Hand power tools At the moment they have become so widespread that not a single craftsman can do without them. However, sometimes this toolkit is not enough, and there is a need serious equipment his workshop. So in my practice, a period came when a belt grinding machine became necessary, allowing me to process the surfaces of large parts.
Industrial copies of grinding machines are too expensive. So I had to come up with something myself. An ordinary manual belt machine, in which a continuous sanding belt moves along a straight surface of the soleplate with the abrasive side outward, seemed to me the ideal structural prototype for a homemade machine. Naturally, my machine will be much larger in size, and it will be installed permanently.
It so happened that I needed to process a large number of parts about two meters long. This determined the dimensions of the table and the future machine itself. (photo 1).
There was no need to choose an electric motor. I installed the motor I have on the machine with a power of 2.5-3.0 kW and a speed of 1500 per minute. If the belt speed is chosen to be about 20 m/s, then the diameter of the drums should be close to 200 mm. Thus, it turned out that at the speed of our engine, the machine does not require a gearbox.
Of the two reels, one plays the role of the leader. It should sit rigidly on the motor shaft, and the other - the tension one - should rotate freely on bearings around a fixed axis. To regulate the tension of the tape, it is enough to shift this axis along the desktop in one direction or another (photo 2). I built the table from thick pine timber, but now I think it should have been made from sheet metal. "
It is quite obvious that the distance between the shafts and the length of the sanding belt depend on the length of the table. The size of the entire platform on which the machine parts are mounted (electric motor with drive drum, work table, driven drum with tension device) is also decisive. On the side of the driven drum, the table must have a bevel (photo 3). ensuring a smooth touch of the tape (especially its glued joint) to the surface of the desktop.
Make a leading sanding belt (photo 4) and tension (photo 5) drums can be made of chipboard. To do this, it is enough to cut blanks measuring 200x200 mm from the slab and assemble a 240 mm package from them. Square tiles- each separately or (if the lathe allows) together, placing the blanks on an axis, - grind to a diameter of 200 mm. The latter option is preferable, since the drum can be made in one installation. It should be borne in mind that the diameter of the drum in the center should be 2-3 mm larger than at the edges. It is known that with such a surface geometry, the flexible tape will be held in the middle of the drum. In my opinion, the optimal tape width is 200 mm. From one roll of emery cloth 1 m wide you can easily glue 5 such tapes.
If at the very beginning I expected to process exclusively wooden blanks (photo 6-10), then during operation I discovered the ability to quickly and efficiently sharpen special tools, for example, various profile fully assembled cutters.
It turned out that the longer the work table, the greater the opportunity for imagination when choosing a technological method for processing a product. Personally, I had to work with a tape of about 4.5 m, while the length of the processed parts reached 2 m. This does not mean that the length of the workpieces cannot be even greater. Under certain conditions, the length of the workpieces being sanded may not matter. If they are narrow, then any of them is the machine's capabilities. Now I don’t have to go to specialized workshops to sharpen cutting tools: planes, jointers, surface planers, etc. (photo 11-13). Such quality of ax sharpening (photo 14), knives, chisels and various chisels I could not achieve before on any universal sharpening equipment. And if you remove wooden table and make it from iron, it will be easy, you can put it on an abrasive belt (photo 15). But when the length of the workpiece is equal to or less than the length of the table, then achieving perfect grinding of the entire surface is much easier than when moving a large workpiece.
Belt is used in cases where it is necessary to perform finishing work on parts, that is, as equipment for 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 you can also use a belt grinder to process metal parts, for which a tape with an appropriate abrasive material is used.
Application areas of the machine
The main tasks performed by the belt grinding machine are: final leveling of the surface being processed, bringing the level of surface roughness to the required level, bringing the processed surfaces to a 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. Conveniently, using a belt machine you can process parts that have different shapes: 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 feed 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 sanding machine, including a tabletop one, has an exhaust device, which is necessary to remove dust generated in large quantities during the processing process. Both a professional and any homemade grinding machine used in a home workshop or garage are powered by an 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. To obtain high quality To avoid problems with the belt machine, do not use abrasive belts that are not glued correctly 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 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 for the sanding belt to move at a speed of 20 m/s when using such a motor, the drums must 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
When working with wooden surface is coming to an end, the final polishing stage begins. To perform grinding without burrs, scratches, and to beautifully round sharp corners of any part, you need to use a wood sander. This tool will help you perform professional grinding even for a beginner who picks up the machine for the first time. If you wish, you can make a grinding machine yourself, using only available tools.
