A circular saw is a rather complex and traumatic tool, respectively, many models are designed to perform certain types of work with a certain intensity. Only assuming exactly at least the scope of the tool, you can decide how to choose a circular saw – which characteristics to pay special attention to, and which ones to neglect.
Device, principle of operation and application of the circular saw
At first glance, the device of a circular saw is as simple as possible – a powerful engine, on the shaft of which a cutting metal disc is put on. In the case of stationary tools, the engine can be located separately and transmit force to the working shaft by a belt through a system of pulleys, but hand tools, which are the absolute majority of household tools, are made in one housing.
The complexity of the device is added by the need to use high-quality materials, strict observance of the centering of parts, plus withstanding serious safety measures. The saw blade rotates at high speeds, so neglecting any of the above points will at best lead to tool breakage.
As a result, an impressive number of mechanical-electronic protective and blocking devices are added to the engine and cut-off wheel, the purpose of which is to instantly stop and de-energize the tool if something goes wrong.
The principle of operation of a circular saw is clear from its design – a rotating disc with teeth cuts the board along which the tool itself is pulled. In the case of a stationary saw, everything happens the other way around – the board is pulled through a circle fixed on the bed and divided into two parts.
There is one important note about the use of a circular saw – it is not suitable for curly cutting and is designed to saw boards and other materials only in a straight line. There are models with an additional graduation of the leading sole, which allows the disc to be set not strictly perpendicular to the surface being cut, but at a certain angle, but the saw is also carried out strictly in a straight line.
- Upper main protective cover.
3. Power-on lock button.
4. Button for switching on the laser switch.
- Support arm.
6.Body with motor.
7. Laser pointer.
8. Adjusting the cutting angle.
- Saw blade.
10.Lower loaded casing.
11. Support sole.
Varieties and selection of the required type of circular saw
To choose the type of circular saw suitable for the planned work, one must imagine their existing varieties.
Circular saws depending on the design
The mobility of the device and the size of the processed parts depend on the design:
one. Stationary. Such a saw is suitable for performing a large amount of repetitive work, for example, in a production facility where a large amount of sawn timber is constantly being processed. Such a tool is installed on a separate frame, has the appropriate dimensions and requires a separate place for installation, and in some cases even a room.
- Desktop. A smaller version of a stationary circular saw – also installed on a stationary base but of a much smaller size. Suitable for large volumes of household work – for example, when building a house, bathhouse or similar structure.
- Manual. A mobile device that can handle a part in multiple planes. It is used to work with different materials: wood, plastic, soft metals, etc. Of all types, it has the smallest power and requires periodic rest, but it is mainly used for such types of work where it is not critical.
Circular saws depending on the intensity of use
Here it is necessary to take into account the scope of the proposed work and the planned speed of its implementation – depending on this, the appropriate type of circular saw is selected:
one. Professional. The materials and design solutions used in such devices allow them to be used without interruption throughout the working day. Usually these are universal tools that are suitable for processing materials of different stiffness and sizes.
- Household. Modern household circular saws, like professional models, can boast of versatility in work, but without fail they require compliance with the load regime. Usually this is about 15 minutes of work for the same amount of rest time.
Circular saws by type of work performed and used materials
Various wooden elements can be cut into pieces with a conventional circular saw. A conventional circular saw is capable of cutting various wood pieces at different angles into pieces. However, there are circular saws for special purposes. Some of them are capable of sinking into wood, others are adapted to work with metal.
one. Metal circular saw. A saw that is supposed to work with metals should be more powerful and adapted to work with different cutting blades – standard abrasive and increased strength. In fact, this is the most versatile tool that allows you to cut any materials: sheets, pipes and profiles made of metal, wooden blanks, plywood, plastic and the like.
- Plunge-cut circular saw. This class includes hand-held circular saws and stationary, with a movable saw blade. The cutting edge of such tools can go down to the center of the part and start sawing from this point, which allows you to cut through holes in the workpieces. Such devices are most often used for working with plywood, OSB and similar sheet materials.
