How to sharpen: basic methods
There are two available methods of sharpening circular saws. manual and with a machine. To correctly sharpen the disk at home, you need to take into account some nuances.
Special-purpose machines for sharpening saw edges are seldom used in the home, because they are very expensive. Therefore, in the absence of such a device, you can handle sharpening improvised devices, such as angle grinder. It is forbidden to hold the circular saw blade without securing it in any way. Otherwise it would not be possible to achieve a cutting angle adequate for the material to be sharpened.
To reliably fix the wheel in the correct position, use a flat stand.
- The surface of the trivet coincides with the axis level of the sharpening wheel;
- on it the toothed wheel is placed in such a way, that the plane of sharpening is perpendicular to the saw blade
- the device is equipped with a swivel hinge.
The stand will help to comfortably position the saw blade for machining relative to the abrasive material. Exactly mark out the following before you start work. To do this, use a colored marker. It is used to draw lines, which will allow you to sharpen the element at the desired angle. Vise will help to securely fix blade on the surface.
The first version of making the simplest sharpening equipment has the following view:
- The workbench is equipped with an emery machine with a diamond-coated wheel on its shaft
- Fixed base is made of particleboard. This base also acts as a guide on which the moving frame will move
- In the next step, a movable frame is made of chipboard or plywood, the walls of which should point downward, and act as a movement mechanism
- On the outer side of the movable frame, a disk retainer of the appropriate diameter is placed, and a slot is made
- The result is a finished sharpening machine for circular saw blades
The manufacture of such a device requires a minimum of time and cost, and the efficiency of its use is 100%. See details at
Quality control of sharpening
On the ground teeth must be no cracks, chips, visible risks from the grinding wheel. The radius of curvature of the cutting edge should not be more than 0,015 mm. Visually, this can be identified as a lack of glare on the cutting edge.
GOST 9769-79 specifies certain tolerance values of sharpening parameters. End run-out of tooth tips should not be more than 0,2 mm (for saws up to 400 mm diameter), radial run-out 0,15 mm. Run-out is checked with an ordinary pointer indicator.
The deviation of the grinding angles must not exceed:
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Solid carbide tooth geometry
The teeth of both solid high-speed steel saws and those with tungsten carbide tips have a specific shape. Some have an isosceles triangle shape, others have a sickle shape, and some are even designed as a trapezium. Such tooth shape meets several requirements.
Firstly, each shape has several surfaces forming cutting edges. Secondly, the type depends on the purpose of the tool: the fine flat tooth is suitable for cutting thin sheet materials, and the trapezoid is suitable for working with hardwood. Thirdly, the shape determines the duration of use: trapezoidal type lasts longer than straight or sickle-shaped type.
Discs are usually used for domestic applications:
- Straight type teeth. for rough cutting of material. The main advantage is that the material is cut quickly.
- Sloped and sickle-shaped teeth. designed for thin materials.
- Teeth with bevel, used for finish cutting of material.
- Trapezoidal shape. for continuous work with materials of different density.
- Tapered teeth are suitable for finishing work with materials that have a smooth, glossy coating.
As can be seen, it is very difficult to sharpen such discs by oneself without knowledge of sharpening technology. The most difficult thing is to maintain the “right” angle so that both the geometry of the cutting edge and the shape of the tooth itself are reached on all teeth.
Incorrectly sharpened circular saw blade at best results in an uneven cut with crooked edges. And in the worst case you will have to repair the electric saw itself because of the appeared run-out.
Carbide inserts requiring sharpening and a new saw
Cutting tooth types
Tooth types There are four planes on the tooth surface. one at the front, one at the back, and two at the sides.
When they intersect each other, they create a single cutting edge that is used to cut surfaces.
- Straight tooth. Most often used only for making a short rip-cut. Quality and precision are of little importance in this application.
- Oblique tooth. Back plane of such part is slanted to the right or to the left. On saws, these teeth often alternate, which is why they are called “alternately slanted”. These are the teeth most commonly used in a tool. angles vary in size depending on the surface finish. wood, chipboard, plastic. They are used for longitudinal and transverse movements. A large inclination angle on tools is used when cutting double sided laminated boards. This helps to avoid chipping of the material. The larger the beveled angle, the easier it is for the saw to pass over the surface. But this greatly increases the likelihood of tooth breakage. On some products, the teeth are slanted not only at the back, but also at the front.
- Trapezoid tooth. The main advantage of this type is that the edge blunts slowly. But they are seldom used alone; they are usually used in tandem with the straight teeth. During the operation of the device, the trapezoidal teeth are located above the straight ones, so they take on the main (rough) work of sawing. Straight teeth perform finishing work. This saw blade design is used for cutting plastic, chipboard and fibreboard.
- Conical tooth. This type of tooth is considered supplementary, because it only helps to cut the lower part of the material (most often laminate). This design allows to protect the surface from chips and cracks. Tapered tines usually have a straight leading edge, but this can also be concave. This type is used for finishing cut.
Important! Each type of tooth needs to be thoroughly sharpened. They cannot be turned at the same angle.
How a circular saw blade works
All electric woodworking machines work on the same principle. Wood disc for circular saw is fixed on the motor axle that gives it powerful rotation. The tools are divided into several groups:
The only difference between these systems is their design. The rotation of the disc in a manual machine is done mechanically. Electric devices imply the presence of an electric motor. All systems are equipped with a saw blade platform for depth of cut adjustment and for setting the desired angle of inclination.
The industry produces the original miniature saws that are equipped with a battery. Such a wood slicer, whose disc mechanism is not very powerful, can operate in areas where there is no electricity supply.
Signs that the saw is blunt
Given the fact that the hacksaw in the process of use is subjected to constant stress, its teeth dull over time. The degree of efficiency of blunt tools is noticeably less. In addition, you should not use such a hacksaw for the following reasons:
- loss of productivity. When sawing wood, more effort and time is consumed by the craftsman;
- the accuracy of the work is impaired. It is practically impossible to cut wood evenly and accurately with blunt teeth. It is especially difficult to work with such a saw in the garden;
- the dangers of using a hacksaw. In the process of operation the tool will stick, get out of the sawing line, jam, which increases the probability of injury.
It is necessary to sharpen the hacksaw urgently, if there appeared a characteristic blunt sound, the tips of the teeth are rounded, it is not possible to make a cut of wood. If the tool has become difficult to work with, it is better to stop sawing, inspect it and proceed to address the issue of sharpening.
Classification of circular saws
Sharpening circular saw blades correctly in order to get a clean cut. Tools are divided into several groups:
Saw teeth have to be set after sharpening. If you work with blunt tools, the drive is more stressed, the quality of the cut is impaired.
If you work with hard wood, the disk must have special grooves in its grooves. Their absence leads to overheating of the blade, the metal will begin to expand, the deformation of the cutting tool will occur. Dangerous vibrations appear and cutting quality suffers.
Types of cutting surfaces
In order to increase efficiency, engineers have developed several types of teeth, differing in their shape and sharpening angle:
Straight. Used for making quick cuts of low quality. Cannot be used for cutting hardwood and very thin materials.
- Beveled shape. These teeth can easily cut composite materials. Cutting double-sided laminated chipboard without splitting. Hard workpieces can be easily cut with teeth that have a beveled back surface. However, they blunt too quickly. To avoid this, the inclination of the teeth alternates.
- Trapezoidal. The main advantage of this method is considered to be the slow blunting. It works in combination with straight teeth. The trapezium is located above the base element. It does “roughing” work, making it easier to machine a straight edge.
- Conical. Blades with this tooth shape are considered auxiliary. They are designed to make preliminary cuts, prevent splintering. These blades are not tools in their own right.
On some blades, the front tooth plane is concave. Cross-cutting cuts are made with this tool.
Proper sharpening angle
Circular saws have teeth with two angles:
Making Saw Blade Sharpener using a Hand Grinder || Angle Grinder Hack
The value of the angle depends on the type of material being processed, the purpose of the operating equipment and the cutting direction. For example, to obtain a longitudinal cut, front angles are made between 15 and 25 degrees. For cross-cutting sawing the front angle will be in the range of 5-10 degrees. A 15-degree angle is good for any material to be cut in the right direction. the angle depends on the hardness of the workpiece. The harder the material, the sharper the teeth need to be ground.
Sharpening with a machine tool
If it is possible to purchase a special machine, then the process in question can be carried out with maximum efficiency. Such a device has a compact size, it can be used at home.
Special attention is paid to the choice of grinding wheel. In this case, note the nuances below:
- It is difficult to sharpen a carbide disc.
- When choosing one should pay attention to grinding wheels made of elbor, with diamond chips or with green silicon carbide.
The sharpening process is very simple when using professional equipment. The disk is fastened by means of a special locking device. It is designed with the design features of the wheel in mind. Let’s pay special attention to the fact that with the use of special machines it is very easy to sharpen circular saws with observance of the necessary indicators. Inaccuracy is minimal. This is due to the fact that the design has a special angle meter. In order not to make a mistake at the time of the work which teeth have already been treated, it is necessary to mark the starting point with a marker.
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Carbide-tipped circular saws can lose their initial performance over time. But this does not mean that one should buy a new cutting tool. In most cases sharpening can be done at home using any suitable machine.
How to sharpen a circular saw with your own hands
Sharpening your saw at home is entirely possible by yourself. For these purposes there is no need to visit a workshop to use a specialized sharpening machine or to purchase one. It is quite expensive, and for sharpening it is used rarely, unless of course you plan to use it for large production purposes.
But holding circular saw blades in hands while sharpening the teeth with a grinding wheel is not the best solution. Circular disk is not a drill, it is much more dimensional. No hardness of hands and excellent eyesight will allow, to make sharpening so that cutting elements would be sharp enough and suitable for effective use. This requires the simplest type of locking device.
To hold the toothed circular wheel in position relative to the plane of the sharpening tool, you can use the most ordinary flat stand.
Its surface position must be in line with the level of the axes on the back disc. Place the toothed wheel on the stand so that the plane of the tooth to be sharpened is perpendicular to the blade of the saw blade. To sharpen beveled teeth on their front and back surfaces, it is necessary to provide movable joints in this fixture.
But in such cases it is difficult to maintain the same value of front and back angle. To avoid this problem, the center of the saw has to be fixed firmly in position with respect to the sharpening blade. This is done by means of a notch for the mandrel, which is mounted on a stand with the saw blades to be sharpened on it, or by placing a special stop on the stand, which fixes the saw blade at the required angle to the abrasive stone.
If you adhere to all the requirements that apply to sharpening a carbide circular saw, then this tool will work as efficiently as possible for a long period of time.