Belt is used in cases where it is necessary to perform finishing processing of parts, that is, as equipment for carrying out finishing technological operations. Most often, such machines are used in the furniture industry; they are used to process parts made from various types of wood. But use tape grinding machine It is also possible for processing metal parts, for which a tape with an appropriate abrasive material is used.
Application areas of the machine
The main tasks that it performs band saw grinding group are: final leveling of the surface being processed, bringing the level of surface roughness to the required level, bringing the processed surfaces to the level of smoothness before coating them with varnish and others finishing materials. The belt machine is also used to eliminate minor defects of the processed surface: depressions, elevations and burrs, processing finishing coating: removing sagging primer and varnish, burr, sanding internal surfaces, processing of curves on the surface of the part.
A factory-produced option, the drawings of which can be used to create a similar homemade device.
The band saw can be used to process parts made from various materials: wood, plain and non-ferrous metals. What’s convenient is that you can process parts that have different shape: quadrangular, round and flat. Using such equipment, it is possible to process round and tubular parts with a large cross-sectional diameter.
Design features of the machine
The working tool of any belt is a belt on the surface of which abrasive powder is applied. It is made in the form of a ring and is placed between two rotating drums, one of which is the leading one and the second is the driven one.
Rotation to the drive shaft of the tape machine is transmitted from an electric motor, which is connected to it via a belt drive. The speed of movement of the belt mechanism can be adjusted, thereby changing the processing modes of parts. The belt of a surface grinding machine can be positioned horizontally or vertically, as well as at a certain angle, which is allowed by some models of equipment in this category.
When choosing a belt sanding machine model for processing a particular part, it is important to consider the length of the surface that needs to be sanded. It is much more convenient to process parts on such machines whose surface length is shorter than the length of the abrasive belt and work table. If such conditions are met, the quality of processing will be much higher.
The belt grinding machine can have different 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 work table, which is also a feeding element, is made in the shape of a caterpillar. In those equipment models that have a work table in their design, the abrasive belt is located in a horizontal plane, and in equipment with a free belt that does not have a work table, it can have a different spatial position.
Compulsory structural element any belt sander, including tabletop ones, is exhaust device, which is necessary to remove dust, in large quantities formed during processing. Both a professional and any homemade grinding machine used in a home workshop or garage are powered by electric motor.
Principle of operation
The main operating parameters of a belt sanding machine include the feed speed and the force with which the belt is pressed against the workpiece. Parameters such as the degree of grain size of the abrasive belt should be selected depending on the material from which the workpiece is made, as well as the degree of roughness that the surface of the machined product should have.
The characteristics of the material being processed, in particular its hardness, primarily influence the grit size of the abrasive belt to be selected. Processing modes that are directly related to each other are feed speed and tape clamping force. So, if grinding is carried out at high speed, but with insignificant pressing force of the abrasive belt, then some areas of the surface of the part may turn out to be untreated. If, on the contrary, you increase the clamping force and reduce the feed speed, you may encounter the fact that burns and blackening of the material may appear in certain areas of the surface being processed.
Another variation of the machine - view from the working surface of the belt
The results of grinding are also influenced by how well the abrasive tape is glued together. In order to obtain high quality processing and not encounter malfunctions in the operation of the belt machine, you should not use abrasive belts that are glued incorrectly or have torn edges. When putting the tape on the equipment shafts, it should be positioned so that the overlapping end of the seam does not ride up against the surface of the workpiece, but slides along it. Learn more about gluing tape in the video below.
Any, including a manual grinding machine, must provide the ability to adjust the belt tension, which is ensured by moving a movable shaft that is not driven. Tape tension is a very important parameter, when choosing which you should follow the “golden mean” rule. If the sanding machine belt is pulled too tightly, this can lead to its rupture during operation, and if its tension is too weak, it will cause slippage and, as a result, excessive heating. The main characteristic for determining the degree of tension of the tape is its deflection, which is measured by lightly pressing on its surface in a tense state.
A manual belt grinding machine can be serviced by one operator, who moves the work table with the workpiece and rotates it so as to bring all areas of its surface under the abrasive belt.
