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Independent production of a belt sander. Belt grinder: we study and do it ourselves Do-it-yourself grinder from a grinder

Nowadays, there are no surfaces that are not smooth. Smoothness is achieved through various grinding devices. Professional equipment costs a lot of money and not everyone can buy it, moreover, such machines have a fairly high weight and dimensions.

Fortunately, the skilful hands of our country have adapted to produce analogues of equipment for such a modest budget. The grinding machine also did not stand aside and was subjected to a modernization of manual craftsmanship. It is with this homemade machine that we will continue to get acquainted.

There is a huge amount of sanding equipment that makes any wood surface very smooth. It is a frame on which a special frame with an electric motor is located (motors of washing machines are used for homemade products) and a mechanism. The mechanism itself, in turn, includes shafts, pulleys and an abrasive belt.

Application area

They are used in all industries where wood is processed. Often, any draft products have an uneven and rough surface. Such blanks cannot simply be painted and put up for sale or installed anywhere. Therefore, for further processing of wood, all its surfaces can be sanded.

Grinding machines are also used for processing sags and chamfering, rounding corners. In addition, the grinding tool gives any surface smooth alignment and calibration.

Types of wood sanding machine

Depending on the surface to be treated, the following types of grinders are distinguished:

Belt sander

This equipment uses an abrasive belt, which is pulled by two shafts. These shafts are driven by an asynchronous electric motor. The abrasive belt does not sag during wood processing, but rests against the working plane, which has a low coefficient of friction. The tape can be placed both horizontally and vertically. The advantage of this equipment is the processing of long workpieces.

Universal grinding unit

In this case, the machine has two working grinding surfaces. One is tape surface and the other is circular (disk). This universal machine was created for the convenience of working on it. By the way, such equipment will significantly save the budget. In such a device, only one engine is used. Based on this, when working on two working surfaces, the load on the motor will not increase much.

Drum grinding tool

In this case, the abrasive tape is wound on two rollers in a spiral manner. Under the rollers is a tabletop with a smooth surface. The gap between the tabletop and the rollers is adjustable to the required distance. With the help of such a machine, it is possible to calibrate the surface of a wood blank.

Disc grinding tool

The working area of ​​this equipment is an abrasive wheel. A circle with Velcro is attached to the axis of the electric motor, on which the abrasive is attached. After starting the engine, abrasive wheel rotates around its axis, thereby carrying out grinding. This type of machine has the ability to adjust the processing speed, and the number of revolutions of the axis will not decrease.

Each of the four types of machines can perform certain operations. Now that we have an idea of ​​what the grinding equipment looks like, it's time to disassemble the design of the machine.

In addition to the above machines, there are also portable ones. grinders. And that's not all, so as not to spend money on machines, people came up with grinders from a drill, from Bulgarian. The fact is that nozzles are fixed on these tools and the same grinding is carried out.

Tip: If you still decide to purchase a factory grinder, then decide in advance on the work and loads that your machine will undergo, and only then make a purchase. The same applies to homemade tools.

Motor power calculation

Important! Before creating any homemade brainchild that performs grinding functions, it is extremely important to correctly calculate the power electric drive. After all, if the motor power is weak or vice versa strong, then you cannot do any work.

The calculation of power is carried out according to a special formula, which belongs to the category of complex mathematical calculations.

The formula looks like this

P=q*S*(K+k)*U/1000*n

Where each designation means the following
  1. q - Means the pressure of the processed wood part on the plane of the abrasive cloth (N / square centimeter).
  2. k - The index of friction of the wrong side of the abrasive on the working surface.
  3. n - The efficiency of the entire system.
  4. K - An indicator of the working plane of the abrasive relative to the workpiece. The priority is the density of the tree and its graininess. The limits of this indicator range from 0.2 to 0.6.
  5. S - The area of ​​the workpiece that is in contact with the abrasive, measured in square centimeters.
  6. U - The speed of rotation of the abrasive, measured in meters per second.

When you calculate the required power of the electric drive of your future unit using the formula, you can safely begin to assemble the machine as a whole.

It's time to get familiar with the design homemade machine. Blueprints all four types of equipment can be found in free access for viewing and download, as well as download all kinds of a photo scheme. As an example for visual study, consider a belt sander.

The design of the machine and its schemes

Any assembly homemade equipment begins with the design of the bed or the foundation of the future machine equipment. This can be done with a metal material, or with a wood material. The following dimensions of the frame are used as standard 500 mm x 180 mm, while the thickness should be 2 cm.

After making the base, you can proceed to the next steps. An asynchronous motor can be installed in several places so that its operation is complete. Prepare a plane on the bed itself or make a platform for the motor, which will be attached to the end of the bed. The other side of the bed is designed to accommodate the shaft, with a pulley for a belt and rollers for an abrasive belt. The tape itself is installed with a slight slope. This is done so that the abrasive smoothly and gently comes into contact with the machined plane of the workpiece.

