How To Choose A Circular Saw: Professional Advice

The electric circular saw (in the popular way “circular”, “parquet”) appeared in the twenties of the last century. As usual, several “organizations” have taken the trouble. At first, a radial-cantilever type of woodcutting machine was developed (Raymond DeWolt), a little later, under the Skilsaw brand, manual models (Salivan and Mitchell) began to be produced. There were also separate patents for side and integrated saws to A. Emmons and A. Steele, respectively. Well, the AEG company helped to “ground” the invention and promote it to the masses, the engineers of which were the first to connect the instrument to the general 220 volt network. Nowadays, the circular saw has reached perfection, the set of options and auxiliary systems for it has not changed for a very long time, not to mention the design features. It’s just that everyone is slowly pulling up to the premium class.

Circulars are considered to be one of the most technically challenging tools, even if you ignore the fact that they can have a full set of electronic bells and whistles available. The fact is that here it is necessary to constructively provide unprecedented safety measures (like all disk machines, “parquet floors” can be very traumatic), as well as to implement high accuracy of many spatial mechanical settings. Self-repair of the circular is considered to be a risky enterprise due to the difficulty of restoring the correct factory adjustments.

The main purpose of a circular saw is to perform longitudinal cutting of wood and its derivatives (OSB, chipboard, fiberboard, MDF, plywood), because this tool perfectly keeps the line, a jigsaw is no comparison here. Naturally, cross-cutting for circulars will not be a problem either. But it would be strange if a modern cutting unit were not sharpened to work on other materials. Indeed, using various types of discs, and in some cases changing the shaft rotation frequency, it is possible to cut laminated workpieces, gypsum fiber board, plastic of various densities, multilayer materials (sandwiches), slate, plexiglass. In a word, almost all sheet panels are perfectly cut, including at an angle to the main plane. The only thing that is too tough for circulars is dense mineral materials (concrete, brick, plaster). True, some units can be equipped with a diamond disc and have a water supply, structurally these are full-fledged circulars (Makita 4101RH). There is still one iron “but” – a circular saw cannot cut along a curved line.

What is a circular for metal

We should also highlight circular saws for metal work. Although they are positioned in the market in this way, they are essentially multifunctional. It’s more about the characteristics of the standard wheel, which comes in the basic configuration (this is not an abrasive, it is a hard-alloy toothed multi-purpose disc). Such units are easy to deal with pipes, tin, complex profiles, sheet steel and stainless steel (Makita 4131). It is very simple to talk with both steel and soft non-ferrous alloys (based on copper, aluminum).

Makita 4131

But what about the angle grinder? Compared with grinders equipped with a cutting disc, we have the following:

  1. The performance is much higher.
  2. The operator is relieved as the machine rests on the sole.
  3. Reduces noise and vibration levels.
  4. Possible bevel work.
  5. There are no sparks, the workpiece hardly heats up and does not “burn”.
  6. Increased safety (the rig is almost completely hidden and not subject to tearing).
  7. The service life of a carbide disc is about 100 times that of an abrasive.
  8. The cutting price is the lowest (only the guillotine is cheaper and faster).
  9. There is no release of mineral dust into the air, as from a stone tool.
  10. The cut is very high quality, without burrs.

Our craftsmen have just tried this device, and in Europe and the USA such machines are used with might and main, quite naturally, with such and such advantages. For example, the EVOLUTION 230 XTREME model cuts sheet steel (class A-3) with a thickness of 12 mm, profiles / pipes with a wall of 4 mm, and, of course, everything else (wood, polymers).

Plunge-cut circular saw

Another class of circulars is the plunge-cut saw. It is designed to plunge into the workpiece anywhere, not just from the edge. The lower automatic cover is completely absent here, and the disc is located above the base plate and lowers only when the “start” button is pressed. Naturally, the cutting depth is adjustable, often in a range of millimeters (DWS520K).

