home Analyzes Saw for longitudinal cutting of wood. Hand hacksaws for wood: parameters, types and applications. Basic parameters of hand tools for cutting wood

Saw for longitudinal cutting of wood. Hand hacksaws for wood: parameters, types and applications. Basic parameters of hand tools for cutting wood

The saw is indispensable when working with wood; there are many options for using this tool, ranging from small carpentry work to complex structures. Let's consider the types and purposes of saws that will be useful to any master.

Hacksaw

An ordinary hacksaw is suitable for large and rough ones; its main advantage is that it does not require a network. Using this tool in combination with a miter box, you can make cuts at an angle.

Bow saw

A hand saw with a thin, flexible tip, designed for small, point cuts in carpentry work, for example, when cutting baseboards.

Hand circular saw

None of the electric saws are capable of performing as many tasks as this tool. A hand-held circular saw will allow you to make longitudinal and transverse cutting, insertion, etc., with the help of the tool it is possible to make partial cuts, chamfer and make workpieces.

Miter saw

Whatever carpentry work you do, the miter saw blade will cut the material at the required angle. With this tool, the master will be able not only to rotate the cutting disk at the desired angle, but also to tilt the blade to cut chamfers.

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Circular saw

This tool, of course, is capable of sawing short boards, but its main purpose is to prepare blanks from long boards. The disk, which is located above the surface of the table, cuts the material, which the master directs towards the blade.

Jigsaw

A jigsaw, also called a reciprocating saw, is indispensable if you need to make a complex cut. The tool has excellent maneuverability, which makes it possible to cut lines of almost any complexity. Thanks to its straight and narrow tip, the jigsaw perfectly makes curved cuts, small holes and filigree cuts.

Sled saw

Appearance This tool resembles a jigsaw, but the sled saw is larger and more powerful. This tool is indispensable for making cuts and various holes, assembling wooden structures, sawing uneven surfaces, sawing in confined spaces and other tasks.

Diamond saw

This tool is designed for cutting materials such as glass, tiles, stone, etc. Diamond saws make it possible to obtain a filigree, even cut without defects. The tool is safe and will serve you well for a long time.

Band-saw

This tool is designed for cutting along curved lines. Band-saw consists of two wheels, with a toothed metal plate fixed between them, which moves on the wheels in one vertical plane, and the steel table guides the material towards the tip. The tool will help you cut thick lumber into thin boards, and it can also work with metal and other materials. There are portable models of this instrument.

A circular saw blade is a working tool designed for... It is an integral part, without which it is impossible to carry out any workpiece processing operations. Saw blades used in hand-held cutting tools.

Depending on the type of disk, the following can be processed:

wood of various species;
wood products - chipboard sheets, OSB, plywood, laminated flooring and other similar materials;
polymeric substances and products made from them, for example, organic glass, polystyrene;
natural stone material, such as marble;
soft metals – aluminum, copper alloys;
products based on iron alloys - pipes, corrugated sheets, etc.

A cutting tool has certain characteristics, parameters, dimensions, purpose, and properties of the material from which it is made.

Basic parameters of a circular saw blade

Outer (external) diameter

Determined by the internal size of the protective casing
– a blade with a large diameter will not fit on a saw with smaller housing dimensions. The main dimensions of cutting tools for hand-held circular saws are in the range of 130-250 mm. The outer diameter does not have a significant effect on the cutting speed, but determines the cutting depth. As the cut increases significantly, the metal of the disk and the workpiece itself heats up.

Internal, landing diameter

It has several sizes: 16, 20, 22, 30, 32. An important parameter is that the diameter must correspond to the size of the power shaft on the saw for which the blade is selected. Some disk models have additional holes that secure the disk to pins.

Number of teeth on the disc

Affects parameters such as cutting speed and cleanliness of processing. With a decrease in the number of teeth, the processing speed increases, the conditions for chip removal improve, but the cleanliness of the cut deteriorates. As the number of teeth increases, the cut becomes cleaner, but the load on the engine increases. Conventionally, according to their quantitative ratio, disks can be divided into three groups:

a large number of incisors, in the range of 80-90 pieces;
average quantity (40-80 pcs.);
small quantity (10-40 teeth).

Discs with an average number of cutters are classified as the universal type. They can process soft and hard wood, make transverse and longitudinal cuts, and be used for processing various wood products.

Tooth inclination

Determined by deviation from the radius of the disk cutting edge surface. When the deviation is towards the back side of the tooth, the inclination is called negative, when back side tilt – positive. For longitudinal sawing, it is more advisable to use a tooth with a positive inclination, since during the processing process a kind of material capture occurs, the disk impacts the part, which contributes to faster cutting of the workpiece as a whole. The inclination of the tooth is divided into:

standard tilt – the angle varies from 5° to 15°;
positive, aggressive tilt is 15-20°;
a typical negative angle ranges from 0° to -5°.

