Do-it-yourself belt sander. Why do you need a wood sander and how to make it yourself at home Small do-it-yourself belt sander

For finishing wood, metal or stone, you can build a belt sander with your own hands. The need for such processing arises quite often. It is needed not only to obtain even and smooth surfaces. With its help, you can remove various kinds of irregularities, bulges and depressions, peel off burrs, remove local defects, remove flash formed during welding, carry out internal grinding, etc.

Manual execution of such processing is very laborious and inefficient, and the cost of industrial grinding machines is quite high. Therefore, it is necessary to invent and build home-made structures, especially since they do not differ in particular complexity.

General information about the design of belt grinders

Belt grinders, with all the apparent diversity of their designs, have common distinguishing features. An abrasive belt is used as a working tool in these designs. Most often, it is connected into a ring and placed between two rotating drums.

Usually there are two such drums: the first is the leader, and the second is the slave. The driving drum is driven by an electric motor through a mechanical transmission. Usually it is a belt drive. It is desirable to have a device that allows you to change the speed of rotation of the main drum, thereby providing a variety of processing modes.

The location of the sanding belt depends on the purpose of the sanding machine and can be any: vertical, horizontal or inclined. The tape is usually mounted on a frame, and workpieces can also be located there. In homemade designs, the blanks are usually held by hand, although there may be other options.

The length of the working part of the sanding belt depends on the size of the workpieces being processed. The grinding process is accompanied by the release of a large amount of dust, so the presence of an exhaust device is desirable. A tension roller is often used to adjust the degree of belt tension.

Depending on what the grinder will be mainly used for, it may have some design features. This applies to the diameter of the drums, the length and speed of the belt, its grain size, the design of the working table, etc. The main types of grinding are:

grinding curved surfaces;
leveling flat surfaces;
alignment of side edges or ends, as well as surfaces of bars, shields and similar parts;
grinding of intermediate layers of paint and varnish coatings.

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Homemade belt sander

The structural prototype of a homemade grinder was a conventional industrial design in which the belt is moved by the abrasive part outward over the flat surface of the desktop. The resulting grinder is distinguished from the industrial design by increased dimensions and a stationary installation.

Since a gearbox or belt drive complicates the design, an electric motor is used, the rotor of which makes 1500 rpm. The power of the electric motor should be about 2-3 kW. With a drive shaft radius of 10 cm, the linear speed of the belt will be about 15 m/s. As already mentioned, the reducer is not needed in this case. Adjustment of the speed of rotation in such a simple design is not provided.

The drive shaft is rigidly mounted on the motor shaft, and the second shaft tensions the belt. The tension shaft rotates on bearings sitting on a fixed axle to reduce friction. This axis can be shifted relative to the desktop in one direction or another, reducing or increasing the degree of tension of the sanding belt.

The desktop can be made from improvised materials: sheet metal or wooden beams. Its dimensions are determined by the distance between the axes of the shafts and the length of the abrasive belt. Near the shafts, the surface of the table must have bevels to ensure smooth contact of the tape (especially its junction) with its plane.

Both drums are easy to make yourself. Chipboard can serve as a material for their manufacture. Squares with a side of 20 cm are cut from the original plate. Their number should be such that the total thickness of the set is about 24-25 cm. Discs with a diameter of 20 cm are made from them on a lathe. There are two options for processing them:

You can grind each workpiece on the machine separately.
A more preferable option is to put the workpieces on the axis, clamp and grind them all together.

The groove should be carried out in such a way that the edges of the drums are a few millimeters smaller than their middle. This is necessary so that the abrasive belt is automatically installed in the centers of the drums.

I have been making knives for several years now and always use 2.5 x 60 cm and 10 x 90 cm belt grinders in my business. For a long time I wanted to get another one with a 5 cm tape, as it would make my work easier. Since such a purchase would be an invoice, I decided to make it myself.

Problems in the design of the future machine:
Three limitations had to be overcome. Firstly, there was no tape 10 cm wide at the place, it could only be ordered online. For me, this option seemed not very acceptable, since there is no greater disappointment than to find that the tape has worn out and needs to be replaced, and you have to wait a week or two for a new one to arrive. Secondly, there was a problem with the rollers. I searched but couldn't find any suitable 10cm tapes. Thirdly, the motor. A belt sander needs a fairly powerful electric motor, and I didn't want to overspend on this project. The best option for me was to use a used motor.