Tip: Before installing the abrasive strip on the rollers, it is necessary to wrap a thin strip of rubber around them. This will reduce strip slip during operation.

As we can see from the diagram and drawing, the design of the grinding equipment is quite simple. All varieties of these machines are assembled according to the same scheme.

Tip: In the process of assembling your future grinding unit, you must comply with all the necessary dimensions, and you must also calculate all the parameters very seriously.

When the design is familiar to us, we can proceed to the assembly process.

The assembly process of the grinding machine

To assemble the grinding tool, you will need the following items:

  1. Wood board.
  2. Wooden bars or metal profile pipe.
  3. Ball bearings.
  4. Electric motor.
  5. Rubber strap.
  6. Rubber belt.
  7. Metal pulley.
  8. Self-tapping screws, fasteners.
  9. abrasive element.
  10. Working tool (drill, grinder, screwdriver, jigsaw, etc.).
  11. Welding machine (if the frame structure consists entirely of metal).

After we have decided on the materials and working tools, we can begin to assemble all the parts and elements into one mechanism. For this, the frame is assembled. It can be metal (consist of a metal-profile pipe) or wood (consist of wooden bars and solid wood).

When the frame is ready

You can start installing the motor. The motor power must be at least 2.5 kW and not more than 3 kW, with the engine speed between 1200 and 1500 rpm. A pulley for a belt is installed on the motor shaft. The motor is mounted on one side of the frame. Motors are often used from washing machines used at home.

On the other side

A shaft with bearings is located, on one side of which a pulley is fixed, and on the other side a roller, an abrasive belt will be put on it in the future. Shaft pulley and motor pulley must be in a flat horizontal plane. The belt tensioner should be located in the same area.

Coming from wood

Either a stand is constructed from plywood or metal, on which the remaining rollers will be placed and an emery tape is worn. There must also be a tension mechanism. In addition, the presence of a working bar is mandatory, on which the abrasive belt will rub.

On the frame, as a rule, from the end, a start button is installed. The electrical circuit of the machine must be grounded.

After

Once everything is done, you can make the first start and configure the equipment properly. When the setting is done, the first workpiece is run and the result of the work is checked. If everything worked out, it means that you did everything right.

For visual clarity and a complete understanding of the entire assembly process, you can download video instructions.

General feedback and summing up

As a rule, there are only positive reviews about this type of equipment on the Internet. Indeed, when in everyday life it is necessary to give this or that wooden thing a smooth surface, then the presence of grinding tools is indispensable.

Video reviews

Video review of a homemade grinding machine:

Video review on the choice of grinding equipment:

Video review of the belt sander:

Video review of eccentric sanders:

The cost of a factory-made grinder is quite high. If a power tool is not affordable, you can try to make it yourself. On such a machine, it will be possible not only to grind wooden blanks, but also to sharpen tools. You can assemble a grinding machine with your own hands in three types: belt, disk and drum.

To assemble a belt type grinder, you will need an electric motor, a solid frame and rollers on which the belt will rotate. Be sure to have a drawing or a detailed diagram at hand indicating all the nodes and dimensions. We suggest looking at the photo for an example of a machine diagram with a wooden frame.

The next photo shows finished construction machine. In this embodiment, the location of the three working shafts is made so that the moving belt forms a vertical grinding plane. A belt drive is used as a drive.

Four rollers can be used in the design of the machine. One of them is leading and mounted directly on the motor shaft. The photo shows an example of such a design. Installing four rollers allows you to get two grinding planes: horizontal and vertical.

The wooden frame smooths out the vibration of a running electric motor, however, the wood is short-lived. It is optimal to cut a workpiece with a size of 50x18 cm from steel 2 cm thick. One edge of the bed is made perfectly even in order to fix the platform for the electric motor to it. For the next part, you will need steel 1 cm thick. The platform is cut out with a size of 18x16 cm, after which it is fixed to the frame with a bolted connection.

A large electric motor power for such a machine is not needed. An engine from an old washing machine will do. If a high performance grinder is required, then it is desirable to find an electric motor with a shaft speed of 1500 rpm with a power of 2.5 to 3 kW. High-quality grinding can be achieved by moving the emery belt at a speed of 20 m / s. To achieve such parameters, working drums with a diameter of 20 cm are used. If the rollers are made thinner, it will be necessary to reduce the speed of the motor shaft using a gearbox, which is extremely inconvenient.

The driving drum can be mounted on the motor shaft. If this option is not suitable, a separate unit is made. The drive shaft with bearings is fixed on the frame. A belt pulley is mounted from this end, and a drive drum is installed from the other end. Then a pulley is also placed on the motor shaft and a V-belt is put on. The driven rollers rotate arbitrarily on bearings.

Belt pulleys will have to be machined on lathe, and rollers can be made from square pieces of chipboard measuring 20x20 cm. The plates are stacked on top of each other until a total thickness of 24 cm is obtained. A hole is drilled in the center of the square plates, a threaded stud is inserted and the plates are tightly tightened on both sides with nuts. A square blank is machined so that a drum with a diameter of 20 cm is obtained.