How to make a belt sander
Many home craftsmen and professionals are wondering how to make a grinding machine with their own hands. The reason for this question is quite simple: the high cost of serial grinding equipment, which not everyone can pay off if not used regularly. In order to make such equipment, you will need several main components: an electric motor, rollers and a reliable frame. Naturally, drawings of such a device or a photo of it would 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 grinding equipment is not difficult to find; it can be removed from an old one. washing machine. You will have to make the frame yourself; for this you can use a sheet of metal with dimensions 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 180x160x10 mm. Such a platform must be secured to the frame very securely using several bolts.
Another version of the bed
The efficiency of a belt sanding machine directly depends on the characteristics of the electric motor that is installed on it. If you are planning 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 ensure that when using such an engine sanding belt moved at a speed of 20 m/s, the drums should have a diameter of about 200 mm. What’s convenient is that if you choose an engine with these characteristics, you won’t need to make a gearbox for your grinding machine.
The drive shaft is connected directly to the electric motor shaft, and the second - driven - must rotate freely on an axis, which is installed in bearing units. In order for the abrasive belt to touch the surface of the workpiece more smoothly, the section of the frame on which the driven shaft is installed should be made with a slight bevel.
You can make shafts for a belt sanding machine from a chipboard with minimal financial costs. Simply cut square blanks of 200x200 mm in size from such a plate, drill central holes in them and place them on the axle with a package with a total thickness of 240 mm. After this, all you have to do is grind the resulting package and make it into a round shaft with a diameter of about 200 mm.
Drawings and detailed analysis of some parts of a machine made of wood.
Wood belt sander (click to enlarge)
Table tilt adjustment mechanism Plate block Belt tensioner Machine assembly
In order for the tape to be located strictly in the middle of the shaft, the diameter of its central part should be 2–3 mm larger than at the edges. And to prevent the tape from slipping on the drum, it is necessary to wrap a layer of thin rubber on it, for which you can use old tire from a bicycle wheel, having previously cut it along its entire length.
The image shows appearance stationary grinding machine. Due to its rather impressive dimensions, in order to optimize space, a shelf for auxiliary tools is built into its structure.
A homemade grinding machine is designed in the form of wooden structure, similar to a workbench. To give greater stability, the legs of the machine are located at an angle.
The unit is driven by an electric motor. In the context of power characteristics, it would be advisable to take an engine with indicators of 3,000 or 1,500 rpm.
The convenience of using a flanged motor lies in the fact that a rectangular plywood sheet allows for guaranteed perpendicular fixation.
An earring for the tension spring is attached to the plywood.
The working surface of the grinding machine consists of longitudinal bars. WITH inside bars there is a frame with transverse spars. It is designed to mount the engine. Therefore, the width of the frame is determined by the area of the chipboard sheet attached to the gearbox.
A hole for the spring is drilled in the side of the frame. It makes it possible to connect the earring with the eccentric by means of a return spring.
On the side of the grinding machine there is an eccentric with a plumbing pin. One end of the return spiral is attached to it. The mechanism is designed to perform the operation of belt tension. Using the eccentric handle, the spiral is tensioned, and passing through the so-called “dead” point makes it impossible for it to arbitrarily return to its original position.
The sanding belt is placed on two drums. The first of them is made in the shape of a cylinder. A plywood sheet is glued to its outer surface. Pre-bored, made in diameter, which will allow you to put the cylinder on the spindle. Basic parameters of the drum: circumference width D – 120 mm; height H – 150 mm.
To prevent the belt from running away, the factory-produced grinding machine has barrel-shaped drums. Here a simpler method is used to achieve this goal. The boundaries of the cylinder are bordered by washers placed on the spindle. Their diameter should be larger diameter drum pad.
On the other side of the unit, to longitudinal bars glued two-layer plywood. The thickness is about 40 mm. The driven shaft is inserted into a specially made hole.
The grinding machine shaft itself is multi-stage and machined from a metal blank. In its structure it has flanges, a “skirt” and a bearing.
Notice the thread on one end of the shaft. It is necessary for vertical fixation, carried out using a nut
The second drum of the grinding machine has the same dimensional parameters as the first. The only difference is that at the top and bottom, it has specially machined places for bearings. The cylindrical block mounted on the shaft is secured with a clamping nut. 
To achieve a greater effect, a special stop made of board was attached to the horizontal surface of the grinding machine. It is located between two reels. The main condition for installing the stop is the obligatory observance of perpendicularity relative to the base. Also, under no circumstances should he touch the reels. This is necessary to prevent the belt from falling and rolling the edges of the workpiece.
