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Author:admin Date:05-03-2020
Composition of saw chain
The saw chain is composed of left cutting teeth, right cutting teeth, middle guide teeth (also called driving teeth) connecting pieces and rivets.
Model and size of saw chain
The saw chain is represented by Latin letters and Arabic numerals. Due to the different countries and manufacturers, the meaning of each letter and number is also different. However, it represents pitch, thickness of middle guide tooth, shape of cutting tooth, as well as some variable characteristic symbols for safety and wear reduction.
Pitch is the center distance between the two holes of the cutting tooth, the middle guide tooth and the connecting piece. On the same type of saw chain, their pitch (hole pitch) is the same, and all of them are expressed in inch. The measuring tools we use are all metric, so we need to convert them when we measure them. 1 inch = 25.4mm, if you want to calculate the metric size, multiply it by 25.4. Example b3l, pitch: 25.4 × 0.404 mm; middle guide tooth thickness: 25.4 × 0.063 mm.
Match of saw chain
The matching of saw chain and chain saw mainly depends on the chain wheel, guide plate length, guide plate head form and guide plate guide groove width of the saw chain. The pitch of saw chain must be consistent with the sprocket, guide plate head gear (if it has teeth), the thickness of middle guide tooth shall be consistent with the guide groove on the guide plate, and the length shall be consistent with the perimeter of guide plate, the number of sprocket teeth and the space distance between sprocket and guide plate It can only be used after matching.
Length of saw chain
Take B3 saw chain used for 18 inch as an example. The saw chain used is riveted into a circular ring. There are 30 left and right cutting teeth in total. There are 4 pitches between each two cutting teeth (the pitch on the cutting teeth is also calculated). 0.404 × 4 × 30 = 48.48 (inch) 1 foot = 12 inch. Divide the data by 12 inches, 48.48 ÷ 12 = 4.04 feet. The length of this saw chain is 4.04 feet. (multiply by 2 when calculating with middle guide tooth)
Each box of saw chain is 100 feet long, and the pitch of each type of saw chain is different, so the number of cutting teeth is different. There are four pitch of guide teeth in the connecting piece attached to each cutting tooth. The calculation formula and data are as follows:
Type A: 100 (feet) ÷ (0.375 × 4 ÷ 12) = 800
Type B: 100 (feet) ÷ (0.404 × 4 ÷ 12) = 744 in general (cutting teeth)
Type K: 100 (FT) ÷ (0.325 × 4 ÷ 12) = 924 (tooth cutting)
Type N: 100 (FT) ÷ (0.365 × 4 ÷ 12) = 822 (tooth cutting)
For normal saw chain, in order to prevent cutting deviation, it should be left and right in pairs, that is, symmetrical. The number of teeth is even. The 100 feet sent by the manufacturer is not exactly an integer. Some more are for the even number of teeth. However, some guide plates are not standard, and the riveted cutting teeth of saw chain must be an odd number. Two left (or right) cutting teeth are on one side, and then a connecting piece and a middle guide tooth are added. Then the total length of the guide tooth is calculated by the middle guide tooth. The distance between each two middle guide teeth has two pitches (the pitch on the middle guide tooth is also calculated). Then its length is the pitch multiplied by 2, multiplied by the number of middle guide teeth, and divided by 12. Take the k-chain with 59 guide teeth as an example:
0.325 × 2 × 59 ÷ 12 = 3.196 feet. The calculation method of other models of saw chain is the same, but the difference is their pitch.
In addition, there are two data to keep in mind: 1 foot = 12 inches, 1 inch = 25.4mm
Filing of saw chain
The left and right cutting teeth on the saw chain are cutting tools. After a period of use, the edge becomes blunt. In order to cut smoothly and keep the edge sharp, it is necessary to file. Precautions for filing:
1. Select a round file suitable for filing the saw chain. The cutting teeth, size and arc of each type of saw chain are different. The standard of round file required for each type of chain is certain. The manual has a detailed introduction, and it must be checked.
