What is the shape of the cutting part of any saw?
Sawing operations and methods of wood making
Sawing is one of the most important operations in wood processing. The quality of workmanship depends to a large extent on the quality of the workpiece and the saving of wood. Properly performed sawing can reduce the allowance for subsequent planing and the time to produce the part.
Manual joiner saws are divided into tensioned with a thin saw blade and untensioned with a free, thicker blade. Tensioned saws include all archer saws. and to saws with a free blade. hacksaws.
According to the direction of cutting, a distinction is made between transverse, longitudinal and mixed cutting.
During cross sawing, direction of cutting (kerf) is perpendicular to fibers.
For longitudinal sawing. parallel to fibers. In mixed sawing, it is directed at an angle to them.
The cutting element of any saw is the band with the teeth cut into it. Each tooth is a cutter. Saws teeth are also characterized by pitch and height: height is the shortest distance between base and apex of tooth; pitch is the distance between the tops of neighboring teeth.
Saws with teeth with straight triangular profile are used for cross cutting of workpieces, and saws with slanted profile of teeth are used for longitudinal cutting.
Hand saws are made with small and large teeth.
Cutting Irregular Shapes on the Band Saw
Cross-cutting saws have sharp cutting edges on tooth tips that alternately cut into wood fibers and remove splintered wood particles as chips.
Slit saws have cutting edges that protrude forward and cut the wood fiber and cut particles that break off along the fiber creating sawdust. The illustrations below show tooth shapes and how to cut through fibers with a longitudinal or crosscut saw.
Important cutting wheel characteristics
Let’s find out how to choose a circular saw blade for wood, guided by the main parameters of the tool. because it is there you can tell if the bit is right for the job or not. And knowing even the small nuances, you can significantly improve the quality of work.
Determines how wide the kerf will be. Also this parameter indicates the strength of the cutting disc. Standard value is 3.2 mm. Using a bit thinner than this can increase the risk of overheating and breaking it. A blade that is too thick wastes a lot of material. As craftsmen say. “transfer to shavings”.
Outer and inner diameter
The size of a circular saw blade determines how deep into the material to be cut. But when buying you have to consider the inside diameter of the protective hood. Otherwise it is not possible to fit too big cutting–off wheels on the circular saw.
Generally, the sizes range from 130 to 250 mm. But if the shroud allows it, it is possible to find a disk with larger outside diameter. However, the machining speed is not affected by these figures. The depth of penetration into the material is important. But the thicker the kerf, the hotter the blade will be.
Also the thickness of the power shaft on the circular saw has to be considered. So that the inside bore of the cutting wheel can fit tightly on the tool. Blades for circular saws are installed with diameters from 16 to 32mm. And some models have additional holes for a firm grip on the saw.
The number of teeth on the saw blade determines how clean the cut will be. The number varies from 10 to 90. And the highest cutting quality can be obtained with the maximum number of cutters. Also in this case it will be easy to work in the transverse direction. And for longitudinal cuts it is better to use a disc with fewer teeth.
Blades with 40 to 50 cutters are considered universal. It’s easy to work in either direction. But there is a nuance. The more teeth the slower the cutting speed. Fewer teeth make it through much faster, but the quality of the cut will suffer.
Tooth sharpening angle plays an important role. It is measured from the radius of the disc. With a negative slope, facing the back side, it is easiest to make longitudinal cuts. Positive (toward the back) allows the blade to run over the material and grip it well. This promotes cross-cutting of the workpiece.
- universal (standard). from 5 to 15 degrees;
- Positive (aggressive). 15 to 20 degrees;
- negative. from 0 to.5 degrees.
But for the best choice, when in doubt about how to solve a particular task, you need to pay attention to the tooth configuration. The flat cutter is suitable for quickly sawing any wood lengthwise. Marked with the English letters FT.
If the cutters are alternately tilted in opposite directions the saw gives a clean enough cut across the workpiece. Such a blade is well suited for plywood, particleboard and composite boards. Marked with the letters ATB.
There is a combined type, when 4 ATB cutters are replaced with one FT one. This consistency allows you to work wood in different directions, solving almost any problem. Marked with the word Combi.
The successive alternation of the FT ordinary tooth and the higher but sharpened trapezium one gives an excellent result in sawing. Not only any wood but also non-ferrous metals can be safely sawn with this blade. Teeth in this model never break off and do not catch sawdust.
But a cutter with a flat tip that ends in a chamfer (double corner) is not afraid of nails or hardened cement. This configuration is specially designed for deck wood. But it can also be successfully used for cutting construction materials.
