How to properly sharpen a circular saw

How to correctly and at what angle to sharpen a circular saw blade

Saw blades differ in the number of teeth and configuration. There are blades:

  • monolithic or solid;
  • with a hard dusting in the working area;
  • with the soldered carbide plates;
  • without teeth, such as a continuous rim;
  • with wide and thin protrusions;
  • with negative and positive front angles;
  • universal circular saw blades.

This variety is confusing when choosing the right blade. We are going to deal with.

Number of teeth

Discs with fewer teeth make a coarse cut. The advantage of fewer numbers is higher cutting speeds. For construction work, a 24-tooth blade with 180 mm diameter is sufficient. Thin slotted blade is good for cutting hardwoods and trimming where a clean edge is required. For a circular saw 180-190mm, a blade with 40 teeth or more will provide a clean cut.

Effective sawdust removal

Tooth position with the tooth pointing down toward the wood surface and forming a positive angle, results in a fast but coarse cut. There is a large gap and recess between them, allowing for better clearing of sawdust. In the photo Positive tooth angle. Negative tooth angle cuts less aggressively, removes less waste less quickly, but the cut is smoother. On a disc, the angle is marked: 5 neg. 5 degrees negative, 10 pos. positive 10 degrees.

Types of teeth by shape and sharpening angle

This distinguishing factor of a circular 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 flatter the cut. Some blades have very large bevel angles for cutting composite material such as plastic or others that are prone to tearing/chipping when the tooth comes out. bevels can be flat (no angle), alternating, strongly alternating or in other configurations, which are discussed below.

Setting

This is the width of the tooth at its widest point and therefore the width of the cut. If it is larger than the tooth thickness, then the setting is normal. Otherwise, the setting is carried out 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 disk;
  • also, but distances with different deviations within 0.3- 0.7 mm.

Thin kerf creates less resistance to cutting 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, increasing demand for users of cordless circular saws.

Rules

As in the case of sharpening chainsaw chains, self-sharpening requires adherence to certain tips.

  • Watch closely for even metal removal along the tooth profile of the saw blade;
  • Never press the saw blade firmly against the grinding wheel. If the circular saw blade sharpening machine is in close contact with the wheel to be sharpened, it will overheat and cause the material to become warped;
  • Check that the sharpening height and profile are maintained after machining is complete;
  • When sharpening discs, use coolant. This is also recommended for chainsaw chain sharpeners;
  • Beware of burr formation when sharpening the circular saw blade;
  • When sharpening edges, remember the following general rule of thumb. Only the front or front and back side of the tooth should be sharpened. Although in practice, many craftsmen with their own hands prefer to sharpen the back side of the saw wheels, considering this method more comfortable;
  • Pobedite products can be sharpened with a diamond sharpening tool. Only tools like these can really bring back the cutting performance of the tool. You can use an ordinary razor grinder, but it will not have the desired effect.
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Main sharpening methods

Circular saw sharpening is made with a fine-grained abrasive wheel, along the planes that form the main working angle of the cutting:

If combined edge restoration is used, the nose corner is sharpened first. In this case the blade can be resharpened 25 to 30 times in the process.

Removing a thin layer from the back of the tooth leads to a quicker reduction in blade diameter and wear on the saw.

At home, you can do circular saw sharpening with your own hands. An arbor is sufficient to sharpen a tipped tool. In the case of a large volume of work, a device is made from an angle grinder or milling machine.

Sharpening circular saw blades with tungsten carbide inserts requires more effort and is done on special machines and with a wheel sharpening tool.

Manual way

Manual grinding with flat grinding disc.

  • Clamp the angle grinder stationary with the wheel.
  • Make a support for the disk. Its plane must be flush with the axis of the grinding wheel.
  • Bring the tooth side until it is in contact over the entire area of the plane to be sharpened.
  • Position 2 clips on the table support on the right and left. They help you align the plane to be sharpened quickly, without adjusting each tooth.
  • Position the taper on the left clamp and turn until it stops on the right clamp after each one step of the circular saw blade rotation.

It is necessary to remove 0,12-0,15 mm from the cutting plate during one sharpening.

To sharpen the circular saw on the back plane, it is necessary to turn it and change the position of locks.

angle grinder for circular saw sharpening

Use of machines

In mass production, it is necessary to sharpen circular saw blades regularly. The shop has special machines with wheels for this purpose. Each has a fixture that aligns the tooth relative to the wheel at the desired angle and allows the tool to move progressively.

In special automatic equipment the blade performs only a rotary movement at a given pitch size. The rotating wheel drives up after each revolution and grinds the next plane.

It is possible to sharpen a carbide disc by hand, using a donkey, but the effect will be weak. Without special devices it is impossible to maintain the angle and remove a uniform layer from all planes.

Sharpening circular saw blades properly and accurately Theory Part 1

What kind of teeth are there on the cutting attachments

At the heart of any cutting device are teeth, the quality of sharpening which affects efficiency and productivity. Teeth on nozzles are made directly from carbide materials. To increase service life, teeth are overlaid with tungsten carbide tips, which allows prolonging the service life of the working tool by 5-6 times.

Number of cutting teeth on the wheel depends on its diameter. The teeth consist of a front and a back, which differ in design, as well as a side. Teeth by appearance (geometry) are classified into the following types:

  • Straight. kind of teeth used for longitudinal sawing of sheet material
  • Trapezoidal shape. the cutting links have a trapezoidal shape, which is an advantage. they need sharpening very rarely
  • Beveled tines are the most common type of tine, which are characterized by having an angular bevel on the back or front. This design allows not only cutting wood, but also other materials, such as hardboard, particle board, plywood and even plastics
  • Conical. they look like a cone, but their main disadvantage is the rapid blunting, so they need frequent sharpening. Not only used for crosscutting, but also for longitudinal sawing of sheet material
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Manufacturers also produce circular saw blades with active and passive links. Depending on the type of teeth, the process of sharpening differs. To properly sharpen the teeth on a circular saw, you need to determine the correct angle of sharpening.

