Choice Of A Circular Saw Blade
Circular saw blade: choosing the right one Circular saw blade is a working tool designed for cutting various materials, used in stationary machines and hand-held cutting tools.
Determined by the deviation from the radius of the disc of the cutting edge surface. With a deviation to the back of the tooth, the slope is called negative, with the reverse side of the slope positive. For longitudinal sawing, it is more expedient to use a tooth with a positive inclination, since in the process of processing a kind of material capture occurs, the disc hits the part, which contributes to a faster cut of the workpiece as a whole. Tooth inclination is subdivided:
- Standard tilt angle ranges from 5 to 15;
- Positive, aggressive slope is 15-20;
- A normal negative angle ranges from 0 to 5.
Types of circular saw blades
Monolithic disk. They are made of high-quality high-carbon or high-speed steel. They are used for processing wood and wood products, as well as for cutting polymer products. They have a number of advantages:
- Simple sharpening of teeth, you can perform this operation yourself, without the presence of complex special devices;
- They are repeatedly re-sharpened, therefore, they have a sufficiently large resource of work.
Disc with carbide-reinforced teeth. The blade is made of durable tool steel. Brazing is a steel alloy with a high content of tungsten or cobalt carbides. Thanks to this solution, these discs have become the most common. They have a number of advantages:
- Allow cutting most of the known materials;
- No need to set teeth;
- Durable and reliable in the process;
- The service life from sharpening to sharpening is several times higher compared to a monolithic disc;
- Give a cleaner cut;
- Increase cutting speed;
- Are produced in a wide range to solve all kinds of problems when cutting materials.
At the same time, there is a significant drawback, such discs are relatively expensive and special equipment is required for sharpening.
Circular saw blade: choosing the right one
The circular saw blade is a tool for cutting various materials. It is an integral part, without which it is impossible to carry out any workpiece processing operations. Saw blades are used in stationary machines and hand-held cutting tools.
Outer (outer) diameter
Due to the internal size of the guard, a large diameter blade will not fit on a saw with a smaller guard. The main dimensions of the cutting tool for hand-held circular saws are in the range of 130-250 mm. The outer diameter does not significantly affect the cutting speed, but determines the depth of cut. With an increase in the cut, the engine is significantly loaded, the metal of the disk and the workpiece itself are heated.
Inner bore diameter
It has several sizes: 16, 20, 22, 30, 32. An important parameter, the diameter should correspond to the size of the power shaft on the saw, for which the blade is selected. On some models of discs there are additional holes that fix the disc on the pins.
Each type of cutter is designed and manufactured to solve a specific task. Subdivided:
- The flat cutter is used for fast rip sawing of soft or hard wood, designated FT.
- The replaceable cutter has a successively alternating replaceable inclination of the teeth to one side or the other. The cutters give an even and fairly clean cut. It is used for cross and longitudinal cuts of wood, processing of plywood, OSB, chipboard and composite boards, indicated by the ATB symbol
- Combination cutter is a sequential change of groups from a combination of four replaceable cutters (ATB) and one flat cutter (FT). Combi. This type of disc is referred to as universal because of the ability to perform different types of cuts.
- The trapezoidal flat cutter is made up of successive flat teeth. The higher one is sharpened under the trapezoid, the lower one is flat. It is used for processing wood and wood products, for polymeric materials and soft non-ferrous metals. Has the designation TCG.
- Replaceable pick with increased slant side, designed for cutting materials prone to splitting and for fine cross-cutting. HiATB is designated.
Circular saws work with wood and other materials. The material to be processed determines the type of cutter to work with. There are 8 main types of discs:
- With alternating incisors.
- Cutters with a bevel angle of the cutting edge.
- Simple flat cutter.
- A cutter with an oblique sharpening.
- Working body with flat trapezoidal teeth.
- Concave profile.
- Taper cutter.
- Incisors in the form of a protruding trapezoid.
Let’s consider them in more detail. The blade with alternating teeth is the most common type of tools for sawing wood. Named because of the alternation of cutters, the cutting edge of which has an angle of inclination to the left or right. Leaves the cleanest cut. The tool, which teeth have a bevel angle of the cutting edge, is intended for sawing soft woods, boards with double-sided coating.
Circular saws, which are equipped with a simple flat tooth, perform rough cutting of all types of wood, up to cutting wood for firewood. Tooling with flat trapezoidal teeth allows the circular saw to work with pressed panels, plastics and even thin aluminum. The concave profile of the cutter indicates that the tool is being used to cut laminate.
