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Chainsaw chain types 1/4、0.325、3/8、0.404;

The saw chain is an indispensable part of the chainsaw. Without the chain, the chainsaw cannot work and cannot be called a saw. It's just an engine, but there are many people who don't know much about saw chains.

The composition of the saw chains

The saw chains are composed of left-cutting teeth, right-cutting teeth, middle guide teeth (also called driving teeth) connecting pieces, and rivets.

The model of the saw chain and the size of the saw chain

The saw chain is represented by Latin letters and Arabic numerals. Due to different countries and manufacturers, the meanings of each letter and number are different, but they all indicate the pitch, the thickness of the middle guide tooth, the shape of the cutting tooth.

The pitch is the center distance between the cutting teeth, the middle guide teeth, and the two holes of the connecting piece. On the same type of saw chain, their pitch (hole distance) is the same, and all are expressed in inches in the imperial system. The measuring tools we use are all metric and must be converted when measuring.

1 inch = 25.4 mm, if you want to calculate the metric size, multiply 25.4 and the size it represents. Example B3L, pitch: 25.4×0.404 mm; thickness of middle guide tooth: 25.4×0.063 mm.

The matching of the saw chain

Whether the saw chain and the chain saw the match, mainly depends on the chain wheel of the chain saw, the length of the guide plate, the form of the guide plate and the width of the guide plate guide groove, the pitch of the saw chain must be the same as the sprocket, the gear of the guide plate head (if it is toothed ) Keep the same, the thickness of the middle guide tooth is consistent with the guide groove on the guide plate, and the length is consistent with the circumference of the guide plate, the number of sprocket teeth, and the space distance between the sprocket and the guide plate.

The length of the saw chain

Take the B3 saw chain used for 18 inches as an example. The saw chain used is riveted into a circular ring. There are 30 left and right cutting teeth. There are 4 pitches between each two cutting teeth (the pitch of the cutting teeth is also counted), 0.404×4×30= 48.48 (inches) 1 foot = 12 inches, the data obtained is divided by 12 inches, 48.48 ÷ 12 = 4.04 feet, the length of this saw chain is 4.04 feet. (Multiply 2 for calculation with center guide tooth)

Each box of saw chains is 100 feet long. Different types of saw chains have different pitches, so the number of cutting teeth is different. The guide teeth in the connecting piece attached to each cutting tooth have 4 pitches. 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) = generally 744 (tooth cutting)

Type K: 100 (feet) ÷ (0.325×4÷12) = generally 924 (tooth cutting)

Type N: 100 (feet) ÷ (0.365 × 4 ÷ 12) = generally 822 (tooth cutting)

A normal saw chain, in order to prevent cutting deviation, should be left and right in pairs, that is, symmetrical, the number of teeth is even, the 100 feet issued by the manufacturer is not just an integer, and some are a little more for the given saw The chain cutting teeth are even numbers. However, some guide plates are not standard, the riveted saw chain cutting teeth must be odd numbers, two left (or right) cutting teeth on one side, plus the connecting piece and the middle guide tooth, then its total length is calculated by the middle guide tooth, There are two pitches for every two middle guide teeth (the pitch on the middle guide teeth is also counted), then its length is the pitch multiplied by 2, multiplied by the number of middle guide teeth, and then divided by 12.

Take K-chain, the number of guide teeth is 59 as an example:

0.325×2×59÷12=3.196 feet. The calculation method for other types of saw chains is the same, the difference is their pitch.

In addition, there are two data to remember: 1 foot = 12 inches, 1 inch = 25.4 mm

The repairing file of the saw chain

The left and right cutting teeth on the saw chain are cutting tools. After a period of use, the cutting edge becomes blunt. In order to cut smoothly and keep the cutting edge sharp, it is necessary to file.

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