 60°. The angles of the saw teeth are as follows: for longitudinal sawing - 60...80°, for transverse sawing - 90 -120°, for mixed - 90°. For sawing shallow grooves and sockets of tenon joints, the so-called reward is used. To regulate the cutting depth, it has a movable stop. Saw blade thickness 0.4…0.7 mm, length -100…120 mm.

Types and techniques of sawing. According to the type of fastening of the part in the workbench, they are distinguished: horizontal sawing along the grain, vertical sawing along the grain, horizontal sawing across the grain and sawing at an angle. When sawing horizontally along the grain, the workpiece is secured by pressing it against the table with clamps (Fig. 4) so that the sawn part protrudes beyond the edge of the workbench. In this case, the worker’s body should be slightly tilted forward, and the saw should be held vertically. First, they make a cut, moving the saw up several times, after the cut becomes deep, they begin sawing, moving the saw up and down. A wedge inserted into the cut prevents the saw blade from jamming.

When vertical sawing along the grain, the workpiece is secured in the workbench with a front or rear clamp (Fig. 6). The figure shows the position of the worker's legs during the sawing process. When sawing a thin board, it is clamped so that it does not bend, lifting it upward as it is sawed. Sawing begins with a cut, after which they work to the full swing of the saw blade, without pressing on it. Short workpieces are sawed starting from one end, and then, turning the workpiece over, from the other. Sawing long boards (along the grain) is carried out by resting their ends on stands (see Fig. 5).

Rice. 8. : a - correct; b - incorrect (cutting angle is too large); c - splintered cut, due to improper sawing, flakes and damage to the edges are possible; g - sawing along the fibers with a hacksaw; d - sawing with a bow saw using a template (miter box); e - sawing with a narrow hacksaw through drilled holes; g - template for trimming the ends of boards placed in bags; 1 and 2 - side posts - guides for the saw; 3 - board attached to the racks; 4 - fastening nail of the auxiliary device; detail A - the position of the hand on the frame of the bow saw during sawing.

When sawing the workpiece across the grain, the sawn end is pushed beyond the edge of the workbench (Fig. 7). Before starting sawing, make a gash; during the sawing process, monitor the position and inclination of the saw blade and ensure that the cut is straight and the sawn surface is flat.

To avoid flakes, the sawn part of the workpiece (Fig. 7, b) should be supported by hand at the end of sawing. For tenon joints or other parts that require mating at an angle of 45 or 90°, use a template (miter box) (Fig. 8, e). With repeated use, the cuts on the wall of the miter box may become excessively wide and it will not give the exact size of the angle. To extend the durability of the miter box, its side walls are made of hardwood boards. To trim boards (one width), use a special template (Fig. 8, jar). The side posts of the template serve as guides for the saw; they are made of hard wood. For boards of a certain width, a custom template is required. Sawing wood by hand is acceptable for small volumes of work.

Classification of types of sawing

Characteristics of the sawing process

Sawing is the process of dividing wood with a saw into volumetric, undeformed parts by turning the volume of wood between these parts into chips.

A saw is a multi-blade cutting tool that works in a closed cut. A kerf is a gap formed in wood when teeth cut narrow shavings (sawdust). The cut has side walls and a bottom with which the blades (teeth) interact.

Sawing wood is classified according to several criteria.

Depending on the position of the saw plane in relation to the wood fibers, longitudinal, transverse and mixed sawing is distinguished.

When cutting longitudinally The plane of the saw is parallel or approximately parallel to the grain of the wood. Sawmill frames, circular saws and band saws, on which logs and beams are sawed into boards, lumber is cut in width or thickness in the longitudinal direction.

When cross cutting the plane of the saw is perpendicular or approximately perpendicular to the grain of the wood. Sawing is performed manually with cross-cut saws, hacksaws or on cross-cutting machines used for cutting logs into round logs, removing wood defects and wane areas from the ends of the lumber, as well as giving the lumber a given length and quality.

For mixed sawing the saw plane is located at an acute angle (10˚...80˚) to the direction of the fibers.