Solutions to design problems:
The first tape problem found a simple solution. Since the 20 x 90 cm belt was freely available in hardware stores at a reasonable price, I could make two 10 cm from it. This imposed restrictions on the size of my machine, but due to cost effectiveness, this option was the best. The second problem was solved using a lathe. To do this, I watched a video on the Internet, and realized that I could make the videos I needed myself. With the motor, the task was more difficult. I had several electric motors in the garage, but for some reason I had to abandon them. Finally, I settled on an old tile cutter that had a 6 amp electric motor installed. At that time, I realized that this power may not be enough. But since the work was at the experimental stage, I decided to first achieve a working version of the machine, and the motor can be replaced later. In fact, for a small amount of work, the motor is suitable. But if you are going to be doing more intensive sanding on it, I would recommend a 12 amp minimum.

Tools and materials

Tools:

Angle grinder with cutting discs.
Drill and drills.
Wrenches for 11, 12 and 19.
Lathe.
Vice.

Materials:

Electric motor (6A minimum, or 12A recommended).
Various bearings.
Nuts, bolts, washers, lock washers of various sizes.
Metal corner.
Sanding belt 20 cm.
10 cm pulleys.
Powerful spring.
Steel bar 4 x 20 cm.
Timber 2.5 x 10 x 10 cm made of wood or MDF.

Electric motor for machine

I had a choice of several motors, but the electric motor that was on the tile cutter had a more suitable casing. To some extent, working on the machine was like an experiment, because I was not sure about the sufficient power of the motor. Therefore, I settled on a modular solution with a belt frame as a single element that can be removed and rearranged to a more powerful base. The speed of rotation of the motor suited me quite well, but I was worried that 6 A would give weak power. After a little testing, I saw that for simple work, this electric motor was suitable, but for more intensive work, you need to choose something more powerful. When designing your machine, pay attention to this point.

As I mentioned, the motor housing was very suitable, as it allowed the creation of a vertical machine that would be easy to move.

First you need to release it by removing the desktop, saw, protection, water tray, leaving only the electric motor. Another benefit of using this motor was the threaded core and nut to hold the saw in place, allowing the pulley to be mounted without the use of a key (I'll explain what a key is later).

Since I had a pulley that was too wide, I decided to use the large pressure washers that usually secure the saw, turning one upside down so that there is a wedge-shaped groove between them. I found that the space between them was too narrow, and to widen it, I put a lock washer between them. The advantage in this method is that the pressure washers have a flat edge, which is fixed with a flat edge for simultaneous rotation with the core.

Belt

The drive belt I used was 7 x 500mm. A standard 12mm can be used, but a thinner one is more flexible and will put less strain on the motor. He does not need to rotate the grinding wheel.

Belt sander device

The device is simple. An electric motor drives a belt that rotates a 10 x 5 cm "master" pulley that drives the abrasive belt. Another pulley 8 x 5 cm is located 40 cm above the main one and 15 cm behind it and is mounted on a bearing. The third 8 x 5 cm pulley rotates on a lever and acts as a tension roller, holding the abrasive belt tight. On the other side, the lever is attached to the frame by a spring.

Determining the drive type

The main issue was to rotate the main pulley directly with an electric motor or with the help of an additional pulley and a drive belt. First of all, I chose a belt drive because I wanted to be able to change the engine to a more powerful one, however, there was another reason. When you do intensive metalworking, there is a risk of running into some problems. Belt drive in such cases will slip, while direct drive will create big problems. With a belt, the device will be more secure.

Frame fabrication and installation

It is important to mention that using a metal angle as a frame can have both advantages and disadvantages. The obvious advantage is that it is convenient to assemble it, like a designer in childhood. But the main drawback is that it is strong only in two directions, but weak when twisting. So, you need to take into account this weakness and calculate what torque can be transmitted from the pulleys to the frame, and compensate for it with the help of additional jumpers.

Cutting:
You can use a hacksaw to cut the corner, but an angle grinder with a cutting disc will make the job faster. After cutting off all the elements, I would recommend sanding all their sharp edges so as not to cut yourself during assembly. Holes can be drilled with a conventional drill and cutting fluid.

Main roller

The main roller is the most important part of the project, as it receives torque from the motor and transmits it to the belt. I used an old bushing to mount it, but I recommend using a bearing instead. The bushings do their job, but they constantly overheat and require regular lubrication. Moreover, they can scatter dirty grease, which is annoying during operation.