The working body, which has bevel teeth, is used by furniture makers as a scoring saw when cutting building materials with a hard coating. The tool, with protruding trapezoidal teeth, can be used on hard and abrasive surfaces. It will not be superfluous to note that all of the above types of teeth have victorious soldering.
Circular saw blades
The circular saw is a widely used construction tool. The working body is a saw blade. Circular saw blades differ in a number of parameters. Let’s take a closer look at these indicators.
Small slots from the outer edge to the middle to a certain depth, ending with a round hole, are called thermal compensation slots. Most often performed on a tool with a large number of cutters and a high working speed in wood. During operation, the temperature compensating groove, as it were, takes over the possible heating of the working body. When overheated, the steel of the saw working body is deformed, its rotation resembles a figure eight, which leads to damage to the lumber, equipment, and the machine itself.
Recommended working speed
The parameter is another factor for a clean cut. Speed-specific attachments can cause a variety of inconveniences when mounted on a circular saw at a higher speed. It can overheat, it can get stuck in the material. With a significant (multiple) excess of the permissible speed, the equipment can split into parts and cause very serious injuries to the machine operator.
Necessary in order to use the tool correctly. A working body of a larger diameter than indicated in the passport of a circular saw for wood may simply not fit in size. The outside diameter defines the depth of the inside or blind cut.
Device and parameters of saw blades
By their design, the working bodies for circular machines are divided into monolithic and carbide. The blades of both devices can be used both for cutting and ripping in wood.
Monolithic discs are made from high carbon steel. They are used when working with all types of wood, but the most preferable for them will be working with soft species. Sawing with such cutting equipment of non-wood materials (plastic, drywall) shows good results.
Cutting elements are called carbide, the teeth of which have special carbide brazing. Tungsten carbide, better known as win, is the most common material used for making carbide taps.
The main parameters of the tool are:
- Landing diameter;
- Working, outer diameter;
- Number of incisors, their inclination;
- Recommended working speed;
- The presence of thermal compensation;
- Material that can be cut with this tool.
An important criterion is the compliance of the equipment with the type of machine for installation on which it is designed: a stationary circular saw or hand tools. The choice is determined by the feed rate of the material to the tool (circular), or the feed rate of the tool to the material (hand saw).
Selection criteria for circular saw blades
There are two types of discs: monolithic, that is, made of solid metal and with cobalt or tungsten carbide plates soldered onto the teeth.
The first, regardless of the quality of the metal from which they are made, dull and quickly enough. To continue to operate, they need to sharpen the teeth and set them. This operation can be done independently, and several times. They are budget-priced and designed strictly for working with wood blanks.
The latter are much more expensive, but they also last much longer, even if we take in comparison the many re-sharpening of solid discs. If carbide is sharpened, the cost of this operation will be almost equal to a new blade. But the durability and quality of the cut of the material justify the price. In addition, they can cut metal, laminate boards, and hard plastic. The plates themselves are patented technologies of the companies that produce these products. It is usually a powder of tungsten or cobalt with various additives, sintered in furnaces and soldered with a special solder using robotics.
Therefore, when choosing a disk, you need to know what work will be done with it. After all, the wrong choice can lead to:
- To disk failure;
- To poor quality work;
- To equipment failure;
- To injury, which is the most unpleasant.
The disc is often exposed to heat, which leads to its deformation during operation. Therefore, special technological holes are required on the disc itself, which not only reduce the threat of deformation by cooling the disc, but also reduce vibration, reduce noise, and so on. Some manufacturers put a special copper rivet on the holes, the holes have an intricate shape that is calculated on a computer.
Discs are made by stamping and laser cutting with subsequent processing. Laser cutting is more accurate and non-contact, which makes it possible not to change the quality of the metal at the cutting site. In addition, it minimizes end runout. For professional work, the best options are from 0.15 mm to 0.05 mm. For household work, such accuracy is excessive, the load there is not so great.
The angle of inclination of the teeth and its shape
Another important indicator will be the angle of inclination of the teeth and its shape. The saw blade is not suitable for trimming jobs, for example. There are no universal disks, this must be firmly remembered. This is due to the fact that the trajectory of the tool rotation in the workpiece itself is different in each case, an incorrectly selected disc can lead to overheating of the motor. In one case, the teeth will cut with the back side, and in the other, sawdust will start clogging all the holes and gaps between the teeth, especially if the teeth are small. Again, unnecessary load on the engine.
