Construction of a private house will be difficult and long without the use of modern tools. The most popular among builders was a circular saw, surpassing other types of saws on wood for its precision and clean cut.
Scheme of the machine for sharpening circular saws and knives.
Since this power tool is a device that is actively used and therefore quickly wears out, sharpening circular saws with their hands becomes very important.
Tools for sharpening circular saws
To properly sharpen a circular saw, you need tools such as:
- mounting vice;
- wooden bar;
- color marker.
What signs suggest that you need to sharpen a saw?
Figure 1. Saw tooth pattern. Planes: a- front, b - back, in - two side. Edges for cutting metal: 1 - main, 2, 3 - additional.
Sharpen the circular saw is necessary only when the need arises. And that such a moment has come, will signal 2 clear signs. In particular, the urgent sharpening of circular saws on wood is required if:
- On the protective covers saws in the area of the electric motor there is a strong heat. Sometimes this temperature increase is accompanied by the appearance of smoke from under the casing.
- To get good results, the circular saw has to be pressed harder than before.
- As a result of the work of blunted teeth of saws on the tree on the saw blades in the wood, the appearance of dark marks, traces of soot are recorded. Perhaps the spread of the characteristic smell of burnt wood.
Types of cutting teeth
To better understand how to properly sharpen circular saws, you should understand the features and the structure of that part of the disk, which produces a cut of wood. This main part is the cutting teeth.
All teeth are made from hard metal. Each of them (Fig. 1) has 4 working flat surfaces: front (a), rear (b), and also two side planes (c). They play a supporting role. One main (1) and two additional (2 and 3) edges for cutting material are formed on the intersection lines of the indicated working planes.
In accordance with the configuration, all cutting teeth of circular saws are divided into the following types:
Figure 2. Sharpening angle chart.
- Straight teeth. Most often used for accelerated longitudinal sawing. Not designed for perfect cut quality.
- Slanted (oblique) teeth. They are characterized by the presence of an angular cut on the back flat surface of the tooth on the left or right side. Sometimes the teeth on the disk with different sides of the bevel alternate and then they are called alternately skewed. Such elements are used for cutting not only wood, but also chipboard, various plastics. With a large bevel angle, high-quality sawing without chipping on the edges of the cut is ensured.
- Trapezoid teeth. In the cross section of the cutting surface have the form of a trapezoid. Thanks to this configuration, do not get blunt for long. Often on the disk alternate with straight teeth. In this case, the trapezoidal elements perform rough sawing, while the straight ones produce finishing.
- Conical teeth Have a conical shape. Usually perform auxiliary functions of pre-cuts the laminate. Such teeth handle the specified flooring to prevent chipping when cutting laminate panels with a main saw.
Principles and angles of sharpening circular saws
Figure 3. The pattern of grinding metal on the saw teeth.
The working parts of the circular saws are sharpened over the 4 main grinding angles. These angles (fig.2), as well as the shape of the cutting tooth, are the main technical parameters of the disk.
So, each tooth of a circular is characterized by front (γ), rear (α) angles, and also cut angles of the front and rear surfaces (ε1 and ε2). The magnitude of these angles depends on the purpose of the sawing device, the material being cut and the direction of sawing.
In particular, the slit saw is sharpened at a relatively large rake angle (from 15 ° to 25 °). The rate of sharpening the front angle for cross-cutting is in the range from 5 ° to 10 °. But the universal version, which performs material processing in all directions, is traditionally sharpened at an angle of 15 °.
In addition, the angles of the cut objects affect the angles indicated. Their values are strictly dependent: the harder the material of which this or that blank is made for sawing, the less pointed the cutting teeth must be.
The main principle of sharpening the teeth of carbide saws is based on the fact that during long-term operation, the most significant wear occurs on the upper cutting edge. As a result of intensive use, its line may round to 0.3 mm or more. As for the planes of the tooth, then most of all wear is fixed on the front surface.
Proper sharpening of the cutting elements should ensure that the edges are such that their radius of rounding does not exceed 0.2 mm. For this, it is recommended to grind metal in parallel on the front and rear planes of the tooth (Fig. 3). This method can be considered optimal. You can sharpen only the front plane, but in this case it will take more time for such an operation, besides, the tooth itself will quickly sink because of the need to remove more metal from the front surface.
0.05-0.15 mm is considered to be the standard layer of the metal being grinded.Back to table of contents
Sharpening saw with your hands at home
Figure 4. In order for sharpening to be correct and fast, the disc should be well fixed.
You can sharpen the saw at home. To do this, it is not necessary to have in your own workshop a specialized grinding machine that costs a lot of money and is used rarely for its intended purpose.
But just holding a disk and sharpening the teeth on the grinding wheel is irrational. No hardness of the hand and excellent eye will be enough to make the cutting element perfectly sharp and suitable for effective work. To this end, care should be taken to manufacture the simplest fixing device (Fig. 4).
To hold the toothed circle of the circular in a strictly defined position relative to the grinding disk will help, for example, the most ordinary flat stand.
Its surface should coincide with the level of the axis of the grinding wheel. The gear wheel itself is placed on the stand in such a way that the sharpened planes of the teeth are perpendicular to the saw blade. For honing beveled teeth on the front and rear surfaces of the specified device do with a movable hinge.
However, in this case it is difficult to withstand the same amount of front and rear grinding angles. To eliminate this problem, the center of the blade circle is rigidly fixed in the desired position relative to the abrasive disk. This is done either by using a slot for a mandrel, which is mounted on a stand for placing a sharpened saw on it, or by installing special stops on a stand that fix the saw blade at the required angle to the grinding wheel.
If you fulfill all the requirements for sharpening carbide circular saws, they will serve a person for a long time and efficiently.