The industry produces several types of machines, differing both in design and purpose. Here are the main ones:
- Eccentric or orbital, in this case the base of the tool simultaneously rotates around its axis and along a certain orbit. It turns out that each time it passes in a slightly different place, so scratches and burrs are rubbed out more and more with each pass.
- Vibration model. Here the working sole carries out reciprocating movements with a frequency of about 20,000 movements per minute. It is through these movements that grinding occurs.
- An angle grinder, which is popularly called a “grinder”. This tool is used for rough processing of parts, large logs, etc. Abrasive wheels of the required grain size are used for processing.
- Tape Sander, which is usually used for working on large surfaces. Structurally, it consists of rollers driven by an electric motor, on which sanding tape is worn.
Making a belt sander with your own hands + (Video)
Do belt sander It’s not at all difficult to do it yourself, you just need to follow these steps:
- pick up suitable materials and details;
- do solid foundation for securing the tool;
- install a suitable tabletop;
- secure the vertical posts with tensioner and drum;
- mount the motor and drums;
- secure with sanding tape.
To process fairly large parts and elements, it is necessary to make a large copy of a serial grinder. For example, if you take an electric motor with a power of 2 kW or more powerful with a rotor speed of 1500 rpm, then you don’t need to install a gearbox. The power of such an engine is quite enough to rotate a drum about 20 cm in diameter and process parts of about 2 m.
You can also use an electric motor from an old washing machine. In this case, the frame is made from a thick sheet of iron, preparing a place for installing the motor and carefully securing it with bolts to eliminate vibration. The design of such a machine consists of 2 drums, one of which is fixed, and the second can be tensioned and rotates on bearings around an axis. It is advisable to make the base for the machine from metal or several sheets of thick plywood. The drums are made on a lathe from chipboard. The tape is cut from sandpaper sheets about 20 cm wide and secured to the frame. The larger the table size, the larger the parts can be stacked and processed in the future. Drawings of finished products can be found online.
https://youtu.be/vDs1gBM_MW4
Making a grinder from a grinder
Many may say that the “grinder” is the same as an angle grinder, but there are some subtleties hidden here. It should be borne in mind that the angle grinder has very high speeds and often quite a decent weight. To polish a surface with a grinder, you need to have considerable experience in this matter and use special polishing discs and circles. The grinder has much lower engine speed and weight. To operate a factory grinding machine, no specific experience or skill is required.
You can independently make a good grinder from a grinder, which is not inferior in its parameters to a factory machine, only by modifying its electrical circuit, by installing the regulator at lower speeds and by using special grinding attachments.
Making a grinder from a drill
To turn an ordinary household electric drill into a grinding machine, you need to equip it with a special attachment - a working drum or a special support plate, depending on the task at hand.
The support or sanding pad is a plastic or rubber base with sandpaper glued on and a shank for clamping into the drill chuck. Discs with a flexible shaft are suitable for working with a loose drill, while those with a rigid shaft are best used only for a well-secured drill.
Sanding drums for household drill Structurally, they represent a regular cylinder, a shank and a stick glued to the cylinder. sandpaper. When using drums working surface The grinder is located parallel to the axis of rotation.
Making an orbital sander
Currently, you can only make an orbital machine with your own hands from a broken orbital machine. This is due to a complex device for rotating the working disk, which is quite problematic to replicate on your own. You should also keep in mind that a machine manufactured by a specialized company will not cost too much, but making it yourself will be very difficult and will take a lot of time.
Making a grinder from a computer hard drive + (Video)
Anyone who has served his time HDD can be converted into a miniature grinding machine. To do this you need to follow these steps:
- completely disassemble the hard drive and remove from the case everything that is located to the left of the magnetic disks;
- cut out a working circle from sandpaper, make a hole in the center of the circle for the spindle;
- stick several strips of double-sided tape onto the rotating disk of the hard drive and secure it with sandpaper;
- make a protective screen to protect the eyes from the possible ejection of the manufactured sanding disc;
- connect the finished design to the power supply from the computer and use it.