The working surface is covered with a kind of platform. It is made of Finnish plywood and has a specially cut curly shape. The platform acts as a work table and at the same time prevents the engine from falling out. Attached using self-tapping screws. 
An expansion table is mounted on the drive block side. It is very convenient when grinding internal radii. Its fastening is also done using self-tapping screws.
The sanding machine is specially designed for the most affordable and popular belt sizes, which are generally always in stock. It is strictly not recommended to glue the tape yourself using rolled sandpaper, which is sold in stores. Since it has a completely different quality, it quickly becomes clogged with resin and dust. And therefore, it is not effective and in cost, it will ultimately turn out to be much more expensive.
To fully utilize the entire width of the belt, an inclined belt is used. It is attached to the desktop using a plumbing pin on one side, and clamped with a thumb on the other.
Several times, the mentioned plumbing pin performs fastening functions. On one side there is a large thread, like a self-tapping screw, and on the other it is metric.
Video: DIY grinding machine.
A grinding machine is also called a grinder, which is translated from English grinder as crusher.
There are crushers for stones, crushers for meat - we have meat grinders, there are garden crushers, releasing wood chips. But if the word is used independently - simply grinder, only one thing is meant: a grinding machine in the field of metal processing.
Grinder is good and useful everywhere, including household– from competent sharpening of a high-quality knife or tailor’s scissors to grinding a complex part made of metal or other “difficult” material. In other words, the tool is needed and will be useful on the farm.
Moreover, it is quite possible to make it with your own hands. To do this, it is not at all necessary to have special equipment and solid professional experience.
Of course, you will have to tinker, but you will do exactly what you need and, most importantly, you will save a serious amount of money, up to several thousand American dollars.
Do we do it with a disk or with a tape?
Grinder drawing.
In terms of the breadth of the product line, grinding machines can only be rivaled by lathes. There are a huge number of grinders on the market – of all shapes and sizes.
The most famous and primitive one is in the form of the famous emery - a pair of grinding stone wheels with a screwed-on motor. These machines are sold with a wide variety of schemes and operating principles.
But if you're planning on making a DIY sander yourself, it's best to stop and choose between two options: disc or belt.
- Disc grinder - a grinding layer of abrasive is applied to the disk, which rotates when turned on.
- A belt machine in which the abrasive is applied to a belt wound on rollers.
Which one is better is a matter of debate. The correct criterion would be “which one is more necessary”. The choice should depend on what exactly you are going to sand. If it's relative simple details made from, say, wood, homemade disc grinding machines for wood are more suitable for you.
If you have serious grinding work ahead for precise finishing with complex parts, choose a tape.
It is necessary to take into account the difference between a suit and a tape, not only in terms of their functional features. Another important factor– drive power. Sanding wooden mortars small size– you will have enough power within the range of 160 – 170 W.
This will easily be produced by an elementary motor from washing machine or even from an old drill.
Old household motors are in no way suitable for a belt grinder. There you will need an engine with a power of at least 400 - 500 W, and not a simple one, but a three-phase one with starting and running capacitors.
For grinding massive and large parts, higher power will be needed: up to 1200 W. Let us immediately note that purchasing capacitors for the machine will cost you not much less than the motor itself.
Selecting a feed
A machine with a tape is more versatile in terms of functionality: it does everything that disk models do, plus much more. Let us immediately note that there are a great many options for amateur models of belt sanding machines.
The fact is that the nature of this machine is very flexible, allowing you to use a variety of available materials, including finds in scrap metal dumps.
The main thing is to know and adhere to three rules:
- The abrasive side of the belt must be adjusted very precisely so that only the workpiece that is being sanded touches it.
- The tape must be evenly tensioned at any time and regardless of the type of work.
- The speed of movement of the machine should be different and should depend only on one thing: the type of part and the nature of the grinding.
Construction of a homemade belt sanding machine
Grinding machine device.
The main parts of the machine are as follows:
- A motor or motor-driven engine powered by electricity.
It is better to install the drive next to the main diameter drive roller. - Base or bed.
It is often fixed directly on the floor, sometimes this thing rides on wheels - whatever is more convenient and necessary for you. - Two tension rollers - driving and driven.
Make of metal or very durable wood with a thin layer of cushioning rubber to prevent the tape from slipping onto the rollers or drum. - Spring and lever for the belt tension system.
The spring is pressed, and the lever is attached to the base and driven roller. - Base for placing a motor with a drive.
- For abrasive tape you need to use paper or cloth.