Shaft:
There are threads on the sides of the shaft with different directions so that the fixing bolts do not unscrew during rotation. If you cut one of the threaded sides, as I did, leave the one that goes counterclockwise, otherwise you will have to make a lock bolt (I will describe how to do it later) and a cotter pin. The main pulley will be put on the cut edge.

Pulley:
Continuing the theme of reuse, I found an old pulley from another project. Unfortunately, I prepared it for the threaded pin that it was supposed to hold on, but, in fact, this is not a problem. In this pulley, I made a rectangular cutout. Then, using an angle grinder, I cut a groove into the end of the shaft. By placing the key in the hole formed by the groove of the shaft and the rectangular cutout of the pulley, I securely fixed them relative to each other.

Production of rollers for a grinding machine

I made the rollers out of several pieces of hardwood 2.5 cm thick. But you can use MDF, plywood or other material. When laying the layers, it is necessary to make sure that the fibers are perpendicular, this will give the rollers additional strength and the layers will not split.

It is necessary to make three rollers: the main roller, the upper roller and the tension roller. The main roller is made from two 13 x 13 cm pieces 2.5 cm thick. The top and idler rollers are made from two pieces of wood measuring 10 x 10 cm.

Process:
Start by gluing pairs of 13 cm and 10 cm pieces of wood, clamping them with clamps. After the glue has dried, cut the corners with a miter saw, then find the center of each piece. Fix them in a lathe and machine them until they measure 5 x 10 cm and 5 x 8 cm.

Top and tension rollers:
Next, you need to install the bearings in rollers measuring 5 x 8 cm. Select a core or spade drill, and drill a recess in the center to the width of the bearing. The inner ring of the bearing must rotate freely, so a hole must be drilled through the roller through the inner ring of the bearing. This will allow the bolt to pass through with a minimum opening.

Main video:
This detail is done a little differently. There are no bearings on it, however, if the shaft is less than 5 cm out of the roller, it will be necessary to grind the roller in width. Measure the diameter of the shaft and drill the same hole in the center of the roller. Try to insert the shaft, it must hold tight, otherwise the roller will shake.

Bolting rollers

Next, you should fasten the two halves of the rollers with bolts, you should not rely only on glue. Remember that the bolt heads must be sunk into the wood as the roller rotates in close proximity to the frame.

Tension lever

The lever is made of a metal bar measuring 10 x 30 x 200 mm with rounded edges. It needs to drill fairly large holes, so I recommend using a drilling machine and a lot of lubricant for this. You will need 4 holes in total. The first is at the pivot point. It is not in the center of the bar, but 8 cm from its edge. The second hole will be on the edge closest to the pivot point. It will serve to attach the spring. Two additional holes must be drilled at the opposite end, approximately 5 cm apart. They should be a little wider in diameter as they will be used for the setup I'll cover next.

When all the holes are made, you can fix the shoulder on the vertical corner between the top roller and the base. The end where the spring will be attached is directed towards the main roller. It should rotate freely, so I recommend using two nuts for fastening, not completely tightening the main one, and using the second one as a lock nut.

Installing rollers

The top roller is fixed statically and must be clearly in the same plane as the idler roller and the main roller. You can do everything by eye, but I recommend checking everything well with a level. To align the roller, you can add a washer, or, if it is not enough, a bolt. They are inserted between the frame and the roller.

It is not necessary to fully install the tension roller. Still need to make a stabilizing device.

Tape stabilization

Wear on the rollers or an uneven surface can cause the abrasive belt to gradually come off the rollers during operation. The stabilizer is a device on the idler that allows it to be angled to keep the abrasive belt centered. Its arrangement is much simpler than it looks and consists of a fixing bolt, a little free play on the idler pulley and an adjusting bolt.

Drilling holes in bolts:
For this purpose, I made a device, in the form of a wedge-shaped cut in the board, which will help to hold the bolt in place at the time of drilling. You can do it manually, but I don't recommend it.

fixing bolt

A fixing bolt is a simple bolt with a hole drilled in it, and which is installed on the bar through a wide hole that is closer to the pivot point of the lever. Since it is located between the lever and the roller, its head must be ground off so that the roller does not cling to it. The bolt must be fixed as shown in the figure.

Bolt holding roller

It needs to be loosened a little so that the tension roller has a little play. But so that it does not unwind, you need to make a castellated nut. To do this, you just need to make cuts on the edges of a regular nut so that it looks like a crown. There will be two drilled holes in the bolt itself: one for the adjusting bolt, and it will be aligned with the hole of the fixing bolt, and the other for fixing the castle nut with the cotter pin.

