Simple device for sharpening circular saw blades and cutters
Circular saw blades, when they lose their sharpness, not only reduce speed, but also cut quality. Therefore, they need to be periodically sharpened. If you just do it with a hinged file, you won’t get much improvement in sawing. So sharpened disc can be sawed unless wood, but it does not allow you to get immediately a clean cut. For qualitative sharpening you need a conductor (fixture). Such a device can be assembled with your own hands.
- angle grinder;
- diamond sharpening disc;
- telescopic drawer rails. 2 pcs;
- Plywood 20 mm;
- bolts, nuts M8;
- worm clamp on the angle grinder body.
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The process of making a fixture for sharpening circular disks and cutters
It is necessary to make the base of the device from plywood with the approximate size of 300×400 mm. In it you need to mill a radius through groove, which will later allow you to fix the angle grinder, and adjust its angle relative to the sharpening wheels.
On the side of the bottom you will need to choose a quarter, for sliding the head of the adjusting bolt. Before bending, 3 holes are drilled for screwing the angle grinder mount. It is better to make them after making the next part.
From plywood cut out the L-shaped bracket for the angle grinder. Drill holes in it as shown in the photo. One of them will work as a rotational axis. It is located at the place of the miller’s attachment when preparing a radius groove. A furniture nut is screwed into it. Opposite another hole is made to fix the part directly into the slot itself. The third hole will allow you to screw the angle grinder to the part.
The part is clamped to the sole with bolts. A wing nut is used over the radius slot. The angle grinder will hold the center bolt screwed into the regular hole for the handle. To avoid screwing the angle grinder with the whole body, a wide hole is made in the base plate. Through it will be possible to screw the bolt through the L-shaped attachment to the tool with a wrench or an allen key. A small plywood insert is glued over the center bolt to raise the pad at the point of contact with the angle grinder.
A semicircular stand is made of plywood for the angle grinder body. It will need to be screwed onto the L-shaped fastener, by putting a clamp in beforehand. That will increase the rigidity of the installed tool.
The next step is to make a table to hold the discs to be sharpened. Cut out a piece of plywood 150×150 mm for this purpose. At the edge you need to saw a narrow strip, 40 mm wide, without reaching the edges by 30 mm. Then 2 pieces of 150×30 mm laths are glued to the U-shaped piece.
Then we saw a plywood circle with diameter of 80-100 mm.
On it directly and will be located disks. It is drilled in the center and a bolt is screwed into the hole. Its head must be recessed flush. This will be the axis of rotation of the disk. Two holes are made on the sides. They are transferred to the U-shaped mount. Through them, the disc and this part will be firmly twisted. At the central bolt is clamped to the washer of such a diameter that the disc put on top does not dangle.
Telescopic guides are screwed to the U-shaped piece from below. A small square of plywood is fixed in the corner on the side. It will be used as a stop when further adjusting and fixing the position of the carriage on the guide rails.
Saw a 100×40 mm strip from plywood and mill a through groove in its center. It must be screwed through it to the base of the conductor. This part will limit the stroke of the carriage by blocking the stop made on the side. It can be clamped with a wing nut.
The last part will be the position blocker of the saw blade. It is an L-shaped base made of bar with a through groove for mounting and adjusting. On top of it is screwed the holder of the limiting pin in the form of a drop. The pin itself is a metal rod. This piece is screwed to the sole on the left side of the sharpening blade.
Sharpening with the machine
If it is possible to buy a special machine tool, then the process under consideration can be carried out with maximum efficiency. Such a device has compact dimensions, it can be used at home.
Particular attention is paid to the choice of abrasive wheel. In this case, note the following nuances:
- Carbide disc is difficult to sharpen.
- When selecting, please look for elbor, diamond or green silicon carbide grinding wheels.
Sharpening process with professional equipment is very simple. The disk is secured with a special locking device. It is designed in accordance with the constructional features of the wheel. Let us pay special attention to the fact that with the use of special machines it is very easy to sharpen circular saws maintaining the necessary indicators. The inaccuracy is minimal. This is due to the fact that the design has a special angle gauge. In order not to make a mistake at the time of the work with what teeth have already been processed, it is necessary to mark the starting point with a marker.
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Carbide-tipped circular saws can lose their initial function over time. But this does not mean that you should buy a new cutting tool. In most cases, sharpening can be performed at home, using any suitable machine.
How to determine the angle of the circular saw blade
The geometry of the carbide tips
The optimum is to have an initial template according to which the geometry of the cutting edge can be corrected. often made of thin-walled stainless steel, less frequently of thick cardboard.
