Marking
In order to freely navigate when choosing saw blades, you should first study the meaning of the marking. Today, the buyer has access to discs from manufacturers all over the world, but different manufacturers have different marking procedures, which can be a little confusing for the consumer at first.
In fact, there is nothing complicated in the different markings, and all the necessary data is necessarily indicated on each disc and packaging. The buyer just has to find them and evaluate them.
Marking example:
D200хd30х3, where
- D – external, “large” diameter, 200 mm,
- d – landing, “small” diameter, 30 mm,
- the remaining number 3 is the thickness of the disk 3 mm.
Sometimes, instead of the thickness of the disc, the number of teeth is indicated.
An example of such markings:
- 205x24Tx20, where
- 205 – outer diameter (205 mm),
- 24T – number of teeth, (24 teeth),
- 20 – bore diameter 20 mm.
Sometimes other markings are used. For example, a simple inscription 250 mm or with a diameter symbol “crossed out zero” 250.
Some manufacturers supplement the digital lines with pictures. For example, after line 335,64, 30/32 there are pictures with explanations. A disk is drawn with arrows indicating the outer diameter and the number 335, teeth and the number 64, the inner diameter with an adapter ring that allows the disk to be used on shafts with a landing diameter of both 30 mm and 32 mm.
The type of tool for which the disk is intended can be depicted - a manual or stationary circular saw.
How to choose a saw blade for wood?
Choosing the right disk is the key to a job well done, equipment safety and health safety. Because, for example, a wood saw blade for a circular saw is not suitable for cross-cutting. When purchasing a tool, you need to pay attention to:
- Number of teeth
. Using this parameter, you can easily determine the purpose of the disk: longitudinal, end or universal. - Tooth sharpening shape
. Flat sharpening, alternating inclined and trapezoid shapes are common. - Sharpening angle
. For circular ones it is positive, for end ones it is negative. - Circular saw diameters
. The internal one must match the landing shaft of the equipment. External – the dimensions of the machine or hand tool. - Disc blade thickness
. The thicker it is, the greater the cutting force and the increased load on the engine. Its power may not be enough to cut.
Marking saw blade for wood
The values marked on the saw wheel provide the following information:
- outer diameter of the disc;
- equipment information (for example, for a hand saw);
- number of teeth;
- working material;
- bore diameter;
- duration of operation;
- rotation speed value;
- direction of movement;
- cutting width;
- company name.
The main parameters you should pay attention to when choosing
These are characteristics, if not met, the disc simply will not fit a particular instrument.
External diameter
On stationary circular saws, especially homemade ones, discs with a large difference in diameter can be used. Small for sawing thin workpieces, large for large-sized wood. In this case, it is advisable to have a set of different disks.
It is irrational and inconvenient to cut thin wood with a large-diameter disk - unnecessary loads on the engine due to the large lever of the disk, a cut that is too thick, and a large protrusion of the disk above the workpiece, which reduces the safety of sawing.
The maximum diameter on stationary circular saws is limited by the size of the slot for the disk or casing, if any.
Minimum – sufficient protrusion above the work table.
On manual circular saws there is no such variation in diameters - a disk of the same diameter that was installed at the factory is used. In exceptional cases, a disc 3-5 mm smaller in size may be suitable, but this will change an important characteristic - the depth of cut. A disk that is too large will simply not fit or will cling to the casing.
Landing diameter
During the Soviet era, only two mounting diameters were provided for stationary circular saws and trimmers - 32 mm and 56 mm. Today, manufacturers all over the world make landing shafts and discs of different sizes: 18 mm, 20 mm, 30 mm, etc.
However, the standards remain, although they have increased. And this is understandable - no backlash is allowed here. The disk must fit tightly on the shaft, otherwise it simply cannot work. A bore diameter that is too small will not allow the disk to fit onto the shaft, while a bore diameter that is too large will cause displacement, beating and vibrations that are incompatible with operation.
Sometimes adapter rings or washers are used to ensure compatibility between different diameters. For example, using a washer with an internal diameter of 32 mm and an external diameter of 56 mm, you can install a disk with a landing diameter of 56 mm on a landing shaft with a diameter of 32 mm.
