How to choose a circular saw: expert advice

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Among the basic set of power tools, many craftsmen do not have a manual circular, and this is a clear omission. We offer you to get acquainted with the capabilities of circular saws, the features of their design and the rules for choosing the right tool for your tasks.

general description

The hand-held circular saw (RCP) is also often referred to as “watercress” (tracing paper with German. Kreissage) in honor of Dieter Kress and the brand of the same name, which was one of the first in the world to start mass production of this power tool. Such a saw is extremely versatile in its application, it can be used both in rough carpentry works and for joinery joints. In addition, the area of ​​application of the RCP is not limited to woodworking, because the type of material to be cut is determined not by the design of the saw, but by the type of the saw blade. So, with the correct selection of equipment, the cressing machine is quite capable of replacing the grinder when cutting rolled metal and sheet steel, but in the efficiency of cutting roofing materials it has no equal.

Bosch GKM 18 V-LI ProfessionalCordless metal circular saw Bosch GKM 18 V-LI Professional

The cutting body is driven by a collector-type electric motor through a reduction gear reducer. In addition, a spindle locking device may be present in the kinematic diagram, which makes it easier to replace the disc, as well as a torque limiting clutch, which protects the motor from overloads when jammed. Structurally, the saw consists of a base platform and a head – a body in which a spindle shaft and a motor are placed on bearings. The head can be raised and tilted relative to the plane of the sole to adjust the cutting depth and make oblique cuts.

Circular saw device

The electrical circuit of the RCP includes, in addition to the engine itself, an anti-jamming capacitor and a button with an accidental start blocker. To eliminate the current surge at start, a soft starter can be installed, regarding which some masters express a negative opinion, they say, it is impossible to start the cut immediately after pressing the button. In addition to the mains voltage supply, a battery version is also possible. In addition to autonomy, such a tool has an additional advantage – the ability to stop the disk at the moment of shutdown due to DC braking.

Electric drive and spindle

Like most power tools, circular saws are characterized primarily by power and spindle speed. The very concept of power for RCP is not a generalizing parameter. This is because with high torque at the periphery of the blade, the saw really does a better job at high-speed cuts, but the quality of processing inevitably suffers. Therefore, a tool with a power of over 2 kW is advantageous to use either for rough workpieces, or if you plan to install a saw on a table.

Also keep in mind that as power increases, the weight and size of the tool also increase. Therefore, if you plan to use the crimping machine only in manual mode, the power should not be maximum, but corresponding to the diameter of the disc. Thus, for saws for a maximum diameter of 185 mm, the power must be at least 1.6 kW, for a 235 mm disc – at least 2.2 kW. Miniature mils for discs up to 100 mm have a practical minimum power consumption of 800 W.

Bosch PKS 66 ABosch PKS 66 A

In general, the gradation by kilowatts is a rather abstract concept, because the power that can be removed from the disc is lower than the consumed one, while the efficiency for different saw models can vary within 65-80%. This parameter, depending on the perfection of the design of the motor and gearbox, is not regulated by manufacturers, but it must be taken into account when trying to evaluate the performance of the saw. We can only say that the relatively low power of a branded tool with a comparable disc diameter should not arouse suspicion..

For most inexpensive tools designed only for carpentry work, the spindle rotation speed is constant and can vary from 3 to 5 thousand rpm depending on the diameter of the disc, that is, the angular speed during rotation is the same for most models. However, there are saws with the ability to adjust in the range from 2 to 5.5 thousand rpm, which allows you to use the tool for sawing not only wood, but also metals and plastic with the appropriate replacement of equipment.

Scheppach CS 55Scheppach CS 55

Power selection is a compromise between speed and ease of use. Otherwise, almost any saw can work effectively with full immersion, you just need to learn how to adjust the feed force. You also need to remember that RCP with a performance margin is characterized by an increased duration of activation, and therefore is better suited for installation in a sawing machine.

Saw base and blade adjustment

The construction of the support sole determines the tool’s capabilities and durability. There are two types of platforms: stamped and cast milled. The latter, as a rule, are made of aluminum, which generally has a beneficial effect on the weight of the tool. In turn, a stamped steel base with a sufficient thickness has greater rigidity and is less prone to deformation during impacts and falls. In the front part, on the side of the saw blade, there is a removable parallel stop for longitudinal cutting of lumber to the required width. It is optimal if this element is fixed in two seats and has a millimeter scale, while completely free from backlash.

The head is fixed on the base of the saw – the motor and the gearbox in a single housing, as well as the spindle holder with a protective cover. In almost all saws, the head is mounted on a swivel joint, and a sector protractor is installed in the front part to give the disc an inclined position with a clearly defined angle of deviation from the normal. You need to pay close attention to the quality of the sole tilt mechanism. If the bracket is made of stamped parts and secured with a pair of rivets, high positioning accuracy and durability should not be expected. On the contrary, the presence of massive brackets in the places of fastening of the movable assemblies testifies to the general reliability, and the spring on the clamping screw will make it possible to set the required angle of inclination with greater accuracy.

METABO KS 55METABO KS 55

Additionally, some saws are equipped with a mechanism for adjusting the blade overhanging the plane of the sole. This feature is very useful for grooving or making carpentry additives. The same mechanism can work in an unlocked state: such crimps are called submersible, they are very convenient to use when starting a cut in the center of the part, and not from the edge. As in the case of the tilt mechanism, the quality of the submersible hinge should not cause any complaints, and the assembly itself must be spared from the slightest backlash.

Casing and body parts (ergonomics)

Most hand-held circular saws have an ABS plastic body in two halves. They form a shell of the engine, combined with a shackle handle, on which a start button is located with a blocking of accidental activation. This is the most successful tool form factor, providing high usability and safety. The additional handle, contributing to a secure hold of the tool with two hands during operation, can be attached either to the body or casing, or directly to the base plate. The choice in this regard is a matter of purely personal ergonomic preference..

Circular saw start lock

The protective cover for the RCP is double-sided. The lower part is removed by turning inside the outer half of the casing when the tool is brought to the edge of the workpiece. The upper half is rigidly attached to the spindle neck and is designed to protect the eyes from flying chips. Also, the upper part of the casing helps to collect sawdust and remove them through a socket directed away from the operator. As a rule, the bell has a round shape for connecting a vacuum cleaner, while practice shows that its most successful direction is back in the plane of rotation of the disk. Otherwise, there is a high probability of clogging of the channel with chips..

Makita 5008MGMakita 5008MG

The issue of ergonomics for such a tool as a hand circular has, if not the first priority, then one of the most important values. This is a rather heavy instrument with a pronounced gyroscopic effect, and therefore it must reliably and comfortably fit into the hand, otherwise the work will be performed with a low level of comfort, which means with low productivity. Smart balancing is especially important for cordless saws.

Milwaukee M12 FUEL Circular SawMilwaukee M12 FUEL Circular Saw

Useful add-ons

Circular saws also have a number of features that do not greatly affect the reliability and durability in general, but can significantly improve the convenience of work. For example, the presence of a laser cutting direction indicator is very helpful when cutting sheet materials without using a guide bar. It is also desirable to have a riving knife, which is not available for every budget model, but it helps to ensure a clean cut when cutting long workpieces and protect the disk from jamming.

If the saw will be used for fine cuts with minimal post-processing, it will not be superfluous to have a constant electronics that maintains a constant speed of rotation of the blade under varying loads. The soft start function will help to extend the life of the engine, and it is better if it is provided not by a thermistor, but by electronics. Saws are also considered more reliable in terms of the drive, in which the motor and gearbox are enclosed in a single metal case..

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