Carbide tines are made in accordance with GOST 9769-79. But their geometry and geometric dimensions are determined by the manufacturer based on the purpose of the saw. If there is no template, it is necessary to define required sharpening angles by yourself. A pendulum-type angle grinder is the way to go.
The technology for making the template with your own hands.
- Take a new disk with tips, which is completely identical to the blunt one.
- Draw precise contours on a hard piece of cardboard.
- Using a pendulum angle gauge, determine the initial geometry of the carbide tips.
- Record data on the template.
It can then be used for self-sharpening on a machine tool or provided as a sample for companies providing similar services.
It is also recommended that the measured values are compared to the reference values. In longitudinal saws the rake angle is typically 15°-25°. For cross models it ranges from 5° to 10°. In universal models the rake angle is 15°.
Important to keep in mind that the rake angle can be negative. Similar models are used for cutting plastic sheets and non-ferrous metals.
Sharpening required
Sharpening circular saw blades when cutting becomes impossible. This can be understood from the three signals:
- Heating the blade guard. Smoke comes out from underneath it, comes out of the cutting area.
- Additional forces are required when infeeding the workpiece during cutting.
- When wood comes into contact with the cutting metal, it creates a burning and smelly odor.
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Geometry of carbide teeth
A carbide tooth has four working planes. the front (A), back (B), and two auxiliary side planes (C). Crossing each other, these planes form cutting edges. the main (1) and two auxiliary (2 and 3). Given definition of tooth edges and facets is given according to GOST 9769-79.
The following types of teeth are distinguished by their shape.
Straight tooth. Generally used in saws for fast, longitudinal cutting, where quality is not of prime importance.
Angled (beveled) tooth with left and right angle of inclination of the back plane. Teeth with different angles of inclination alternate with each other, which is why they are called alternate-slotted. This is the most common tooth form. Depending on the angle of sharpening, cross-cutting saws are used for cutting in both longitudinal and cross-cutting directions of various materials (wood, wood particle board, plastics). Saws with a steep back angle are used as a scoring tool when cutting double sided laminated boards. Their use avoids chipping of the coating on the kerf edges. Increasing the bevel angle lowers cutting forces and reduces the risk of chip breakage, but also reduces tooth life and strength.
Oblique toothed tooth with a beveled back surface
Teeth can be angled not only on the back plane but also on the front plane.
Bevel Tooth with Beveled Front Plane
Trapezoid tooth. A feature of these teeth is a relatively slow blunting rate of the cutting edges compared to alternately beveled teeth. Usually used in conjunction with a straight tooth.
Alternating with the last tooth and rising slightly above it, the trapezoidal tooth performs roughing while the straight tooth following it performs finishing sawing. Saws with alternating straight and trapezoidal teeth are used for cutting double-sided laminated panels (chipboard, fiberboard, etc.).) as well as for sawing plastics.
Conical tooth. Tapered tooth saws are auxiliary saws and are used to notch the bottom layer of the laminate, protecting it from chipping as the main saw passes through.
The vast majority of tooth flanks are flat, but saws with a concave flank also exist. These are used for finish crosscutting.
Tooth sharpening angles
There are four basic circular saw blade sharpening angles that, along with the tooth shape, determine its characteristics. These are the front angle (γ), the rear angle (α) and the bevel angles of the front and rear planes (ε1 and ε2). The angle of sharpening (β) is auxiliary as it is given by the front and rear angles (β=90°-γ-α).
The values of the sharpening angles are determined by the purpose of the saw. t.е. by which material and in which direction it is intended to cut. Saws for longitudinal sawing have a relatively large rake angle (15°-25°). For cross-cutting saws the angle γ normally varies between 5° and 10°. Universal saws designed for crosscut and longitudinal sawing have an average value of the front angle. usually 15°.
Angle of resharpening depends not only on cutting direction, but also on the hardness of the material to be sawed. The higher the hardness, the smaller the front and back angles should be (less tooth sharpening).
The rake angle can be either positive or negative. Saws with this angle are used for cutting non-ferrous metals and plastics.
Tools
Doing the sharpening of the saw with your own hands is allowed only with the use of special devices. There is a sharpening machine for this purpose, which helps to carry out the process on an automatic rather than manual. The result is then more accurate.
In addition, other handy devices are used for sharpening:
There is no substitute for these tools. If at least one of them is not available, it is not possible to grind.