Its width can be very different - in the range from 5 to 30 cm. Grit level - from 80. - Metal pipes with a thickness of 2 mm or more.
- Metal corners in accordance with the dimensions of the machine.
- Special magnetic stand for metal parts.
- Rail type guides.
Diagram of the grinding machine.
Stages of work:
- We make the frame of the base or bed.
– we cut the corners according to the dimensions of the bed;
– weld the frame and corners;
– we fix a chipboard board at the bottom of the frame to reduce vibration during operation. - Making a work surface.
– cut a steel sheet to size and weld it directly to the base;
– weld the rail guides to the top of the frame;
– we make a carriage from corners with wheels for moving along the guides of the bed;
– on both sides of the working surface we mount and fix bearing supports;
– fix the screw with the handle on the carriage; - We fix the electric motor to the working area lifting system.
- We fix the gear supports.
- We install a tape with an abrasive coating.
– cut the tape with a margin of a few centimeters at an angle of 45°;
– glue it together overlapping with glue on the sides with the abrasive washed off with water;
– dry the gluing area with a hairdryer; - We are preparing for a test launch of the machine.
– we treat all machine parts with machine oil;
– supply electrical power;
- We do a test run.
Safety precautions when working on a sanding grinder
Like any other work on any other machines, grinding on a homemade belt sanding machine is subject to fairly strict safety rules that must be strictly adhered to.
The principle of operation of the grinder.
These rules are as follows:
- It is strictly forbidden to touch anything that moves with your hands while the machine and working surface are operating.
- Wear safety glasses while working to protect against hot abrasive particles.
- Carefully check that the connections and fastenings of all moving parts of the grinder are tight.
- Monitor the condition of the braiding of electrical wires.
- A protective casing is a must, even though it slightly narrows the viewing angle.
One of the final operations in the manufacture of products is grinding. To do this you can use sandpaper, grinder or grinder. Most often, sanding is required in furniture production. The most productive and accurate will be the tape type.
It can be used for finishing Not only wooden parts, but also metal, using the appropriate abrasive material. You can get rid of grooves and burrs, remove old coating, get a smooth surface, or calibrate a part.
Types of grinding equipment
For finishing wooden products There are several types of grinding equipment.
Varieties depending on the type of grinding surface:
- Disk. The part is processed on a work table perpendicular (or at an angle) to which there is an emery disk connected to the engine. Designed for cleaning cylindrical, conical or spherical parts. Productive and compact machine.
- Drum. The working body of the equipment, as the name suggests, is a drum. To increase productivity or combine rough and fine grinding, install two drums with different sizes abrasive grains. Designed for processing long flat workpieces (boards, slats).
- Tape. The grinding part is an abrasive coated belt. The machine is different high performance and relatively low cost.
Belt Sanding Machine
Types of machines depending on the type of workpiece:
- Cylindrical grinders. They are used to process conical and cylindrical outer surfaces of workpieces.
- Centerless. Designed to work with long parts or without a hole in the center.
- Internal grinding. Grind holes of different shapes. Most in demand in industry.
- Surface grinding. Allows you to process the ends and periphery of the circle. They can be equipped with tables that rotate or move longitudinally.
The most in demand not only in production, but also in private households are belt surface grinding machines.
Construction of the tape machine
A wood sanding machine consists of a motor that rotates the drums using a V-belt drive.
A tape with abrasive particles, which is connected at the ends, is pulled onto the drums. It can be located both in a vertical and horizontal position, as well as at an angle.
For ease of processing parts, many machines have a table mounted perpendicular to the working body. To regulate the processing mode of workpieces, you can change the speed of movement of the drums.
For the convenience of working on a belt sanding machine, you need to take into account the difference in the length of the belt and the size of the workpiece. The tape should be longer than the surface of the workpiece. In this case, grinding will be more efficient and of higher quality.
The nuances of the execution of the tape machine may vary. The desktop can be movable or rigidly fixed. The work table can also be made in the form of a caterpillar, additionally performing the function of feeding material.
Or there is a complete absence of a desktop and the presence of a free tape, which can be in any position. The width of the abrasive belt may vary.
Any surface grinding belt machine is equipped with a device for aspirating dust that occurs during grinding.
The operating parameters of grinding equipment are the speed of movement of the belt, the force of pressing the part against the belt, and the tension of the belt. If the belt speed is too high and the pressure is too low, some parts of the workpiece may remain unsanded.