A 1 mm thick adapter ring allows the use of a 32 mm disc on a 30 mm diameter shaft, etc.
Thickness
The parameter matters. Thin disks have a number of advantages and disadvantages over thicker ones. Advantages:
- saw faster
- with less noise
- make a thin cut with a minimum of sawdust waste.
The latter is especially important when sawing expensive wood. Sometimes only 2-3 mm determine how many, for example, bars will come out of the board - 5-6 when cutting with a thin disk or 4-5 with a thick cut.
A thin disk makes a cut 2-3 mm wide. Thick – 3-4 mm. Sometimes a large disk with a wide tooth set can make a cut 5-6 mm wide.
Disadvantages of thin disks:
- prone to bending, so sometimes the cut can turn out wavy,
- can quickly overheat, sometimes to the point of turning blue, which can damage the disk completely. Overheated disks begin to “wiggle” with different amplitudes, sometimes up to 10 mm or more.
Thicker and more massive disks are slower but more stable.
Variety
Two fundamentally different types of disks are used:
- Made entirely from cutting tool steel, they are called backed or solid.
- With soldered cutting teeth made of various durable alloys.
The first ones belong to the outgoing type. Widely used in times when there were no technologies for precise and durable soldering of carbide alloys. Nevertheless, monolithic disks retain a number of advantages:
- very long service life, it is limited only by the fact that over time, after many sharpenings, the diameter of the disk decreases to critical sizes,
- ease of sharpening and straightening teeth,
- possibility of changing the shape and sharpening angles of the tooth,
- no soldering, solid tooth strength.
Disadvantages - they require regular editing, sharpening and regrinding of the teeth, since they are inferior in strength to teeth made of carbide alloys.
They were not cheap, since not only the teeth, but the entire array are made of special tool steel.
In order to carry and hold cutting teeth made of hard alloys without wobbling or overheating, other, cheaper steels are suitable. They are used today on disks with soldered teeth.
The quality of such a disc largely depends on the composition of the hard alloys. Most manufacturers keep their ingredients secret. However, it is well known that the most durable were the old Soviet wheels with “Pobedit” teeth.
Today, tungsten carbide, cobalt and other elements are used in alloys. Simple, household discs are not particularly durable: they chip, the solder comes off, and quickly wears down to zero after several sharpenings due to their small size. But professional, expensive discs from brands with a good reputation can last a long time and require sharpening less often.
Number of teeth
The cleanliness of the cut primarily depends on the number of teeth. It is important that not only the number of teeth differs, for example, per 10 cm of circumference, but most importantly, their size. If there are many teeth, they are small in size. Small teeth cut slower and cleaner, and tear out less material.
The differences in the operation of a disk with a small number of large teeth and a large number of small teeth are very significant.
- When a coarse-fine-toothed disc operates, there is less friction and it is easier for the engine.
- The disk heats up less.
- Large sparse sawdust is formed.
- The disc cuts faster.
- At the exit, a large tooth can tear out pieces of material, especially on plywood, chipboard, etc.
- Circular stripes and marks from teeth may remain on the cut.
A disk with fine teeth and a large number of them produces fine sawdust.
- If the wood becomes hotter due to friction, it may burn.
- Requires a reserve of engine power, since friction can cause the disc to slow down.
- A small tooth at high speeds is less likely to tear the material at the outlet.
- The cut at high speeds is streak-free, clean, and looks like it has been polished.
For simple, quick cutting, discs with sparse, large teeth are better suited. For better cutting, for sawing diagonally and across the grain, a tooth with many small teeth is better suited.
We also recommend reading interesting articles about how to properly use a hand-held circular saw and techniques for even sawing with a circular saw.
Tooth geometry
All modern discs use two tooth shapes:
- "Eagle Beak"
- Straight pointed teeth.
The form of the first option is well tested, verified and calculated. The cutting tip of the tooth brought forward throws out sawdust. The void under the carbide tooth does not create friction, facilitates the movement of the disc, and reduces heating. Such discs are successfully used for longitudinal, diagonal and transverse cuts.