Home machining of the toothed blade

To process the circular saw it is not necessary to have a special machine for sharpening circular saws with your own hands. To fix the blade in a certain position, you can use a flat stand, which has several nuances:

  • The surface must be flush with the center of the sharpening disc.
  • The sharpening plane must be at a 90 degree angle relative to the toothed wheel.
  • To create different inclinations, the fixture must have a swivel joint.

To select the desired angle, the mark is made with a colored marker. The saw blade must be set in a high-powered bench vice. Do not allow even the slightest movement of the special stand.

Ways of increasing the service life of circular saw blades

Tooth angles for sharpening

The process of forming a new cutting edge is labor intensive and time consuming. Therefore, there are a number of recommended conditions for increasing the life of the blade.

First of all, please read the manufacturer’s recommendations. They specify the number of revolutions (maximum and minimum) for various types of processed materials. For metal this parameter should be less than for wood.

Hardfacing inserts have a long service life. But it is more likely to chip or break. Alternatively, soft ones are virtually immune to these defects. But their service life is shorter than that of a solid saw blade.

No roughness on the cutting surface is allowed. They can lead to chips and cracks later on.

The video shows an example of a self-made disk sharpening machine:

The correct sharpening of circular saw blades is often ensured by a good fixation of the cutting equipment. There are two options: the tooling can be removed from the tool and fixed in a vise using wooden bars on the workbench or to sharpen directly on the tool. then for fixation it is necessary to stick a bar between the teeth, having set it in any surface. It is important to remember that the saw has to be deenergized before you start sharpening. Whichever way you go, make sure you keep the disc firmly in place so it doesn’t rotate.

To help you know which tooth you have started sharpening, you should mark the disk with a highlighter on the body of the disk. You will know that you have ground the teeth a full circle so you do not have to grind them a second time.

Manual sharpening of circular saw blades is carried out with a file. A tool with a flat blade is best. it slips easily between the teeth. Note that the main wear occurs on the top cutting edge of the tooth. During sawing it interacts with the material most intensively and is gradually rounded. The leading edge of the tooth is also ground very finely.

First the back side of the tooth is ground. Run the file over it several times, exerting slight force. Each tooth is ground in alternating, even strokes.

It is important to remember! When sharpening circular saw blades it is necessary to act on each cutting segment with equal force and to file the same number of times. This will help to evenly sharpen the entire disc. the teeth will be uniform.

After sharpening each tooth in turn, when the circular saw blade has completed one complete rotation, you will return to the starting point. Then sharpen the front side of the teeth. Repeat the same steps until the burr has been fully retracted.

It is important to remember! When sharpening, it must be ensured that the tooth tip remains perpendicular to the blade plane. This will ensure a smooth and fast cut later on when sawing workpieces.

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To be sure of the quality of sharpening, the teeth should be carefully inspected. There must be no chipping, rips or cracks on the cutting part, and no glare on the edge. If the edges are shiny, carefully file them down.

After all teeth have been sharpened, check the cutting characteristics. Clamp the cutting attachment to the tool, turn on the power, and cut a block of wood to try it out. Good sharpening is indicated by a clean cut, smooth running, and quiet operation. If you see loud noises and unevenness in the sawing action check the height of the teeth. they might be uneven. To align all cutting segments, hold a marker against the cutting edge and turn the machine fully in the opposite direction of rotation. Examine the surface: there should be a mark on each tooth to help compare the height of all segments. Find the teeth with the highest height and carefully reduce their length with a file.

Signs of wear

Sharpening saws is a common activity, as is sharpening chainsaw chains, done with your own hands. You can trust the carbide-tipped, pobedite-tipped fixture to a specialist. This is because the carbide tips are very hard, making sharpening with a regular file impossible. This requires an expensive diamond grinding tool.

The first thing you need to do is determine the current condition of the saw blades. Chainsaw discs and chainsaws have certain signs of wear. If you know about them, you will easily know that the sharpness of a circular saw has significantly deteriorated.

  • Your circular saw is starting to get too hot on the engine cover.
  • physical effort on your hands is required to cut the workpiece. A similar phenomenon is characteristic of blunt chainsaws.
  • From time to time the engine may emit smoke.
  • When processing your workpieces you get an unpleasant smell of burning.
  • The edges of the circular saw blade become blackened. It’s a fouling. It can also show up on the chainsaw chain surface.
  • The wood starts to move jerkily on the machine, although during normal sharpening the movement should be smooth.
  • Unusual noise in the machine during operation.
  • The tooth geometry of your circular saw is disturbed.

Machines

All machines that provide sharpening have the same principle of operation. The only difference is in the performance of the equipment.

The tool kit includes an abrasive wheel as well as sanding material.

The use of machines to sharpen the teeth offers a number of advantages

  • The possibility to keep to a given angle;
  • Increases the efficiency of production operations and their speed;
  • it is possible to use a wide variety of discs.

Even hard coatings can be sharpened with the machine. The grit size of the sharpening disc varies. As an example, if the diameter is 126 mm, the speed can be 2300 revolutions per minute.

The speed of the disc can be varied between 510 and 720 rpm, all depending on how brittle the disc is.

The functionality of the machine determines whether the workpiece or the spindle will move. Movement of the entire device is also possible.

Tilt angle can be measured with a pendulum angle gauge; some machines have a built-in scale to determine the angle of inclination of the teeth.

Teeth are normally ground first at the front, then at the back.

Much depends on the performance of the abrasive, and special attention needs to be paid to it

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