A do-it-yourself grinder is made from really very necessary “junk” that is in every workshop or pantry. The tool is used for final processing of parts, grinding, rounding corners.
There are several types of such a device. The most common is a grinder with a vibration principle of operation. One of its main elements is a flat sole fixed on the base. It transmits movement from the motor to the abrasive surface. The harder you press the device, the more powerful the vibration movements will be. Such a machine has a low speed, it is noisy, hands get tired quickly with it, but at the same time, such a tool is cheap and compact.
A subspecies of such a device is a device with a deltoid sole, which is brought forward.
Grinding machines types and purpose
Tape devices. Such a machine works on a different principle. A tape of abrasive material (sandpaper), glued into a ring, rotates on spindles. When working with it, you do not need to apply great efforts, since the rotation of the tape is quite fast. These machines have speed control functions, a system soft start. For more fine work tape machines have support frame. When working with such a tool, a lot of dust arises, so they often have a dust collector or the ability to connect to a vacuum cleaner. Various attachments can be attached to the spindles.
eccentric device. This is the most versatile type among grinders. It can process almost any surface and materials. For curved planes, such a device is ideal. It has a round platform. The rotating abrasive is fastened with special clips or Velcro. The sole of the machine performs both rotational and vibrating movements at the same time.
Angle grinders. They are electromechanical and pneumatic. They are quite versatile, they can cut, grind, clean surfaces made of stone, metals. The device is very similar to the grinder, basically it is the grinder, but with special circles.
Polishing machines differ from angle polishers only with polishing nozzles.
Straight grinders perform small works with high processing precision. The spindle is parallel to the frame, like the shaft of a pen. Such machines are small in weight and size, they can be manipulated with one hand. Their main purpose is the grinding of corners, the processing of edges and small planes, such as planks and lintels. They look like a thick pen, they are used to engrave, cut and polish small objects.
Multifunctional grinders. They can combine several types of devices in one device, for example, a vibrating and tape machine, using replaceable nozzles.
DIY grinder video
Tools and materials for assembling a grinder
- wooden bars, metal elements for the base table;
- sheets of plywood, chipboard;
- old motor, computer hard drive, power supply;
- bolts, screws, bearings, self-tapping screws;
- screwdriver, screwdrivers, drill;
- spring, steel, metal, textolite plate;
- welding inverter, if such work will be carried out;
- abrasive tape, circle, glue.
Making a grinder from a hard drive
Now it's not a problem to get a broken hard drive from the computer (but the circle should spin up) and an old computer power supply. If there is no house, then at any repair point they will be sold for a penny.
Such a device will be oversized, for small parts. It is done simply: the disk is disassembled, an abrasive is glued onto the rotating plane, connected to the power supply - the device is ready. It must be mounted on a workbench for stability, it can be equipped with a regulator, a servo tester for speed control and a switch.
Do-it-yourself angle grinder is made from a grinder, it is enough to make the necessary nozzle-circle from an abrasive. You can, of course, make it from scratch by selecting the necessary electric motor, placing it in a casing, attaching handles. But you need to remember about the safety of working with such a tool.
Belt grinder machine. Such devices consist of:
- working body: abrasive, two drums, leading and driven. There may be more drums in the machine;
- electric motor;
- casing, machine base, frame, table.
The do-it-yourself machine is equipped with a speed change function, the tape can be placed both vertically and horizontally.
Stages of manufacturing a grinder-machine of a tape device
- Preparation;
- equip the base-frame for the machine, it is rigid and stable;
- pick up the countertop, the larger it is, the larger parts can be processed;
- fix racks with tension parts and rotating drums;
- fixing the engine and drums, installing an abrasive belt.
To process large parts, they make an overall machine. To do this, take an electric motor, well suited from old, powerful enough household appliances like a washing machine.
The bed is made from a thick metal sheet.
Do not indicate the dimensions of the sheet, since in any case they come from individual preferences and the availability of materials, it can be, for example, 500x180x30 mm, more or less. A cutout for the motor is milled in the sheet, all this is attached to the bed, the necessary holes for the fasteners are drilled. All parts, and especially the engine, must be tightly fastened so that there is as little vibration as possible.
The motor can not be equipped with a gearbox if it is powerful enough. The do-it-yourself machine is created from two drums, one is firmly fixed on the shaft, the other is tensioned with it, you can adjust the degree of tension.
The frame is made up of thick wooden parts, but it is possible with metal ones. If there is a suitable metal and an inverter for welding, it can be welded. The plate for the support is made from thick plywood, I take several sheets, textolite is also suitable.
The second shaft is beveled, so the tape will smoothly touch the table. For drums, several sheets of chipboard are taken, they are glued and turned to the required diameter, in the center they are made several mm thicker, so the tape will hold well. Single row ball bearings are used for drum spindles. The abrasive belt makes its movement along the frame on which it is attached.