Of course, this design does not have high power, but it is quite possible to sharpen a small knife or scissors.
Grinding machines from the manufacturer are expensive and therefore if they are used infrequently, then you involuntarily think about whether to buy it or not.
And if, in addition, there is no free money, then you have to make something with your own hands. This is what happened with this homemade grinding machine.
The simplest hand-held sander was taken as a sample (read about how to choose an eccentric sander). In such a sander, the abrasive belt moves along the surface of the sole, with the rough side outward (abrasive).
That is, in the future belt grinding machine I laid down the same principles in advance, changing only the dimensions in the plans - I need a large machine so that it can be used to process parts of at least 1.9-2 meters by grinding, and it must be installed permanently.
The entire design of the grinding machine is based on an electric motor with a power of 2.8 kilowatts and a speed of 1500, I already had it, so I didn’t have to buy anything.
There was no need to install a gearbox, because with an electric motor of such power, in order to achieve a normal belt speed (which will be quite enough for grinding) of 20 meters per second, the diameter of the drum should be only about 20 centimeters.
The design has 2 drums: one, rigidly fixed to the shaft - the driving one. The second is tension, it rotates around an axis on bearings.
To tighten or loosen the sanding belt, just adjust this axis in either of the 2 directions.
The machine table is made of thick boards, if possible in the future I will remake it and make it out of metal sheets.
The length of the working part of the machine, as well as the grinding belt itself, depends, first of all, on the length of the working surface of the table. The second shaft is equipped with a bevel as shown in photo No. 3, this is necessary to ensure that the tape touches the edge of the table as smoothly as possible.
Both drums can be made from ordinary chipboard. To do this, cut square tiles 20 by 20 centimeters and assemble them into a workpiece of 24 cm and then grind them on a lathe to a diameter of 20 centimeters. When making a drum, take into account the fact that the tape will stick to it better if it is a couple of millimeters larger in diameter at its center.
About the sanding belt. Through trial and error in practice, I found that the best width of the sanding belt is 20 centimeters - with this width you can perform all the tasks facing the machine and, moreover, cut 5 such belts from a meter roll of sandpaper, without any residue.
In addition to grinding wooden parts, for which it was originally intended, such a homemade machine is very convenient and quick to sharpen any tools with cutting surfaces - knives, chisels, axes, knives, secateurs, etc. The sharpening quality is excellent.
In principle, if the design includes making the table not from wood, but from metal, then it is possible to sharpen more complex, special tools, the sharpening of which cannot be handled by any universal device.
Let me emphasize once again that in this machine a lot depends on the length of the table. It is this that gives you scope for possibilities, because when a part is shorter than the length of the working surface of the machine, it is much more convenient to process it and the processing will be of higher quality. For example, with a sanding belt length of four and a half meters, you can easily process wooden workpieces 200 cm long.
Another advantage of such a do-it-yourself grinding machine is that with some skill you can also work with parts that have curved surfaces (as shown in photo 16) - to do this, just remove the wooden table and, placing the workpiece on the bed, grind the part the reverse, bottom side of the working tape.
DIY belt grinding machine: photo
Below are other entries on the topic “How to do it yourself - for a homeowner!”
For wood - a highly efficient device for processing material planes. Using such units, you can quickly and efficiently process wood, obtaining perfectly smooth surfaces.
Classification
A wood sander is used at the final stage of wood processing. During the work, special rough circles, tapes, and powdered pastes are used.
Currently, based on their purpose, the following units are distinguished:
- Automatic cylindrical grinding devices.
- Devices designed for processing the internal surfaces of parts and workpieces.
- Surface grinding machines.
- Specialized models that are used to implement narrowly focused tasks.
Areas of application
The areas in which a wood sander can be used are extremely varied. The latest advances in the field of carpentry processing of parts make it possible to replace large turning units with more convenient to use mobile devices.
Such common solutions as drum and belt sanders for wood can be successfully used for:
- Rough abrading of workpiece surfaces.
- Precise processing of wood planes.