If the part is pressed too hard and the tape feed speed is low, on the contrary, the part can be damaged. The belt is tensioned by moving the driven drum.
The working machine itself may differ in grain size. It is selected depending on the required smoothness of the part and the material of the workpiece. It is the hardness of the workpiece that primarily affects the nature of the abrasive surface.
The quality of the tape gluing affects the work. It must be correctly connected, intact and without damage, so that during the grinding process there is no disruption to the operation of the equipment.
When pulling the tape onto the drum, you need to ensure that the seam during operation does not cling to the material being processed, but slides along it. That is, the connection of the tape should lie in the direction of movement, and not against it.
DIY grinder
Making your own grinding machine
At home professional equipment does not pay for itself soon due to irregular use. You can make a belt sanding machine with your own hands to save money on purchasing such a tool.
A homemade surface grinding machine has the main structural components - a motor, a frame and drums.
How to make a grinding machine? For the frame it is better to choose a metal sheet, minimum dimensions which is 500x180x20 mm. The larger the dimensions of the working surface, the more convenient and the more different parts can be processed. It is important to process the side of the frame to which the platform with the electric motor will be attached very smoothly.
The guillotine can help deal with this. The platform for the engine must be made of sheet metal with dimensions 180x160x10 mm. But you definitely need to check whether its dimensions correspond to the dimensions of the engine. The sheet is attached to the frame with several bolts.
The motor for a homemade belt sander can be a motor from a washing machine.
Washing machine engine
It is worth selecting an electric motor with a power of up to 3 kW and a rotation speed of about 1500 rpm. It is important to fix the unit on the site firmly and securely.
For a DIY woodworking machine to work effectively, the belt speed should be about 20 m/s. To ensure this mode, the diameter of the drums must be 200 mm.
With such parameters, there is no need to use a gearbox. The driving drum is connected directly to the motor shaft, and the driven drum rotates freely on the shaft in bearings.
To save money, you can use homemade drums:
- Make 20x20 cm squares from chipboard sheets.
- Make a stack 24 cm thick from sawn squares.
- From a package folded in this way, cut out a disk with a diameter of 20 cm. When making drums, you need to take into account that in the section the diameter of the outer part should be 2–3 mm less than the diameter of the central part. This will ensure that the belt is centered on the drum.
The width of the sanding belt should be 200 mm in accordance with the width of the drums.
It is necessary to select the appropriate width of the sanding belt
To make it, you can take sanding strips and carefully glue them together. As good foundation Can be canvas fabric.
To prevent the belt from slipping when moving, it is recommended to cover the drums with rubber. For example, you can use inner tubes for a moped or bicycle. The desired height of the rubber layer should be 3 cm.
By making a belt sanding machine, you can get a set of not only equipment for grinding wooden workpieces, but also a tool for high-quality sharpening of cutting metal objects.
Video: How to make a mini belt sander
During construction and repair work Men often need to process wood, stone or metal. For quality work, it is advisable to purchase a belt sanding 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 sanding machine with your own hands.
Purpose of a belt sanding machine
Wood is widely used in a wide variety of manufacturing organizations. Many different parts and products are made from wood. 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 is usually used on final stages production, when parts are subjected to finishing machining. Such devices are convenient to use in furniture production and different products made from wood for consumer use. Depending on the material used, belt sanders work with wood or metal.
The main purposes of using wood sanding machines are to final level the surface, bring their roughness level to the required value, obtain smooth and smooth surfaces for wood products and wood material before veneering or after coating with varnish and other finishing materials, removing local irregularities in the form of depressions and elevations, peeling off burrs and removing local deposits of varnish and primer, removing burrs, internal grinding and grinding of curves.
Belt grinding machines for metal work with various materials and formats that are popular in metalworking: plain and alloy steel, non-ferrous metals in the form of quadrangular, round and flat blanks. Grinding machines allow efficient and effective minimal costs time to grind round timber and large diameter pipes.
Depending on the type of processing and type of feed, belt grinding machines are intended for:
- for grinding curved surfaces with a free sanding belt;
- for processing 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 block parts, their ends and side edges;
- for intermediate sanding of paintwork.
Belt Sanding Machine Design
Belt grinding machines are produced by modern foreign and domestic manufacturers in a wide range. Grinding machine prices vary widely. They also differ in possible performance and 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 element, which is most often connected into a ring and placed between rotating drums.