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The use of grinding and roughing discs
It is known that cutting wood with an angle grinder is considered to be quite a traumatic operation. No special experience is required to carry out grinding work. Grinding operation refers to the category of basic, originally intended for the angle grinder functions. Already on the basis of it, the tool had new opportunities and received its subsequent development. angle grinder is used for grinding the surface of completely different materials, through special grinding plates.
Each such plate is made in layers. For its production is used:
In addition, there are a number of other devices in addition to grinding plates. For sanding and polishing wood, the most commonly used tool is the flap disc. It has several rigid blades, the working surface of which is covered with sandpaper.
Petal discs are used for roughing surfaces. Besides, in order to remove big layers you can use so called skinning tool, which is a metal cup with wire brushes fixed inside it. It is worth emphasizing that grinding is considered one of the safest operations, which is carried out with an angle grinder.
Discs for milling and cutting wood
Cutting and milling work in wood with an angle grinder is dangerous enough, because the tool is not designed for this purpose. But in some cases the angle grinder is still used for cutting and milling work on wood.
The reason for this danger is the increased speed. Compared with a circular saw, an angle grinder has a high rpm, for which no circular saw blade is designed. In this case, cutting discs for angle grinder, which can be used, must be a certain brand. The most suitable size is a disc with a diameter of 125 mm.
In the process of working with an angle grinder, which has a circular disc, the latter may burst and break. To avoid this, you should use a special kind of saws for wood and protective guards, and in some cases even weaker types of power equipment.
For sawing wood popularly used special chain saws, which allow you to perform milling, modeling, peel the wood bark and create cups in logs for log houses. When choosing such cutting discs you should consider not only the diameter of the tool and the depth of cut, but also the shape, frequency, number of teeth.
- If you plan to use wood saw blades for 125 mm angle grinder not so regularly, and at the same time there is no clear idea of what kind of wood you will work with, it is best to choose products with alternately beveled teeth.
- Sawing needles or any other softwood is performed with cutters that have straight teeth.
- The trapezoidal tooth has the widest range of applications. Medium-density chipboards can be cut with the 125 x 22 saw blade. Can also be used for bilaminated chipboards, USB boards and low density fibreboard.
Please note that the angle grinder works at high RPM, which can cause severe overheating of the discs. And the use of water cooling in such a situation is not possible. In order to avoid overheating and deformation of the cutting tool, it is therefore recommended to use circular blades with a width of approx. 2 mm and a depth of 20 mm. Their cavity may be empty or filled with copper alloy. This design compensates for the expansion of the metal disk and prevents it from deforming.
Specialists also give recommendations on the observance of safety when milling wood with an angle grinder. Such measures imply:
- mandatory use of work gloves to protect hands and goggles for the eyes;
- the use of discs with fine teeth;
- Hard fixation of the cutting equipment;
- check the material to be worked for foreign objects (nails, self-tapping screws, etc.).
Wood milling angle grinder does not allow for high precision machining. When milling a wooden bar is necessary to use thick types of cutters, which differ in their high cost. Self-made disks for such works are strictly prohibited.
For beginners milling and cutting wood with an angle grinder. a dangerous occupation, so for safety reasons it is better to abandon this work, not having the proper experience.
How to sharpen a circular saw with your own hands
You can sharpen your saw at home all by yourself. For these purposes, there is no need to visit a workshop to use a specialized sharpening machine or purchase one. It is rather expensive and is rarely used for sharpening unless you plan to use it for large production purposes.
But holding saw blades in your hands while you sharpen the teeth with a grinding wheel is not the best solution. A circular disc is not a drill, it is much bulkier. No amount of hand strength and excellent judgement will make it possible to sharpen the cutter so that it is sharp enough for effective use. Provide the simplest fixing device for this.
To keep the toothed circular wheel in the required position in relation to the plane of the sharpening tool, one can use the most ordinary flat stand.
The position of its surface should correspond to the level of the axes on the rear disc. Tooth wheel is placed on the stand in such a way, that the sharpened tooth plane is perpendicular to the saw blade blades. To sharpen beveled teeth on front and back surfaces it is necessary to provide movable joints in this device.
But in such cases it is quite difficult to maintain the same values of the front and back angle of the tool. To eliminate this problem, the center of the saw must be rigidly fixed to the sharpening wheel according to the desired position. This is done by means of slots for a mandrel, which is mounted on the stand with placing the saw blades to be sharpened on it, or by placing a special stop on the stand, which will fix the saw blade according to the required angle to the abrasive stone.
If you follow all the requirements for sharpening a carbide circular saw, then this tool will work most effectively for a long period of time.
