During 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 various production 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 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 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 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 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 filling, 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. Can be used as an abrasive material natural minerals or artificial materials, which have high hardness, such as green and black silicon carbide, white and normal monocorundum, and normal electrocorundum.
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 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 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 run 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 grain size 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 milling machine for metal, it is required to mount the platform with the 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 surface of the desktop, 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. 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.
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 skating rinks 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 reverse side working tape.
Needing a grinder for occasional woodworking and not wanting to spend money on professional equipment, you can independently assemble a power tool using improvised materials, as in this project.
materials
To make a grinder with your own hands you will need:
- suitable electric motor;
- fasteners;
- grinding disc;
- pieces of plywood;
- sandpaper;
- drill;
- saw;
- roulette.
In this project, the basis of the tool was an old electric motor from air compressor. It is powerful enough to ready product worked no worse than special equipment for wood processing.
Step 1. Be sure to attach the purchased grinding disc to the existing engine. This will help you decide on the parameters of the pedestal for the motor.
The base, after carefully making calculations, assemble from boards or pieces of plywood. Be sure to mount the motor on it.
Step 2. Cut out the base for the disk from plywood, carefully sand the edges of the cuts with sandpaper. Using the motor pulley, mark the holes in the center of the disk. Drill them with a drill, and bolt the pulley and the round plywood base together with bolts.
Step 3. In fact, grinding tool ready, you will need to fix the disc itself on the plywood base, and you can work in peace. Or you can, as in this project, assemble a box from the remnants of lumber so that the power tool looks nice on the outside, and also display the tool start button on its front part. Before assembling the box, be sure to make careful calculations.
Work with the received tool should be extremely careful and in compliance with safety rules. The speed of rotation of the disc is high and the probability of grinding off nails or injuring hands during processing of small parts is high.
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. Such machines have speed control functions, a soft start system. For more precise work, tape machines have a 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 fine work with high 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.
corner Sander it is made from a grinder with its own hands, 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.
One of the main ways to process wood (after sawing, of course) is sanding. The manual method has been known for a long time - a wooden block is 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
On 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 linear velocity 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 manual fixtures. In the mass production of wooden products, such a sledge is an indispensable attribute of any workshop.
The main feature is a predictable result throughout the entire plane. You can level the ends of a sufficiently large length.
The 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.
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.
It 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, spanners other.
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. Cut off the pieces of pipe you need. cutting machine or Bulgarian. 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.
Then this adjusting unit is assembled on a long steel plate, which is welded horizontally to a thinner steel pipe, which is pulled 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 this 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. It's all made from sheet metal suitable thickness and this 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 to obtain the desired thickness. Turning wheels on lathe or on the motor you found for the grinder. The drive wheel is fixed on the motor shaft, and the driven wheel rotates on the bearing.