A visually noticeable feature of submersible circulars is the absence of an automatic lower protective casing and a special design of the base plate, which allows you to adjust the cutting depth with millimeter accuracy. This allows you not only to make through cuts, but also to make straight and curly (if the saw design allows you to make cuts at an angle) grooves, grooves and slots.
Before choosing a circular saw for wood for your home, it is imperative to consider such devices, since they have maximum versatility.
Circular saws by type of electricity supply
Here you need to very carefully evaluate the advantages and disadvantages of each of the types of tools:
one. Network. The main mass of circular saws is made with a power supply from the 220 (household hand-held) or 380 Volt (stationary professional) mains. They have only two drawbacks: the need for an electrical network and the ability to get tangled in the wire.
- Rechargeable. For such a saw, you also need an outlet, but only in order to charge the battery. Then it works completely offline, though only for 30-50 minutes, depending on the battery capacity. The main disadvantage of such devices is the battery charging time, which is 5-8 times longer than the battery life.
As a result, given the high cost, it makes sense to purchase cordless tools only for frequent short-term work in hard-to-reach places, it is much easier to take a cordless saw than to lead a temporary power cable. For example, it can be roofing or similar work at high altitudes, where you have to constantly move with the tool.
Criteria for selecting a circular saw
When you have decided on the type of circular saw, you can proceed directly to the selection of its performance characteristics, on which productivity and convenience of work depend.
Traditionally, the power of a circular saw motor is tied to the diameter of the saw blade – the larger the blade, the more watts the circular motor should have. But here healthy competition comes into play – in the struggle of manufacturers for their customers, they can equip models of approximately the same characteristics with engines of different power.
Here you need to understand the direct relationship – the more powerful the engine, the more force is transmitted to the place where the disk is attached to the shaft. This means that a more powerful electric motor allows the saw to run more stable, better withstand blade speed, process tighter materials and generally run longer without rest.
The only drawbacks are the likelihood of getting a tool with a disc mount, which was originally designed for less weak models. When buying, you need to pay attention to the fasteners – ideally, for a more powerful engine, they should be at least more massive, although much depends on the quality of the materials. It should also be borne in mind that excess power is an additional expense – for purchase and maintenance.
Circular saws are conventionally divided into three classes in terms of engine power:
Which of these tools to choose depends solely on the planned amount of work.
Disk rotation speed
In most cases, the higher the rotational speed of the circular saw blade, the easier it is to work with. The higher the speed, the better the following characteristics:
- Less chance of disc jamming in the workpiece.
- Dense materials are easier to process.
- Less torque needed.
- Cleaner cutting line.
There are enough of its own nuances – for example, the cleanliness of the cut also strongly depends on the shape and number of teeth on the disc, but basically this is the case. Additionally, it should be borne in mind that a high rotation speed is an increased temperature at the cutting point, which means that materials like plastic or laminate may end up with melted edges after sawing. If you plan to work with such materials, then the best way out would be to find a circular saw with an adjustable number of revolutions of the disc rotation.
Sometimes this characteristic is confused with the diameter of the bore, but the latter is usually not so important and only shows whether a certain blade will fit in the saw seat. The full diameter of the disc is fundamental for the circular saw as a whole, because it is for it that all other characteristics are selected.
The relationship here is very simple – the larger the saw blade diameter, the more powerful and with a higher torque value the engine should be – this affects the starting speed, smooth operation and a decrease in the likelihood of jamming. The more powerful the engine, the more difficult the filling must be to protect and stabilize the saw operation – in turn, all this leads to an increase in the weight, size and cost of the circular as a whole.
All these difficulties are necessary and important, since the larger the diameter of the disc, the thicker the part it will be able to cut in one pass.
Base plate and cutting depth: straight and angled
The cutting depth indicates exactly how much the blade can be immersed in the workpiece. Nobody gives an exact classification here, but it is conventionally accepted to divide saws according to the following cutting depths:
- 4-5 cm is the initial, least powerful class of instruments.
- 5-6.5 cm – representatives of the universal “golden mean”.
- 5-14 cm – heavy, professional devices.