How to determine the grinding angle of the circular saw
It is best to have an original template available so that the geometry of the cutting edge can be readjusted. It is often made of thin-walled stainless steel, less often of thick cardboard.
Carbide tines are made according to GOST 9769-79. But their geometry and geometric dimensions are defined by the manufacturer based on the purpose of the saw. If you do not have a template, you must determine the required sharpening angles yourself. A pendulum angle gauge is recommended for this.
The technology of making a template with your own hands.
- Take a new disk with tips, which is completely identical to the blunted one.
- On a hard sheet of cardboard draw the exact contours.
- Using a pendulum angle gauge, determine the initial geometry of the carbide tips.
- Record the data on the template.
In the future, it can be used for self-sharpening on a machine or provided as a sample for companies providing similar services.
Additionally it is recommended to compare the data obtained with the reference. Saws for longitudinal applications usually have a cutting angle of 15°-25° at the front. For crosscut models, this ranges from 5° to 10°. On universal models the rake angle is 15°.
It is important to remember that the rake angle can be negative. Similar models are used for cutting plastic sheets and non-ferrous metals.
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Determining the degree of wear
Determining the degree of wear on the teeth is one of the prerequisites for proper tool sharpening. The easiest and simplest way is to compare two identical saws. a new, unused saw and an old one that needs straightening. Simply lay the discs on top of each other and the difference is obvious.
And if the saw has already been in use, then a template must be made to measure each of the saw’s teeth. It is a prerequisite for dressing tools. Before you sharpen a circular saw blade yourself with a template made of tin or plastic, measure each tooth and determine the surface to be processed to achieve the desired angle of the cutting edge.
Advice! It is better to use discs of Ural Machine-Building Plant from Yekaterinburg as a template, they are the best saws that meet all the requirements of GOST.
Roughing and scraping
Working part in the form of a steel cup or two combined discs, the edge of which is mounted twisted scrapers, brushes or just a metal wire. To remove rust, corrosion and various coatings such as paint, varnish, polymer, dried cement, etc. Indispensable for auto body repair, various machinery and equipment. The cross section and the strength of the wire determines the degree of processing.There are diamond and abrasive roughing discs with working faces like those of sharpening discs. Used to remove plaster, concrete, stone, and other high-strength finishes.
sanding and polishing
- cord brushes. roughing treatment for surface leveling or cleaning;
- End abrasive nozzles. specially designed for sanding the ends of parts;
- Petals. special discs in the form of abrasive blades of different grit, its degree determines the quality of grinding;
- felt (cloth) wheels. ideal for mirror polishing, also with the use of a special liquid or fine abrasive paste;
- Fiber pads. good option for metal surfaces;
- chain wheels and solid grinding discs should be used only with grinders, complete with additional handles, allow you to perform rough treatment of logs, beams and other types of wood.
Professional equipment from 150 thousand. up to 1.5 million
Professional sharpening machines are intended for use in the repair shops of large sawmills or by service companies specializing in such tools. All of them are equipped with industrial controllers with a selectable program for the machining of the specific saw blade model.
| № | Model | Max. tool diameter (mm) | Drive power (W) | Weight (kg) | Control type | Price (.) |
| 1 | MF1263 | 630 | 300 | 260 | automatic machine | 165 000 |
| 2 | Unimac 600A 288,000 | 630 | 300 | 250 | p/automatic | 288 000 |
| 3 | GRIGGIO GA U5 | 400 | 560 | 115 | p/automatic machine | 451 000 |
| 4 | OS-2M | 1500 | 1 100 | 270 | p/automatic | 525 000 |
| 5 | OTOMAT-96 | 750 | 1 000 | 850 | automatic machine | 1 500 000 |
Tools required
You can sharpen circular saw blades 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.
The following tools can be used to perform the disc sharpening job with your own hands:
You can also use a circular saw sharpening machine, which does not require the tools above.
When should circular saws be sharpened?
It is quite important to determine when to sharpen circular saws. Severe wear and tear can lead to the inability to carry out such work. There are three clear signals that can be identified that determine when circular saw blade sharpening is necessary:
- Smoke production, heating of the blade guard. The cutting attachment usually has a special guard, which may become hot if the blade becomes blunt. It should also be noted that in special cases there is smoke due to the strong heating of the cutting zone.
- Also with mechanical feed, when the pressure is adjusted with your own hands, a great deal of force should be applied to get the desired result.
- When you work with wood or other material, there are traces of carbon in the cutting area and a corresponding smell.
In the above situations, it is recommended that the circular saw blade be sharpened.