Top of the best models
The top 5 modern hand-held wood saws are represented by the following models:
- Bahco 2600-16-XT11-HP. The saw handles cross-cutting and rip cuts equally effectively. Blade is specially coated against friction forces. Equipped with resistant teeth and ergonomic non-slip handle. Weighs less than 0.5 kg. The only drawback is the high price.
- Gross Piranha 24109. Classic saw with a blade strength of 66 HRc and a length of 40 cm. Teflon coating, ergonomic handle, 3-year durability of the cutting part, the ability to handle raw wood. the main advantages of the model. Disadvantage. it is not intended for sawing large-sized workpieces.
- ZUBR EXPERT. Quality model from domestic manufacturer at the best price. Characterized by a 40 cm blade, 5 mm tooth pitch, ergonomic plastic handle, versatility of use and high cutting speed thanks to special toothing.
Types of Steel
Hacksaw blades of any type are made from various types of steel, including. alloyed or carbon steel. The hardness of the blade. as measured by the Rockwell test. indicates the quality of the product.
Hardened hacksaw blades made of hardened high-quality tool steel. They are very hard, but in some situations are poorly susceptible to bending stress. Flexible blades contain hardened steel on the teeth only. Hacksaw. a flexible sheet of metal. They were sometimes called bimetallic blades.
Early blades were made of carbon steel, now called “low-alloy” steel, and were relatively soft and flexible. They did not break, but they wore out quickly. Over the decades, metal blades have changed, different alloys have been used and tested in practice.
High-alloy metal blades cut accurately but were extremely brittle. This limits their practical application. A softer form of this material was also available. it was highly resistant to stress, more resistant to breakage, but was less rigid, so it bent and resulted in a less accurate cut.
Since the 1980s, bimetal blades have been used extensively in the manufacture of wood hacksaws. The advantages were obvious. there was no risk of breakage. Over time, the price of the product dropped, so such cutting elements are used as a universal option everywhere.
Carbon steel is usually the mildest and cheapest of the other types. It began to be used in domestic tools. The material is valued by craftsmen because it can be easily sharpened. Most woodworking tools are made of carbon steel because other material is sometimes quite expensive to use.
Stainless steel is heat-treated, its hardness coefficient is 45. Used to make tools with a quality cutting edge. Can be used in harsh conditions, but is more expensive than carbon steel.
High-alloy is widely used in toolmaking. It is available in different versions: M1, M2, M7, and M50. Among them, M1 is the most expensive grade. Although few hacksaws are made of this material, the described steel type has a longer service life. Not used for large tools because of its inherent brittleness. Hacksaws made of high-alloy steel are often marked HS or HSS.
Carbide carbide steel is used in the manufacture of hand tools because it allows you to perform tasks efficiently. Being very hard, the alloy is carefully machined so that it can be used in the future, as products can break easily.
steel circular saw blades are most commonly made of high-speed steel. The most popular would be BS4659, BM2 or M2.
Design and function
The design of a manual hacksaw includes two components: directly the hacksaw blade and the holder, which is a special frame, to which the saw blade is attached. This part is more often called a frame or a machine. It can be sliding or solid. The former are considered more comfortable, because they allow you to fix the blades of several sizes. On one side of the holder there is a static head and a tail part with a handle, on the other side there is a moving head, a screw to create tension of the saw blade.
There are special slots in the heads, they are used to attach the metal part.
A blade in a frame is fixed under the following scheme: its ends are placed in slots so that teeth were directed from the handle direction, thus the holes on the saw blade edges and small holes in its heads should coincide completely.
Then pins are inserted into the slots and the blade is drawn well, not too loosely, but at the same time not too tightly. If the saw blade turns out to be over-tensioned, it will break from any misalignment while sawing, and a weakly tensioned one will start to bend, which often leads to deterioration of the cut, and can also be the reason of tool breakage.
Depending on the density of the metal used, the teeth range from 0 to 13 degrees, and the back angle varies from 30 to 35 degrees.
Saws made of soft metals have a pitch of 1 mm, and those made of hard metals have a pitch of 1.5 mm. Saw blades made of steel have a 2 mm pitch. For carpentry work mainly use a blade with a small pitch of 1.5 mm, then at a length of 20-25 cm the tool includes 17 cutters.
When cutting with a hacksaw, at least 2-3 teeth are involved at a time. In order to minimize the risk of the saw jamming in the work material, the cutters are “bent”, i.e. each pair is carefully bent in different directions by 0.3-0.6 mm.