During the groove of the rink, a thickening is provided in its central part. In relation to the edges of the drum, the difference should be 3 mm. Due to the thickening, the tape will not move out of the rollers. The surface of the wooden drum is covered with rubber. An old bike tube will do. The rubber will prevent the belt from slipping on the rollers.

For the manufacture of a sanding belt, cloth-based sandpaper is suitable. You can cut a single strip of the required length, the edges of which are glued end-to-end. If there is no long strip of sandpaper, cut off a strip of strong fabric and sew it into a ring. Sandpaper is cut into rectangles, and then glued to a strip of fabric. When making a sanding belt, it is important to choose a quality adhesive so that the sandpaper does not peel off.

Making a disc grinder

The disk machine is considered the easiest to manufacture. The principle of its operation resembles an ordinary electric emery. The assembly of the grinding machine is presented with an instruction with a step-by-step photo:

  • The power plant of the machine is a three-phase electric motor. This choice is not accidental, since a phase change when connected allows you to organize a reverse. The motor can be connected to a 220 V network through capacitors.

  • The working disk is cut out of plywood 1.5 cm thick. Two identical blanks are glued together. The result is a disk 3 cm thick. A hole is drilled strictly in the center, the diameter of which is equal to the thickness of the electric motor shaft.

  • To assemble the bed, it is better to use edged board, and the guides and the desktop are cut out of plywood 1.5 cm thick. Wood for the manufacture of the machine better fit than metal. Wood dampens motor vibrations.

  • The working disk can be ground and even sharpened. It is important to choose the right abrasive materials. They must be Velcro and fit for purpose. If you need to grind a product made of stone or granite, a Turtle diamond wheel is glued onto the working disk.

  • To grind a wooden blank, a sandpaper circle is glued onto the working disk.

  • There are similar circles on Velcro for metal. On such a disk, you can sharpen knives, axes and other tools.

When designing a disc grinder, it is important to take care of safety. From above, the rotating working disk is covered with a protective arch. An adjustable heel is provided on the desktop, which serves as a stop for the workpiece.

The tabletop of the machine should not be varnished or painted. Over time, an unevenly worn coating will make it difficult to move the workpiece.

Production of a drum machine for grinding boards

For the manufacture of a drum machine, a frame is assembled. You will need a hardwood beam. From below, an electric motor with a pulley is attached to the frame. A drum with bearings will fit from a used conveyor. The sandpaper is cut into a tape and wound tightly end-to-end on a working roller. At the edges of the drum, the paper is fixed with clamps.

Attach the working roller from above to the frame. Under it will be the tabletop of the machine. A pulley is mounted on the drum shaft and a belt drive with a motor is created. The tabletop is made adjustable with screws so that boards of different thicknesses can be sanded. To avoid vibrations of the machine, it is advisable to fix the legs of the bed to the floor.

If you try and make an effort, then any considered unit will work no worse than a factory-made grinding machine.

Useful item in the workshop. For those who work with wood, such a device is simply necessary, as it is universal, which greatly simplifies the work. But, unfortunately, such machines have a rather high price and therefore have to be invented. This article will discuss a functional, and most importantly convenient, grinding machine, with detailed drawings and photos. Each item is considered in detail, and if something is not clear, you can always watch the video.

Introduction

There are many options for different grinders, but the most important thing is that it be easy to use. This design option meets many requirements, and captivates with its simplicity, but at the same time functionality. A distinctive feature of this design is that it is used as a driving element conventional drill, and its installation takes less than one minute, and most importantly, it is easy to remove it from the machine and use it for your own purposes.

This article will cover all step by step steps creating a universal grinding machine, but before starting work, you need to prepare well and calculate the full amount of work.

Preparation for work

You can’t do without a tool, so you need to prepare a high-quality and serviceable hand and power tool, namely:

  • Sawing machine (or from a jigsaw;
  • Milling machine;
  • Grinding machine or ;
  • Drill or (and, of course,);
  • Electric jigsaw with;
  • Drilling machine;
  • . such as "Cyclone".
  • Various hand tools(tape measure, pencil, screwdriver, etc.).

Before starting work, it is important that all the material is at hand, then the work will go quickly and smoothly. Thus, to assemble a stationary grinder, we need the following material:

  • sheet (size 25 * 36.5 cm);
  • fasteners (bolts, nuts; screws, etc.); sealed bearings;
  • furniture fittings;
  • metal stand;
  • sanding belt.

In order to make any workpiece from, you need to know the basic characteristics of the material. In the article "" some characteristics were given (thickness dependence, number of layers, deviations, thickness differences, etc.). An additional table may be useful:

Plywood brand

 Bakelized plywood Aviation plywood Construction plywood
Sheet thickness* 5-18 1-12
Water resistance high Above average FSF - increased FC - medium
Density, kg/m3 About 1,000 500-650 Depending on the type of wood: softwood plywood density– 660 hardwood plywood density - 800
Tensile strength, MPa Along the fibers - 80 Shirts - 65-80 —

Main structural elements

The manufactured machine has quite simple design, and consists of the following elements:

  1. Base;
  2. Tabletop for placing blanks;
  3. Two side covers of the case;
  4. One leading roller and two slaves;
  5. Tape adjustment mechanism.