Almost all types of work with wood are related to its finishing or preparation of wood for work, use in everyday life. For this stage of work, grinding of wooden parts is mandatory. Home crafters or professional craftsmen know how important it is to sand wood well, to round sharp corners, remove extra millimeters, burrs. A wood sander is a great tool for this kind of work.
Wood sanding work
There are two methods - manual and mechanical. For the first, emery is used, it is quite laborious and time consuming. Emery can be attached to a wooden block, there are also special shoe holders for it. The second method is carried out using a power tool, it is fast, with a minimum of effort. Some do-it-yourself work cannot be done as well as with grinders and machines.
Several types of such devices are made:
- Angle grinder or grinder. Used for rough grinding of large objects - logs in baths, wooden houses. In the grinder, an emery or similar grinding wheel of different grain sizes is used.
- Vibrating grinder. Due to the reciprocating movements of the surface, the soles are polished. The sole is fastened with clips or Velcro, has a different shape, vibrations are carried out at a speed of 20,000 movements per minute.
- Orbital or eccentric machine. Its sole rotates simultaneously around its axis and in orbit.
- Belt sander. Used for rough and fine finishing of large surfaces.
Its mechanism is quite simple, these are two rollers or rollers on which an emery tape rotates. The device of the tape device of the design is the same for all ( appearance may vary slightly) and consists of:
- working body, this is an abrasive belt and two drums on which it rotates, one is a leader, the other is a slave;
- electric motor;
- bases of the machine (if it is stationary), bed, work table.
The speed of this machine can be changed. The tape is placed both vertically and horizontally.
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Manufacturing process of grinder and machine tool by yourself
Manufacturing steps:
- select and prepare the necessary spare parts and materials (described above);
- make a stand for the machine, table, base, fix it;
- mount the countertop of the desired length (the more, the more sizes material can be processed);
- vertical racks with a tensioner and a drum are mounted;
- install the motor and drums;
- install sanding tape.
As an example, a conventional mass-produced belt grinder is taken. You can make such a device or the like, having spare parts from broken power tools and quite available materials. In such a machine, the abrasive belt moves along the sole of the device with a rough plane outward.
For grinding large parts, a grinding machine is made with sufficient overall dimensions, the principle of its operation is the same as for smaller devices. It can process parts with a size of about 2m and more.
To assemble such a device, you need an electric motor with a power of approximately 2 kW or more, the number of revolutions is 1500. You can do without a gearbox, since such a motor easily reaches a speed of 20-25 m / s, the drum size is 20 cm in diameter.
The engine can be taken from a used washing machine. The bed is made of a thick iron sheet with parameters 500x180x30 mm. On the one hand it is cut into milling machine, a place for the motor will be mounted here. Dimensions are: 180x160x10. It is attached to the frame with three bolts, holes are drilled in it for them. Mount the engine tightly so that there is no vibration.
The design consists of two drums, one firmly fixed on the shaft, the second tension, it rotates on bearings around the axis. Grinding surface tension is adjusted by pulling it to one side. The basis for the machine is made of wood, and preferably of metal plates. Such a base plate is made of three sheets of thick plywood, textolite. The second shaft is equipped with a bevel, providing a smooth touch of the tape to the edge of the table. Drums are made from wood board (chipboard), blanks are taken and turned into lathe up to a diameter of 20 mm. It can be done 1-2 mm more in the center, so the tape holds tighter. The wheel spindles are made from two single row ball bearings.
The emery tape is cut from canvases, its optimal width is 20 cm. It is mounted on a frame (sole) along which it moves. This machine is also used for sharpening tools. The length of the table on which such a machine is mounted determines the size of the parts that can be processed on it, so the longer it is, the better for different sizes of material.
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Using appliances: features
Devices of this kind are used for:
- curved planes using a free grinding surface;
- for flat planes with a fixed table or its manual mechanized movement;
- for the ends of parts, edges;
- for preparatory processing under a paint and varnish covering.
You can design a grinder, the frame of which will be made of wood. Having equipped it with three shafts, an inclined horizontal and vertical working plane is obtained. Such a device has a wooden frame, which effectively reduces vibration. Wood is used like maple, it is quite soft and durable at the same time. The working surface is lined with plastic, but it can be made entirely of wood. It is made so that it can be tilted. The length and dimensions of the tape are selected according to the size. She moves along three wooden pulleys. The upper lever with the drum is equipped with a spring, this allows you to stretch the tape. The position of the belt is adjusted by a guide pulley with two adjustable bolts.
