Video: How To Choose A Chainsaw
2023 Author: Douglas Hoggarth | [email protected]. Last modified: 2023-05-24 11:23
Household saws are the most primitive. Their help is usually resorted to from time to time, for example, when it is necessary to prepare firewood for the fireplace. The functional abilities of such saws are minimal. They are designed for an average of 20 operating hours per month (about 40 minutes per day), and their low power is compensated by their light weight and ease of handling.
Semi-professional models perform any work - from repair and construction to felling trees. Their only drawback is the inability to use it for 8-10 hours a day for a long period. They often serve as loppers in felling.
Professional saws are powerful (typically over 2.5 kW) and feature a wide range of functions. They are used mainly as shaft saws, they can work tirelessly all year round for 10-16 hours a day. The main feature of a professional tool is 8 hours of work without interruption. Such saws are made of durable and wear-resistant materials, and their resource ranges from 1300-2000 hours (for household models, this figure is 2-3 times lower).
Resource of work.
There is no precise and clear definition of the term “resource of work” that would be used by all manufacturers and sellers in the same way. Commoners interpret it as the time before sending the tool to the landfill, and experts - as the time until the first overhaul of the engine or a decrease in compression by 40%. As you can see, it is rather difficult to give an exact figure, and it is practically unrealistic, therefore, the main focus here is on the availability of a branded service.
The main advice for operating a chainsaw (as, indeed, any other tool) is as follows: choose the right operating mode and avoid significant overloads. The formula of love is right here too: how the instrument is treated, so much it serves.
When purchasing a chainsaw, buyers often ask a question about the speed of sawing wood with a tool of a particular brand (for example, whether it is necessary to press on it while doing this). First of all, this depends on the condition of the saw headset, and in particular the chain. When working with a blunt chain, the sawing efficiency drops significantly, and the likelihood of saw failure increases, as the load on the engine increases. Therefore, with a professional approach to the process, it is recommended to regularly edit the chain (for example, at the end of the working day). In addition, the shape of the cutting tooth and the chain pitch make a significant contribution to productivity.
The best result is achieved with the optimal choice of chain and engine power. Saw power is the second important parameter that characterizes its activity and determines the stringent conditions for the applicability of this model.
The most dangerous moment during the operation of the saw is the so-called kickback, or a sharp throwback of the tool towards the operator. This happens when the end of the guide bar meets the surface of the wood being treated.
The only way to avoid injury is to stop the chain quickly. This function is performed by a special brake (called inertial brake), which is driven by a shield located in front of the operator's left hand. It is a kind of lever that can take two positions. Before starting, the shield is switched to the position "closer to the hand" and thus is cocked. At the moment of the kickback, the operator's hand rests on it, and the guard is triggered, instantly activating the chain brake. In addition, it can change position without interacting with the operator's hand - simply due to inertia.
Another way to avoid kickback is to exclude the dangerous sector from the sawing process. This is done with another shield (protective sector) that covers the end of the saw head and prevents the tool from kicking. However, this method is used much less often than installing a chain brake. Moreover, Swedish saws (Husqvarna, Jonsered, Partner) are deliberately not equipped with such guards. This is because Swedish safety standards provide for end-of-line operation. Felling a tree by a Swedish lumberjack is very similar to cutting loaf of bread: the operator first bites into the wood with the end of the tire, and then makes a circle around the trunk. In this way, you can cut a tree twice as thick as the length of the tire. In Russia, this method is allowed only for high-class fellers.
Prolonged contact with a strongly vibrating instrument can lead to severe joint diseases, so an anti-vibration system is a must, especially on professional models. The simplest variety is a set of rubber gaskets located between the handles and the body. However, such an anti-vibration system is already practically irrelevant - in modern chainsaws, as a rule, the principle of two masses is implemented: the engine block is separated from the handle block and the fuel tank.
Anyone who has worked with a powerful saw for several hours at least once knows the enormous stress on the hands due to vibration. In the absence of sufficient vibration protection, this is fraught with impaired blood circulation and other unpleasant consequences. Therefore, if there is no desire to acquire occupational diseases along with the specialty of a lumberjack, you should pay attention to what kind of vibration protection this system provides. It is even better to ask to start the chainsaw when buying and hold it in your hands.
