Among the fairly extensive list of hand saws and hacksaws, it is worth highlighting one type of saw that is in demand - the bow saw. Such a device can be created for cutting metal parts, as well as for working with wooden materials. In this article we will talk about what a bow saw is, what its features are and what you need to consider before purchasing.
Design
The saw was called "bow" not because it can be shot, and not even because it looks like Robin Hood's weapon, but because its design has the same principle of elasticity as in the ancient bow.
The entire structure of the machine is based on durable, well-finished and often varnished racks. There are only three racks - two on the sides and one horizontal. Racks are made from hardwood, for example, oak, hornbeam or ash. In the lower part vertical racks there are identical symmetrical through holes to attach the handles. The horizontal stand is called the middle stand. The working handle is not even a subject of carpentry, but of carpentry, because the comfort and level of productivity of the entire work directly depends on its quality. The handles have a rounded shape; there are cuts and holes at the end to secure the working blade.
A bow saw blade is often a thin strip of tool steel with a slight “notch.” The greater the width of the blade, the lower the maneuverability of the entire saw, and the lower the tension force in the clamps.
Any bow-type saw has a bowstring, which brings it even closer to the throwing weapons of ancient times. However, the purpose of such a bowstring is absolutely peaceful - it is necessary for strong and reliable tension of the blade between the handles. The bowstring is created from natural materials, for example, linen rope or hemp twine. Synthetic material didn't justify themselves. Their elasticity and durability are insufficient for cutting massive timber.
On axis central symmetry, in the space between the middle post and the bowstring, there is an auxiliary bar - an arrow. During the rotation of this part, tension occurs on the hemp or linen bowstring, as a result of which hacksaw blade freezes firmly between the handles.
Threaded handles and reliable design make the performance of such a saw very high for short and long cuts, as well as for cutting timber along and across the grain. Bow saw can overcome knots and cut along radii and curved patterns.
Comparison with a hacksaw
This tool is used to implement longitudinal sawing. The saw has a special beam in which the saw blade is stretched. The bow itself contains 2 stands and handles, as well as a spacer, a tension string and a fixing twist. Sometimes, as a substitute for twisting, you can find a screw with a nut connected to a metal bowstring in the design. There are circular bow saws used for cutting along a curved line.
Speaking of comparison regular saw(two-handed or hacksaw) with a bow saw, it is worth noting a number of advantages over a conventional saw:
- a bow saw will help make a more even and accurate cut
- during work you will put in much less effort than when working, for example, with a hacksaw. in certain cases, even two people can work with a bow, which is impossible when working with a hacksaw
- simple maintenance. Bow saw blades do not require turning, setting or adjusting. A worn file just needs to be replaced with a new one.
- The blade of a bow saw, clamped in the place of the cut, almost never jams. Yes, it is possible that the movement of the saw is sometimes difficult, however, it does not “chew” the saw tightly, as is often the case with conventional saws.
Despite their external similarity, bow saws from different manufacturers are radically different from each other. For example, there are differences in almost all structural components of the instrument - this is a different shape of the beam or handle, different method fixing and tensioning the canvases, as well as their tension.
Operating rules
To make working with a bow saw comfortable and safe, you should follow these recommendations:
- insert the blade into the slots of the handles and fix it through the side holes with dowels
- bring the saw to your chest so that the bowstring touches the body, and carefully examine the position of the blade with one eye. Its location should be strictly perpendicular to the line of sight
- by slowly and carefully turning the handle, you can achieve a smooth position of the serrated blade in the fixing holes
- After adjusting the blade, you need to slowly rotate the arrow, tighten the bowstring and stretch the racks to securely fasten the blade
- You should not sharpen or straighten working blades for bow saws yourself. The best option is the purchase of factory-made blades characterized by sharpness and precisely set “toothing” of blades
- You can’t be distracted while working, because you can saw off the board along with it, and you shouldn’t throw a saw sticking into the workpiece during a break, because you can break the blade, and it’s very difficult to start work from this position.
Before starting work, it is necessary to inspect the instrument and make sure that there are no cracks or defects on the wooden parts of the stands, and that the string is intact.
To make cross cuts as convenient as possible wooden blanks must protrude (“hang”) from a fixed support. Experienced craftsmen begin to saw from the thumbnail of the hand holding the beam or timber. After the blade has “bitten” into the workpiece, it can be lightly rested not on the nail, but on the joint of the thumb. But for maximum cutting accuracy, as well as for making curved cuts, it is worth using templates or a miter box.