Pointed teeth, analogous to the teeth on a two-handled saw or a hand saw, are better at sawing wood crosswise. That's why today they can be found on miter saws, especially the older ones. They are very effective for this. This tooth shape is not suitable for longitudinal sawing - it creates strong friction, noise, the disc overheats, and the wood burns.
Sharpening angle
This indicator differs between different drives and manufacturers. The main difference is the positive and negative front sharpening angles.
Negative - the cutting edge of the tooth is tilted back, from the radius axis by 5-10 degrees. Used on special discs for plastic, metal, MDF, laminate, scoring discs, etc.
Positive - the tooth is inclined forward, from the radius axis by 10-20 degrees. The most popular option for standard discs for wood and other soft materials.
Other differences, top view of the tooth:
- A tooth with a straight edge, directly perpendicular to the cut. Enters the workpiece with its entire plane at once.
- A tooth with a triangular, beveled edge. Enters the material with the sharpest protruding edge first.
For flawless operation, the first option requires constantly sharp sharpening and sufficient engine power.
The second option is, by definition, sharper, since it first enters the material with a sharp edge. But such teeth are prone to chipping due to the heavy load on the thin tip.
Teeth sharpened to simulate a set pattern. After one (left-right), such teeth are sharpened with a small angle relative to the disk.
The most unpretentious discs are those with a simple straight edge. They take the impact load when entering the material with the entire plane, therefore they chip less. It is important that they are easier to sharpen even by hand on a diamond disc.
It is enough to maintain only one angle of positive forward tilt. Teeth with more complex, angular sharpening can only be sharpened on special machines that allow you to maintain all angles at the same time.
Sometimes there are discs with teeth of an unusual shape - “Kremlin wall”, alternating large and small teeth, etc. These constructive delights are bought for testing. Perhaps they find application somewhere, but not widely.
We recommend reading the guide on how to sharpen a circular saw blade yourself; in it we discussed in detail all the nuances and methods of sharpening circular saws.
By watching the video, you can understand how disks of one design or another behave in practice, and understand which one is better to choose for a specific purpose.
Other options
The cutouts on the disc are important. Metal expands when heated. Moreover, if it heats up evenly, it will simply increase slightly in size. But if, due to friction with wood, one part of the disk heats up and expands, while the other, closer to the center, remains cold, the disk is likely to warp. To prevent this from happening, compensation cuts are made.
In addition to the function of “thermal seams”, such cutouts reduce friction, vibration and noise, and promote cooling of the disk using air. The more serious the manufacturer, the more carefully the size, geometry, and location of such cutouts are verified and tested in laboratory conditions.
Basic parameters of a circular saw blade
Outer (external) diameter
It is determined by the internal size of the protective casing - a blade with a larger diameter will not fit on a saw with smaller casing 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, the engine is significantly loaded, and the metal of the disk and the workpiece itself are heated.
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 processing cleanliness. 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 the deviation of the cutting edge surface from the disk radius. When the deviation is towards the back side of the tooth, the inclination is called negative; when the inclination is on the reverse side, it is called 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:
- Flat cutter - used for fast longitudinal cutting of soft or hard wood, designated FT.
- Replaceable cutter - has a sequentially alternating, replaceable inclination of the teeth in one direction or the other. The cutters give an even and fairly clean cut. Used for cross and longitudinal cutting of wood, processing plywood, OSB, chipboard and composite boards, indicated by the ATB symbol.
- A combination cutter is a sequential change of groups from a combination of four replaceable cutters (ATB) and one flat cutter (FT). Designated as Combi. This type of disc is considered universal due to its ability to perform different types of cuts.
- Trapezoidal flat cutter - made of successive flat teeth. The higher one is designed as a trapezoid, the lower one is flat. It is used for processing wood and products made from it, for polymer materials and soft non-ferrous metals. Designated TCG.
- Replaceable cutter with large beveled side - designed for processing materials prone to splintering, as well as for finishing crosscuts. Denoted HiATB.
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.
Selecting a nozzle to solve a specific problem
Each disc packaging indicates its special purpose. Discs are often found for relatively universal purposes, for materials that are similar in structure and density. For example, for wood, chipboard, fiberboard, plywood.