Depending on the type of saws used, there are different the following types sawing:

– longitudinal frame sawing, sawing with band, circular and jigsaws;

– cross-cutting with circular, chain and jigsaws;

– mixed sawing with circular, band and jigsaws.

Depending on the number of simultaneously working saws in the machine, a distinction is made between individual and group cutting methods. Cutting logs and lumber with one saw is called individual cutting, and cutting with several saws is called group cutting.

For individual sawing logs are sawn into lumber with separate cuts on circular saws, band saws, vertical or horizontal machines. The cutting is carried out taking into account individual characteristics quality zones of each log. This cutting method is effective when sawing valuable wood, cutting large-diameter logs and logs with significant defects.

For group sawing sawmill frames, multi-saw circular saws and band saws, as well as milling and sawing machines are used.

Depending on the position of the workpiece relative to the center of the circular saw, sawing with the peripheral zone of the saw, the middle zone and the central zone of the saw, as well as sawing with the upper and lower zone of the saw are distinguished.

When working in the peripheral zone saws, the teeth of the saw protrude above the surface of the workpiece by an amount approximately equal to the height of the tooth.

When working in the middle zone saw teeth protrude above the surface of the workpiece by an amount equal to approximately one third of the radius of the saw.

When working in the central zone The center of the saw is located at the middle of the cutting height. This type of sawing is used in milling and sawing machines.

The peripheral and middle working zones of the saw can be located on the upper or lower sections of the saw, which is observed in circular saws with a lower and upper saw shaft.

At divorce (Fig. 2, A) the tips of the teeth with a length of 0.3...0.5 of the tooth height are bent alternately in different directions. At flattening (Fig. 2, b) the tips of the teeth are flattened and shaped, giving them the shape of blades located symmetrically relative to the saw body.

The sawing rule can be formulated as follows: when inserting a tooth into wood, you first need to cut the fibers, and then, with the least resistance, separate them from the massif and remove the chips from the cut.

Wood saws differ in the size of the cutting teeth. This indicator determines what kind of cut the cut will be, what types of wood the hacksaw is suitable for, and how convenient it will be to work with it. But, besides this, there are other indicators that you need to pay attention to when choosing a tool. Therefore, the question of how to choose the right hacksaw for wood requires careful study.

Technical characteristics of a hacksaw for wood

For a wood saw, the main importance is:

canvas width;
blade length;
tooth size;
handle;
blade steel grade.

The length of the blade affects the width of the cut workpiece, and also greatly facilitates the work. A long stroke makes it possible to apply less effort, because in one movement the cut is made by a large number of teeth. Moreover, the longer the canvas, the stronger it will spring. When working with hardwoods such as ash, maple or oak, a hacksaw will cause a lot of inconvenience and will quickly become dull.

From a practical point of view, short hacksaws, with a cutting blade length of up to 35 cm, best used for one-time small work. They are great for those who live in an apartment because they don't take up much space. So, in a private household, it is advisable to immediately choose a long hacksaw (50–55 cm). This will make it possible to work with workpieces, as well as cut trees.

As a rule, the width of the blade is 10–20 cm. Narrower blades are not allowed due to technical reasons (they break even with a slight bend), wider ones are quite inconvenient to work by hand. When choosing a saw for wood, you must remember that thin workpieces are easier to saw with a narrower blade, and, conversely, thick ones (roof joists, tree trunk, etc.) - wide.

Regular pens are made of plastic. It is best to choose a handle with a rubberized backing. This will protect your hand from calluses and make it possible to make a tighter grip.

The saw tooth is the most important part of the tool, so we will dwell on this point in more detail.

Purpose and types of teeth

The following types of teeth are distinguished in wood hacksaws:

for universal cutting;
for cross cutting;
for longitudinal cutting.

Longitudinal cut most often done either with a jigsaw or circular saw. But there are also hand saws for these purposes. As with power tools, the tooth on a hacksaw looks like a hook. The angle between the teeth can be 45–60 degrees.

Hook shape makes it possible to cut in only one direction. It is best to cut along the grain. In this case, the saw easily penetrates the wood and the cut comes out most accurate and even. The purchase of this hacksaw is appropriate only for those people who want to make furniture with their own hands. Because it is not suitable for any other purposes.