The wood bow saw is excellent for longitudinal sawing. To do this, the canvas must be fixed at an angle from 0˚ to 90˚ relative to the horizontal post. The pressure applied will be less than in the crosscut process, so the procedure will take a little longer. This cutting is done with both hands. Masters advise placing the board or timber in a horizontal plane and moving the saw towards you, holding it by the handle and side stand.
If you need to make a curved cut, you should purchase a narrow blade, the width of which does not exceed 8 mm. Blades for curved slots are sold with rectangular teeth and a significant spread - almost up to 2.5 denominations of the nominal thickness of the entire blade. If you need to cut a thick board that has many knots or oblique layers of wood, you need to choose the widest blade, up to 5 cm wide. It should have a small gap, but significant thickness. It is not recommended to make figured and curved cuts on such material.
Bow saw Bahco
Bahco bow saws are considered one of the best in the world. Thanks to the light steel frame, significant tension of the blade is ensured, up to approximately 120 kg, as well as fast and uncomplicated sawing. There are two series of such saws:
- series 51. These saws are equipped with dagger teeth for cutting old and dry timber
- series 23. These saws are equipped with a splitting tooth for cutting green lumber.
The tips of the teeth of absolutely all saws of this brand are electrically hardened high frequency, have sharp edges that work when moving in two directions.
The main advantages of Bahco bow saws:
- have an ERGO™ frame
- ergonomic handle with finger protection system. This tool is very convenient and safe.
- very robust construction
- the canvas is made of steel highest quality and coated with impact-resistant enamel and corrosion protection
- empty lightweight 24" frame that weighs less than a kilogram
- The latest fastening system puts a strong tension on the blade (up to 120 kg), guaranteeing a straight cut.
Let's look at two saws, 530 and 759 mm. They have different size, different shapes, as well as various mechanisms for tensioning the web.
The 530 mm (21“) long saw has a triangular shape. For pruning trees, this saw can be called the most convenient, because it can be inserted into the narrowest gaps between branches. With one such saw, it is comfortable to saw only thin-sized logs; even 10-centimeter logs cannot be sawed, because the beam already clings to the log, and the blade jumps during cutting. Overall, this tool is quite useful for gardening work, but you can’t call it a hiking option. Note that in the Bahco product line there is a bow saw for the same 530 mm blades, but it has a more familiar shape, which resembles a truncated triangle.
The canvas is equipped with a lever tension mechanism. It is secured at the front with a partially hollow cotter pin inserted into two holes in the beam. The holes have different diameters; for this reason, the cotter pin does not fall out on the new saw. However, many craftsmen note that this will not last long, because the cotter pin is made of a fairly soft metal, and through certain time the flaring gets crushed and it falls out at the most inopportune moment. At the same time, this is not the end of the world. To restore the functionality of the saw, you only need to have a nail or a small piece of wire.
At the back, the canvas is inserted into a special lock, which has a more reliable fixation. It can only be broken if the canvas is pulled too hard, and the lever axis can also be twisted.
The 759 mm long saw has a serious appearance. It is trapezoidal in shape, the bevel towards the front edge is invisible. The blade is mounted on rigidly mounted pins and tightened with a screw. The handle, which has a protective bracket, is tightly attached to the beam. This tool cuts perfectly. There is no particular difference between a blade for dry wood and a blade for green wood. This tool has an eccentric blade protection system.
To operate a bow saw, the blade must be positioned correctly in relation to the machine. Its tilt angle should be 30°; Correct rotation is adjusted using a knob. The saw blade should be straight, without distortion and well tensioned. They saw slowly, but with confident movements; If you rush, the cut will turn out uneven.
On a high-quality bow saw in working condition, turning the handles should be difficult. After work, it is recommended to loosen the screw so as not to expose the stand to stress and not to stretch the canvas.
At longitudinal sawing The material to be sawed must hang outwards. When cutting crosswise (Fig. 1, a), the workpiece lies horizontally; when sawing longitudinally (Fig. 1, b), it can be in horizontal and vertical positions. Usually they start sawing from the nail of the thumb of the left hand (Fig. 2), which is why this technique is called “by the nail”. When sawing, the marking mark must be visible at all times. For precise cross cutting of boards, a miter box (shtosslad) is used, which is a box with cuts in the side walls made at a certain angle (Fig. 3).
For sawing wood with cross-layers, knots and other defects, a bow saw with a thicker and wider (up to 50 mm) blade is used. A circular saw, which has a narrow blade (up to 8 mm), rectangular teeth and a large set (2 - 2.5 thickness blades), as well as high machine stands, without special effort You can perform curved sawing, since a large spread of the blade gives a wide cut, in which the blade can easily be turned in the required direction.