- Obtaining refined surfaces.
- Cleaning of timber and panel parts, their side and end edges.
- Intermediate sanding of paint and varnish coatings.
Thanks to its wide range of uses, a wood sanding machine is one of the most popular units among professional carpenters. Manufacturers are constantly improving popular models and offering consumers a whole host of additional tools to perform complex, specific tasks.
How to assemble a wood sanding machine with your own hands
We propose to consider the features of self-assembly of a drum device for processing the external surface of wood. This will require several functional design elements. Some of them can be found in the household.
Engine
To assemble a wood sander, the easiest way is to remove the motor from an old washing machine. Fortunately, Soviet-made models gather dust idle in many closets. From here you can get belts, pulleys and electrical parts.
However, any motor with a power of 200 to 300 W is suitable for assembling the grinding unit. It is desirable that its design be compact in size.
If it is necessary to obtain maximum efficiency indicators, you will have to find asynchronous motor, capable of delivering 1500-3000 rpm.
Drum
This structural element can be made using all kinds of leftovers building materials. Sometimes, to assemble a drum sanding machine for wood, it is enough to take a pipe covered with old linoleum, rubber rings glued together or cylindrical bars mounted on a metal axis. Let's look at the first of these options.
To make a drum, it is enough to use a piece of PVC pipe, a metal rod, a strong board, screws, glue and linoleum. Plugs are cut out of wood corresponding to the cross-section of the existing tube, in which holes are drilled for the rod. Such locking elements are inserted into the pipe and secured with screws.
A metal rod is passed through the plugs and seated on epoxy glue. A layer of dense linoleum is glued on top of the polyvinyl chloride pipe. As an alternative, you can use rough rubber. This shell will act as the basis for securing the sandpaper. You can fix the latter on the finished drum using double-sided tape or staples for a stapler.
Frame
For making a case where a homemade wood grinding machine will be placed, it is suitable regular plywood. You can make a design of a rather unassuming structure. Just install side panels, work table and additional reinforcement struts. If desired, you can make a metal shell.
Installation
The engine is securely mounted on a statically installed base. The rotating axis is threaded through a pre-prepared hole in the housing wall. The grinding drum is installed in the upper part and rests on bearings in cages that are fixed on the side walls of the structure.
Pulleys are attached to the axis of the drum and engine. The drive belt is being tensioned. Wiring and switches are connected. Clamping bolts are screwed into the sides of the housing, and adjustment bolts are screwed into the lower part.
To give the structure a complete and attractive look, you can treat the surfaces with paint. Naturally, it is necessary to undertake such work before assembling and installing the unit. To increase safety during operation of the device, the design can be supplemented with a protective casing placed above the drum.
Finally
Thus, we tried to consider the main classes of grinding machines, their areas of application, and also gave an example of self-assembly of the unit drum type. Ultimately, the decision to purchase a factory device or assemble it from existing materials depends on the size of the budget, goals, available funds and the needs of each individual user.
For finishing wood, metal or stone, you can build a belt sanding machine 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, remove burrs, remove local defects, remove burrs formed during welding, carry out internal grinding, etc.
Manual execution of such processing is very labor-intensive and low-productivity, and the cost of grinding machines industrial production quite high. That’s why we have to come up with and build homemade structures, especially since they are not particularly complex.
General information about the design of belt sanders
Belt grinders, despite the apparent diversity of their designs, have common distinctive features. An abrasive tape 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 reels: the first is the leading one, and the second is the driven one. The drive drum is driven by an electric motor through a mechanical transmission. This is usually a belt drive. It is desirable to have a device that allows you to change the rotation speed of the drive 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 anything: vertical, horizontal or inclined. The tape is usually mounted on a frame, and the workpieces can also be placed there. In homemade designs, the workpieces are usually held by hand, although there may be other options.
The length of the working part of the sanding belt depends on the size of the workpieces being processed. The grinding process is accompanied by the release of a large amount of dust, so it is advisable to have exhaust device. To adjust the degree of belt tension, a tension roller is often used.
Depending on what the grinding machine will be primarily 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 work 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, panels and similar parts;
- sanding of intermediate layers of paint and varnish coatings.