2. Pay attention to the direction and angle of file repair. File forward along the edge direction. When pulling back, it should be light and do not use force back and forth as much as possible. Generally, the included angle of saw chain edge is about 30 degrees, while the front is high and the back is low, and the included angle is about 10 degrees. These angles vary according to the hardness and softness of the material to be sawed and the usage habits of the saw hand. At the same time, pay attention to the symmetry of the left and right cutting teeth. If the deviation is too large, it will deviate and be sawed obliquely.
3. Pay attention to the height of limit gear. A part protrudes in front of each cutting tooth, which is the limit tooth. It is 0.6-0.8mm lower than the top of the edge. The cutting amount of each tooth is so thick each time. When filing the edge, pay attention to its height. If there are too many files on the edge, the limit tooth will be higher relative to the edge, and the cutting amount will be smaller each time, affecting the cutting speed. If the edge is lower than the limit tooth, it will produce It is impossible to cut without eating wood. The limit gear is too low. Each tooth is too thick to be cut each time, which is likely to lead to "hacking" and the sawing is not moving.
Maintenance of saw chain
The saw chain runs fast. Taking 3 / 8 saw chain as an example, the number of sprocket teeth is 7. When the engine turns at 7000 rpm, the saw chain runs at a speed of 15.56 meters per second. The driving force of sprocket and the reaction force during cutting are all concentrated on the rivet shaft. The working condition is bad and the wear is serious. If the maintenance is not paid attention to, the saw chain will be scrapped soon. The maintenance shall be carried out from the following aspects:
1. Always add lubricating oil;
2. Keep the cutting edge sharp and the symmetry of left and right cutting teeth;
3. Often adjust the tension of the saw chain, not too tight or too loose. When the adjusted saw chain is lifted up by hand, a middle guide tooth is fully exposed from the guide plate slot;
4. Clean and clean the dirt in the guide plate slot and saw chain in time, because the guide plate and saw chain will be worn during sawing, and the worn iron chips and fine sand will accelerate the wear. The gum on trees, especially the grease on pine trees, will melt and adhere to the saw chain in the process of sawing, so that all the joints are sealed, hard and the engine oil cannot enter, cannot be lubricated, and will accelerate the wear. It is recommended to remove the saw chain and wash it in kerosene every day after use.
The saw chain is composed of left cutting teeth, right cutting teeth, middle guide teeth (also called driving teeth) connecting pieces and rivets.
Model and size of saw chain
The saw chain is represented by Latin letters and Arabic numerals. Due to the different countries and manufacturers, the meaning of each letter and number is also different. However, it represents pitch, thickness of middle guide tooth, shape of cutting tooth, as well as some variable characteristic symbols for safety and wear reduction.
Pitch is the center distance between the two holes of the cutting tooth, the middle guide tooth and the connecting piece. On the same type of saw chain, their pitch (hole pitch) is the same, and all of them are expressed in inch. The measuring tools we use are all metric, so we need to convert them when we measure them. 1 inch = 25.4mm, if you want to calculate the metric size, multiply it by 25.4. Example b3l, pitch: 25.4 × 0.404 mm; middle guide tooth thickness: 25.4 × 0.063 mm.
Match of saw chain
The matching of saw chain and chain saw mainly depends on the chain wheel, guide plate length, guide plate head form and guide plate guide groove width of the saw chain. The pitch of saw chain must be consistent with the sprocket, guide plate head gear (if it has teeth), the thickness of middle guide tooth shall be consistent with the guide groove on the guide plate, and the length shall be consistent with the perimeter of guide plate, the number of sprocket teeth and the space distance between sprocket and guide plate It can only be used after matching.