Tooth configuration

Each type of cutter is designed and manufactured to solve a specific task. Subdivided:

Disc thickness

Determines the actual cutting width.
The standard size is 3.2 mm. In addition, the thickness of the disc affects the strength of the cutting tool itself. Reducing the parameter leads to heavy operating conditions, overheating of the disk and failure. A larger size causes increased consumption of the processed material, that is, “translation into chips.”

Circular saws are used in processing various materials. Accordingly, the cutting tool is designed for specific tasks.

Types of circular saw blades

Monolithic disk. They are made from high quality
high carbon or high speed steel. They are used for processing wood and products made from it, as well as for cutting polymer products. They have a number of advantages:

inexpensive;
simple sharpening of teeth - you can perform this operation yourself, without the presence of complex special devices;
They are sharpened many times, therefore, they have a fairly long service life.

A disc with teeth that are reinforced with carbide brazing. The blade is made of durable tool steel. Brazing is steel alloys with a high content of tungsten or cobalt carbides. Thanks to this solution, these disks have become the most common. They have a number of advantages:

However, there is a significant drawback - such disks are relatively expensive and require special equipment.

When choosing a blade, you must take into account the technical parameters of the circular saw:

engine power;
maximum speed;
mounting size on the motor shaft;
inner diameter of the protective casing.

Motor power affects the type of disc –
negative angle, a large number of teeth create heavy load on the engine, which will have to operate in “peak” mode.

The number of revolutions or spindle rotation speed is interconnected with certain disk sizes that the manufacturer recommends. Installing a cutting tool deviating from the recommended ones can lead to abnormal operation, resulting in possible breakage of the disk, saw and damage to the material being processed.

The mounting dimensions of the disk (inner diameter) and the corresponding one on the motor shaft must match, otherwise the tool cannot be installed on the saw.

The external size of the disk cannot exceed the internal size of the casing - if this parameter is violated, the tool will not be installed on the saw.

The type of disk is influenced by a number of factors:

type of work performed, material processed;
device, design of cutting tool;
number of teeth, their design.

Work performed and material processed. Since different discs are produced, it is necessary to decide on the types of operations (what types of cuts will be carried out), and also take into account what the cutting tool will process.

Depending on the type of operation and material, the type of disk is selected: monolithic or with carbide tips.

The processing mode and type of material determine the number of teeth, their type and inclination. The most popular is the average number of teeth with trapezoidal sharpening with a positive angle.

Disc quality

There are several signs by which you can almost accurately determine whether a product is of high quality or poorly made:

The disc must be marked, and the inscription must be applied using a laser tool and not with paint.
The blade must be subjected to a grinding and polishing procedure - the purity of the processing can be seen by looking at it if you “play” with the disc in the light.
The cutting tool disk is subjected to balancing and calibration procedures - the operation is roughly reminiscent of balancing a car wheel. After such treatment, the cutting tool will not “beat” and there will be no vibration during operation.
To compensate for possible temperature expansions, special slots are made on the disk, ending with small relief holes.
Some manufacturers reinforce the disc with several circular stiffening rings.
Another indicator of quality is the name of the manufacturer, its trademark. Today these are European, American, South Asian, Russian and Chinese manufacturers (listed in descending order of quality). By the way, some Russian manufacturers produce products comparable in some respects to European or American ones.

In general, choosing the right circular saw blade is almost a science. If you have no experience, then it is better to seek advice from professionals, especially those who have had the experience of working with a circular saw for at least 2-3 years.

Video about replacing a circular saw blade.

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. The long stroke makes it possible to apply less effort, because in one movement the cut is made big amount 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 a 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.

Back 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 - the production of 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 availability 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 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 the sharp edges, eliminating injury and damage to the surface of the canvas.

Any main cutting element hand saw- a series of teeth cut on the blade and representing cutters in the form of wedges. 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.

When cross-cutting, 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. Leading edges of teeth rip saws they 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. On the base, two guide rectangular triangles with equal legs are installed, welded from a 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 set, the wider the cut and, accordingly, less likely jamming of the saw in it. However, a cut that is too wide due to the large tooth set requires a lot of 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 wing nut (4) and screw (5) for fixing the amount of spread.

A simple wiring is made in the form of a small steel die free form with 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. Saw teeth with different heights when sawing wood are in different conditions: they cut unequally and are also loaded unequally. 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 the sharpening angle β, rake angle γ, cutting angle δ, pitch t and 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 - cavity of a dog tooth.

Each tooth in a longitudinal 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 in the opposite direction, they make an idling 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 correct choice of the 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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Details Category: Wood processing

Sawing with a carpenter's hacksaw

Sawing is one of the most critical operations in the wood processing process. The quality of manufacturing of parts and wood savings largely depend on the quality of its execution. By correctly performing the sawing, you can reduce the allowances for subsequent planing and the time for manufacturing the part.