The cutting depth is not always determined solely by the difference between the outer radius of the saw blade and the bore. To a greater extent, it is necessary to look at how much the disc protrudes beyond the plane of the base plate, since this part additionally “eats” 1-1.5 cm, and normal work is simply impossible without it. You also need to consider the ability of the circular saw to make cuts at an angle, which again is determined by the design of the base plate.
If the circular saw allows you to cut at a variable angle, then in the characteristics the manufacturer usually indicates the cutting depth for 90 ° and 45 °.
For an example of adjustment and cutting at an angle, see the video:
When choosing a circular saw with the ability to adjust the cutting angle, special attention should be paid to the quality of the base plate and the fasteners and graduations located on it. The main features of quality are the simplicity of changing the position, the ease and reliability of fixing the clamps, as well as the absence of backlash. Not all manufacturers succeed in completely getting rid of them, but if the base plate of a new tool “backlash” after fixing all the “lambs”, then you should think about finding an alternative.
The base plate material is often cast light alloys, but not uncommon, and platforms made of stamped steel. The former are lighter and keep their shape well, while the latter are more resistant to impacts.
The presence of a large number of auxiliary and protective systems is due to the high risk of injury to the circular. They protect the tool from breakage, and the owner from injury, so it will be useful to find out which types of protections are installed on the saw by the manufacturer.
Constant speed control system
The block for maintaining a given rotational speed of the disk under load is also called constant electronics. It is based on a controller that receives data on the engine speed. When the operator starts to drive the saw faster or it just hits a knot or a denser part of the workpiece, the engine speed decreases and the controller signals the electronics to increase power, which happens without operator intervention. The same thing, but exactly the opposite, happens in the opposite case – when the rated speed is exceeded, the engine power decreases.
For this function to work correctly, the circular saw motor must have a certain power reserve, which is not always possible on weak and even middle class devices. If the presence of this option is indicated on a budget saw, then you should pay attention to the ratio of the blade diameter to the engine power.
If the simplest stabilizing device can equalize the rotational speed of the disk to only one given standard frequency, then the presence of a stabilizing mechanism on an engine with a smoothly varying number of revolutions is considered the highest class.
Soft start system
The importance and usefulness of this function does not have to be proven, especially considering the average speed of rotation of the electric motor shaft:
- The service life of the electric motor is increased, since when it starts up, excessively high starting currents do not occur in the winding.
- If, for some reason, the saw is started already in a partially cut groove, then the possibility of cutting the saw teeth into the material and the accompanying sharp jerks of the tool is excluded.
- When used in the design of a gearbox, the soft start system significantly brightens up his life, which otherwise would surely be spoiled by sudden jerks at the start.
Overload protection system
Practice shows that most often, overheating of the motor of an electric tool is not allowed by beginners, but by masters with extensive experience, who, due to haste or for some other reason, stop “listening” to the state of the engine. In this case, the safety of the windings and their protection from overheating is taken over by the motor overload protection system, which monitors the level of energy consumption and cuts off the power when there is a sharp jump in the load on the network.
The weight of the steel blade creates a fairly high inertia of rotation, which is fully manifested after a power outage at idle speed. When the trigger is released, the disc can spin for a minute or two with enough force to cause injury. To eliminate this possibility, an electrodynamic brake system is used – after releasing the start button, the motor rotor is decelerated by countering the movement of the stator field, making only a few revolutions.
Such a system protects the operator from injury, the workpiece from accidental damage, and the circular itself from kickback if the disc teeth catch on a hard surface.
Watch the video for a demonstration of the electrodynamic disc brake operation:
When the saw blade stops abruptly, none of the existing braking systems is able to instantly stop the engine so that its inertia does not create a kickback that pulls the saw out of the operator’s hands. To protect against such accidents, a slip clutch is used, which, instead of trying to stop the engine, simply breaks the contact between it and the saw blade. The latter remains in the material, while the engine continues to rotate by itself. However, the operator will immediately turn it off, because when the slip clutch is triggered, a short-term “howling” of the motor will occur due to a sharp increase in revolutions from a decrease in load.