Bolt for setting:
Once the idler is in place, the adjusting bolt can be installed, which will pass through the holes of the fixing bolt and the bolt on which the idler rotates. The system works by tightening the adjusting bolt, causing the idler wheel's axis of rotation to shift its angle of rotation outward, thus causing the belt to move closer to the mechanism. A spring at the other end of the arm adjusts the tension in the opposite direction. I recommend securing the adjusting bolt with a locknut, as vibrations can loosen it.

Note: It is possible to add a spring on the back of the idler, but I have not found any reason why this is worth doing. A slight advantage is that in this way the roller will have less play. But I will add that I did not do this, and I did not have any problems.

Completion of work on the manufacture of the machine with your own hands

When everything is done, you need to check all the bolts again, and make sure that the stabilization mechanism is assembled correctly. Then you need to turn on the device for the first time, which can be scary. It's like driving a car where the steering wheel and transmission don't work. I recommend turning the motor on and off for a very short time so that the machine does not spin at full speed.

In fact, the hardest part for me was the spring setting. If you pull too hard, the tape will not be able to rotate ... Too weak - and it is impossible to hold it, it flies, which in itself is dangerous.

Ready!

That's all. You should end up with a decent medium power belt grinder that can be converted to a more powerful one if desired.

Hope you enjoyed this tutorial. Thank you for your attention.

The rotation on the drive shaft of the tape machine is transmitted from the electric motor, which is connected to it by means of a belt drive. The speed of the belt mechanism can be adjusted, thereby changing the modes of processing parts. The belt of a surface grinder can be located horizontally or vertically, as well as at a certain angle, which is allowed by some models of equipment in this category.

When choosing a model of a belt grinder for processing a particular part, it is important to consider the length of the surface that needs to be grinded. It is much more convenient to process parts on such machines, the surface length of which is less than the length of the abrasive belt and the desktop. Under such conditions, the quality of processing will be much higher.

The belt sander can be of various designs: with a movable and fixed work table, with a free belt. A separate category includes wide-belt equipment, the peculiarity of which is that their desktop, which is also a feed element, is made in the form of a caterpillar. In those models of equipment that have a working table in their design, the abrasive belt is located in a horizontal plane, and in equipment with a free belt, in which a working table is not provided, it can have a different spatial position.

An obligatory structural element of any belt grinder, including a desktop one, is an exhaust device, which is necessary to remove dust, which is formed in large quantities during processing. Both professional and any homemade grinder used in a home workshop or garage is powered by an electric motor.

Principle of operation

The main parameters of the belt grinder are the feed rate and the force with which the belt is pressed against the workpiece. Parameters such as the degree of grit of the abrasive belt should be selected depending on what material the workpiece is made of, as well as the degree of roughness that the surface of the machined product should have.

The characteristics of the material to be processed, in particular its hardness, primarily influence the grit size of the abrasive belt. The processing modes that are directly related to each other are the feed speed and the belt pressure. So, if grinding is carried out at high speed, but with a slight pressing force of the abrasive belt, then some parts of the surface of the part may turn out to be untreated. If, on the contrary, you increase the pressing force and reduce the feed rate, then you may encounter the fact that burns and blackening of the material may appear in certain areas of the treated surface.

Another variation of the machine is a view from the side of the working surface of the tape

The results of grinding are also influenced by how well the abrasive tape is glued together. In order to obtain a high quality finish and not to experience a malfunction of the band machine, do not use abrasive belts that are not glued correctly or have torn edges. When putting on the tape on the shafts of the equipment, it should be positioned so that the end of the seam, which is overlapping, does not lift up on the surface of the workpiece, but slips along it. Learn more about gluing the tape in the video below.

Any, including a manual grinding machine, should provide for the possibility of adjusting the belt tension, which is ensured by moving a movable shaft that is not driven. Tape tension is a very important parameter, the choice of which should be guided by the "golden mean" rule. If the belt of the grinder is too tight, then this can lead to its breakage during operation, and too little tension will cause slippage and, as a result, its excessive heating. The main characteristic for determining the degree of tension of the tape is the arrow of its deflection, which is measured by lightly pressing on its surface in a taut state.

The manual belt grinding machine of the group can be operated by one operator, who moves the desktop with the workpiece and rotates it so as to bring all parts of its surface under the abrasive belt.

How to make a belt sander

Many home craftsmen and professionals are wondering how to make a grinder with their own hands. The reason for this question is quite simple: the high cost of mass-produced grinding equipment, which, with irregular use, not everyone can recoup. In order to make such equipment, you will need several basic components: an electric motor, rollers and a reliable frame. Naturally, the drawings of such a device or its photo will not be superfluous. Also at the end of the article you can watch videos on assembling a tape machine on your own.

The motor for belt sanding equipment is easy to find, it can be removed from a used washing machine. The bed will have to be made independently, for this you can use a sheet of metal with dimensions of 500x180x20 mm. One side of the frame should be cut very evenly, since it will be necessary to attach the platform on which the electric motor will be mounted to it. The platform for the electric motor should also be made of a sheet of metal with dimensions of 180x160x10 mm. Such a platform must be fixed to the bed very securely with a few bolts.

Another version of the bed

The efficiency of a belt grinder directly depends on the characteristics of the electric motor that is installed on it. If you are going to make a grinding machine with your own hands, then an electric motor with a power of 2.5–3 kW, developing about 1500 rpm, is quite suitable for you. In order to use such a motor to move the sanding belt at a speed of 20 m/s, the drums must have a diameter of about 200 mm. Which is convenient, if you choose an engine with such characteristics, then you do not need to make a gearbox for your grinding machine.

The drive shaft is connected directly to the motor shaft, and the second - the driven one - must rotate freely on the axis, which is installed in the bearing units. In order for the abrasive belt to more smoothly touch the surface of the workpiece, the section of the bed on which the driven shaft is installed should be made with a slight bevel.

It is possible to make shafts for a belt grinder with minimal financial costs from a chipboard plate. You simply cut square blanks 200x200 mm in size from such a plate, drill central holes in them and put them on the axle with a package with a total thickness of 240 mm. After that, you just have to grind the resulting package and make a round shaft out of it with a diameter of about 200 mm.

Drawings and a detailed analysis of some parts of a machine made of wood.

Wood belt sander (click to enlarge)

Table Tilt Adjustment Mechanism Plate Unit Belt Tensioner

I welcome all those who work with metal and not only, I present to your attention a simple, convenient, powerful grinding machine. With this tool, you can easily and quickly form bevels on knives, sharpen axes and many other tools, perform grinding, and so on. As a power unit, a 220V engine with a power of 2 kW is used, the revolutions of which are 2800 per minute.
The belt on the machine is set with dimensions 1000x50, and the speed is 20 m/s.

This is very convenient to use, it quickly changes the belt. It is also reliable, there is practically nothing to break, such a powerful engine is difficult to overload. The machine is also assembled easily from available materials. The most important thing is to find a suitable engine for homemade. So. Let us consider in more detail how to assemble such a machine.

Materials and tools used by the author:

List of materials:
- motor 220V, 2 kW, 2800 rpm;
- square steel pipes;
- Sheet steel;
- wires;
- nuts and bolts;
- shock absorber (will work as a tension);
- finished wheels (or you can carve them yourself out of wood);
- dye.

List of tools:
- cutting machine or grinder;
- drilling machine;
- Bulgarian;
- vice;
- welding machine;
- chisel, hammers, wrenches, etc.

Manufacturing process of belt sander:

Step one. Base and stand
And as a basis, we need thick sheet steel. The metal must be strong, because here we will mount the engine, as well as weld the rack. We select a suitable piece of metal and mark it. The author drills holes in the corners of the sheet, they are needed in order to screw the legs. The legs will need rubber, we fasten them with bolts and nuts, so our machine will not walk on the floor and will be securely fixed.

Next, we prepare the blanks for the manufacture of the rack. Our stand is telescopic, that is, it is a pipe of a larger and smaller diameter, they go into each other. We cut off the necessary pieces of pipe on a cutting machine or grinder. Next, we weld a wider pipe vertically to the base. The pipe must be welded evenly and as tightly as possible. We use the corners to weld the pipe strictly vertically. That's all, the rack is ready, let's move on.

Step two. Adjusting node
The manufacture of the adjusting unit is the longest in this homemade product. This node is needed in order to change the angle of the upper driven wheel. Thanks to this parameter, we center the belt on the wheels. This assembly is made of steel plates, the process of assembly and operation of this assembly is shown in more detail in the photo. There is nothing complicated in manufacturing, we cut blanks, drill holes, cut threads where required.

This adjustment assembly is then assembled on a long steel plate that is welded horizontally to a thinner steel tube that slides out.

Step three. Assembly
The author showed us only the main points on the assembly of the machine, other details were behind the scenes. So, for example, you will need to install some kind of spring that will “push apart” the telescope and thereby stretch the sanding belt. The author has a shock absorber, something similar can be found in some washing machines. You can also adapt an old Soviet aluminum pump for this by installing a spring inside.

You will also need to install work planes on the frame, this is the table itself and the thrust platform. This is all done from sheet metal of suitable thickness and should not be a problem.

As for the wheels, you can carve them yourself from wood, plywood is suitable as a material, several layers need to be glued together to obtain the desired thickness. We grind the wheels on a lathe or on the engine that you found for the grinder. The drive wheel is fixed on the motor shaft, and the driven wheel rotates on the bearing.

When carrying out construction and repair work, men often need to process wood, stone or metal. For quality work, it is advisable to purchase a belt sander. But what to do when finances do not allow you to make such a purchase? To do this, it is enough to build a belt sander with your own hands.

Purpose of the belt sander

Wood is widely used in a variety of industrial organizations. Wood is used to make many kinds of details and products. In order to properly process a wooden blank and give it the appearance of a finished product, it is customary to use various equipment, including belt sanders.

Belt grinding equipment, as a rule, is used at the final stages of production, when the parts are subjected to fine machining. Such devices are convenient to use in the manufacture of furniture and various consumer wood products. Depending on the material used, belt sanders work with wood or metal.

The main goals of using grinders for wood are the final leveling of the surface, bringing their level of roughness to the required level, obtaining even and smooth surfaces for wood and wood products before veneering or after coating with varnish and other finishing materials, removing local irregularities in the form of recesses and elevations, deburring and removal of local varnish and primer deposits, deburring, internal grinding and grinding of roundings.

Belt grinders for metal work with various materials and formats that are popular in metalworking: plain and alloyed steel, non-ferrous metals in the form of square, round and flat blanks. Grinding machines allow you to grind round timber and large diameter pipes rationally and with minimal time.

Depending on the type of processing and type of feed, belt grinders are intended for:

for sanding curved surfaces with free sanding belt;
for processing a flat surface with a fixed table, manual movement of the iron and table, as well as mechanized movement of the work table and manual movement of the iron;
for processing panel and bar parts, their ends and side edges;
for intermediate sanding of paint and varnish coatings.

The design of the belt sander

Belt grinding machines are produced by modern foreign and domestic manufacturers in a wide range. Grinding machine prices vary considerably. They also differ in their possible performance and their design. However, they also have something in common. They are united by the fact that absolutely all machines have an abrasive belt as a working body, which is most often connected into a ring and placed between rotating drums.

One drum is the leader and the other is the slave. This means that the first of them is equipped with a mechanical transmission, which is most often based on a belt drive, through which torque is transmitted to it from an electric motor. Any belt grinder is designed so that the speed of the driving drum, and therefore the speed of movement of the abrasive belt can be changed, providing different modes of surface treatment.

The abrasive belt can be positioned vertically or horizontally. In addition, there are equipment modifications on sale in which the working body is installed at a certain angle. The abrasive belt is mounted on a bed, on which the workpieces are usually located. Workpieces can be held manually by the operator, or with the help of special devices that facilitate the work of users and make the processing procedure more efficient and safe.

The machine table is made of metal sheets or thick boards. If the design provides for the manufacture of a table precisely from metal, then it will turn out to sharpen more complex products. The length of the working part of the belt grinder and the grinding belt itself primarily depends on the length of the products that will be sanded on the machine.

If the part has a shorter length than the working surface of the machine, then it will be much more convenient to process it, and the processing will turn out to be of better quality. For example, with a sanding belt length of 4.5 meters, wooden blanks can be easily processed, which have a length of 200 centimeters.

Belt grinding machines are divided into equipment with a fixed and movable work table and devices with a free belt. A special group is wide-belt grinding machines, in which the table, which is made in the form of a caterpillar, is also a feed organ. On machines with tables, the tape is placed horizontally, on designs with a free tape, it is installed in different ways.

Since a lot of dust is inevitably generated during the grinding process, all belt grinders are usually equipped with special powerful hoods that remove most of it during the process itself. Grinding machines are powered by an electric motor, which has a power of about 2.8 kilowatts. With a high power motor, the normal belt speed reaches 20 meters per second.

Abrasive belts for grinding machines

The cutting tool of belt grinders is a sanding belt, which consists of a fabric or paper base and abrasive grains that are attached to it with adhesives. Abrasive belts are produced by two methods: mechanical and electrical. The first method consists in uniformly pouring abrasive grains onto a base that is covered with glue, and the second method occurs in an electric field that orients the grains upwards with the sharpest edges to improve the cutting properties of the grinder.

Abrasive grains are poured onto the base in a bundle densely or rarely. The most effective is an abrasive belt with a rare backfill, when the grains occupy less than 70% of the area, because the wood dust generated during the grinding process is not able to clog between their grains. Natural minerals or artificial materials that have high hardness, such as green and black silicon carbide, white and normal monocorundum, and normal electrocorundum, can be used as abrasive material.

For the purpose of gluing the grains, synthetic resins and skin glue are used. As a base, use a fabric such as calico and twill, or a special grade of paper. The size of the abrasive grains is indicated by a number that corresponds to the mesh size of the sieve in which these grains are retained, and is displayed in hundredths of a millimeter.

If you are interested in how to make a belt sander, then you should pay attention to the following sizes of grinding powders and abrasive grains and their classification: grinding grain - from 2000 to 160 microns, grinding powders - from 125 to 40 microns; micropowders - from 60 to 14 microns, very fine micropowders - from 10 to 3 microns.

Sanding paper is supplied to woodworking enterprises in sheets or rolls. On the non-working surface of the skin there is a marking with the specified characteristics of the skin and the manufacturer. For a belt sander, skins are used in rolls and cut into strips of a certain length and width. The length of the cutting tool is determined, depending on the method of its connection - overlap or butt at an angle.

The ends are cut off at a 45 degree butt joint and then glued onto a linen backing 80 to 200 millimeters wide. At one end of the tape, when gluing with an overlap, abrasive grains are removed with hot water over a distance of 80 to 100 millimeters, then the other end of the tape is applied to the bare base smeared with glue. Compress the connected ends and dry them using a special tool or size press.

Sheet skins are used for combined belt sanders. For grinding discs, it is customary to cut the skin in the form of a circle according to a pattern, the diameter of which is 60 - 80 millimeters larger than the diameter of the disc. Using a rectangular template, blanks are cut out for a bobbin. After cutting, they have smooth edges without tearing. The presence of unglued ends or seals when gluing the tapes can cause the tape to break prematurely.

The skin is cut for wide belt sanders into sheets according to a template that is made of plywood or aluminum sheet. The skin is cut in such a way that the edges are even, and the difference in the length of the side edges is no more than 1 millimeter. One of the beveled edges is cleaned, removing the abrasive at a width of 20 millimeters. The cleaned edge and the longitudinal edges are pasted over with a strip of tracing paper, which has a width of 40 millimeters, which protrudes beyond the edge of the skin by about 10 millimeters.

Lubricate the beveled edge with tracing paper with glue and keep it in the air, depending on the viscosity and type of glue. Then the beveled edges are connected and a strip of skin is applied to the junction, the junction is compressed and held in a press. Ready-made endless tapes are usually hung on special brackets and kept for at least a day in a dry room before being installed on a grinding machine.

The principle of operation of the belt grinder

The belt sander consists of a worktop with a working table for attaching the cutting tool. This table is fixed in different positions relative to the table top. The material for the countertop is usually laminated chipboard with a thickness of 25 millimeters. The working table on rollers moves manually or in the transverse direction by means of a mechanical drive on round guides that are attached to the calipers.

Above the table is a working tape, put on non-drive and drive pulleys. The sanding belt is tensioned and adjusted using a screw device with a pneumatic cylinder. Twin belt sanders have two identical sanding tools that are placed in series on the bed and have sanding belts that move towards each other.

Grinding is performed with the transverse movement of the working table and the longitudinal movement of a short iron, which presses the tape against the material being processed. Sanding belts are driven by an electric motor through a belt drive. Waste that is generated during grinding is captured by a dust collector, which is connected to the exhauster network.

When assigning a grinding mode, it is recommended, according to a certain roughness and properties of the material that is being processed, to choose the grit of the skin, the feed rate and the force of pressing the tape to the product. It is customary to choose the grain size of the skin, depending on the hardness of the processed materials and the required surface roughness. Clamping force and feed rate are interdependent quantities. With a small effort and a high feed rate of the skin, some places on the surface can not be sanded, with high pressure and low feed, burns and blackening of the material are possible.

Before installing the tape, check the quality of its bonding. Do not use incorrectly glued and torn sanding belts with an uneven edge. Using the handwheel, you can reduce the distance between the pulleys and put on the tape. The place of gluing is placed so that the outer end of the seam on the side of the abrasive is directed against the working movement of the sanding belt.

The belt tension can be adjusted by moving the tension roller for the belt grinder or the non-drive pulley. It is not advisable to stretch the tape too much, because this leads to its rupture. But the sanding belt slips over the pulleys at low tension and heats up very quickly. The tension force is set, depending on the strength of the base of the cutting tool and is determined by the arrow of its deflection with a slight pressure on it.

How correctly the tape runs can be checked by turning the pulley manually or briefly turning on the electric motor. The axis of the pulley, when the tape slips, is turned by the handle at a small angle and fixed with a locking device. After setting up the belt grinder, the dust extraction system is turned on, trial processing of parts is carried out and their quality is checked.

The manual feed belt sander can serve one worker. By moving the product relative to the cutting tool in the longitudinal direction, and turning the part around the axis, the operator sequentially brings into contact with the tape all the sections that form the surface to be machined. When slowing down or moving carelessly, grinding may form.

It is customary to grind individual parts of the part in several passes. It is possible to achieve high-quality alignment with the correct regulation of the pressure that is exerted on the ironing handle, and the speed of movement of the table and ironing. The pressure when approaching the edges must be reduced to prevent their grinding off. To increase the quality and productivity of grinding, small bars are placed on the table in a row, several pieces at a time.

Belt grinders with mechanical feed of products are served by two operators. One of them places the part on the conveyor, orients it along the width of the working table and directs the product under the clamping elements of the machine. Parts must not be moved sideways when being picked up by the conveyor.

It is not allowed to feed into the machine blanks that have an unequal thickness, and parts with gross surface defects. The feed rate and pressure of the clamping beam, as a rule, are not regulated during processing. The second operator takes care of receiving the finished parts and ensures that there is no unacceptable chamfering or grinding.

Production of a belt sander

The price of belt grinders from an industrial manufacturer is quite high, so when they are used infrequently, craftsmen involuntarily think about whether to buy equipment or not. An alternative to buying an expensive machine is to assemble it yourself. The main parts of the machine are the frame, rollers and engine.

The engine can be removed from an old washing machine. Cut out the bed from thick iron measuring 500 by 180 by 20 millimeters. Cut one side evenly on a metal milling machine, it is required to mount the platform with a motor. Dimensions of the working platform - approximately 180 by 160 by 10 millimeters. Make a markup and drill three holes in the end face of a flat-cut bed. It is necessary to pull the platform to the frame with three bolts.

Remember that the longer the desktop is, the more options you will get when choosing a technological method for grinding and processing the product. If the length of the workpiece is less than or equal to the length of the worktable, then you can achieve perfect grinding much easier than when moving a large workpiece.

The engine must be tightly placed on the frame. It should have a power of about 2.5-3.0 kW and a speed of about 1500 revolutions per minute. If you choose a speed of about 20 m/s for the sanding belt, then the diameter of the drums should be about 200 millimeters. Thus, with sufficient engine speeds, a gearbox for a grinding machine is not required.

One of the two drums will play the role of a leader, which should be rigidly fixed to the engine shaft, and the other tension drum should rotate freely around a fixed axis on bearings. The table on the side of the driven drum must have a certain bevel, which will ensure a smooth touch of the sanding belt on the desktop surface, this is especially true for a glued joint.

You can make a tension drum and a drum that leads the sanding belt from chipboard. To do this, you need to saw blanks from a plate with overall dimensions of 200 by 200 millimeters and assemble a package of 240 millimeters from them. Square tiles or their package should be folded on the axis and machined to a diameter of about 200 millimeters.

Remember that in the center the diameter of the drum should be 2-3 millimeters larger than at the edges. With such a surface geometry, the flexible sanding belt will be located in the middle of the drum. The optimal width of the tape is an indicator of 200 millimeters. From a roll of emery cloth, which has a width of 1 meter, it is easy to glue 5 similar tapes.

It is necessary to glue the cutting tool end-to-end, placing a thin dense material from below, for example, a tarpaulin. Glue is recommended to use the highest quality that you can get. On the rollers, without fail, stretch the rubber, the width of which reaches 30 millimeters. Rubber can be taken from the cameras of a moped or bicycle.

On a home-made belt grinder, in addition to grinding wooden products, for which it is actually intended, it is very convenient to sharpen tools with cutting surfaces - chisels, knives, axes, secateurs. Another advantage of this grinder is the ability to work with parts that have a curved surface - for this you need to grind the workpiece with the reverse side of the working belt.