DeWalt DWS520K

The submersible mechanism (something similar is implemented in the wall chasers) allows for local repair of the roof, dismantling several selective floorboards, and cutting an opening in the countertop. Grooves, slots, gutters can be made without much difficulty. For correct work with sandwiches and laminated materials – the top layer can be cut with a preliminary cut to an incomplete depth of the workpiece, thereby eliminating the risk of chipping. All this is done not only perpendicular to the plane of the part, but also under a variable slope.

Cordless circular saw

More recently, such units seemed to us to be sheer fantasy. But as time goes on, wireless technologies are reaching a new level. Batteries have become so capacious, special motors are so economical, and chargers are fast, that even for such a powerful tool as a circular, the developers managed to organize an uninterrupted power supply. We take two modern batteries and a half-hour charge – that’s it, there will be no energy problems (Makita BSS 610 RFE). It’s even easier if your circular saw is equipped with a unified battery from the same manufacturer as the rest of your tools. The power characteristics (output power, torque) of wireless circulars are in no way inferior to those of similar networked machines – Bosch GKS 18 V-Li (cutting depth 51 mm). Well, as for mobility and ergonomics,

Makita BSS 610 RFE

Main selection criteria

Power, speed, disc diameter, cutting depth

The diameter of the cutting disc (outer, not the size of the bore) – it can be said without exaggeration that this is the main parameter of the circular. Based on it, manufacturers are forced to compose a specific model. The larger the disc, the more powerful the motor must be in order to spin it up to the required speed, the more torque is required to maintain this speed and there is no jamming, the more technologically advanced the stabilization system should be so that there is no beating, vibration and noise, the heavier , overall, the saw will be more expensive. But on the other hand, large tooling allows you to saw more massive workpieces, thicker material.

However, it is not enough just to pay attention to the size of the circle, it is much more important to have an accurate idea of ​​the maximum cutting depth. Developers almost always indicate these parameters in their passports, both for perpendicular and beveled cut. There is some conditional separation:

  1. Light class (40-50 mm) – sheet materials, work “on site”.
  2. The middle class (50–65 mm) is the most widespread and versatile.
  3. Heavy class (65–140 mm) – these are massive, purely professional machines.

The convention is that many companies issue their own special classification (Makitov people, for example, do not release babies at all and move a little forward in this matter). It turns out that we, ordinary users, can only listen to our needs, choose a priority in the ratio of “maneuverability / versatility / strength”, based on the specifics of the proposed work. For example, Hitachi C13U (weight 13 kg, disc 335 mm, 2000 watts) and Hitachi C6MFA (weight 3.4 kg, disc 165 mm, 1010 watts). The ratio of the straight cut depth for these models is 128 mm to 57 mm, respectively.

Left: Hitachi C13U, right: Hitachi C6MFA

I would also like to note that in case of emergency, you can cut a very bulky part by making a cut from both sides (yes, for correct operation, the disc does not have to go through the workpiece).

What else gives a power reserve? If there is a need to compare two circulars with the same depth, then a stronger motor of one of them will provide better frequency stability, longer continuous operation time, and will allow faster cutting of denser material. Watts under the hood are traditionally correlated with the diameter of the rig and, again, conditionally, the units are credited to one of the three corresponding classes:

  1. Up to 800 watts.
  2. 800 to 1200 watts.
  3. More than 1200 W (for example, Hitachi C9U2 – 2 kW, Makita 5143R – 2.2 kW).

Makita 5143R

Disk rotation speed – what does it give, besides the speed itself? There are two main nuances. First, the faster the shaft moves, the cleaner the cut is (however, the cleanliness depends more on the type of disc – the number and shape of teeth). Second, high speed is the opposite of torque. Third, high speed is high temperature, and some plastics can melt during sawing. If the frequency has become a stumbling block (read “choice”), then you need to compare saws with the same diameter of the cutting disc. Better yet, find a model with an idle speed control.