Manufacturing of a grinding machine

Side covers

Before cutting, you need to mark up. To do this, you need to determine the size and shape of the workpiece itself. Below is shown detailed drawing details.

An example of marking the side cover of the grinding machine is shown in the photo below.

For more comfortable cutting internal details and critical elements, with an electric jigsaw and a sawing machine, you can drill holes. For accurate and high-quality work, it is better to use a substrate. Please note that the cutout for the movable roller is needed on only one workpiece.

The main parts of the part requiring holes are shown in the photo.

After, only on one of the blanks, we cut out a smaller hole for the bracket. It is better to work with a jigsaw, while it is better to fix the structure with clamps.

The second part of the cover is not needed yet, since the main work will be carried out with one part of the wall. After that, you can start gluing the base for the bearings. For gluing the squares, ordinary PVA glue, wood glue or any other glue intended for wood is used. The size of wooden squares is 5 * 5 centimeters.

After that, the glued elements must be fastened with clamps or left under pressure for a while. It is important to ensure reliable contact when gluing blanks.

It's time to cut the hole for the bearing. Best of all, a milling cutter will cope with this task. After cutting, excess elements can be removed with a knife or other cutting tool.

As a result, if all the work was done correctly, the following design will be obtained.

We press the bearings on both sides, as shown in the photographs. These bearings will be designed for the drive shaft.

After that, with the help of a hexagon, the fittings are installed in a pre-prepared hole.

As in the case of bearings, furniture fittings are installed on both sides.

The next step to do is to install the shelves. The largest shelf, consists of a board and has a size of 32.5 * 6.5 cm and has a thickness of 1 cm. Installed with four self-tapping screws, as shown in the photo.

The second shelf measures 22.8*6.5 cm, with the same thickness. Attaches with three screws.

And the last shelf has dimensions of 10.2 * 65 cm, 1 cm thick and is attached to two self-tapping screws.

After that, both blanks are finished, and now you can proceed to the next step - assembling the mechanism for adjusting the position of the sanding belt.

Assembling the Tape Adjustment Mechanism

We begin the assembly of the main moving element of a stationary grinding machine. First, you need to glue two bars together. The larger beam is 6.8 * 4 cm in size, the smaller one is 3.2 * 3.8 cm in size. The smaller beam should be exactly in the center of the larger one.

While the movable element dries, you can start gluing the retainer. To do this, you need to glue two cubes 2 * 2 cm in size and 1.8 cm thick on both sides of the beam 7.8 * 2 cm. It should turn out as in the photo.


Next, we drill a hole on the side, but not through, we also install the fittings. A handle will be inserted into it to adjust the tape. After all the steps have been completed, the part is ready.

Then, you need to make a hole for the drive nut in the latch, this is done in two stages. The first one involves drilling out the seat with a feather drill or a Forstner drill.

If all the steps are performed correctly, you will get the same blank as shown in the picture below.

Everything is ready, and you can start pressing the nut. It is important to install the nut evenly so that it "sits" in a special hole and is "flush". It should turn out like this:

The blanks are completed, you just need to place them on the wall of the future grinding machine. But before that, you need to drill a hole in the side. It will help to install the adjustment knob for the position of the sanding belt.

We install the latch, with a movable element, using two self-tapping screws. It is important that the moving part is placed on the correct side. The futorka should be directed towards the hole. Here is what should happen in the end.

Two blanks will be enough. We drill a through hole in the middle and insert a bolt into it. After that, we install the handles in the side sleeve of the movable element and in the drive nut of the latch. As a result, the following construction will turn out.

Production of rollers

Rollers are movable, and the most important element of the entire system. Therefore, it is important to make them as high quality as possible. As in the case of handles, we make them using a crown drill. It is necessary to cut out six parts of the driven rollers.

As well as other parts of a stationary grinder, they can be glued with PVA glue or wood glue. To compress the blanks when gluing, it is better to use screws and nuts with washers. The photo below shows how to do it.

After gluing, you can remove the screws and prepare the rollers for further work. In the driven rollers, you need to install two bearings, in the drive roller you need to install two drive nuts. The procedure was carried out before, so it makes no sense to describe it again. As a result, you should get the following result:

Everything is installed, which means that you can tighten one bolt with a nut on all rollers of the grinding machine. It is important to tighten the nuts so that the bearing has free play. Now you can proceed to the penultimate stage.

Installing rollers

First, you need to install the drive roller in the cover where the bearing is located. So, as shown in the photo.

The last shelf is attached on top and our machine takes on a similar shape. The time has come for the final stage.