There is another version of tapering, it is called “corrugated. With a small tooth pitch, 2-3 teeth are offset to the left side and the next 2-3 teeth to the right. If the pitch is medium, one tooth is set to the right, another to the left, and the third one is not set. In such a case, together with the teeth, metal is seized, thus obtaining corrugations.
The blades are made in sizes from 15 to 40 cm, with a width of 10-25 mm and a thickness ranging from 0.6-1.25 mm. Usually cemented steel or carbon alloy is used as a basic material, less often tungsten or chrome alloys are used.
The teeth can be sintered or simple, the first are disposable, the second can be sharpened.
Depending on the features of the blade and the structure of the teeth, there are several types of hacksaws:
- manual. the length of the saw blade does not exceed 550 mm, the teeth are of medium dimensions;
- wide tool. optimal for frequent and intensive use, the size of the blade. more than 600 mm, the teeth. large, the pitch. large.
Depending on the shape, the functional purpose of the hacksaws also differs.
Thus, the usual saw for everyone has a standard rectangular shape. these tools are universal.
For sawing dry twigs and other similar jobs it is worth choosing products with a rounded blade: such sabre saws glide over wood quite easily and quickly.
The shape of the handle plays a significant role in the usability of hacksaws.
it is important that the device is in harmony with the operator’s hand and that it is physiological. Hands often sweat during work and start to slide on the surface, so when buying hacksaws preference should be given to models with grooves and recesses, as well as rubberized tabs that prevent slipping.
Electric cutting tool
Modern manufacturers offer an electrified version of devices for cutting surfaces of different materials to perform large amounts of work at minimal physical cost.
Electric sabre saw. The ability to use blades of different lengths or widths as cutting devices, as well as a variety of tooth sizes predetermines the versatility of using this tool. This makes it possible to work successfully not only with wooden products, but also to effectively cut metal and plastic.
The main parameter of the sabre saw (piranha) is considered its power, which is in the range of 400 to 1600 watts. The cutting depth is completely dependent on the power of the unit. Household sabre saws have a cutting length of up to 90 mm, but the professional tool is capable of cutting parts up to 200 mm.
Appearance of electric motor forced the inventors of the tool to think about the idea of replacing the reciprocating motion of the blade by circular rotation of the cutting device. This is the principle used in circular saws, which have the advantage of high power and mobility in comparison with handheld hacksaws.
Structurally, electric circular saws are divided into units without a gearbox and geared models. In the first version, the disk is mounted directly on the rotor shaft of the electric motor, which reduces the weight of the entire unit and makes it more affordable.
The geared units transmit the rotation to the saw blade from the electric motor through a gear system, on the shaft of which the blade itself is mounted. The angle of the cutting teeth is considered to be a peculiarity of the working discs. In passive elements the teeth are tilted counterclockwise (the sharpening angle is negative), and in active blades they are bent along the rotation.
Active sawblades are used in wood processing, while passive sawblades are more commonly used on metal products. Operating characteristics of circular saws directly depend on the power of the electric motor used (0.65-2.5 kW).
When cutting firewood and felling timber, the depth of cut is the main indicator, not the accuracy and cleanliness of the cut. This is exactly the kind of task that a chainsaw with a powerful gasoline or electric motor is used for.
Cutting depth depends on the bar length of the chain saw. The bar is called the two plates connected to each other, one end of which has a drive sprocket, and the other end of which has a tensioning mechanism. Chainsaws with an electric motor have a capacity of 1.5 to 4 kW. For a household, it’s enough to choose a tool with a capacity of up to 2 kW and a guide bar length of 30-40 cm.
An electric jigsaw uses a narrow cutting blade that moves up and down at high frequency. Thanks to this movement the device is able to cut out various curvilinear details from plastic, plywood and ceramics precisely and correctly.
Manufacturers of this jigsaw offer a whole set of special blades, which differ in frequency and inclination of the cutting teeth. Quick installation and change of blades is the main operational advantage of this type of cutting tool.
The technical characteristics of household models are:
- cutting depth of steel sheet from 4 to 20 mm, and wood. 45-80 mm;
- Motor power from 400 to 900 watts;
- frequency of movements up to 3 thousand revolutions per minute.
Some models use a very useful option. a laser pointer, which helps to clearly see the marking line.
tool of band type
Operating device of this device is a closed steel band with teeth, which is driven by an electric motor.
Cutting with a band saw is much easier than with a jigsaw, which tends to get out of hand and vibrates a lot. The ability to hold the workpiece with both hands greatly increases the accuracy and quality of cutting any curvilinear elements.
