Comparison Sturm AG915S vs Hitachi CM5SB

The largest number of discs or cutters (see "Work item") that can be installed on the tool at the same time. However, cutters are used only one at a time — this is due to their technical features. But several disks can be installed at once — usually 2, less often 3 or more.

The "repeated" tool is very useful for situations where you need to cut a wide furrow — wider than the thickness of the disc. With one disc, two passes would have to be made for this (along one edge of the furrow and along the second), and besides, manually control the parallelism of both slots. 2 or 3 disks allow you to cope with the task in one pass, and you do not need to monitor parallelism — the distance between the slots remains unchanged anyway. This distance can usually be adjusted; see "Working Width" for details.

Power consumed when operating an electric tool (see “Type”). Essentially, this is the power of the electric motor installed in the tool.

This indicator primarily determines electricity consumption and connection requirements. Thus, devices with a power of up to 3.5 kW can operate from a regular 230 V outlet; at higher values, as a rule, a connection to a 400 V network is required.

Also, based on power consumption, the general capabilities of tools are often assessed and compared - operating speed, ability to cope with hard materials, etc. Technically, this is not entirely true, since such characteristics depend not on the consumed, but on the useful power (see above). However, the latter is indicated relatively rarely in the characteristics, and the difference in energy consumption most often more or less corresponds to the difference in output power. So it is quite possible to say that the higher the power consumption, the “stronger” the tool as a whole, the greater the cutting depth and operating speed it can provide, and the better suited for hard materials.

The diameter of the blade/cutter for which the tool is designed.

A larger blade can provide greater depth of cut, but requires a more powerful motor. Accordingly, this parameter is directly related to the power and performance of the tool: the more powerful and heavier the unit, the usually larger the diameter of the working element in it. Note that some models allow the installation of cutters / discs and a smaller diameter than the standard one, but you cannot install a larger work item.

The maximum speed of rotation of the disk / cutter provided by the tool.

The higher the speed, the higher the speed of the cutting edge relative to the material, the higher the processing speed and the more accurate the cut is. On the other hand, as the speed increases, the torque decreases. So for the same blade/cutter diameter, higher RPMs will be beneficial on relatively soft materials, while a slower tool will be better for hard and stubborn materials.

The width of the furrow that the tool can cut. This parameter is relevant for models with a cutter (see "Work item") and units with several discs (see "Working discs / cutters"). In the first case, the processing width corresponds to the width of the cutter, in the second — to the distance between the discs. This distance can be changed by installing special washers on the spindle; therefore, in many tools, the processing width is indicated by a range, from minimum to maximum.

The depth to which the tool can cut through the material. This characteristic is directly related to the diameter of the blade / cutter (see above) — for greater depth, a larger diameter is required. However, units with the same working element size may differ in the depth of processing due to the difference in engine power and some design features.

In many models, the depth can be adjusted; for such devices, the minimum and maximum depth values \u200b\u200bare indicated in the characteristics.

— Self -propelled. A feature found exclusively in joint cutters (see "Device"). Such a tool has a wheel drive and is able to move independently; the travel speed during operation adjusts to the cutting speed. At idle, it is also low; however, the self-propelled design saves a lot of operator effort, especially when it comes to powerful heavy units — for them wheel drive is almost a must.

— Soft start. Function applicable to models with an electric motor (see "Type"). Without a soft start system, the motor consumes high current at the time of starting, which leads to noticeable voltage fluctuations in the network; and spinning up to operating speed occurs very quickly, with a jerk — as a result, if the hold is not strong enough, the tool can be released from the hands. Soft start avoids these phenomena: the control electronics limits the starting current, preventing power surges and sharp jerks of the tool.

— Maintain momentum. Maintaining constant engine speed regardless of the load on the disc / cutter. For this, electronics are used that control the power of the engine: at a low load, the power decreases, and with an increase in resistance, it increases, due to which the speed of rotation of the disk / cutter remains unchanged. Working at a constant speed has a positive effect on both the quality of processing and the service life of the discs / cutters....

— Electronic engine protection. Control electronics to prevent damage to the tool when overloaded or overheated. In the event of critical situations, such a system turns off the power to the engine in order to avoid breakdowns. You may need to press the unlock button to continue working. Such protection is found only in electric motors (see "Type").

— Brushless motor. The presence of such an engine provides a number of advantages over traditional collector engines: in particular, they are more economical in terms of energy consumption, less noisy, and also do not spark, which can be important in conditions of increased fire danger. The disadvantages of brushless motors are complexity and high cost.

— Safety clutch. Special coupling located between the motor shaft and the spindle; may be disposable or reusable. With a critical increase in resistance on the disk / cutter (for example, if the disk is jammed), this clutch is destroyed or opened, preventing engine damage and sharp jerks of the tool. This type of protection is also found in electric tools and in units with internal combustion engines (see "Type").

— Laser marker. Indicator light showing where the cut line will go when the tool is moving straight ahead. This feature is especially convenient since the blade or cutter is usually hidden from the operator's eyes by a protective cover.

The length of the network cable can tell you how far from the outlet you can operate the device. Therefore, for domestic use, it is more relevant to choose models with a short cord, for construction work or use in production, in the garage a longer cable is better.

Approximate noise level produced by the instrument during operation (actual volume may vary depending on performance).

The lower the noise, the more comfortable the use of the tool, the easier it is to work with it without headphones or other noise protection equipment. It is easiest to evaluate a specific volume level using comparative tables. In general, wall chasers and jointers are quite noisy equipment — in most models, the volume exceeds 90 dB (loudness comparable to the sound of a moving freight car at 7 m), and in the most noisy this figure reaches 118 – 119 dB, which is only slightly below the human pain threshold . If the volume is more than 100 dB, it is highly recommended to use protective headphones or earplugs.