The final stage

The first thing to do is to attach the second cover of the machine to the hinges.

Then put the base of the machine on the screws, for greater stability.

After that, the sanding belt is installed and fixed.

Then the tabletop is made. It is important that the tape has free play, and should not cling.

And at the end, a drill stand is installed.

Conclusion

Outcome

Our handmade grinder is ready! If you follow all the instructions described above, you will get a real friend and helper who will rightfully take his rightful place in the workshop.

Dimensions

Here is a table with overall dimensions our homemade tool:

The dimensions of the walls and adjacent elements:

Dimensions of bracket elements:




Table top dimensions: Vkontakte

Grinder (English) literally - a crusher. Meat grinder is a meat grinder, rock (stone) grinder is a stone crusher; stick (wood) grinder - garden crusher of branches and rods into chips. But there is also a completely unambiguous meaning of the word grinder: in mechanical engineering and metalworking, this is a grinding machine. A useful household item. For example, it is impossible to guide a dull meat grinder knife on a whetstone by hand. On a manual knife sharpener - somehow possible, with a solid working skill. And on the grinder - no problem. The same - if you need to grind a part of a complex shape without violating its profile. Or just sharpen scissors or a professional knife. All kinds of cutters for wood and metal are best corrected also on the grinder. It is quite possible to design and assemble a grinder with your own hands, without having sophisticated equipment and skills to work on it. In terms of money, this will mean savings from 50-90 thousand rubles. up to 3-6 thousand USD.

To make a grinder yourself, you will need to order a maximum of 4-5 turned parts, and it is often possible to do without turning from outside at all. For example, how to make the simplest grinder literally from trash, see the video below:

Video: do-it-yourself tape grinder from trash

Or another option, how to make the grinder stronger and more resilient from scrap metal:

Video: scrap metal grinder

Disk or tape? And drive

Almost more varieties of grinding machines are used in industry than lathes. Emery known to all craftsmen - a motor with a pair of grinding wheels (or one circle) - this is also a grinder. For yourself at home, it makes sense to make either a disc end (plate) or a belt grinder. In the first, the abrasive is applied to a rotating hard disk; in the second - on an elastic tape running around a system of pulleys and rollers. Disc is more suitable for grinding simple wooden parts and coarse or medium purity - metal. On a belt grinder, it is also possible to produce precise and clean finishing of profiled parts of complex shape, incl. large, see below.

A disc grinder is very simply obtained from the same emery or a motor of suitable power, see below. It is necessary to order an adapter from the motor shaft for the shank of a cup-shaped grinding wheel on a metal base. Or under a chuck, then on the same motor it will be possible to build a mini lathe, see fig.:

A worn-out “plate” is suitable: a disc made of thin (4-6 mm) fibrous plastic is glued onto the edge of its side, and an abrasive is placed on it. How to make an end grinder, see next. video clip.

Video: homemade end grinder



The difference between a disc grinder and a belt grinder is not only in the possibilities of use. If you take ordinary home crafts, then a drive power of 250-300 W on the shaft is enough for a disk grinder. For small wooden parts - and 150-170 watts. This is a motor from an old washing machine, a straight (ordinary) drill or a screwdriver. But for a belt grinder, you need an engine from 450-500 W: three-phase with batteries of starting and operating capacitors. If it is supposed to process a large size, then the motor power is from 1-1.2 kW. Moreover, capacitor banks for both will cost a little less than the engine itself.

Note: a 100-200 W drive uses a mini belt grinder (see below) for fine dressing of knives, grinding / polishing jewelry, etc.

A drill or screwdriver as a grinder drive is also convenient in that it allows you to quickly change the speed of the abrasive (see below) with a standard speed controller. It is only necessary, firstly, to make a holder for the drill, rigidly fixing the tool. Secondly, an elastic adapter from the drill to the disc shank, because it is difficult to achieve their precise centering without special equipment, and the runout will negate the accuracy of processing and can damage the tool-drive.

Drawings of the drill holder for using it as a drive for a home metal-cutting machine are given on the left in the figure:

Since the shock and irregular alternating loads on the drive in the grinder are an order of magnitude lower than, say, in a lathe, it is possible to make a drill holder for it from hard wood, plywood, chipboard, MDF, on the right in Fig. The diameter of the mounting (large) hole is along the neck of the drill. It is highly desirable to use a drill without an impact mechanism and with a steel shell on the neck (for the installation of the front handle).

Coupling

For the adapter, you will need a piece of steel bar (not necessarily turned) of the same diameter as the shank of the grinder drive shaft, and a piece of reinforced PVC hose (garden irrigation) with a gap so that it is tightly pulled over the bar and shank. The length of the “free” hose (between the ends of the rod and the shank in it) is 3-5 cm. The length of the protruding part of the rod should be sufficient for a reliable clamp in the drill chuck. After assembling the coupling in place, the hose on the shank and rod is tightly tightened with clamps; can be wire. Such a coupling completely parries the misalignment of the drive and the driven shaft up to 1-1.5 mm.

