Woodworking Saw Bands
The service life of a band saw on wood directly depends on the quality of its sharpening. It can be performed both independently and by resorting to the services of specialized companies. In the first case, you need to familiarize yourself with the technology and a number of features in detail.
Band Saw Design
The band saw belongs to the category of cutting tools and is an integral part of specialized equipment for wood processing. It is a closed tape, on the outer edge of which the teeth are located.
For the manufacture of special grades of steel are used. 9HF, B2F or C75. In the manufacturing process, the teeth are treated with high-frequency currents. This increases their hardness. It is this fact that affects the separation of cutting edges and maintainability. Often, several types of steel are used in the manufacture. The main tape is made of spring, and the cutting part is made of steel with a high content of tungsten or cobalt.
Features of the use of band saws for wood:
- wood requirements. The harder it is, the faster the blade becomes dull;
- installation conditions. Be sure to observe the indicator of tension. If it is less than required, sagging will occur. With strong tension, the probability of breakage of the web will increase;
- periodic sharpening. This will require a special machine.
The implementation of the last paragraph will increase the life of the tape structure. However, sharpening yourself is problematic. you need to choose the correct wiring, observe the angle of processing of the blades.
When buying a used saw, you need to pay attention to the presence of repair welds on the blade. They indicate frequent tool breakage.
Shapes and sharpening angle
At the first stage, the type of band saw is determined. The main indicator is the shape of the teeth. Depending on this parameter, they are divided into dividing, joinery or intended for sawing logs. The initial geometry and wiring angle are determined by the manufacturer. It is recommended to find out these data at the stage of procurement of components. They are needed to determine the parameters of the machine.
For hardwoods, the rake angle should be minimal. This ensures optimal contact of the processing material with the metal. If you plan to process soft varieties. to increase the processing speed, you can use models with a large value of the rake angle.
The determining parameters for self-updating the cutting edge are:
- tooth pitch. This is the distance between the cutting structural elements. Frequently encountered values are 19, 22 and 25 mm;
- tooth height. Magnitude from its base to the top;
- angle. The main value that you need to know to form the cutting plane. For carpentry models, it is 35 °. In dividing saws, the angle is from 18 ° to 22 °. In structures for processing timber. 10 °.15 °;
- divorce. Determines the deviation of the tooth from the general plane of the blade.
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After performing work on the machine, ideally, these characteristics should remain unchanged. For each model, the manufacturer determines the maximum deviation value. If during operation it is achieved, it is necessary to purchase a new model.
In order to eliminate resonance in some types of cutting tools make a variable pitch of the teeth. This does not affect manual sharpening, but requires careful setting of parameters during automated.
Band Saw Wiring
Before forming the cutting edge, the correct tooth alignment should be made. Throughout the entire period of operation due to constant loads, their location may change. Therefore, the geometry is first adjusted, and then sharpened.
The layout is the bending of the teeth relative to the plane of the main blade. This procedure is performed only on a special machine. In case of large discrepancies along the entire length of the tape, premature damage or breakage of the web is possible. Therefore, before that, you should determine the type of wiring.
The angle of inclination should correspond to the original. The type of wiring is also taken into account, which may be as follows:
- classic. Alternate bending of the teeth relative to the blade to the right and left sides;
- cleansing. The first and second teeth deviate to the right and left, and the third remains unchanged. This technique is used for saws that are designed to handle hardwood;
- wavy. The wiring angle for each tooth is individual. As a result, they form a cutting edge resembling a wave. The most difficult type of wiring.
During the bending of the deformation, not the entire tooth is exposed, but only a part of it. Often the deviation occurs at 2/3 of the total height.
The average divorce value is limited to values from 0.3 to 0.7 mm. This applies to standard wood band saw models.
The right choice of the type of grinding wheel is important. It must match the grade of steel of which the band saw is made. For tool steel structures, corundum circles are used. If it is required to improve the cutting properties of bimetallic models, elbor or diamond wheels should be used.
Depending on the technical capabilities, it is possible to carry out full-profile processing or each cutting part separately. In the first case, you need an elbor circle, the end of which has the same shape as that of a saw. For the second option, the processing of each tooth is performed.
First you need a machine. It should have the function of regulating the speed of rotation of the disk and changing its location relative to the tool. After fixing the canvas in a special frame, you should perform such actions according to the following instructions.
- Emery heads down. At this time, the front face with the cutting edge is processed.
- The formation of a slice in the valley. This is done without tearing off the canvas. This stage allows you to remove microcracks and bumps. An important point is the reduction of surface tension, which is the main cause of deformation of the canvas.
- The circle moves up. The back part of the tooth and its cutting edge are machined.
By the same method, all other teeth are updated. It is important that the entry and exit angles are the same everywhere. Otherwise, with differences in geometry in one of the parts, performance deteriorates.
After the completion of the treatment, it is recommended to fine-tune. treat the surface with fine-grained emery. The geometry of the web should not change during this process.
With prolonged contact of the circle with the metal, the temperature on the surface of the latter can sharply increase. To eliminate this effect, special coolants are used that come directly from the machine. The feed is made continuously to avoid the formation of a glow zone. In this part, the mechanical strength will be deteriorated.
To avoid chipping, the presence of metal components must be checked before processing the wood. Particular attention is also paid to fixing and uniformly feeding the workpiece for sawing.
In the video you can find recommendations for amateur sharpening: