How to correctly and at what angle to sharpen a circular saw blade
Circular saw blades differ in the number of teeth and configuration. There are blades:
- monolithic or solid blades;
- With a hard dusting in the working area;
- With soldered carbide plates;
- without teeth, such as a continuous rim;
- with wide and thin protrusions;
- With negative and positive front angles;
- universal blades.
This variety is confusing when choosing the right saw blade. Let’s get to the bottom of this.
Number of teeth
Blades with fewer teeth make rough cuts. The advantage of fewer teeth is higher cutting speeds. For construction work, a 24-tooth disc with a diameter of 180 mm is sufficient. A thin slotted blade is good for cutting hardwood and trimming where a clean edge is required. For a circular saw 180-190 mm, a blade with 40 teeth or more makes a clean cut.
Efficiency of sawdust removal
Tooth position with teeth pointing down toward the wood surface and forming a positive angle, results in fast but coarse sawing. There is a large gap and depression between them, which contributes to better clearing of sawdust. Pictured Positive tooth angle. Negative tooth angle cuts less aggressively, doesn’t remove less waste as quickly, but the cut is smoother. The angle is marked on the blade: 5 neg. 5 degrees negative, 10 pos. positive 10 degrees.
Types of teeth by shape and sharpening angle
This distinguishing factor of a saw blade is the angle of the tooth across or perpendicular to the rotation of the blade. The higher the bevel angle, the cleaner and smoother the cut. Some blades have very large bevel angles for cutting composite material such as plastics or others that are prone to tearing/chipping when the tooth exits. Bevels can be flat (no angle), alternating, highly alternating or other configurations, which we discuss below.
This is the width of the tooth at its widest point and therefore the width of the cut. If it is greater than the tooth thickness, then the setting is normal. Otherwise, the branching is performed by specialists, using the following methods:
- 1 through 2 teeth are set in the opposite direction;
- each tooth is alternately set to the same distance from the plane of the blade;
- also, but distances with different deviations within the range of 0,3. 0,7 mm.
The thin kerf produces less cutting resistance and is therefore better suited for low-powered saws. Initially thin discs vibrate or wobble, causing problems when cutting wood. New blade technology with a vibration-reducing design has made some improvements in the thin-cutting blade segment that has increased demand for users of cordless circular saws.
How to know when it’s time to sharpen a blade
Cutting blades for wood and wood-based materials abrasion and wear over time, contributing to reduced performance. To restore the cutting tool efficiency, it is necessary to sharpen the teeth. The following factors will tell you when you need to sharpen the tines on your disc:
- To cut wood, it is necessary to apply pressure to the material to be sawn
- Smoke is seen rising from under the blade guard
- The guard is heating up excessively
- Signs of burning smell. This means that the teeth are not sawing the wood, but cutting it
Working with a defective power tool tip results in decreased productivity and increases the likelihood of premature failure of the power tool and the tip itself. A drop in performance puts more strain on the electric motor which eventually overheats and fails.
When to sharpen a circular saw
There are absolutely certain signs that tell us about the condition of the tool. Sharpening of saws is necessary when the following is evident:
- Smoke and a peculiar smell of burned wood is produced while working, and the blade guard that covers the saw’s teeth gets hot quickly.
- When moving the tool along the workpiece, you need to apply considerable force, as if pushing the saw forward.
- After sawing the material and visual inspection of the saw’s edge you can see black carbon build-up or many chips, fiber burrs, dented areas.
- When carefully examining the saw teeth with a magnifying glass it is possible to see that the cutting parts have rounded edges instead of sharp ones.
All these facts should be stopped immediately, otherwise there is a great risk of material deterioration and circular saw wear to the state where sharpening will be of no use for it anymore.
What the tool is for
There are several types as well as forms of hacksaws. And the tool is intended both for metal and woodworking.
To work with metal surfaces the tool is divided into:
The first are now used very rarely, while the second is present in almost every home. A single-handled saw has a solid metal blade that has a series of teeth. The blade has a high stiffness, it has good elasticity and strength. The tool consists of two parts: a metal blade and a convenient, most often wooden (or plastic) handle. It is necessary to hold such a handle at work with one hand, and to move a saw forward and backward on a surface. Moving, the teeth of the blade enter into the surface deeper and deeper, deepening at a time by a couple of millimeters.
A wood hacksaw is used for sawing different surfaces:
- Wood that has different shapes;
- for pruning branches;
- when carrying out repair work;
- When working in the carpentry workshop;
- when working with chipboard.
In addition, a piranha type wood hacksaw may be useful for working on laminate.
The size of the teeth is measured based on the number of cutters per inch. The more teeth per inch, the better the cut.
When choosing a hacksaw it is necessary to take into account that the number of teeth on the file blade has its own marking and is denoted by the three letters “TPI”. You should also know that if you need to cope with the work faster or a rough cut is necessary, then you can use a hacksaw with a long blade that has a large tooth. But for a qualitative cut, when it is necessary to perform the work accurately, it is necessary to use a hacksaw with fine teeth.
The saw, which has large teeth, and the interdental step is about four to eight millimeters, is used for sawing thick bars and small logs. And hacksaws with a tooth distance of three to three and a half millimeters will cope with the sawing of medium-sized boards.
To work with small pieces of wood it is necessary to use a fine hacksaw, which has a cutting gap of two to two and a half millimeters.
If you are holding a hacksaw, which has straight teeth, then the tool can be used to cut wood across. If it is necessary to saw a wooden bar lengthwise, then it is advisable to use a hacksaw with teeth that are slightly inclined forward.