When choosing a disk for working with a tree, you need to look at the following parameters:
To work with longitudinal cuts, it is necessary to choose a saw with a positive tilt angle and with a small number of teeth. For example, in the size 250×30 mm, the number of teeth should be in the range from 18 to 24 pieces;
To work with face cuts, we take the number of teeth from 24 to 48 pieces.
If these are saws for working with non-ferrous metals or a laminate board, we select the number of its teeth should be from 64 pieces and more, with both a positive angle and a negative angle of inclination of the teeth.
Tooth shape in disc
Also the shape of the tooth matters. For wood materials, we choose a flat tooth, for non-ferrous metals and plastics, a trapezoidal tooth.
Tooth shape at discs
There are also discs that have variable teeth. Here they can be used for both radial and pendulum cutting. These saw blades for hand-held circular saws are used to make high-quality sawing of sufficiently hard, for example, wet and coarse wood. In this case, the teeth have a negative angle. The saws are ideal for domestic use in the construction of a country house or summer cottage.
In total, three angles of inclination are distinguished: a positive angle, a negative and zero angle, that is, a straight line.
Tooth angle diagram
A blade with straight or zero inclination teeth is used for dry cutting of non-ferrous metals and laminates.
You also need to pay attention to the thickness of the disc. For wood of normal density, a disc is chosen that is thinner, within 2 mm, for non-ferrous metals and laminate, the average thickness of the disc will be 3.2 mm.
All the necessary data is indicated on the disc, and everything must be marked with a laser or etching. If everything is written in paint, this is a poor-quality disc and the paint may just come off soon.
In addition, the disc must be packed in cardboard to avoid damage during transport. Then it will be possible to store the disc in this cardboard.
Circular saw and the choice of blades for it
Choosing the right blade for your saw and not missing is an art. Of course, at first glance, what’s so difficult? But the quality of work and productivity, as well as personal safety, depend on the disk. After all, circular saws are perhaps the most traumatic tool.
Therefore, the choice of disk must be taken seriously. Very often, both professionals and amateurs prefer to buy one disc, exploit it to the fullest until it dies. It is understandable somewhere, the cost of a good carbide disc is quite high, in equivalent it can reach 100 conventional units.
If you go to an authorized center, they approach business responsibly, they have detailed information about products, catalogs, and they themselves are quite good specialists.
Dimensions for disc selection
To select a disk, you need to consider it as an internal size, it goes in size as the second digit. For example, consider circular saw blades for a 255 × 30 circular saw. Here the bore diameter for the shaft fit is 30, the fit must be tight. This is an important condition for safe work. Sometimes it is necessary to use a disc with a larger inner diameter, then it is possible to use such a tool in the presence of special adapter rings. But for professional use this is not desirable.
Adapter rings to disc
The first number, 255 mm, is the outer diameter of the disc. The cutting depth also depends on this size. It depends on the power of the tool, the more power of the saw, the larger the diameter of the blade it can accept. Conversely, the higher the rotational speed, the smaller the disc diameter needs to be installed on it. In addition, the saw usually has a protective guard, and you need to choose a blade that will fit this guard. Typically, for hand saws, this diameter will be from 130 to 250 mm.
There are also such interesting types as a saw blade for concrete, stone, brick for a circular saw. They have diamond brazing on the cutting edge instead of hard alloy. There are different discs for wet sawing and dry sawing. Special cooling holes are required on them and during operation, in order to avoid overheating of the tool, they take frequent breaks. The tool is mostly used by professionals.
Diamond blade for dry cutting in concrete
There are also saw blades for corrugated board for circular saws. The peculiarity of working with corrugated board is. That several layers of polymer coating are applied to the metal sheet, which is afraid of temperature changes and may lose the quality of the coating. Therefore, you need to use a disc with special carbide fine teeth from Pobedit, while the cut is very accurate. To prevent damage to the polymer layer, a special device is made of plywood, a conductor, 1500 x 300 mm in size, then a groove is cut in the middle, along which the saw will go.
If we consider the manufacturers of blades, then the best quality blades are Bosch circular saw blades for hand-held circular saws. They have really good workmanship, not only their composition for soldering hard alloy, but the blade itself is made of first class steel. Its coating not only protects against corrosion, but also reduces friction during operation. Tensile ring knurling is used as protection against deformation.