One drum is the master drum and the other is the slave drum. 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 sanding machine is designed in such a way that the speed of movement of the drive 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, equipment modifications are available for sale in which the working element is installed at a certain angle. The abrasive belt is mounted on a frame, on which the workpieces are usually located. Workpieces can be held by the operator manually or with the help of special devices that make the work easier for consumers and make the processing procedure more efficient and safe.
The machine table is made from metal sheets or thick boards. If the design provides for the table to be made of metal, then it will be possible to sharpen more complex products. The length of the working part of the belt grinding machine and the grinding belt itself primarily depends on the length of the products that will be sanded on the machine.
If the part is shorter than working surface machine, it will be much more convenient to process, and the processing will be of higher quality. For example, with a sanding belt length of 4.5 meters, you can easily process wooden workpieces that are 200 centimeters long.
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 caterpillar-shaped table is also a feeder. For machines with tables, the belt is placed horizontally; for designs with a free belt, it is installed in different ways.
Since the grinding process inevitably generates a lot of dust, all belt sanding machines are usually equipped with special powerful hoods that remove most of it during the process. technological process. Grinding machines are powered by an electric motor, which has a power of about 2.8 kilowatts. With motor high power The normal speed of the belt reaches 20 meters per second.
Abrasive belts for grinding machines
The cutting tool of belt sanding machines is a sanding belt, which consists of fabric or paper base and abrasive grains that are attached to it using adhesives. Abrasive belts are manufactured using two methods: mechanical and electrical. The first method consists of uniformly pouring abrasive grains onto a base that is covered with glue, and the second method occurs in electric field, which orients the grains upward with their sharpest edges to improve the cutting properties of the grinder.
Abrasive grains are poured onto the base in a bundle tightly or sparsely. The most effective is considered to be an abrasive belt with a sparse backfill, when the grains occupy less than 70% of the area, because wood dust generated during the grinding process is not able to get clogged between their grains. Natural minerals or artificial materials, which have high hardness, for example, green and black silicon carbide, white and normal monocorundum, as well as normal electrocorundum.
For the purpose of gluing grains, synthetic resins and hide glue are used. As a base, fabric such as calico and twill, or special grade paper is used. The size of the abrasive grains is indicated by a number that corresponds to the size of the sieve cells in which these grains are retained, and is displayed in hundredths of a millimeter.
If you are interested in how to make a belt sanding machine, 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 sanding machine, 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 - lap or butt at an angle.
The ends are cut off when gluing end-to-end at an angle of 45 degrees and then glued onto a canvas lining with a width of 80 to 200 millimeters. At one end of the tape, when gluing with an overlap, the abrasive grains are removed hot water over a distance of 80 to 100 millimeters, then place the other end of the tape on the exposed base coated with glue. Compress the joined ends and dry them using a special device or a size press.
Sheet sandpaper is used for combined belt-grinding machines. For grinding discs It is customary to cut the skin in the form of a circle according to a template, the diameter of which is 60 - 80 millimeters larger than the diameter of the disk. Using a rectangular template, blanks are cut for the reel. After cutting, they have smooth edges without tears. The presence of unglued ends or seals when gluing tapes can cause premature rupture of the tape.
The skin is cut for wide-belt sanding machines into sheets according to a template made of plywood or aluminum sheet. The skin is cut in such a way that the edges are smooth and the difference in the length of the side edges is no more than 1 millimeter. One of the beveled edges is cleaned, removing abrasive to a width of 20 millimeters. The cleaned edge and longitudinal edges are covered with a strip of tracing paper, 40 millimeters wide, which protrudes beyond the edge of the sandpaper by about 10 millimeters.
Lubricate the beveled edge with tracing paper with glue and leave it in the air, depending on the viscosity and type of glue. Then the beveled edges are joined and a strip of sandpaper is applied to the joint, the joint is compressed and held in a press. It is customary to hang finished endless belts on special brackets and keep them for at least a day in a dry room before installing them on a grinding machine.
Operating principle of a belt grinding machine
A belt sanding machine consists of a table top with a work table for mounting the cutting tool. This table is fixed in different positions relative to the tabletop. The material for the countertop is usually laminated Chipboard thickness 25 millimeters. The worktable on rollers is moved manually or laterally by a mechanical drive along round guides that are attached to supports.