When sharpening a bow saw secured in a vice, the file may slip and injure your hand. And holding your hand on the sharp edge of the file is not very comfortable. To insure yourself against possible injury, place a tip made of a rubber tube (length 3...4 cm) cut along the length on one side onto the file head.
After purchasing a bow saw, carpenters sometimes shorten the mullion, change the string, make wider bow stands, since shortened machines are convenient to use, wider stands reduce their deflection when tensioning the bowstring, and with a bowstring thickness of 10 mm, an even and strong tension is obtained and it is eliminated gap The string in the places where it adjoins the posts is usually wrapped with fishing line at a distance of 25...30 mm from the posts. At the same time, if the twist breaks, the bowstring does not fall off the machine.
For convenience, additionally clean the handles in the bow saw with fine-grained sandpaper and coat the entire machine with oil varnish.
To tension a bow saw, it is advisable to use a lever bowstring instead of a twisting one (Fig. 4). Such a bowstring can be easily made from two pieces of cable with a diameter of 2...3 mm. The device uses a metal lever, the end of which is bent and inserted into the hole in the mullion. The degree of tension depends on the position of the hole into which the lever fits. It takes seconds to loosen or tighten the tension on the saw blade. In addition, the cable is an “eternal” bowstring. The mullion can be made of wood, for which you need to choose a hard species (for example, beech).
To reduce friction of the bow saw blade against the walls of the cut, its thickness should be reduced. To do this, attach the canvas horizontally with a clamp to a metal base. At a distance 4...1 times the width of the blade, fasten a metal plate on the base with a thickness 5 times the thickness of the saw (Fig. 5). Then, using a coarse file, resting its end on a metal plate, remove the layer of metal from the saw. Do the same operation on the other side of the saw. After removing the metal, sand the blade with fine-grit sandpaper.
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| Rice. 4. Stretching device for a bow saw: 1 - stand; 2 - cable; 3 - lever; 4 - middle. | |
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| Rice. 5. Reducing the thickness of the bow saw: 1 - saw blade; 2 - metal base; 3 - plate placed to form a thinning angle; 4 - file; 5 - clamp. |
Modern bow saw represents curved arc a metal tube (or rod) between the ends of which a cutting blade is stretched. A rigid arc allows you to make the cutting blade thin, long, and narrow. Depending on the size of the arc, a blade with a large tooth (4 - 5 mm high) can be from 30 to 90 cm long. The cutting blade is attached using bolts, pins or an eccentric bracket, which makes it easy to adjust the degree of its tension.
The cutting blade of some bow saws is secured using rotary couplings. They make it possible to rotate the plane of the blade relative to the plane of the saw itself. At the beginning of the cut, the saw should be held so firmly that the force of the hand is significantly greater than the weight of the saw. The hand gets tired quickly, but the cut will be smooth.
Another simple rule: the teeth of a bow saw should cut into the wood due to the weight of the saw itself. If you try to apply force, the thin and narrow cutting blade will begin to “play”, which will greatly complicate the process itself. All bow saws whose arc is made from a metal tube have plastic, metal or wooden handles of different configurations and are intended only for direct hand operation.
The bow saw is one of the most common types of saws still in use today. The design of this tool includes several structural parts, one of which is the bow saw blade. Such a blade can have different sizes and tooth shapes, can be made from a variety of metals and have various purposes. Therefore, in this article we will take a detailed look at blades for bow saws for wood, and also find out what you need to know in order to choose such a blade in a store or hardware supermarket.
Main features of the saw blade
When choosing or purchasing a saw, it is important to pay attention to the main features of the part, namely parameters such as blade length, density and stability, fastening method, etc.
Length of blade for bow saw. Determining the length of the bow saw blade is very simple - to do this, it is enough to know the length of the frame in which it should be installed. So, the frame can have a wide variety of sizes - it can be a saw with a length of 350 mm, 500 or 700 mm, and so on. Also, important feature in this case, it is the length calculation system - it can be inch or metric. Therefore, if the length of the bow saw is expressed in inches, then inch blades should be selected accordingly.
Canvas material. Several types of steel are used as material for the manufacture of bow saw blades. Naturally, all these types are high-strength, so the following types are used:
- V high carbon steel;
- V high-strength tool steel;
- s hardened steel.