Hand saws are divided into tension saws with a thin saw blade and loose saw blades with a loose, thicker blade. Tensioned saws include all bow saws, and for saws with a free blade - hacksaws.

Below you can watch a fragment of a film about making hand saws and hacksaws. Full version the film can be downloaded.

According to the direction of cutting the fibers, they are distinguished transverse, longitudinal and mixed Sawing
At transverse sawing the direction of the cut (cut) is perpendicular to the fibers.
At longitudinal sawing - parallel to the fibers. At mixed sawing - directed at an angle towards them.

Cutting element any saw is tape with teeth cut into it. Each tooth represents cutter. Saw teeth are also characterized step and height: height- the shortest distance between the base and the top of the tooth; step- the distance between the tops of adjacent teeth.
For cross cutting For workpieces, saws are used whose teeth have straight triangular profile, and for rip sawing - saws with inclined profile teeth

Hand saws are available with fine and coarse teeth.

Have saws for transverse sawing, the sharp cutting edges of the tops of the teeth alternately cut the wood fibers and remove the broken wood particles in the form of sawdust.
Have saws for longitudinal sawing, the cutting edges of inclined teeth protruding forward cut off the wood fibers and the cut particles are chipped along the fibers, forming sawdust. The figures below show the shapes of the teeth and the patterns for cutting fibers with longitudinal and transverse saws.

Technical characteristics of saw teeth

Tool	(triangle)	Point angle
*Bow saws*
Transverse	Isosceles
Dissolute	Oblique
	Rectangular
Fine-toothed	Rectangular
Circular	Rectangular	50-60 or 80-85	Straight or small boring
*Hacksaws*
	Isosceles or rectangular	Depends on the shape of the teeth
	Rectangular
Obushkova	Rectangular
Award	Isosceles

Purpose of sawing tools

Types of hacksaws and special saws	Purpose	Appearance and device
Wide	Cross rough sawing
Narrow (trigger)	Through sawing on a plane and curved sawing
Obushkovaya (slotted)	Finishing shallow cuts and adjusting products during assembly
Award (blade made from scraps of old saws)	Shallow sawing of grooves

When sawing, the saw blade rubs against the walls of the separated parts of the wood. And so that it does not get pinched in the cut, the saw teeth must be divorced(set of teeth), i.e., alternately bent in different directions. This makes the cut a little wider and makes sawing easier. Below is the views wiring for spreading the teeth.
There are wiring different forms. In the picture below on the left( A) shows the main types of wiring. On the image b And V- shows correctly set teeth for transverse ( b) and longitudinal sawing ( V).

When sawing workpieces, retreat from the marking line by 2-3 mm.

The hacksaw blade should move at right angles to the workpiece.

Sawing control carried out along the marking line. It should remain to the left of the sawing point on the workpiece.

For more precise sawing of wood or plywood blanks, saws with fine teeth are used. The inclination of the saw is shown in the figure.

This is how they work with a hacksaw. The marked workpiece is placed on a board (1) on a carpentry bench that has a stop (2). With your left hand you press the workpiece against the stop, and with your right hand you make a cut. In this case, the hacksaw is pressed against the stop and several short smooth movements are made towards you. After sawing, the hacksaw is moved along its entire length, aligning it with the marking line of the cut.

By moving the saw along the line, an incision is made, then the block is removed and the part is sawed off. At the end of sawing, the pressure on the saw is eased so as not to break off the wood fibers at the exit of the saw. The position of the hands when sawing is shown in the figure.

For precise sawing of bars and boards at angles of 90°, 45°, 60° and others, they are used miter box . Miter box has a grooved shape. It consists of a bottom 1, two sidewalls 2, between which the workpiece to be cut 3 is clamped. The sidewalls have cuts made at the desired angle. Saw blade 4 is inserted into these cuts and sawing is performed at the desired angle.

Application miter box eliminates part marking, increases cutting accuracy, reduces time spent on part marking, thus increasing labor productivity. The use of a miter box is especially effective in mass production details. The miter box may look like the one shown in the photo.

For ease of sawing, they also use tsulagu. Tsulaga very quickly made from a sheet of plywood or board and two bars. Thanks to the lower bar, it is easy to press it to the tabletop, and the upper one serves to support the workpiece. Tsulaga can be made with a movable sawing stop large quantity identical parts.

Sawing techniques using tsulagu, miter box, stops, are shown in the figures.

For sawing various workpieces and figure sawing they use different saws and hacksaws. Examples are given in the figure.

Securely secure the workpiece when sawing.
Use stops, miter boxes and other devices.
Sawing only with a serviceable, sharply sharpened saw.
Do not allow the saw to skew when sawing.
Do not make sudden movements with the saw.
Do not keep left hand close to the saw blade.
Place the saw on the workbench with the teeth facing away from you.
Do not blow away sawdust or sweep it away by hand. Use only a brush.