Return to contents
Homemade belt sander
The structural prototype of a homemade grinding machine was a conventional industrial design in which the belt moves with the abrasive part outward over the flat surface of the work table. The resulting sander is distinguished from the industrial design by its increased dimensions and stationary installation.
Since a gearbox or belt drive complicates the design, an electric motor is used, the rotor of which makes 1500 rpm. The power of the electric motor should be about 2-3 kW. With a drive shaft radius of 10 cm, the linear speed of the belt will be about 15 m/s. As already mentioned, a gearbox is not needed in this case. There is no provision for adjusting the rotation speed in such a simple design.
The drive shaft is rigidly mounted on the electric motor shaft, and the second shaft tensions the belt. To reduce friction, the tension shaft rotates on bearings sitting on a fixed axis. This axis can be shifted relative to the work table in one direction or another, decreasing or increasing the degree of tension of the sanding belt.
The desktop can be made from scrap 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 table surface should have bevels to ensure smooth contact of the tape (especially its joint) with its plane.
Both drums are easy to make yourself. The material for their manufacture can be chipboard. Squares with a side of 20 cm are cut from the original slab. Their quantity should be such that the total thickness of the set is about 24-25 cm. They are made from them at lathe discs with a diameter of 20 cm. There are two options for processing them:
- You can grind each workpiece separately on the machine.
- A more preferable option is to place the blanks on the axle, clamp and grind them all together.
The groove should be carried out in such a way that the edges of the drums are several millimeters smaller than their middle. This is necessary so that the abrasive belt is automatically installed in the centers of the drums.
I have been making knives for several years now and always use 2.5 x 60 cm and 10 x 90 cm belt sanders in my work. For a long time I wanted to buy another one, with a tape width of 5 cm, as this would simplify my work. Since such a purchase would be expensive, I decided to make it myself.
Problems when designing a future machine:
Three limitations had to be overcome. Firstly, there was no 10 cm wide tape available locally; it could only be ordered online. This didn't seem like a very viable option to me, as there is no greater disappointment than finding out that the tape has worn out and needs to be replaced, and you have to wait a week or two for a new one to arrive. Secondly, there was a problem with the rollers. I searched but couldn't find any tape suitable for 10cm. Thirdly, the motor. A belt sander requires quite powerful electric motor, and I didn’t want to spend too much money on this project. The best option for me was to use a used motor.
Solutions to design problems:
The first problem with the tape had a simple solution. Since the belt 20 x 90 cm was on sale in construction stores at a reasonable price, I could make two 10 cm from it. This imposed restrictions on the size of my machine, but due to price efficiency, this option was the best. The second problem was solved using a lathe. To do this, I watched a video on the Internet and realized that I could make the videos I needed myself. With the engine the task was more difficult. I had several electric motors in the garage, but for some reason I had to give them up. Finally, I decided on an old tile cutting machine that had a 6-amp electric motor. At that time, I realized that this power might not be enough. But since the work was at the experimental stage, I decided to first achieve a working version of the machine, and the motor could be replaced later. In fact, the motor is suitable for small amounts of work. But if you're going to be doing more intensive sanding on it, I'd recommend the 12 amp minimum.
Tools and materials
Tools:
- Angle grinder with cutting discs.
- Drill and drill bits.
- Wrenches for 11, 12 and 19.
- Lathe.
- Vise.
Materials:
- Electric motor (6 A minimum, or 12 A recommended).
- Various bearings.
- Nuts, bolts, washers, lock washers of various sizes.
- Metal corner.
- Sanding belt 20 cm.
- 10 cm pulleys.
- Powerful spring.
- Steel strip 4 x 20 cm.
- Beam 2.5 x 10 x 10 cm made of wood or MDF.
Electric motor for machine
I had a choice of several motors, but the electric motor that was on the tile cutting machine had a more suitable casing. To some extent, working on the machine was like an experiment, because I was not sure that the motor had enough power. Therefore, I settled on a modular solution with the frame for the belt mechanism as a single element, which can be removed and rearranged on a more powerful base. The rotation speed of the motor suited me quite well, but I was worried that 6 A would provide weak power. After a little testing, I saw that this electric motor was suitable for simple work, but for more intensive work, you need to choose something more powerful. When designing your machine, pay attention to this point.