In addition, the coating of the blade teeth can be coated with a special Teflon coating to prevent corrosion processes or any others that arise due to external environmental influences.
Shape of blade teeth. Is enough important characteristic when selecting and using a bow saw blade. The blade teeth may have different shape– these can be trapezoidal or triangular-shaped teeth, they can also be teeth with a forked triangular tip (Kremlin-shaped teeth), and so on. In addition, a feature of bow saw blades for wood is that it has different quantities teeth per inch of blade. This indicator indicates how neat the cut made with this blade will be. The greater the number of teeth per inch of blade, the more accurate the cut will be; accordingly, the fewer teeth, the more “rough” the cut will be.
Consumer analysis of bow saw blades
Today, you can easily buy a blade for a bow saw, but at the same time, you need to know the most suitable options. Therefore, we will present several types of saw blades that are highly popular in the market.
Stanley Fleam Tooth canvas. This blade is intended for use in a bow saw and has hardened teeth of a traditional shape. The material used to manufacture this blade is Swedish high-strength steel. The surface of the teeth themselves is hardened, so when examining this blade you will notice that they have a slightly dark tint in contrast to the rest of the surface of the blade. This blade is best suited for quick cuts, longitudinal and cross cuts.
Thanks to the successful geometry and tooth spacing, the occurrence of vibrations during operation is eliminated and minimized. The blade length of this blade is 610 mm. Thus, if the blade does not fit the frame of the bow saw, you can install a special adapter that will adjust the size of the blade to the size of the saw itself.
Bahco bow saw blade. This model bow saw blades, has been around since 1969. So, the company has developed its own version saw blade, which was made of bimetallic material. Thanks to the properties of this material, the fabric is very elastic, and at the same time durable and wear-resistant. In addition, the blade has high cutting ability. The length of the blade is 530 mm, and the cutting has 51 teeth. In turn, this makes it possible to ideally work with old and dry timber, wood, etc. And thanks to the triangular shape of the teeth, the blade is also well suited for cross-cutting raw wood.
Intertool bow saw blade with an “American” tooth. The material used to make this blade is Swedish high-strength steel. The teeth of this blade have a hardened structure, which ensures a long service life of the tool, and thanks to the correct geometry of the teeth, any vibration is eliminated during operation, and a clean, high-quality cut is ensured.
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Bow saws have long occupied a place of honor among carpentry tools. And although their design and design have changed significantly over the years, the basic principle of operation of these saws remains the same. What is the advantage of this tool and what makes it stand out from the rest?
What is a bow saw used for?
It is convenient to use a jigsaw to make short, mainly transverse cuts, and a hacksaw to make long, longitudinal cuts. And only with the help of a bow saw can you make a variety of dividing cuts, both with dry and wet wood. In addition, for a bow saw for wood, it does not matter how the wood is cut - along or across the grain. If we add to this the ability to work with one hand (the first “bows” were exclusively two-handed), it turns out that the tool in question can be used for cutting wood:
- in longitudinal;
- in transverse;
- in figured;
- in an angular direction.
The only insurmountable obstacle for bow saws is the transverse dimensions of the workpieces - for thick logs it is still better to use a power tool. However, you have to work much less often with thick logs...
Do you know which hacksaw is better for wood?
Three circumstances give versatility to bow saws for wood:
Modern manufacturers of bow saws and accessories for them - trade marks Bahco, Stanley, Intertool, Fiskars and others complete their products different types and designs of saw blades, which increases the ease of use of the tool.
The device of a bow saw for wood
The modern “onion” includes:
The frame of a bow saw for wood has special requirements - it must be rigid and at the same time light, so as not to increase physical stress during sawing. A special tubular profile with a very small width satisfies the task. This makes it easy to bend it during the manufacturing process to the required frame configuration without losing the strength of the part, providing the saw with the necessary mobility.
One of the main differences in the design of modern bow saws for wood is the principle of saw blade tension. For example, the Gardena or Proline brands use a handle with an eccentric for tensioning: by using it, changing the angle of inclination of the handle relative to the longitudinal axis of sawing, you can thus adjust the tension force.
Manufacturers of saws from Bahco Stanley have taken a different path: there a special screw mechanism for tensioning the saw blade is mounted in the handle. The choice is determined by ease of use, however, the presence of a screw mechanism provides increased tension accuracy, and does not depend on random movements of the user, when the position of the handle during sawing can randomly change. That's why swivel mechanism It is recommended to use tension if you have some experience working with a bow saw.
