The tooth of the chain planes the wood like a planer, and the thickness of the chips is controlled by the height of the limiter.
Intensive work of the saw leads to a rapid blunting of the chain. Several sharpenings may be required within one day. The problem is aggravated by the fact that the tooth quickly becomes dull when it encounters the ground. It is enough to hook the soil once or twice, and the work can be stopped. the chips become shallow, and the saw ceases to go deeper into the tree.
The earlier blunted teeth are sharpened, the less material needs to be removed during sharpening, as a result. the chain life is longer. Determining the moment when sharpening is already required is quite simple. An important feature is the feed force. A properly sharpened chain retracts into the cut even with a slight pressure. If on the contrary, a chainsaw is forced to saw with an increased feed force, then the teeth become dull. A dull chain can also be recognized if, instead of a large thick chip, only small chips fly out of the cut.
In this situation, the chainsaw should be sharpened urgently. Do not saw with a blunt or defective saw chain. the result is a strong tension in the body, a large cyclic load, poor cutting results. In addition, this means a decrease in productivity, high fuel consumption and increased wear on all nodes of the chainsaw.
Chain Tooth Parameters
To achieve optimal cutting properties, certain angles are attached to the tooth blades. The tooth back that slopes at an angle back forms the posterior angle of the upper blade. This angle is needed for cutting the upper blade into the wood.
The tapering back of the tooth blade forms the posterior angle of the end blade. This angle is needed for side cutting chips.
The edge of the end blade forms a rake angle with the sliding surface of the cutting link. The front angles of different types of chains vary from 60 to 85 °.
The rear corner of the upper blade characterizes the tilt of the upper blade back.
This angle is measured relative to the sliding plane of the cutting link and, depending on the type of saw chain, has a value from 50 ° to 60 °. The upper blade is the main blade, and the rear corner of the upper blade. this is the most important angle. The rear corner of the upper blade is difficult to measure, its correct value is formed subject to other prescribed values.
The grinding angle or the angle in the plan is obtained by measuring from the upper cutting edge at a right angle to the guide rail.
The angle of sharpening can be changed, depending on the application. The main rule: the greater the angle of sharpening, the higher the cutting performance when cutting unfrozen soft wood. Reducing the angle of sharpening when cutting frozen and / or solid wood contributes to a smoother stroke of the saw and a reduction in vibration. However, sharpening angles of more than 35 ° and less than 25 ° should be avoided (chains are excluded for longitudinal cutting, in which this angle is 10 °).
The rake angle, the angle of sharpening and the angle of the upper blade change when sharpening. These angles have a decisive influence on the cutting ability of the chain. Be sure to follow the prescribed values.
On each cutting link in front of the tooth blade there is a depth limiter. The height difference between the top edge of the depth gauge and the front edge of the tooth back is defined as the distance of the depth gauge.
Video: How To Sharpen A Stihl 180 Chain
The depth of penetration of the upper blade into the wood (chip thickness) and, thereby, productivity, depend on the distance of the depth gauge. The depth gauge distance is set depending on the chain pitch and type of execution. Normally, it should be 0.5-0.8 mm, usually 0.6 mm. High values will lead to an increased tendency of the chainsaw to recoil, too much grip and vibration of the chain. Low values result in poor performance. Since the distance of the depth gauge with each sharpening of the saw is reduced due to the reduction of the upper edge of the tooth, the depth gauge also needs to be filed periodically. after 5-10 sharpening the chain.
General rules for sharpening chainsaw chains
On the holder with a round file there are mowing lines that allow it to be correctly positioned relative to the chain. The holder is mounted on the sharpened tooth in accordance with the orientation lines. In this case, the plate itself rests on the upper edge of the tooth and the depth gauge, and the file is located under the cutting edge.
Using a toolholder ensures that the file adheres to the tooth at the correct height. There are various tool holders for different steps of the saw chain. The right choice of tool holder in combination with the correct file diameter ensures that the file protrudes 1/5 of its diameter above the tooth back. Use only special files for sharpening chains.
Before sharpening the chain of the chainsaw, it is advisable to fix the tire. When sharpening, it is necessary, while maintaining the position of the holder and pressing the file against the edge to be sharpened, to make several (2-3) turning movements away from you. No need to try to press the file too hard, the movements should be smooth and measured. Turn the file regularly to avoid one-sided wear. All other teeth are ground in the same way. It is more convenient to first sharpen the teeth of one direction, then change position and do the same with the teeth of another direction.
When sharpening all teeth, make the same number of movements with a file at the same pressure. This will result in the same tooth length. All cutting teeth must be the same length. Different tooth lengths cause uneven chain travel and cracking in it. If the length of the teeth is not the same, all cutting teeth should be filed to the length of the shortest tooth.
After several sharpening of the cutting teeth, the depth gauge grinds. To do this, a template is superimposed on it so that the limiter falls into the slot, and the tip protruding from the slot is ground with a flat file.
The principle of using a different set for sharpening chains of chainsaws does not differ from the first, although its design has differences.
A round file is also used for sharpening a cutting tooth, and for sharpening a depth gauge. flat. A special template provides sharpening parameters for both cutting teeth and limiters. In the first case, it is superimposed on the chain so that it falls into its slots. A file overlaid on the template and brought under the cutting edge rests on the guide rollers. The direction of file movement should be parallel to the side edges of the template.
When grinding the limiter, the template is superimposed so that the limiter falls into the slot next to which SOFT (for soft wood) or HARD (for hard wood) is written. As in the case of the first fixture, grinding is performed by smooth smooth movements of the flat file away from you.
Chainsaw sharpening machines
Stihl produces two modifications of hand-held machines. stationary FG 2 and mobile FG 1 mounted directly on the bus. There are analogues of lesser-known companies, comparable in price with the simpler devices described above.
The working part of these devices is structurally reminiscent of a beam saw, into which a round long file is inserted instead of a saw blade. FG 1 and FG 2 not only sharpen the chains, but also straighten them, adjusting the length of the upper edge of all the teeth to the same size. on the smallest tooth, which is taken as the control. A rather complicated configuration mechanism allows you to set all the necessary parameters. Sharpening is performed in 2-3 movements, after which they proceed to the next tooth, saving for it all the settings that were made for the control tooth. This ensures the same grinding parameters for all teeth. When grinding the limiter, the round file changes to a flat one.
Simple and easy to use electric grinding machine for chainsaw chains. It has a tuning system that allows you to set the chain at the right angle and bring the disc exactly to the edge to be sharpened. There are machines that automatically clamp the vise when lowering the disc onto the chain.