Ribbon is still better.

A belt grinder allows you to do everything that a disc grinder does, and more. Therefore, further we will focus on how to make a belt sander with our own hands. Amateurs, focusing on industrial designs, sometimes make grinders very intricate, see fig.:

And this is justified: the design and kinematics of the belt grinder are very flexible, which makes it possible to successfully use improvised materials and old scrap metal. You just need to follow 3 principles:

  1. Do not do as in the second photo from the left: the tape with the abrasive side should only touch the workpiece. Otherwise, the abrasive will eat both the bypass rollers and itself. The accuracy and cleanliness of processing during one working operation will be unpredictable;
  2. The design of the machine must ensure uniform belt tension, regardless of the nature of the operation being performed;
  3. The speed of the belt movement must correspond to the nature of the operation being performed.

Kinematics and design

As mentioned above, there are many designs of grinders. Thinking about what and how to build a grinder for yourself, it is better to focus on industrial samples designed for fully mechanized precision and clean grinding of large-sized profiled parts: since the propeller blade of an aircraft or a wind turbine “skins” as it should, then it will cope with any other work.

Kinematic schemes of grinders for the specified purpose are given in Fig.:

Basic kinematic diagrams of belt grinders (grinders)

Pos. A - the most complex and perfect, with three rocker arms. If the length of the tensioning roller rocker is approx. 2 times less than the working one, then by adjusting the tension of the springs, it is possible to achieve a uniform tension of the tape when the working rocker moves 20-30 degrees up and down. By tilting the bypass rocker, firstly, the machine is reconfigured for tapes of different lengths. Secondly, in the same way, you can quickly change the belt tension for different operations. The working branch of the tape can be any, except for the one running from the drive pulley to the tension roller, i.e. a grinder with 3 rocker arms is both horizontal and vertical at the same time.

The scheme with a coaxially swinging rocker (pos. 2) is simpler, cheaper and not inferior in processing accuracy to the previous one, if the length of the rocker between the axes is at least 3 diameters of the workpiece. In order to knock down the profile by grinding, the course of the rocker arm is limited by stops within 10 degrees up and down. The clamping of the tape to the part is most often gravitational, under the weight of the rocker with a bypass pulley. It is possible to quickly change the tension of the tape within certain limits by pulling the rocker up with a weak adjustable spring, which partly compensates for its severity. The grinder of this scheme can work as a grinder for small parts from a sliding table. In this case, the rocker arm is rigidly fixed horizontally, and the running surface of the tape will be a bypass pulley. According to the scheme with a coaxial rocker arm, for example, a fairly popular BTS50 grinder was made. The disadvantages of the scheme are, firstly, the technologically complex rocker arm hinge coaxial with the drive shaft. Secondly, the need for an elastic band: if you make the bypass pulley sliding spring-loaded, the machining accuracy drops. This disadvantage when processing small parts is completely eliminated by an additional tension roller, see below.

A scheme with one misaligned rocker arm in industry is used quite rarely, because. in principle, it does not allow to achieve a uniform tension of the tape. However, it gives an accuracy that is quite sufficient at home and allows you to build a very good simple grinder.

What's good for what

Now let's see what is possible to "squeeze" out of this or that scheme from the point of view of an amateur master. And then we’ll try to figure out how to make a belt for the grinder ourselves and do without custom-made turned parts.

3 rockers

Competent amateurs build their grinders exactly according to the scheme with 3 rocker arms, on the left in fig. below. Far from all propeller blades are ground, but in this case another advantage of this scheme operates: if the grinder is used as a vertical one, then the working branch of the tape is elastic. This allows a skilled craftsman, for example, to guide cutting edges and blades with literally micron precision.

In industrial grinders for home use the 3-rocker scheme is also widely used (in the center) for the same reasons. Repetition of them independently in most cases is quite possible. For example, drawings of the popular KMG grinder abroad can be downloaded.

The dimensions, however, are inch - an American typewriter. For the drive, in any case, it is possible to use an angle grinder drill (on the right in the figure, it is quite suitable in terms of power) with a homemade pulley and rollers, see below.

Note: if you are making a stationary drive, try to get an asynchronous motor at 2-3 speeds from a worthless washer with horizontal tank. Its advantage is low turnover. This makes it possible to make the drive pulley of large diameter and thereby eliminate belt slippage. A slippage of the tape in the work is almost certainly a damaged part. Most washing machines with 2-3 speed 220 V asynchronous motors are Spanish. Shaft power - 600-1000 watts. If you come across one, do not forget about the standard phase-shifting capacitor bank.

Coaxial rocker

In its pure form, grinders with a coaxial rocker are not made by amateurs. The coaxial hinge is a complicated thing, you can’t make an elastic band yourself, and a purchased one is expensive. Grinders with a coaxial rocker at home are most often used in the variant for fine precision work from the table, i.e. with a rigidly fixed horizontal beam. But then the need for a yoke as such disappears.