Power and weight
Manufacturers avoid increasing the power of household models, as this leads to an increase in the weight of the tool. In addition, high power is not the most important factor when using a chainsaw in a household. A favorable weight-to-power ratio is also important for a professional, since this parameter significantly affects the convenience of work and, as a result, the quality of work. In general, the class of professional chainsaws is characterized by a significantly greater variation in power (from 2 to 6 kW) than for household ones. This is due to the variety of conditions in which such a tool is used (tree trunks of different thickness, hard or frozen wood, etc.).
In Russia, professional felling is carried out in winter, since in summer the forests are usually impassable. The wood is frozen and hard in winter, so you should choose especially strong and durable chainsaws for felling.
Types of tires
There are several types of bar and chain bars to suit different purposes and users. The saw headset for household saws will suit those users who take the tool occasionally and do not have special professional skills. To keep these operators as safe as possible, manufacturers use a narrow, flat bar with a low profile chain that has very little kickback tendency. The lightweight tires are ideal for work in which the weight of the chainsaw plays a role (for example, cutting at height). These tires consist of two steel plates with selected grooves, the voids between them are filled with polyamide. This design can significantly reduce the weight of the tool.
For professional use and long-term use, tires with replaceable heads have been created. They are installed on saws of medium and high power.
In the technical characteristics of the chainsaw, the word "recommended" is usually added to the tire length indicator. What does this mean? The fact is that the longer the tire, the more resistance it provides to the torque of the engine crankshaft. If the power of the chainsaw is insufficient, additional efforts will have to be made, which will lead to premature wear of the saw headset and the engine. In addition, since most of the power is wasted, fuel consumption increases.
Thus, the length of the bar should be consistent with the saw power and “recommended” means in fact the maximum (shorter tires can be used, but longer ones are undesirable).
Low profile chains are intended for non-professional use. As a rule, their pitch is 0.325 inches, so the main advantage of such a chain (the minimum level of vibration) smoothly flows into its disadvantage - reduced performance.
3/8 '' and 0.404 '' chains are recommended on heavy duty chainsaws. Their vibration level is increased, but their activity is much higher. It is these chains that are optimal for felling and crosscutting thick trees. There is also a special class of problems that ordinary chains cannot cope with (they become dull very quickly). This is sawing dirty or frozen wood. There are special carbide-tipped chains for such work.
Why 3/8 and not 0.375?
Many wondered more than once what a chain step is and why it has such strange designations: in one case - in the form of a decimal fraction, and in the other - a simple one.
The answer is that in theory, pitch is the distance between the two nearest teeth, while in practice it is the distance between the rivets of the chain, halved. The chain pitch is measured in inches and can be equal to 0.325; 0.375 or 0.404.
As the world experience has shown, users often confuse the numbers in the marking, because 0.375 and 0.325 differ by only one digit. In order to avoid such incidents, manufacturers decided to adhere to a single notation system, according to which the chain pitch takes three values: 0.325, 3/8 and 0.404 inches.
How to choose a saw headset
It should be remembered that the components of the saw headset (chain, bar, drive sprocket, or sprocket) from different companies are usually incompatible. The differences lie in the parameters of the driving sprocket (in accordance with which the chain pitch should also be) and the thickness of the driving link of the chain, which varies within 1.3-1.6 millimeters. Therefore, choosing a specific model, be it an electric or chainsaw, the buyer almost always becomes a fan of components of the same brand.
Many people think that the larger the chain pitch, the more aggressive it is. In fact, everything is a little different. It turns out that the aggressiveness of a saw with a particular chain is highly dependent on power and, accordingly, torque.
The power of the tool determines the saw's ability to pull the chain through the cut. The designers of many companies fought over this process. As it turned out, for saws with a small cylinder volume (and, therefore, with low power) chains with a 3/8 inch pitch are unprofitable - with a wide tooth pitch, the chain bites more into the wood, but the engine is not able to pull it through. The result is uneconomical work with only part of the canvas. Conversely, heavy duty saws equipped with a 0.325”chain simply pull the chain through with virtually no damage to the tree.
The following pattern was derived. For saws with a cylinder capacity of 40-50 cubic centimeters, a 0.325 inch chain is more effective, while a 3/8 inch chain is optimal for more powerful machines. At the same time, in the category of 40-50 cubes, both those and other chains are used - the choice is due to the specific features of the model.