Electronics on guard

Advanced circulars are stuffed with electronic systems to the eyeballs. This is quite predictable, since this tool is powerful and dangerous – the user needs help so that the mission is not impossible. If there is a financial opportunity, you should not give up additional options, for performance and safety there are no unnecessary trifles.

For the benefit of the correct speed mode, the system for maintaining a constant spindle speed under load, the so-called constant electronics (DeWalt DWS520K), works. A special controller constantly reads the speed and in case of a local drop in revolutions (for example, when the feed is accelerated or when the tooling hits the compacted area of ​​the material), it is stabilized by an automatic increase in the outgoing power. The probability of a disc jam is reduced to almost zero, but the quality of the cut only improves. Obviously, this requires a certain power reserve (this is the prerogative of relatively large machines). Another point is the idle speed adjustment, preset. It is needed for manual selection of process parameters for materials with different physical characteristics (Metabo KSE 68 Plus). Not all models can boast of this option. And, by the way, the possibility of presetting is not a prerequisite for the presence of constant electronics, the only available frequency can also be stabilized.

In order not to overload the network when turning on the tool, since the starting currents, albeit in a short period of time, significantly exceed their rating – almost all more or less powerful circulars have a soft start system. The rig does not accelerate immediately, which eliminates the jerk of the tool and protects the gearbox parts from unnecessary shock loads, the unit lives much longer (“Fiolent” PD 3–70E).

If the operator is in a hurry to finish what he started and does not listen to the “well-being” of the circular saw, the overload protection system will receive a signal from overheated motor windings or react to a sharp drop in power consumption and turn off the power, preserving the performance of an expensive tool.

The electrodynamic brake stops the disc abruptly after releasing the start button (AEG BKS 18). The system is designed to protect the operator from possible injury, the part from damage, and the machine from kickback.

Mechanical features

If the rig is deafly jammed, the motor can fail very quickly, there is a possibility of a kickback. To protect against such a nuisance, a slip clutch is used. The working shaft of the motor will continue to rotate even if the disc is stationary. Don’t worry, the system won’t work unnecessarily.

Protection against accidental activation is realized by installing an additional button in the area of ​​the main handle. To apply power to the motor, you must press it simultaneously with the start button (Skil 5064AA). To make such a chord unintentionally is, perhaps, impossible at all, especially since the “fuse” is usually recessed in the head. Often (for other tools) this button allows you to lock the trigger on, this will not work here – the toothed disk must always be under control.

For the convenience of replacing the disc, the spindle can be locked with a button or a lever, in some models literally in any position (you do not need to scroll to look for the gripping point – Bosch GKS 65 CE Professional). If there is no lock, you have to wield two keys at once. The nut itself can be tightened with a wrench / screwdriver, or it can be made in a “toolless” version – quick-clamping.

A lot of the functionality of a circular depends on its base plate. Note that it is on it that all mechanical adjustments and fasteners for auxiliary elements are installed. Traditionally, platforms made by casting light alloys are considered to be of higher quality. They unambiguously indicate the professional class of the instrument, as they keep their geometry well (“Interskol” DP-235 / 2000M). However, do not discount thick stamped steel pads. They are more resistant to shock loads (do not crack from an accidental impact), have a lower impact on the price of the product, and are also used in tools for professionals (Bosch GKS 65 CE Professional).

An important point is the adjustment of the inclined cut. Angle sawing is realized precisely by changing the position of the platform relative to the entire upper part and the disc in particular. Usually the tilt is set at different angles: 30 °, 45 °, and in some machines it is extended to 50–55 °. The mechanism for setting the cutting depth is also located here. As a rule, this is all made in the form of grooves in the shape of a quarter circle (in some cases graduated) and rods with wing / lever clamps. The main advantage of quality control elements is speed, reliability and accuracy of fixing (Kress 1400 HKS). Backlash here is extremely unwanted guests.