As I mentioned, the motor housing was very suitable as it allowed us to create a vertical machine that would be easy to move.
First you need to free it by removing the work table, saw, protection, water tray, leaving only the electric motor. Another benefit of using this motor was that it had a threaded core with a nut to hold the saw in place, allowing the pulley to be installed without using a key (I'll explain what a key is later).
Since I had a pulley that was too wide, I decided to use the large clamp washers that are usually used to secure the saw, turning one over so that there was a wedge-shaped groove between them. I found the space between them to be too narrow, so I put a lock washer between them to widen it. Advantage in this method is that the pressure washers have a flat edge that locks with the flat edge to rotate simultaneously with the core.
Belt
I used a 7 x 500 mm drive belt. You can use a standard 12 mm, but a thin one is more flexible and will put less strain on the motor. He doesn't need to rotate the grinding wheel.Device of a belt grinding machine
The device is simple. An electric motor drives a belt, which rotates a 10 x 5 cm “main” pulley, which drives the abrasive belt. Another pulley 8 x 5 cm is located 40 cm above the main one and 15 cm behind it and is mounted on a bearing. The third 8 x 5 cm pulley rotates on a lever and acts as a tension roller, holding the abrasive belt tightly. On the other side, the lever is attached to the frame by a spring.
Determining the drive type
The main question was to rotate the main pulley directly with an electric motor or with the help of an additional pulley and drive belt. First of all, I chose a belt drive because I wanted to have the option of replacing the engine with a more powerful one, however, there was another reason. When you do intensive metal processing, there is a risk of encountering some problems. The belt drive will slip in such cases, while the direct drive will create big problems. With a belt, the device will be more secure.Frame manufacturing and installation
It is important to mention that using a metal corner as a frame can have both advantages and disadvantages. The obvious advantage is that it is convenient to assemble, like a construction set in childhood. But the main drawback is that it is strong only in two directions, but weak when twisted. This means that we need to take this weakness into account and calculate what torque can be transmitted from the pulleys to the frame, and compensate for it using additional jumpers.
Cutting:
You can use a hacksaw to cut the corner, but an angle grinder with a cutting disc will make the job faster. After cutting all the pieces, I would recommend sanding down all the sharp edges to avoid cutting yourself during assembly. The holes can be drilled using a conventional drill and cutting fluid.
Main video
The main video is the most important detail project, since it receives torque from the motor and transmits it to the tape. I used an old bushing to secure it, but I recommend using a bearing instead. The bushings do their job, but they constantly overheat and require regular lubrication. Moreover, they can scatter dirty lubricant, which can be annoying during operation.
Shaft:
There are threads on the sides of the shaft with different directions so that the mounting bolts do not unscrew when rotating. If you cut off one threaded side like I did, leave the one that goes counterclockwise, otherwise you'll have to make a locking bolt (I'll describe how to make that later) and a cotter pin. The main pulley will be placed on the cut edge.
Pulley:
Continuing with the theme of reuse, I found an old pulley from another project. Unfortunately, I prepared it for the threaded pin that it was supposed to be held on, but, in fact, this is not a problem. I made a rectangular cutout in this pulley. I then used an angle grinder to cut a groove on the end of the shaft. By placing the key in the hole formed by the shaft groove and the rectangular cutout of the pulley, I securely fixed them relative to each other.
Making rollers for a grinding machine
I made the rollers from several pieces of 2.5 cm thick hardwood. But you can use MDF, plywood or other material. When laying layers, you need to make sure that the fibers are perpendicular, this will give the rollers additional strength and the layers will not crack.
It is necessary to make three rollers: the main roller, the top roller and the tension roller. The main roller is made of two 13 x 13 cm pieces of 2.5 cm thickness. The top and tension rollers are made of two pieces of wood measuring 10 x 10 cm.
Process:
Start by gluing together pairs of 13 cm and 10 cm pieces of wood, clamping them together with clamps. After the glue has dried, trim the corners using miter saw, then find the center of each part. Mount them in the lathe and turn them until they measure 5 x 10 cm and 5 x 8 cm.