Cross cut tooth the most popular. Externally it looks like an isosceles triangle. The tooth angle is 45–55 degrees. This design makes it possible to cut well both while the blade moves forward and in the opposite direction. As a result, cross cutting occurs without special effort, quickly and as accurately as possible. When choosing a hacksaw, you must take into account that this type of tooth is only suitable for dry workpieces. The saw will tear fresh wood, and the sharpening will deteriorate.

For fresh wood use triangular teeth with parallel sharpening. This means that the teeth are ground in a checkerboard pattern and only on one side. As a result, a free channel appears between the teeth inside the cut, through which wet sawdust can freely exit without complicating the advancement of the blade.

The next option is combined teeth. Here the triangular ones intersect with the semicircular ones. Moreover, a semicircular tooth is larger than a triangular one. As the blade moves forward, long and narrow teeth make a guide cut, and when the blade returns to its original position, the triangular tooth enlarges the cut channel and removes shavings and sawdust. We must not forget that the smaller the angle between the triangular and semicircular teeth, the more accurate the cut will be.

Saws for universal cutting It is advisable not to choose; as a rule, they have a different set of teeth, which theoretically should perform any job equally well. But in practice, these hacksaws become dull much faster, and their sharpening is usually more expensive than a new saw.

And what is most important is that in any high-quality saw, the teeth must be made of hardened steel.

Types of hacksaws for wood

There are several types of saws, including:

regular;
narrow;
onion;
with a butt.

The cheapest saw for wood is narrow hand saw . This tool is suitable for cutting branches when working in the garden and small work with workpieces. As a rule, either double-sided triangular teeth or parallel sharpening are used.

You need to understand that This hacksaw can only be used with workpieces no more than 7-12 cm thick. A very short blade does not make it possible to create leverage; accordingly, cutting thick parts requires a large load.

Conventional saws can be with any type of teeth. The choice will depend only on what tasks you plan to purchase the tool for. You only need to pay attention to the fact that it is not advisable to use these saws during furniture production. Or you need to buy special large miter boxes so that you can cut at a certain angle.

Backed saws used as an auxiliary tool. Their main task is to make small cuts in the part.

Bow saws- This is an analogue of an electric jigsaw. They make it possible to make the most accurate cut and work with different workpieces at different angles. Exist:

transverse;
sweeping;
thorny;
rounded.

Swinging hacksaws make it possible to perform longitudinal cutting. Today there are canvases 40-80 cm long. Longer workpieces can only be sawed using a power tool.

Cross saws used for cutting workpieces across the grain. They can make cuts at right angles and at any other angle. Moreover, perfectly smooth edges emerge at the incision site.

Circular hacksaws narrower ones, used for figured cutting. They are used to make curves and other complex elements. Feature– use of very flexible steel grades.

Tenon hacksaws make it possible to create simple geometric shapes on a workpiece.

The difference between bow saws is that the fastening mechanism is purchased once, and you do not spend money on saws directly, purchasing new blades.

Manufacturers of wood saws

Professional saws distinguished by good quality and compliance with the specified characteristics. By purchasing tools from trusted manufacturers, you will be confident that this product will serve you reliably and for a long time. Among the trusted manufacturers it is necessary to highlight:

Bahco is a Swedish company that is part of the SNA Europe corporation. For more than 200 years of history, the company has never changed its basic concept - producing high-quality and affordable hand tools. Bahco saws are characterized by durability and reasonable price.

You can also find Sandvik saws on the market. This company is part of Bahco, so the quality of the product is general requirements companies.

American saw manufacturer Stanley, also focuses on the accessibility of its products. The company is distinguished by a large staff of engineers and designers. Thanks to their developments, the cutting edge and blade of hacksaws differ from domestic GOST, but this does not affect the quality at all. This company is great for those who choose a hacksaw for the dacha. Because the combined large teeth make it possible to produce any type of cut.

German company Gross younger than other companies. It achieves the competitiveness of its product due to its very low cost. However, the products are of quite high quality and meet all standards. The only drawback is that the choice of products is very small.