Another advantage of the well-thought-out platform is the ability to set the saw in a stationary position. This refers to the option of creating a machine without using a special table . This moment will be relevant for all cars, but even more so for especially powerful and heavy ones.

To perform a high-quality straight cut, circular saws are already equipped with a parallel stop in the basic configuration, by the way, it can also be light-alloy. However, the most accurate sawing work can be achieved using a guide bar. The tire is bought separately (often they come from other manufacturers), but the sole must have a special groove. If you need to work “hand-held” on the markup, you need to control the line; for this, a special slotted opening is made in front of the base plate. An interesting option is implemented in the EVOLUTION 180 XTREME saw, where a laser line builder is built into the handle, during operation you just need to combine it with the marking.

EVOLUTION 230 XTREME

A compulsory accessory for the circular saw is a spring-loaded cover that completely hides the blade and releases it only at the start of sawing (you need a stop on the workpiece). The cover should slide easily and always return to its original position. To prevent the disc from being squeezed from the sides by the already cut material and not stopping, a “riving knife” is used in the design.

Ergonomics and more

The circular is a manual tool, therefore, when choosing, special attention should be paid to the overall ergonomics of the product. Interestingly, some manufacturers even make a left-handed tool with a mirrored layout.

The most important role in the comfort of any circular is assigned to the shape and location of the handles. Obviously, there will be different requirements for each user. Most of the questions are raised by the front handle, which is most often straight, located perpendicular to the plane of movement of the saw blade. This design is good if you work from yourself forward, but most often the tool is guided from the side – therefore, most craftsmen prefer the mushroom version, which is easily held in any position (DeWalt D23620). Someone may be more suitable for the bracket design (DeWalt D23650K).

DeWalt D23620

Give preference to models with rubberized handles, they help to securely hold and control the tool during operation.

It will not be superfluous to hold a few circulars in your hands before buying, most likely, a lot will become clear to you regarding the weight distribution of specific cars and their balance. Be sure to do this if you plan to do a lot of fieldwork.

Evaluate the visibility of the working area, the specific design features of the circular saw have a very serious effect on this circumstance. It is also important how efficiently sawdust is removed from the disc. Here, blowing of the surface is used (directed from the operator), a branch pipe is integrated for connecting an industrial vacuum cleaner and connecting a bag. There are options with a dust container.

Take a look at how the power cord entry point is executed. Unfortunately, users very often cut the power cable, so it is better if it is directed straight back, and the inlet sleeve will be as long and rigid as possible. Maximum freedom and safety will be provided by a long power cord – 4 meters is no longer a rarity for professional models. Otherwise, you will have to regularly fight with the extension block.

Sooner or later, the circular saw will require replacement of the carbon brushes, otherwise the engine anchor is at risk. Therefore, it makes sense to “monitor” this node as well. Well, if there is a separate window for quick access to the brushes, then you don’t have to disassemble the case, or go to the service for this if the device is under warranty. An excellent option is self-disconnecting brushes: graphite is worn out – the chain is broken (Sparky TK 70). The next nuance lies in the indication of the status of the brushes, this is a very useful gadget for the traditional brush assembly.

Most likely, under load you will not be allowed to test the saw, but if the seller allows, plug in the saw and run it at idle, listen to the noise and vibration levels. Evaluate how strong the air flow is generated by the tool – this largely determines the efficiency of cooling the motor and the quality of cleaning the working area from debris.

If you plan to work with circular only from time to time, then pay attention to the hobby class models from well-known manufacturers (Bosch PKS 55 A, Black & Decker CD601). They are designed for relatively short work (15 minutes work – 15 minutes rest) no more than 4 hours a day. This will be enough for home use, and you will be able to save a lot. Ironically, household models often outlive their professional counterparts a lot, and the developers provide them with a double warranty (2-3 years).

In general, carefully predict the load that the circular saw will receive at your disposal, and based on this, select the characteristics of the desired model. We hope we’ve provided you with enough food for thought.

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