Length of saw chain
Take B3 saw chain used for 18 inch as an example. The saw chain used is riveted into a circular ring. There are 30 left and right cutting teeth in total. There are 4 pitches between each two cutting teeth (the pitch on the cutting teeth is also calculated). 0.404 × 4 × 30 = 48.48 (inch) 1 foot = 12 inch. Divide the data by 12 inches, 48.48 ÷ 12 = 4.04 feet. The length of this saw chain is 4.04 feet. (multiply by 2 when calculating with middle guide tooth)
Each box of saw chain is 100 feet long, and the pitch of each type of saw chain is different, so the number of cutting teeth is different. There are four pitch of guide teeth in the connecting piece attached to each cutting tooth. The calculation formula and data are as follows:
Type A: 100 (feet) ÷ (0.375 × 4 ÷ 12) = 800
Type B: 100 (feet) ÷ (0.404 × 4 ÷ 12) = 744 in general (cutting teeth)
Type K: 100 (FT) ÷ (0.325 × 4 ÷ 12) = 924 (tooth cutting)
Type N: 100 (FT) ÷ (0.365 × 4 ÷ 12) = 822 (tooth cutting)
For normal saw chain, in order to prevent cutting deviation, it should be left and right in pairs, that is, symmetrical. The number of teeth is even. The 100 feet sent by the manufacturer is not exactly an integer. Some more are for the even number of teeth. However, some guide plates are not standard, and the riveted cutting teeth of saw chain must be an odd number. Two left (or right) cutting teeth are on one side, and then a connecting piece and a middle guide tooth are added. Then the total length of the guide tooth is calculated by the middle guide tooth. The distance between each two middle guide teeth has two pitches (the pitch on the middle guide tooth is also calculated). Then its length is the pitch multiplied by 2, multiplied by the number of middle guide teeth, and divided by 12. Take the k-chain with 59 guide teeth as an example:
0.325 × 2 × 59 ÷ 12 = 3.196 feet. The calculation method of other models of saw chain is the same, but the difference is their pitch.
In addition, there are two data to keep in mind: 1 foot = 12 inches, 1 inch = 25.4mm
Filing of saw chain
The left and right cutting teeth on the saw chain are cutting tools. After a period of use, the edge becomes blunt. In order to cut smoothly and keep the edge sharp, it is necessary to file. Precautions for filing:
1. Select a round file suitable for filing the saw chain. The cutting teeth, size and arc of each type of saw chain are different. The standard of round file required for each type of chain is certain. The manual has a detailed introduction, and it must be checked.
2. Pay attention to the direction and angle of file repair. File forward along the edge direction. When pulling back, it should be light and do not use force back and forth as much as possible. Generally, the included angle of saw chain edge is about 30 degrees, while the front is high and the back is low, and the included angle is about 10 degrees. These angles vary according to the hardness and softness of the material to be sawed and the usage habits of the saw hand. At the same time, pay attention to the symmetry of the left and right cutting teeth. If the deviation is too large, it will deviate and be sawed obliquely.
3. Pay attention to the height of limit gear. A part protrudes in front of each cutting tooth, which is the limit tooth. It is 0.6-0.8mm lower than the top of the edge. The cutting amount of each tooth is so thick each time. When filing the edge, pay attention to its height. If there are too many files on the edge, the limit tooth will be higher relative to the edge, and the cutting amount will be smaller each time, affecting the cutting speed. If the edge is lower than the limit tooth, it will produce It is impossible to cut without eating wood. The limit gear is too low. Each tooth is too thick to be cut each time, which is likely to lead to "hacking" and the sawing is not moving.
Maintenance of saw chain
The saw chain runs fast. Taking 3 / 8 saw chain as an example, the number of sprocket teeth is 7. When the engine turns at 7000 rpm, the saw chain runs at a speed of 15.56 meters per second. The driving force of sprocket and the reaction force during cutting are all concentrated on the rivet shaft. The working condition is bad and the wear is serious. If the maintenance is not paid attention to, the saw chain will be scrapped soon. The maintenance shall be carried out from the following aspects:
1. Always add lubricating oil;
2. Keep the cutting edge sharp and the symmetry of left and right cutting teeth;
3. Often adjust the tension of the saw chain, not too tight or too loose. When the adjusted saw chain is lifted up by hand, a middle guide tooth is fully exposed from the guide plate slot;
4. Clean and clean the dirt in the guide plate slot and saw chain in time, because the guide plate and saw chain will be worn during sawing, and the worn iron chips and fine sand will accelerate the wear. The gum on trees, especially the grease on pine trees, will melt and adhere to the saw chain in the process of sawing, so that all the joints are sealed, hard and the engine oil cannot enter, cannot be lubricated, and will accelerate the wear. It is recommended to remove the saw chain and wash it in kerosene every day after use.