Upper and tension rollers:
Next, you need to install bearings in rollers measuring 5 x 8 cm. Choose a core or spade drill, and drill a recess in the center to the width of the bearing. The inner race of the bearing must rotate freely, so you need to drill a hole that goes through the roller through the inner race of the bearing. This will allow the bolt to go through with a minimal hole.
Main video:
This part is done a little differently. There are no bearings on it, but if the shaft extends less than 5 cm from the roller, you will need to grind the roller down to width. Measure the diameter of the shaft and drill the same hole in the center of the roller. Try to insert the shaft, it must hold tightly, otherwise the roller will shake.
Bolting the rollers
Next, you should fasten the two halves of the rollers with bolts; do not rely only on glue. Remember that the bolt heads need to be recessed into the wood, since the roller rotates in close proximity to the frame.Tension lever
The lever is made of a metal strip measuring 10 x 30 x 200 mm with rounded edges. It is necessary to drill quite large holes in it, so I recommend using drilling machine and lots of lube. A total of 4 holes are needed. The first is at the pivot point. It is not in the center of the bar, but 8 cm from its edge. The second hole will be located on the edge closest to the rotation point. It will serve to attach the spring. Two additional holes need to be drilled at the opposite end, approximately 5 cm apart. They need to be a little wider in diameter as they will be used for tuning, which I will talk about next.
When all the holes are made, you can attach the arm to the vertical angle between the top roller and the base. The end on which the spring will be attached is directed towards the main roller. It should rotate freely, so I recommend using two nuts for fastening, not tightening the main one completely, and using the second one as a locknut.
Installation of rollers
The upper roller is attached statically and must be clearly in the same plane along with the tension roller and the main roller. You can do everything by eye, but I recommend checking everything well with a level. To align the roller, you can add a washer, or, if it is not enough, a bolt. They are inserted between the frame and the roller.
There is no need to install the tension roller completely. We still need to make a stabilizing device.
Belt stabilization
Wear on the rollers or uneven surfaces can cause the abrasive belt to gradually come off during operation. The stabilizing device is a device on the tension roller that allows it to be at an angle that keeps the abrasive belt centered. Its design is much simpler than it looks and consists of a locking bolt, a slightly free-playing tension roller and an adjusting bolt.
Drilling holes in bolts:
For this purpose, I made a device in the form of a wedge-shaped cutout in the board, which will help hold the bolt in place during drilling. You can do this manually, but I don't recommend it.
Fixing bolt
The retaining bolt is a simple bolt with a hole drilled in it and is installed on the bar through a wide hole that is located closer to the pivot point of the lever. Since it is located between the lever and the roller, its head must be ground off so that the roller does not catch it. The bolt must be secured as shown in the figure.The bolt on which the roller is attached
It needs to be loosened a little so that the tension roller has a slight play. But to prevent it from unwinding, you need to make a castle nut. To do this, you just need to make cuts on the edges of a regular nut so that it looks like a crown. There will be two drilled holes in the bolt itself: one for the adjustment bolt and it will be lined up with the locking bolt hole, and another for securing the castle nut with a cotter pin.Bolt for setting:
Once the tension roller is in place, you can install the adjusting bolt, which will pass through the holes of the retaining bolt and the bolt on which the tension roller rotates. The system works when you tighten the adjusting bolt, causing the axis of rotation of the tension roller to shift its rotation angle outward, thus causing the belt to move closer to the mechanism. A spring at the other end of the lever adjusts the tension in the opposite direction. I recommend securing the adjusting bolt with a locknut as vibrations can loosen it.
Note: You can add a spring with reverse side tension pulley, but I haven't found any reason why this should be done. A small advantage will be that in this way the roller will have less play. But I will add that I did not do this, and I did not have any problems.
Completing the work of making the machine yourself
When everything is done, you need to check all the bolts again and make sure that the stabilization mechanism is assembled correctly. Then you have to turn the device on for the first time, which can be scary. It's like driving a car, where steering wheel and transmission do not work. I recommend turning the motor on and off for very short periods of time to prevent the machine from spinning at full speed.
In fact, for myself the hard part It turned out to be the spring setting. If it is pulled too tightly, the tape will not be able to rotate... Too loosely and it cannot be held, it will fly off, which in itself is dangerous.