Protection against accidental activation
Unintentional turning on of the circular saw is so fraught with the creation of a traumatic situation that the designers tried to eliminate this possibility altogether. To do this, the saw starts only after pressing two separate buttons, one of which is often recessed into the plastic of the case.
On many instruments, manufacturers install a separate button that allows you to fix the instrument when it is on. It’s useless to look for such a lock on a circular saw – safety is paramount.
To make it more convenient to change the working discs, the saw motor shaft can be fixed with a separate button or lever – sometimes for this, fast disc braking mechanisms are used and fixation can occur in any position. It may be the other way around – in some cases, manufacturers consider the spindle stopper to be an unnecessary function, and then the disc has to be changed with two keys.
The disc tightening nut does not need to be tightened with a wrench. In some cases, it is tightened with a screwdriver or, in general, is made with a quick-release – for hand tightening.
Rip fence and guide rail
When deciding which hand-held circular saw to choose, not the last question will be the accuracy of its operation, for which parallel stops and guide rails are used. The first of these is, in fact, an ordinary stand or ruler on which the saw sole rests when it is guided along the workpiece. In general, a good method, but it requires some skill in controlling the circular – you have to guide the saw and simultaneously press it against the rip fence.
The guide bar is a great cutting accuracy, since the tool does not have the ability to “wiggle” to the side during operation. To do this, a special groove is provided in the saw sole, with which it is “put on” on a previously exposed guide rail.
If it is necessary to maintain the direction of the cut manually, various sights are used – from a slotted opening on the base plate to a laser line builder, which will show where the saw is “going”.
Spring loaded casing
For maximum protection of the user, the saw blade is hidden from him by covers – the main one at the top and spring-loaded at the bottom. It looks like the entire disc is hidden under the shrouds and, when turned on, rotates under them. When sawing the workpiece begins, the spring-loaded casing catches on its edge and is taken away under the main one. When the saw is removed from the workpiece, the spring-loaded guard immediately returns to its place, protecting the user from possible contact with the rotating blade. Also, this design does not allow you to stumble or otherwise catch on the saw teeth, even when it is stopped and de-energized.
Saw blade ergonomics
For household needs, a hand-held circular saw is most often used, which means that the issue of ergonomics should be given special attention. At the same time, it will not work to give any unambiguous recommendations, since everyone has their own concept of convenience.
About 10% of people on Earth are left-handed, and manufacturers must take this into account when releasing mirror models of instruments.
Handle shape and location
If the rear handle is more or less standard, then there are at least three types of the front handle: straight, mushroom and staple. The first is more suitable when working with a saw “from oneself”, the second is more convenient to guide the saw from the side, and the third is universal, but larger than a mushroom.
They do not slip in the hands, help to better control the work process.
Depends on the design features of each tool, so before buying it is better to evaluate it with your own eyes.
It is carried out by blowing sawdust from the working area or by connecting to a saw of an industrial vacuum cleaner.
To prevent the wire from twisting at least near the saw itself, the cable is led out of its body through a long and rigid inlet sleeve.
Replacing carbon brushes
It is not required so often, but in any case it is better if there is a special window for this operation. Additionally, the brushes can be self-disconnecting – when the graphite rod is grinded, the chain is broken, and there can also be an indication of the status of the brushes.
To evaluate it, you need to take one by one and just hold in your hands several different models of circulars. This will immediately show you exactly what to look for.
The store likely won’t have a board or similar piece to test the saw’s performance under load. And sellers do not particularly welcome such experiments, although they should simply plug the saw into the network. This will allow you to check at least the stability of operation, the noise level and the absence of vibrations at idle. Also, the airflow can be used to assess how well the engine cooling works.
These are all the main points that must be considered before choosing a circular saw for a summer cottage or at home. The main thing is to remember that the wrong choice of a power tool is, at best, an overpayment for unclaimed functions and increased power consumption, and at worst, its uncertain operation and the possibility of failure at the most inopportune moment. We hope this review will help you choose the right model.