There are also domestic manufacturers offering high-quality and relatively inexpensive saws. Among which:

Piranha;
Bison

Saws Bison Manufactured in China, however, they meet the requirements for teeth and steel. Disadvantages:

cannot be used for working with hard wood;
continuous work time is no more than 10 minutes (then a pause of 15 minutes);
Do not leave it outside (it will quickly rust, even with low humidity).

Despite this, the characteristics of the hacksaw are suitable for pruning trees.

The Piranha company is relatively small and has been operating relatively recently. Like everything new, its products are quite affordable and different good quality. Saws Piranha are presented in only a few options. Large country The manufacturer of this product is China. But the products of this company are coated with Teflon, which protects the hacksaw from corrosion, even if you forget it on the street.

About safety and comfort

When choosing a hacksaw for wood, pay attention to the handle. The most convenient is a two-component handle with rubberized insert. It provides a strong grip, does not allow the palm to slip and does not rub the hand.

For working with workpieces of various sizes and performing different types cuts a set of replacement blades is far from superfluous. Saws are often equipped with equipment with different cutting edges and different shapes- for cutting down branches, making transverse and straight cuts, etc. It is also quite convenient when the hacksaw is equipped with a case for carrying and storage, or at least a plastic plug that covers sharp edges, eliminating injury and damage to the surface of the blade.

Saw

Wood has to be sawed both along the grain and across, and depending on the purpose, saws are divided into longitudinal (with an oblique tooth) and transverse (with a straight tooth). The cross-cut saw has teeth in the shape of an isosceles triangle, sharpened on both sides (Fig. 28).

The teeth of a rip saw look like a series of narrow chisels located one after another. They have an asymmetrical shape and are slightly tilted forward; the leading edge is almost perpendicular to the longitudinal axis of the saw.

A crosscut saw cuts fibers equally well when moving forward and backward, while a rip saw cuts fibers only when moving forward.

Saws with large teeth are used for rough cutting of workpieces, as well as for sawing mainly soft and damp wood. For fine work and sawing dry and hard wood, you need to use fine-toothed saws. It is difficult to saw a board if the distance between the tips of the saw teeth is almost the same as the thickness of the material. The saw will stick its teeth behind the edge of the board and will not move.

For sawing logs, thick boards, and firewood, a two-handed transverse saw is usually used. Two people operate this saw. The saw is set with its teeth at the mark at which the material needs to be sawed off, and a small cut is made with two or three short movements, after which they begin to saw at full swing. Each of the workers takes turns pulling the saw only towards himself and when reverse stroke does not push it forward, but only supports it by the handle, freely releasing the saw when its partner pulls it towards him.

Bow saws and hacksaws are usually used for carpentry and carpentry work. An amateur can get by with one hacksaw, as it is quite suitable for both longitudinal and transverse sawing. In addition, a hacksaw has a number of advantages: it is simple in design, universal, and thanks to the wide blade, it goes straighter in inexperienced hands. A circular hacksaw is used for filing along curved lines. There are also hacksaws for sawing tenons, ends, etc., which will be discussed below.

Clean, neat work hand saw depends mainly on good sharpening, setting and correct handling with the tool.

When sawing, hold the hacksaw firmly right hand, and the index and thumb It is better to guide the hacksaw along the blade (Fig. 29, A). This grip contributes to the correct and smooth movement of the tool, since the muscles of the forearm do not tense as much as when fully gripping the handle of the saw (into a fist). This is especially true for small hacksaws.

You should start sawing by moving not forward, but towards yourself. Guide the saw thumb with the left hand along the mark (Fig. 29, B), with a slow movement they pull the saw towards themselves and thus make a cut of sufficient depth. The saw is directed along the marking line so that left-hand side The teeth passed exactly along the marking line, and the allowance for the width of the tooth spread was on the part being sawn off. If a very clean end is required, then a small allowance is left, which is then removed with a plane.

When starting sawing, you need to ensure that the saw blade forms a right angle with the plane of the object being cut (Fig. 29, B). It is convenient to check the correctness of the cutting plane with a square (Fig. 29, D) or an evenly cut block. The saw can be oriented along the rectangular edge of the workbench on which sawing is being done, making sure that the saw blade moves parallel to the edge. For greater cutting accuracy, the board or block should be marked on all sides.

