Band saws are used as cutting tools in band saws. They are a metal tape with applied teeth. They have a lot of advantages.
When compared with circular tools, the saw cut width of a band saw is much smaller, which, in turn, has a positive effect on sawing expensive wood or cutting an elite brand of metal.
The band saw has a good cutting speed, while providing excellent quality cut edges. With its help, you can cut absolutely any workpiece.
In order for the saw to possess the above characteristics, it is necessary to timely and efficiently carry out its wiring and sharpening.
In branded centers the cost of sharpening saws is low, but the quality of work is not always happy. Therefore, we will try to help you in this matter if you decide to sharpen and distribute the band saw yourself.
Band Saw Composition
Saws for cutting wood are stamped from tool steel, which has a hardness of 45 HRC.
For cutting metal, domestic manufacturers use steel grade 9HF, B2F, foreign use. C 75 and others. Saw teeth using the above steel, due to quenching by high-frequency currents, acquire the highest hardness. Quite often, when working with metal, a tape bimetallic tool is used.
Bimetal sheet made of so-called spring steel, and the tape with teeth is made of a metal alloy with high impurities of cobalt and tungsten. This high-speed alloy is connected to the base of the saw using an electron beam.
Teeth and sharpening angles
Band saws have different tooth geometry: it is affected by the properties and type of material being sawn. So, for working with wood, a joiner’s saw is used, for cutting logs, dividing. Each species, respectively, has its own tooth geometry.
For band saws designed to work with wood, the sharpening angle is determined by the manufacturer, but the following is characteristic. the harder the material, the rake angle should be smaller.
For saws with constant tooth pitch when working with metal two tooth shapes are characteristic. “positive rake angle” and standard. Standard teeth are used for working with thin-walled materials, and teeth with a positive rake angle are used for cutting thick-walled metal.
For workpieces with small thick walls (pipes, sheet metal), saws with a small tooth pitch are used. otherwise there is a risk of breaking or damaging the tooth. With thick-walled workpieces, it is best to work with a tool with a small number of teeth per inch.
To remove the effect of vibrations, a number of saws are made with a variable tooth pitch.
Band saw tooth alignment
When working with a tool, the quality of the cutting edge of the teeth inevitably decreases. Therefore, the correct sharpening and wiring of band saws is an integral part of the cutting workflow.
Remember, divorce should be done before sharpening, not after.
Wiring is the process of bending the teeth to the sides to reduce friction and clamp the blade. There are three types of wiring:
- cleaning. it is necessary to leave every third tooth in its original form. It is used in tools for cutting especially hard alloys and materials;
- classic. the teeth need to be bent left and right strictly alternately;
- wavy. each tooth bends by a certain value, as a result, a wave is formed. This type of wiring is the most difficult.
It must be remembered that during a divorce, two-thirds or a third of the top of the tooth is bent, not the entire tooth.
Video: How to Sharpen a Band Saw on a Machine Tool Video
Recommended values for divorce by manufacturers are approximately 0.3 to 0.7 millimeters. Wiring is carried out using adjustable tools.
The right tool sharpening process
It has been proven in practice that over 80 percent of tool breakdowns occur due to improper sharpening of the teeth of band saws. The need for sharpening is determined by eye. as the walls drank or the kind of teeth themselves.
Sharpening wheels for band saws are selected depending on the hardness of the tooth. To sharpen a tool made of tool steel, a corundum circle is used. Bimetal saws are sharpened with diamond or borazon abrasive. The shape of the circle for the tool should be determined based on the parameters of the saws. It can be cup, profile, dish-shaped and flat.
Before using the saw in work, it is necessary to hold it for about eleven hours in a suspended, inverted state.
Tool sharpening requirements do it yourself:
- it is necessary to evenly remove metal along the tooth profile;
- exclude excessive pressure of the circle (this can lead to tooth damage);
- mandatory use of coolant;
- ensure the integrity of the tooth geometry;
- preventing burrs.
The standard instruction states that the sharpening of the tool should be carried out either on the front edge of the tooth, or on the back and front. In practice, many craftsmen, and professionals, sharpen exclusively on the back face. so, in their opinion, it is more convenient.
This tool is enough unpretentious in terms of sharpening, despite the mass of requirements and rules. Sharpening can be done either manually or using a special grinding device; to use circles, different in material and shape, for processing, etc.
Before sharpening a tool, you need to familiarize yourself with the main types of implementation of this operation. Also on the Internet you can watch the video.
Types of sharpening
- Full profile view. It is the most high-quality look, it is made automatically on special. the machine tool. A finely selected elbor circle passes in one motion the entire interdental cavity along with the faces of adjacent teeth. In this case, the formation of angular shapes at the base of the teeth is excluded. The only drawback of this type of sharpening is the need to carry a certain number of different circles for saws with different profiles.
- Sharpening the edges of the cutting part. It can be made manually or on a professional machine. If you want to grind with a machine, you need to choose the right circle. in most cases, these are flat samples. Based on practice, contact the special. sharpening equipment is necessary only in cases where the volume of work is very large. With a small amount of work, it is better to sharpen manually. on a conventional machine tool or using an engraver. When performing work on sharpening, for safety reasons, it is necessary to use safety glasses or a mask.
If you don’t have an engraver or a machine, then you can sharpen an instrument with the old-fashioned conventional method. using a file. With diligent and regular execution of the operation, the skill of manual high-quality sharpening will very quickly appear.
- When sharpening the tool on the machine, before starting sharpening, you need to make sure that the grinding wheel is correctly positioned relative to the saw.
- It is necessary to remove such a layer of metal from the sinuses in order to reliably eliminate all microcracks.
- If the saw was operated without quality service longer than the allotted by the manufacturer, the layer of metal removed in one sharpening should be increased.
- As a reference, always use a new tool to check the grinding results.
- The shape of the saw blade is a parameter that has been verified and developed over the years. Therefore, it is not worthwhile to derive your parameters and hopes for a good quality of work.
- Subject to the operating rules and requirements of the manufacturer, the band saw will serve you until its width is reduced to 65 percent of the original base. The width decreases during the re-sharpening of the teeth.
- It is imperative to remove burrs during the sharpening process of the tool, otherwise this will lead to the formation of microcracks during the sawing process.
- After finishing work, the tool must be immediately cleaned of sawdust and resin, and before sharpening, the saw must be carefully inspected. Otherwise, clog the grinding wheel with chips, which will lead to improper sharpening of the band saw.
Errors during sharpening
Mistake number 1. Burnt cavities of the teeth of the saw.
The reason lies in the excessive pressure of the wheel for sharpening the saw. The result will be a quick dulling of the tool.
Error 2. Imperfect geometry of the sinuses and the wrong angle.
A number of conditions can lead to this error:
- wear of the clown of the sharpening device;
- error during calibration of the inclined angle;
- improperly selected grinding wheel profile.
Now you know how necessary sharpen the band saw correctly, and what fixtures and tools may be required for this. You can also additionally find a video of this process on the Internet.