In this photo, you can see how the teeth are arranged on a wood hacksaw for cross-cutting and for longitudinal cutting.
According to the type of teeth and the density of the metal blade, files have different names:
- wood saw bahco;
- Irwin wood hacksaw;
- Zubr wood hacksaw;
- Stanley wood hacksaw;
- wood saw Gros;
- wood sander Sweden.
Therefore, in the arsenal of tools, it is necessary to have several hacksaws designed for different types of work, both on wood and on metal.
How to sharpen: basic methods
There are two methods of sharpening circular saws available. manually and with a machine. To sharpen the disk correctly at home, you need to take into account some nuances.
Special machines for sharpening saw edges are rarely used in the home, because their cost is high. Therefore, in the absence of such a device, you can cope with sharpening with improvised devices, such as an angle grinder. Do not hold the circular saw lightly in your hands, without securing it in any way. Otherwise, it will not be possible to achieve a sufficient angle of cut for further work on the material.
To reliably fix the wheel in the correct position, use a flat stand.
- the surface of the stand coincides with the level of the axis of the sharpening disk;
- On it the toothed wheel is placed in such a way that the sharpening plane is perpendicular to the saw blade;
- The construction of the device is supplemented with a swivel joint.
The stand helps to comfortably position the saw blade for cutting relative to the abrasive material. Before starting work, a clear marking is carried out. Use a colored marker for this. With it, lines are drawn which will make it possible to sharpen the element at the right angle. A vice helps to firmly fix the blade on the surface.
With the help of a machine tool
When the craftsman has access to a special sharpening machine, the processing of elements is fast and efficient. The machine is small, so even a beginner will be comfortable working with it. No problems even in domestic applications.
When buying such a device, look at the abrasive wheel. For its selection, certain nuances are taken into account:
- It is best to buy a wheel made of diamond-coated elbor or green silicon carbide;
- If a carbide disc is being sharpened, problems can arise even when the machine is used.
The process of using a sharpening machine is very simple. The operator must conveniently position the disk on the device and clamp it using a special clamp. It is advisable to mark the first tooth with a marker before starting work. This will help to avoid confusion during sharpening, and not to check the teeth, which have already been treated. To select the angle of sharpening on the device there is a special meter. Set the desired angle on it, after which the device will perform the task itself.
Circular saw. a useful tool, without which you can not do without in construction. It helps to make cuts in surfaces and change their shape and size. To sharpen discs use special machines or improvised materials. To do the work with your own hands is not so difficult, you need to adhere to the recommendations listed and do not be afraid.
The basic angles are those defined by the shape of the teeth. It is front and back, as well as a bevel on the front and back planes.
For a longitudinal sawing front angle, it is recommended to set the degree between 15 and 25. For transverse. 5 to 10 degrees. For universal saws of both sections, it is more correct to choose an average value of 15 degrees.
The size of the angle is also determined by the hardness of the cut material.
You can buy a machine for sharpening carbide circular saws at a cost starting from 15 000. You can also splurge on more expensive devices. For example, the PP-480Z will cost its owner 280,000. vary and depend on the purpose of the device, its functions, power and performance. For a small workshop or home use, you can buy a machine for sharpening circular saws JMY8-70. Its
Methods of grinding circular saws
Any kind of sharpening machine can be used for sharpening a new cutting edge. It is important to initially choose the right emery wheel and use it to sharpen the edge. For this you need to use corundum or diamond models.
The best option is to use special equipment designed for this work. But because of its high cost, it is impractical in many cases. An alternative method is to use a sharpening machine with the ability to change the angle of the corundum disc.
On no account sharpening by hand by yourself. Firstly. it will take a very long time. Secondly. the result will not meet the standards. If there is no possibility to sharpen the wood saw blade yourself, it is recommended to use the services of specialized companies.
Professional sharpening of circular saws with their own hands is performed according to the following rules:
- The main deformation occurs on the top edge of the tooth. Rounding of the edges should be between 0.1 and 0.3 mm. This is where the machining should begin;
- The sharpening is performed along the leading and trailing edges. This will ensure that it is possible to repeat the procedure up to 25 times;
- the value of removal must not exceed the value of 0,05-0,15 mm;
- The machining level of the leading and trailing edges must be identical.
After the wood discs have been sharpened, it is advisable to finish them off with a fine grit emery cloth. It can be done manually or with a special machine.
Experts advise using special corundum discs, the end surface of which has a specially shaped groove. It will make the procedure easier to perform.
The blades for circular saw blades can be sharpened with your own hands only if you have special tools. There is also a machine that allows you to automate the process, to make it more efficient.
To perform the work on sharpening the disk with your own hands, you can use the following tools:
It is also possible to use a sharpening machine for circular saws that does not need the tools mentioned above.
When to rebuild circular saws?
A rather important question can be called determining when to sharpen circular saws. Severe wear and tear can make such work impossible. You can distinguish three clear signals that determine the need to sharpen the circular saw blade:
- Smoke is produced, the guard is heated. The cutting attachment is usually equipped with a special guard, which may become hot if the blade becomes blunt. It must also be noted that in special cases smoke may be produced due to overheating of the cutting zone.
- Also with mechanical feed, when the pressure is adjusted by hand, great force must be applied to obtain the desired result.
- When machining wood or other material, there are traces of soot and a corresponding smell in the cutting zone.
In the above situations it is recommended that the circular saw blade be sharpened.