There is another category - powerful saws with a high torque (for example, the domestic Ural-2TE). Chains with a pitch of 0.404 inches are possible on these machines.
And finally, we must not forget: when changing the chain to another with a different pitch, you will have to replace the driving sprocket.
Requirements for gasoline and oils
On any saw, a two-stroke carburetor engine and two tanks are installed (one for filling the fuel mixture, the other for oil for lubricating the chain). The volume of the fuel tank is from 0.3 to 1 liter, and the volume of the oil tank, as a rule, is 1.5-2 times less. This volume ratio leads to the fact that the chain oil and the fuel mixture run out approximately at the same time, namely after 30-45 minutes of operation (at full load).
The need for preparing a fuel mixture is understandable to everyone who is familiar with two-stroke engines: the difference between the operating cycle of a two-stroke engine and a four-stroke engine leads to the fact that it is impossible to use an oil pump system to lubricate all rubbing parts (piston, shaft, etc.), and oil has to add directly to gasoline. All this is quite important, since if you try to work only on gasoline or if the proportions of the gasoline-oil mixture are violated, the tool will quickly break.
Recommendations for the brands of gasoline and oil, as well as the proportions of the fuel mixture are as follows. For Russian chainsaws, 76 gasoline and conventional oils for two-stroke engines (motorcycle oils) are used, which are added to the mixture in an amount of about 4%, that is, in a ratio of 1/25. Foreign models require gasoline with an octane rating of 92 (or higher) and branded oils from chainsaw manufacturers (while the oil content in such a mixture should be about 1/40).
In principle, domestic oils for two-stroke engines are also suitable for foreign chainsaws, but two circumstances should be borne in mind. First of all, you need to be sure that the gasoline is clean. Second: motorcycle oils are designed for engines with a speed of up to 8.5 thousand per minute, and since the revolutions of foreign-made chainsaws can reach 11-14 thousand, the use of these oils reduces the service life of the tool by an average of 7-10%. So whether the game is worth the candle, you have to decide for yourself.
It is easier to lubricate the saw unit with oil: in all models of household and professional chainsaws, you can use ordinary oils for "Zhiguli" (for example, engine oils are recommended for Husqvarna models, and transmission oils for Stihl).
Attention should also be paid to the features of the seasonal operation of the instrument. If the saw is operated at low temperatures, even with the correct choice of all ingredients, the quality of the oil and fuel mixture may be unsatisfactory (crystallization occurs and the viscosity increases significantly). In this case, the saw itself must be adapted to such conditions - for example, it is necessary to provide for the possibility of heating the carburetor during operation. In addition, it is advisable to first warm up the saw (if it was stored in an unheated room) in order to avoid unwanted consequences due to the presence of condensation.
Purchase and operation
When buying a saw, the natural desire of every customer is to check the functionality of the tool. There are pitfalls in this seemingly simple process. It's all about the design features of chainsaws. For your information: any chainsaw must not be started without a pre-installed and adjusted saw headset (tires, sprockets and chains), otherwise the clutch will immediately fly out. So do not rush to pull the cable - it is better to carefully read the instructions. (By the way, if an imported saw entered our market by official means, the instruction must be in Russian.)
After buying a chainsaw, it is imperative to run it in for 40-50 minutes at low speeds (this approximately corresponds to the use of a fuel tank), then turn off the engine and check the chain tension. Next, you need to make several cuts, applying weak efforts, and only then proceed to full operation.
Each new chain (or bar) should be run in for a few minutes. All this is done to ensure that the sprocket, bar and chain are well heated and oil gets on all lubricated parts of the saw headset. In about 90% of cases, the cause of saw failure is a careless attitude towards the saw headset, and in particular, poor maintenance of the chain. In other words, when the chain is sharpened, it does the work, when it is blunt, it is a person. In addition, there is an additional increased load on the engine. In addition to the obvious inconveniences, such an increase in load leads to a significant decrease in the tool life.
How to quickly start the saw
After the obligatory pre-start check of the saw headset and refueling with fuel and oil, the saw is ready for use. Next, you need to pull out the suction, completely take out the slack in the starting cable and start the tool with a strong jerk (with a sluggish tension, there is a high risk of flooding the candle, which will somewhat complicate subsequent start attempts). If done correctly, the saw starts the first time.