To fasten the saw blade to the opposite part of the “string” (frame), removable cotter pins or wing screws are used. The latter are more reliable, since the cotter pin, usually made of mild steel, wears out over time and can spontaneously come out of the mounting hole.
Bow saw blade
The versatility of this tool also determines changes in the design of the saw blade, in particular its teeth. Most often used:
- Saw blades with uniform tooth pitch. They are designed for smooth cutting of wood with a relatively short length.
- Canvases with the so-called “American” tooth, when after 3..4 ordinary teeth there is a double or “Kremlin” tooth. This configuration of the cutting part of the saw blade allows for longer and more complex cuts. The frequency of alternation determines the accuracy of the result: the closer the double teeth are located to each other, the less clean the cutting line will be.
- Spatial teeth with wide spacing. A blade with such teeth is useful for maximum sizes sections of cut wood. The cutting force and the amount of waste increase, but sawing productivity becomes the highest possible.
Depending on the tasks assigned, the material of the saw blade also changes. For tools of relatively small sizes (350 mm, partly 530 mm), blades with a uniform pitch are used, which are made of structural chromium-nickel steel of type 45Х, 40ХН or 45Г. The blades undergo high-frequency hardening, as a result of which their surface hardness reaches 45...48 HRC. However, such blades are very sensitive to changes in the sawing axis, which easily changes due to the flexibility of the blade, and break at extreme bends.
For blades with double teeth, high-carbon steel 7HF or even high speed steel. The durability of such blades (if they are not made in China) is very high, since as the percentage of carbon in steel increases, its elastic properties increase. In addition, the blades do not need to be cooled, since the vanadium and tungsten contained in such steels are highly heat resistant.
For wide set teeth decisive factor Durability is considered to be abrasive wear from friction of wood on metal. Therefore, the Finnish company Fiskars applies a Teflon coating to the tools it produces, which reduces the coefficient of friction, thereby increasing the durability of the saw blade. Other manufacturers (for example, Bahco) produce bimetallic blades: the base is made of structural steel, and cutting part- from the instrumental.
K category: Carpentry work
Bow saw
Purpose and structure of the saw. The bow saw is so called because it looks like a bow (it also has a bowstring!) - an ancient weapon for throwing arrows. This saw is designed for longitudinal and cross cutting of wood.
There are bow saws various designs. But the saw shown in Fig. is most often used. 24.6. A steel toothed blade is stretched in the saw machine, and the upper part of the machine is tightened with a bowstring.
The machine consists of two racks, two handles, a center and a twist (otherwise known as arrows). The stands are made from hardwood. There are holes for handles at the bottom of the racks. The pens themselves -round shape(to make it more convenient to hold) are also made of hardwood. Each handle has a cut into which the end of the toothed blade fits. And to secure the canvas, small holes are drilled in it and the handles. Special pins or nails are inserted into the holes, connecting the handles to the blade and, ultimately, to the saw machine.
The thin blade of the bow saw is made of durable, so-called tool steel; it can be easily tensioned in the machine. A thin blade makes sawing wood faster and easier.
There are holes in the middle on the sides into which the racks are inserted (exactly in the middle of their height). The middle connects the racks to each other and expands them, allowing you to adjust the tension of the canvas. The twist rests on the centerpiece.
Rice. 1. Saws: a - hacksaw; b-bow saw
A bowstring, made of thin, strong linen or hemp rope, tightens the posts. When the twist (arrow) rotates, the bowstring twists and tightens the upper ends of the posts. At the same time, the lower ends of the racks diverge, tensioning the saw blade.
Preparing the saw for work.
Before you start sawing wood, you need to check and adjust your bow saw. Here is the sequence of operations:
1. Loosen the string slightly by turning the twist counterclockwise.
2. Take the saw by the handles and lift it with outstretched arms so that the bowstring is pressed to the chest at shoulder level.
3. Close one eye (preferably the left one) and check whether the canvas is tensioned and installed correctly. First they look at the canvas at the right handle, and then at the left. By slightly turning the handles, you achieve such a position of the serrated blade so that only its back is visible, and not the sides. In this case, the canvas is installed without distortions.
4. Stretch the saw string, rotating the twist in the opposite direction.
Remember!
1. You can only work with a working saw.
2. When starting to saw, you must always use a guide.
3. Do not hold your hand near the teeth of the saw blade while working.
4. Finish sawing carefully, never leave the saw in the cut!
5. Be careful when moving the saw from place to place. The saw is carried in the lowered hand, bowstring forward. The teeth of the blade should be pointing down.
6. Don't be distracted while working!
- Bow saw