At work, this design looks like this: A motor with a drum of 90 mm rotates another one with a size of 75 mm, and that, in turn, the third. Rotation is carried out using an abrasive belt. Thus, the device has one vertical grinding surface and one inclined.
The frame is made of six elements, it is mounted on a plywood base with a thickness of 25 mm. The bearing parts and the frame are made of wood, these are the base of the bearing supports, the rocking chairs of the table, the rear rack, the upper arm, the plane for the material being processed. Bearing supports must be placed on a sufficiently large block, on which the support is mounted on the bearings of the input shaft.
Rollers, drums and pulleys are made from 7 or 8 glued pieces of 6 mm fiberboard, sawn to the appropriate shape. They have a bearing hole. The axis on which the drum with bearings rests is made of metal. For axles, you can take shafts from broken electric motors, they are even and already polished. The same design for the two guide pulleys. Ball bearings are used, ordinary ones, they prevent the side sliding of the drums if the tape moves inaccurately.
The design may differ in the size of the parts. For the frame, you can use various materials - metal, plastic.
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 grinding machines industrial production pretty 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 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 makeshift designs the blanks are usually held by hand, although there may be other variations.
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 a large number dust, so it is desirable to have an exhaust device. 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
A constructive prototype of a homemade grinder served as a common industrial design, in which the belt is driven by the abrasive part outward over the flat surface of the work table. 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 line speed the movement of the tape 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 beam. 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.
During construction and repair work men often need to process wood, stone or metal. For quality work it is advisable to purchase a tape grinding machine. 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 sanders are generally used for final stages production, when parts are subjected to finishing 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 value, obtaining even and smooth surfaces for wood products and wood material before veneering or after coating with varnish and other finishing materials, removal of local irregularities in the form of depressions and elevations, deburring and removal of local varnish and primer deposits, deburring, internal grinding and grinding of roundings.
Metal belt grinders 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 billets. Grinding machines allow you to rationally and with minimal cost time to grind round timber and large diameter pipes.
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 very technological process. 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 the base, which is covered with glue, and the second method occurs in electric field, which orients the grains upward with the sharpest edges to improve cutting properties 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.
For woodworking companies sandpaper comes 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 lapping, abrasive grains are removed hot water for 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 disk. 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. cleaned edge and longitudinal edges 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 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 has, the more you will get more possibilities 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 the plate overall dimensions 200 by 200 millimeters and from them assemble a package of 240 millimeters. 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. Optimal width 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.
glue cutting tool it is necessary 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 homemade belt sander, except for 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 reverse side working tape.
One of the main ways to process wood (after sawing, of course) is sanding. Manual way known for a long time wooden block wrapped in sandpaper, and with the help of such a simple device, the workpiece is given the desired shape.
The method is unproductive, and requires a fair amount of physical effort. Masters who work with wood regularly use small-scale mechanization.
Types of grinding machines
For sale are a variety of ready-made fixtures, with which you can process wooden blanks of any size. To understand the mechanism of work, consider some of them:
Based on the name, the working surface is made in the form of a disk.
The design is quite simple - a circle with good rigidity is put on the axis of the electric motor. The outer surface has a Velcro coating on which sandpaper is attached. No gearboxes or drive mechanisms are required. The grinding force is small, the rotor axis copes well with the loads.
In the transverse plane, at the level of the center of the disk, a handrest is installed. It can be hinged, which allows you to process workpieces at a fixed angle.
A feature of disk machines is the adjustment of the processing speed without changing the number of revolutions of the axis. You simply move the workpiece along the radius of the circle. With a single angular velocity, the line speed at the periphery is higher.
A strip of sandpaper connected in a continuous band is stretched between two shafts. 
And in working area does not sag under the pressure of the workpiece. A persistent working plane is installed under the tape, made of a material with a low coefficient of friction. Pressing the material being processed to the plane, the operator gets an endless abrasive surface.
The quality, and the ease of processing, cannot be compared with hand tools. In the mass production of wooden products, such a sledge is an indispensable attribute of any workshop.
main feature- predictable result throughout the entire plane. You can level the ends of a sufficiently large length.
Working surface can be horizontal or vertical, as well as the direction of the tape.
Such a device can be attributed to grinding units with some stretch. The main application is the horizontal alignment of planes using the jointer method. 
The principle of operation is as follows - sandpaper is fixed on one or two drums. The most common method is spiral winding. Below, under the drum, there is a flat table. The distance between the processing surface and the table is adjustable. By setting a fixed height, you can calibrate the same type of products, aligning the thickness of the workpieces. 
Grinding machine two in one
To save space (and money), manufacturers often combine two types of fixtures in one design. 
This not only reduces acquisition costs, but also improves user experience. When processing one part, you can enjoy the advantages of two grinding units at once: disc and belt. In this case, the engine is used alone, and the load on it does not increase much.