There are no good “everything” discs. If the manufacturer claims that it is for wood, metal, concrete, etc., then in the end such an item will not cut anything.
For wood
For basic, regular cutting, discs with large, sparse teeth are well suited. For example, outer diameter 200 mm X 24 teeth. For clean, diagonal, cross-cutting, options with medium or fine frequent teeth are better suited.
For clean cutting of chipboard and laminate
For these materials, the smaller and more frequent the tooth, the less chipping and scoring there will be. However, even then there is no guarantee of cutting without damage. These materials are sawed on special machines with a second scoring disc that rotates in the opposite direction.
Using a regular circular saw, these materials can be sawed without damage with the above-mentioned disk, but with preliminary trimming of the cladding, or with the cut area covered with protective adhesive tape.
For aluminum
Metal discs are used. For example, for non-ferrous metals or thin steel. Such discs have fine teeth, a negative angle, and are made of special metal-cutting steel.
Application of saw blades
As already mentioned, saw wheels are installed on equipment and used for sawing. For comfortable use of a saw blade, being guided only by the above rules is not enough. It is very important to know the types of saw blades and their differences.
Carbide saw blade is the most popular type. We recommend using it in your work. The base of such a circle is most often made of tool steel, and its teeth are reinforced by soldering. This type of tool is durable, it rarely bends or splits, and the soldering tips become dull much less often than the teeth of other types. The cutting speed is also satisfactory. Due to its thoughtful design, the carbide wheel processes not only wood, but also laminate and plastic.
Unfortunately, such a universal tool also has its drawbacks. Its soldering tips are very difficult to sharpen yourself. This will require additional equipment.
The solid saw blade is a less popular type, and there are several reasons for this. There are no solders on these wheels, and therefore the teeth become dull as quickly as possible. Without regular maintenance of their sharpness, the tool simply will be of no use, but sharpening the teeth is a very problematic matter. Monolithic wheels are available with two types of teeth: sharp and curved. Sharp ones are suitable for cutting any type of wood and making clean cuts. Curved ones are needed only for soft rocks and simple cutting.
How to choose a miter saw
The difference between a miter saw and a regular circular saw is that it cuts primarily across the wood. Sometimes diagonally, rarely along the grain, for example, if you need to make cuts for a groove/tenon. Therefore, universal-purpose discs are suitable for it (for longitudinal and cross cutting, as on a regular circular saw).
Cross cutting blades will also work well. For example, old-style monolithic ones with straight, well-sharpened teeth.
Another difference from a circular saw is that the miter makes short cuts. Therefore, discs, as a rule, last longer than those on a circular disc.
A disc with a large, sparse tooth cuts faster, but can tear the material. The optimal number of teeth for trimming: for a disk with a diameter of 250 mm - about 40. 80-100 teeth for this diameter - on special disks for plastic, metal, etc.
Rating of the best
Saw equipment is a popular (consumable) product. Therefore, there are many who want to occupy this niche with their low-quality goods. The problem is that counterfeit manufacturers may use reputable brand names.
It is safer to choose discs from reputable brands that have protection against counterfeiting (holograms on the packaging, website addresses where you can confirm the origin of the product, etc.).
If you don’t already have such a tool, then before purchasing, be sure to read a detailed article on how to choose a circular saw, and also check out the rating of the best circular saws for the home.
Best expensive
SMT, Italy. Cost from 2,400 to 10,000 rubles, depending on the size and number of teeth.
Original SMT products belong to the professional class, they cut efficiently, last a long time, and require sharpening less often.
This manufacturer is widely represented on sites where equipment for the mass consumer is sold. There are other manufacturers of professional disks; you should look for them on sites selling professional equipment. The prices for such products are high.
Middle price segment
Manufacturers of power tools often produce accessories for their products. At the same time, they are interested in their instrument having a good reputation. Therefore, saw blades of the same name as the tool are usually of good quality. These include: Bosch, Metabo, Zubr, Makita, Dewalt.
Prices from these manufacturers are comparable. More often, preference is given to the Bosch and Makita brands due to traditional German and Japanese quality and good reputation.