It is necessary to position the object being sawed so that the sawn part does not narrow the cut with its weight and does not pinch the saw. When longitudinal sawing, it is useful to insert a wedge into the cut from the end (Fig. 29, D). It should not be hammered too hard, otherwise the board may split. In order to expend less force when sawing, the saw is held at an angle to the plane of the board. Typically this angle is 60°, but when cross-cutting soft wood and less than 20 mm thick, an angle of about 40° is more advantageous. We must remember that what large quantity the teeth are in contact with the wood at the same time, the better the cut will be; this should be guided by practical definition saw angle.

When sawing plywood, flakes usually form on the opposite side of the sheet. To avoid them, it is recommended to cut the outer layer of plywood on the bottom side along the markings with a pocket knife.

It is necessary to ensure that the saw is always well sharpened and set apart. Setting and sharpening teeth require some experience, so it is useful to first learn, try to set and sharpen an old, broken saw, and only then start sharpening a new one.

It is more convenient to separate and sharpen the saw if it is fixedly fixed in a bench or bench vice (in the latter case, two narrow wooden spacers must be placed under the jaws) (Fig. 30, A). The saw is clamped in such a way that the protruding cutting part does not vibrate when working with a file.

If the saw blade is bent, it should not be straightened in a vice or with a metal hammer. First you need to try to straighten it with your hands, and if this fails, then place the saw on a flat wooden surface and straighten it with a mallet (Fig. 30, B).

When sawing, the teeth do not work equally. Sometimes their height is violated as a result of careless sharpening of the saw. To align the teeth at height, they are filed from above along the blade with a flat file. At the same time, it is very important not to tip the file to one side, otherwise after setting and sharpening the teeth will have an irregular shape. This task is greatly simplified if you make a special block. A hole is drilled in a small block along the axis and a longitudinal cut is made. A triangular file is firmly fixed in the hole (Fig. 30, B). Then the block is placed on the saw and, with reciprocating movements along the blade, the teeth are filed to the desired size, checking them with a long ruler.

The setting of the teeth is done so that the width of the cut is greater than the thickness of the saw, otherwise it will jam, which will significantly complicate the work. The setting consists of alternately bending the teeth through one in opposite directions; a value equal to approximately half the thickness of the canvas (0.25 - 0.7 mm). For sawing soft wood, the tooth set must be larger than for dry and hard wood.

It is not necessary to bend the entire rubber tooth from the base, but only the upper third of it.

It is most convenient to install a saw with a special wiring (Fig. 31, A), but an amateur may not have one and will have to use pliers. Having clamped the saw, as indicated, the teeth are bent one at a time in one direction, then the saw is turned over and the previously missed teeth are bent in the same direction. In a crosscut saw, the teeth are bent outward from the sharpening chamfer.

The distribution uniformity has essential, since a saw with incorrectly bent teeth will make an uneven cut and will be pulled to the side. It is convenient to check the correctness of the setting using a simple template shown in Figure 31, B. When viewed longitudinally, correctly set teeth should have the profile shown in Figure 31, B.

Sharpening is usually done with a triangular or diamond-shaped file with a fine notch. The teeth are sharpened by moving the file away from you; when moving back, it should not touch the saw blade. You need to work with a file without strong pressure.

The teeth of the crosscut saw are sharpened at an angle of approximately 45° (Fig. 32, A). The sharpened teeth of the cross-cut saw should look as shown in Figure 32, B.

The rip saw is sharpened by straight sharpening, moving the file perpendicular to the blade, as in Figure 32, B. In this case, there is no need to turn the saw in the clamp.

After sharpening the teeth, the saw is placed with the blade on a flat board and the burrs formed during the sharpening process are removed. This can be done either with the same file or with a whetstone.

If saws are used exclusively at a work table, then for ease of use you can make a special stand, shown in Figure 33, A.

If you need to keep the saw in a box to protect the teeth from dulling, you can use a bar with a cut groove (Fig. 33, B) or a piece of an old rubber hose. During long-term storage, the saw blade must be lubricated with machine oil to prevent it from rusting.