The main performance parameter of band saw equipment is considered to be a rather large cutting depth, which is in the range of 8 to 50 cm. Other characteristics fully depend on the cutting blades used.
The design of a band table saw for metal has little difference compared to a fixture for cutting wood. However, it can only make cross-cutting cuts in steel angles, pipe, or rebar.
How to choose?
The choice of a particular type of saw, as seen above, depends on what tasks are to be solved with its help, because the different categories of such a tool are not always interchangeable. For this reason, let us focus on some other criteria.
When selecting an electric band saw, pay attention to the power source. Let’s say right away that non-electric saws are rare these days, and we are talking about either low-powered hand tools or gasoline-powered ones. with high power, but a characteristic smell and deafening roar. As for the electric machines, they are usually powered either from the network or from a battery. The mains-powered desktop models always give out more power, in the conditions of daily work in the workshop they will be the priority. Cordless saws are somewhat limited in range, they are designed with mobility in mind, so they cannot be large. Their use is most convenient outside the workshop. on site.
When choosing a battery model, note that there are different types of batteries. In the past, nickel-cadmium batteries were actively used, which were resistant to low temperatures, but today their use has declined due to the fact that they are heavy and require regular full discharges before charging, without which they quickly reduce the maximum amount of charge. Nickel-metal hydride batteries are an improved version of the nickel-cadmium batteries, all the shortcomings of their predecessor are somewhat reduced, but they are still expressed to some extent, and the cost has become higher. Modern lithium-ion batteries can be charged at any time, they are relatively lightweight and less harmful to the environment, but the problem is their higher cost, as well as an accelerated process of discharging in the cold.
That being said, many manufacturers are outfitting their cordless saws with two different types of batteries at once.
If the model you like has only one battery, choose it based on the potential working conditions.
Useful at! All about hand saws: types, types, selection, sharpening and storage. Photo Review
Welcome to our page “Useful! All about hand saws: types, types, selection and storage. Photo Review”!
In light of the resurgence of interest in carpentry and carpentry, interest is also gaining in good tools, pleasing to the hands and soul. We present the review “Arsenal Master”: Hand saws: purpose, classification, technical features and characteristics. How to Pick, Store, Sharpen, and Use a Sawsaw.
This photo review has been created for introductory purposes and is not a product, you can print this page on your own and completely free.
A brief photo review (quick links down. navigation through page):
How to use a hacksaw?
Mechanisms of work with basic locksmith tools, which includes a hand hacksaw, are ordinary, but failure to comply with them can lead to a broken saw or a bad cut. Top rules for handling your equipment:
- Master’s exercise of the comfortable standing position with a firm footing. Arms at the elbow should be bent 90º.
- Clamping of cut surface firmly. If possible, it is better to clamp the material in a vice.
- Hacksaw blade must be firmly placed perpendicular to the surface. It is important to rule out any rocking motion of the tool to prevent its damage.
- Metal tools are held with 2 hands, while the wood or aerated concrete tools are held with one hand.
A hacksaw for aerated concrete
A special kind of tool is hacksaw
A special kind of tool is the Foamed Concrete Saws for aerated concrete blocks, which is especially designed for dividing or removing excessive parts of aerated concrete. This fragile material requires special tools with hard-alloyed tips on the teeth. Thanks to this technology is possible:
- Extend tool life. Special tips prevent abrasion and wear of the teeth, so you can saw a huge amount of aerated concrete.
- Hacksaw for drywall or wood is significantly sharper, but it can not be used for foam blocks, because the materials have different density and hardness. Special tooling simplifies and speeds up the process of cutting blocks into pieces.
- No need to take expensive electric or gasoline devices to work with cellular concrete.
The greatest number of varieties of hacksaws are created for working with wood. Among their popular favorite are:
- Traditional saw, also known as a standard or ordinary saw. It is a standard tool with a wide cutting blade for straight longitudinal or cross cutting. Number and size of teeth may vary depending on the modification.
- Cylindrical or narrow tool. Differs from the traditional model in that the blade for the hacksaw is significantly narrower. The sawmore maneuverable. It is more convenient for cutting sheet material on this contour.
- The bow saw has a narrow curved bracket. Such tool is comfortable for cutting branches of trees and other work in the garden. Some varieties have a special connector for connecting a rod to work with the highest branches.
- Saws. It is also referred to as a tenoning or bevel tenoning. It is used by carpenters or Joiners to remove projecting grooves or nicks, in other words to obtain a smooth cut.