Ready!
That's all. You should end up with a decent, medium-power belt sander that can be converted to a more powerful one if desired.
I hope you enjoyed this master class. Thank you for your attention.
A homemade grinding machine is not that uncommon; assembling it with your own hands is quite possible.
A sanding machine is indispensable when finishing wood parts.
A grinding machine is a necessary thing and will always come in handy around the house.
If you come across spare parts in large quantities, besides, you have free time and a desire to try yourself as a design engineer, then the homemade grinding machine in your hands will be suitable for work.
So, you will need:
- motor (its role can be played by any other motor taken from any electrical device);
- electric drive (the most ordinary battery from a computer Ups is suitable for these purposes);
- screws;
- wires;
- switch;
- board;
- sandpaper;
- glue;
Assembly and installation stages
Once you have all the necessary tools, you can begin to make the grinding unit. To start with wooden board, pre-treated with varnish, you need to attach the motor. Finding it is as easy as shelling pears; many people probably have an old, non-functional computer hard drive at home. By disassembling it, removing the top cover and removing the head block, you will get an ideal workpiece - a motor. If you want your sander to have more power, then it makes more sense to use a more powerful motor. For example, from a fan. And if you plan to make a serious stationary grinding machine, then in this case you need to take an electric motor from an unnecessary washing machine. Then, in addition to the grinding function, it will also be able to act as an angle grinder.
The next step will be the installation of the electric drive. In order for the motor to work, you need to provide it with an uninterrupted power supply. If your grinder has a small motor, then the power supply to it must be done in a special way. For example, through a battery.
After the main components of the homemade product are sufficiently firmly fixed to the board, they will need to be connected to each other. This operation can be performed using ordinary wires. Don’t forget about the switch; be sure to integrate it into the overall circuit.
If you attach a felt attachment to a sanding machine, you will get a polishing machine.
Now you need to make your own grinding wheel. To do this, take sandpaper and cut out two circles of suitable diameter. After that, glue them together. You now have a finished grinding wheel, made by yourself. Of course, you can buy a ready-made circle at any specialized store. By the way, they also sell circles in small sizes.
Next, we proceed to attach the circle to the motor using two simple bushings. When attaching, be guided by the diameter of the motor axis, as there is a possibility of a mismatch in diameter. IN in this case you can simply match the plastic bushings to the diameter of the axle.
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 variety of production 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 the production of furniture and various consumer wood products. 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 even 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 common in metalworking: plain and alloy steel, non-ferrous metals in the form of quadrangular, round and flat workpieces. Grinding machines allow you to grind round timber and large diameter pipes efficiently and with minimal time.
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 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 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 of 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 has a shorter length than the working surface of the machine, then 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. Special group- wide-belt grinding machines, in which the table, which is made in the shape of a caterpillar, 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 a high-power motor, 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 that have high hardness can be used as abrasive materials, 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 with hot water over a distance of 80 to 100 millimeters, then the other end of the tape is applied to the exposed base lubricated 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 sandpaper in the form of a circle according to a template, the diameter of which is 60 - 80 millimeters larger than the diameter of the disc. 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 into sheets using wide-belt sanding machines 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 tabletop is usually laminated chipboard with a thickness of 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 a screw device with a pneumatic cylinder. Double belt sanders have two identical grinding tools, which are placed sequentially on the frame 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 feed speed, some areas of the surface may 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 gluing. Do not use incorrectly glued or torn sanding belts with uneven edge. 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 is receiving finished parts and ensures that unacceptable edge rounding and sanding does not occur.
Making a Belt Sanding Machine
The price of belt grinding machines from an industrial manufacturer is quite high, so when they are used infrequently, craftsmen involuntarily think about whether to buy the 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 cut blanks from the slab with overall dimensions of 200 by 200 millimeters and assemble a package of 240 millimeters from them. 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. Optimal width tape 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 sander, except for sanding wooden products, for which it is actually intended, it is very convenient to sharpen tools with cutting surfaces - chisels, knives, axes, pruning shears. Another advantage of this grinding machine is the ability to work with parts that have a curved surface - to do this, you need to grind the workpiece with the back side of the work belt.