Above the table there is a working belt mounted on non-drive and drive pulleys. The sanding belt is tensioned and adjusted using screw device with pneumatic cylinder. Double belt sanders have two identical sanding tools that are placed in series on a bed and have sanding belts that move towards each other.
Grinding is carried out by the transverse movement of the work table and the longitudinal movement of a short iron, which presses the belt to the material being processed. The sanding belts are driven by an electric motor via a belt drive. The waste generated during grinding is collected by a dust collector, which is connected to the exhaust network.
When assigning a grinding mode, it is recommended to select the grain size of the sandpaper, the feed speed and the pressing force of the belt to the product based on the specific roughness and properties of the material being processed. The grain size of the skin is usually chosen depending on the hardness of the materials being processed and the required surface roughness. The clamping force and feed speed are interdependent quantities. With little force and high speed of feeding the sandpaper, some areas of the surface may not be sanded; high pressure and low feed rates, burns and blackening of the material are possible.
Before installing the tape, check the quality of its gluing. Do not use incorrectly glued or torn sanding belts with uneven edges. Using the handwheel, you can reduce the distance between the pulleys and put on the belt. The gluing area is placed so that the outer end of the seam on the abrasive side 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 tighten the tape too much, as this will cause it to break. But the sanding belt, with low tension, slips along the pulleys 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 slight pressure on it.
How correctly the belt runs can be checked by turning the pulley manually or briefly turning on the electric motor. When the belt slips, the pulley axis is turned by a handle at a small angle and secured with a locking device. After setting up the belt grinding machine, the dust suction system is turned on, a trial processing of the parts is carried out and their quality is checked.
A manual feed belt grinder can be operated by one worker. By moving the product relative to the cutting tool in the longitudinal direction and rotating the part around its axis, the operator sequentially brings into contact with the tape all areas that form the surface to be processed. If you slow down or move carelessly, sanding may occur.
It is customary to grind individual sections of a part in several passes. High-quality leveling can be achieved by properly regulating the pressure applied to the handle of the iron and the speed of movement of the table and iron. The pressure must be reduced as you approach the edges to prevent them from being sanded 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 grinding machines with mechanical feed of products are serviced by two operators. One of them places the part on the conveyor, orients it along the width of the work table and directs the product under the clamping elements of the machine. When being picked up by a conveyor, parts must not be moved laterally.
It is not allowed to feed into the machine workpieces that have 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 receives finished parts and ensures that unacceptable edge rounding and sanding does not occur.
Making a Belt Sanding Machine
Price of belt grinding machines from 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 motor can be removed from an old washing machine. Cut the frame from thick iron measuring 500 by 180 by 20 millimeters. Cut one side straight milling machine for metal, it is required to attach the platform with the motor. The dimensions of the working platform are approximately 180 by 160 by 10 millimeters. Make markings and drill three holes in the end of the evenly cut frame. It is necessary to tighten the platform to the frame with three bolts.
Remember that the longer the work table is, the more options you will have 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 work table, then you can achieve a perfect grind much easier than when moving a large workpiece.
The engine must be placed tightly on the frame. It should have a power of approximately 2.5-3.0 kW and a rpm of about 1500. If you choose a sanding belt speed of approximately 20 m/s, then the diameter of the drums should be about 200 millimeters. Thus, if the engine speed is sufficient, a gearbox for the grinding machine is not required.
One of the two drums will play the role of a drive drum, which should be firmly 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 should have a certain bevel, which will ensure smooth contact of the sanding belt with the surface of the work table, this is especially true for a glued joint.
You can make a tension drum and a drum that guides the sanding belt from chipboard. To do this, you need to saw blanks from the slab overall dimensions 200 by 200 millimeters and from them assemble a package of 240 millimeters. Square tiles or a package of them should be folded on an 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 a similar surface geometry, the flexible sanding belt will be located in the middle of the drum. The optimal tape width is 200 millimeters. From a roll of emery cloth that is 1 meter wide, you can easily glue 5 similar tapes together.
Glue cutting tool it is necessary end-to-end, placing a thin dense material, for example, a tarpaulin, underneath. It is recommended to use the highest quality glue you can get. Be sure to stretch rubber onto the rollers, the width of which reaches 30 millimeters. Rubber can be taken from the inner tubes of a moped or bicycle.
On a homemade belt sanding machine, 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, pruners. Another advantage of this grinding machine is the ability to work with parts that have a curved surface - for this you need to grind the workpiece reverse side working tape.