An example is a mini grinder, the drawings of which are given in Fig.:

Its features are, firstly, an overhead bed for the tape (pos. 7), which greatly expands the possibilities of use. For example, a planer iron is straightened on this grinder with an angle stop literally by itself. In this case, the grinder works, so to speak, like a self-propelled donkey (emery bar). After removing the bed, we get a grinder with an elastic band for precise grinding / polishing of rounded small parts. Secondly, the tension shaft (pos. 12). Clamping it with a groove with nuts, we get a relatively fixed tension of the tape for working with the bed. And having released the nuts, we put the grinder into the mode of gravitational tension of the belt for fine work. The drive is not necessarily through a pulley (pos. 11). Can be screwed directly behind the drive shaft shank (pos. 16) from the drill through the adapter, see above.

A specialized tool grinder (for example, for aiming and dressing turning tools) generally loses any semblance of the original scheme. A high-speed motor is taken for it (a power of 200-300 W is enough). The drive pulley, respectively, of small diameter. The bypass pulley, on the contrary, is made larger and heavier, for inertia. All this together allows you to reduce the runout of the tape. The tension roller for the same purpose, plus for greater uniformity of the tape tension, is taken away and spring-loaded with a long, not very strong spring. How to make a cutter grinder, see the video below.

Video: cutter grinder


One rocker

In amateur practice, grinders with misaligned rocker are good because they do not need precise details at all. For example, hinges can be made from card loops. At the same time, the accuracy of processing remains sufficient for ordinary amateur requests.

The original scheme in this case is also modified: the rocker is rotated 90 degrees, carried up and spring-loaded, on the left in Fig. It turns out a simple vertical grinder. And, importantly, it works without problems with a home-made inextensible tape. Both tension spring (in the center) and compression spring can provide belt tension. Its strength is not important, as long as the tape does not bend excessively during operation. No adjustments are required during use.

Consumables and parts

The only one consumable for a belt grinder - a tape (not counting grease for bearings and joints. The tape can be ordered in the desired length (see at the end), but you can also make it yourself from emery cloth on a textile basis. It is highly desirable - flexible, unimpregnated. In general, the procedure for making a tape for a do-it-yourself grinder is this:

  • We cut off the workpiece - a strip of the desired length and width.
  • We prepare a mandrel (not necessarily round) with a length along the generatrix slightly less than the length of the tape.
  • We circle the mandrel with the workpiece inside out.
  • We bring the ends of the workpiece exactly end-to-end and securely fasten.
  • We put a piece of glue stick for a hot glue gun on the joint.
  • We heat with a building hair dryer until the glue melts.
  • We impose a patch of thin fabric on the joint.
  • We press something hard through the Teflon film until the glue hardens.

There are three significant points here. The first is to use a rough PET film with a thickness of 25-50 microns (sold) instead of fabric on the patch. It is very durable, but try running your finger over a PET bottle. Not very slippery? A rough PET film under tension cannot be stretched over polished metal. And instead of a patch, it is better to seal the wrong side of the tape with a continuous strip of PET film with an overlap of 2-3 cm. The beating of the tape will be no more than 0.05-0.1 mm. This is less than from the thinnest calico and even less than the error in the thickness of the skin-blank.

The second - fill the finished tape into the machine and grind something obscene with it without strong pressure. The hem on the seam will come together, and the tape will become no worse than the branded one.

But the most important thing is that in terms of elasticity, the best adhesive for gluing the grinder tape is not expensive and difficult to use thermal or assembly, but ordinary PVA. If the tape is pasted over with a lining along the entire length of the inside, then its strength for PVA is more than enough. How to glue a tape for a PVA grinder, see the video

Video: gluing the grinder tape with PVA glue

Pulley

The generatrix (lateral surface in section) of the drive pulley of the grinder must be straight. If you use a pulley-barrel, then the tape will bend like a trough along its entire length. The rollers do not allow it to slip, see below, but the pulley generatrix must be straight.

A pulley for a grinder that is not designed for particularly precise work, firstly, does not have to be turned. In the scheme with 3 rocker arms, the beating of the tape from its misalignment will go out on the rollers before it reaches the working branch. In a simple vertical grinder, the belt runout will be sufficiently damped by the tension spring. Therefore, it is quite possible to make a pulley for a grinder without a machine, see video:

Video: drive wheel on a grinder without a lathe

The second is that the pulley, rollers and, in general, all the details of a home grinder can be made from plywood. In production, this is certainly not an option, even if the plywood grinder is offered for free with an additional payment: the grinder needs a salary, and the wooden grinder in the workshop will completely wear out before it pays for itself. But you won’t drive the grinder at home day after day in 3 shifts. And no tape slips along the plywood pulley. Incl. homemade. So you can safely make a grinder pulley out of plywood:

Video: plywood grinder pulley


It is much more important to correctly calculate the diameter of the pulley according to the speed of the motor and the required speed of the belt. Too slow running belt will tear the processed material; too fast - it will be erased by itself, without really processing anything. In which case, what tape speed is needed is a special conversation, and a very difficult one. In general, the finer the abrasive and the harder the material to be processed, the faster the belt should move. How the speed of the belt depends on the diameter of the pulley and the speed of the motor, see the figure:

Fortunately, for most abrasive-material pairs, the allowable limits for belt speed are quite wide, so choosing a grinder pulley can be easier:

Video: which wheel is needed for a belt grinder

Videos

The rollers of the grinder, oddly enough at first glance, are its most important details. It is the rollers that keep the tape from slipping and ensure its uniform tension across the width. Moreover, there can be only one video in kinematics, see, for example, the video above about the cutter grinder. Only barrel rollers will cope with this task, see below. But the “trough” of the tape after any roller should straighten out before it reaches the working area.

Rollers with flanges (sides, edges) will not hold the tape. The point here is not only and not so much with the misalignment of the axes of the rollers: the grinder belt, unlike the drive belt, must withstand, without slipping, the loads from the workpieces. If you make rollers with flanges, then, just touching something to the tape, it will crawl onto the flange. In the grinder, you need to use Type 3 barrel rollers (highlighted in red on the left in the figure).

The dimensions of Type 3 rollers are also given there. It is advisable to take the diameter of the rollers no more than 0.5 of the width of the tape (so that the “trough” does not go far), but not less than 20 mm of steel turned and not less than 35-40 mm of plywood. The tension roller (the probability of the tape slipping from it is greatest), if the working branch of the tape does not leave it, can be 0.7-1.2 in diameter of its width. Plywood rollers are made in the form of a thick shell into which the bearing is pressed; then the roller is mounted on the axle (in the center in the figure) and finished clean, see e.g. track. video:

Video: barrel roller for grinder


Not every turner can machine a profile barrel roller exactly according to GOST. Meanwhile, there is a way to make rollers for the grinder without significant difficulties. The same garden reinforced PVC hose will help out, on the right in fig. previously. On the roller blank with a straight generatrix, its segment is pulled tightly and cut off with a margin along the edges to the thickness of the hose wall. It turns out a roller with a complex generatrix profile, which holds the tape even better and gives it a smaller “trough”. Don't believe? Try to get into the graveyard of planes or missiles and dig into them. You will find rollers with exactly the same generatrix profile. It's just that the mass production of rollers of a complex profile is much more expensive than Type 3 barrels.

And another option

All critical parts of the grinder - one-piece belt, non-slip coated pulleys, rollers - can be purchased separately. They will cost not so cheap, but still not in thousands of foreign and not in dozens of native "leather jackets". The remaining parts of the grinder, either flat or from professional pipes, are made using a conventional bench drill or drill. Here is where you can order grinder parts:

  • //www.cora.ru/products.asp?id=4091 - tape. Do lengths and widths at the request of the customer. Advise on abrasives and processing modes. The prices are acceptable. Delivery time - questions to Ruspost.
  • //www.equipment.rilkom.ru/01kmpt.htm - spare parts (accessories) for grinding machines. There is everything, the prices are divine. Delivery - see prev.
  • //www.ridgid.spb.ru/goodscat/good/listAll/104434/ - the same, but foreign-made. Prices are higher, delivery is the same.
  • //www.pk-m.ru/kolesa_i_roliki/privodnye_kolesa/ - drive wheels. You can find suitable for the grinder.
  • //dyplex.by.ru/bader.html, //www.syndic.ru/index.php?option=com_content&task=view&id=36&Itemid=36 – spare parts for grinders. Ribbons are not made to order - choose from the catalog. Rollers without axles; axles are sold separately. The quality is impeccable, but everything is very expensive. Sending - within 2 weeks to the border. Then - their customs, our customs, Ruspost. Total ok. 2 months It may not reach if some local bureaucrat considers the goods to be sanctions. In this case, there are no problems with the return of the payment due to the complete absence of real opportunities for an ordinary citizen to receive one.
    • (2 ratings, average: 5,00 out of 5)

All materials in any production, in addition to manufacturing, require additional and finishing processing. Vivid examples of such treatments are grinding and polishing of the product. These two types of mechanical action on the surface of the part, bring it appearance to perfection. However, everyone knows that in order to perform these operations by hand, it will take a lot of time and effort, and only a very experienced master can ensure even processing. To facilitate this kind of work, a person came up with various devices and mechanisms to help himself. Some of them will be discussed further.

General purpose and types of machines

The machine is intended for the final processing of parts and blanks from different materials by exposing them to a surface with an abrasive or diamond coating. The machine, its constituent mechanisms and fixtures allow maintaining the accuracy of size and shape, and also ensure the creation of an ideal surface of a part or workpiece.

With the help of the machine, you can process flat parts, surfaces outside and inside, parts of various geometric shapes, grind or polish threads and gear teeth. According to their characteristics, grinding machines are divided into:

  • Cylindrical grinding.
  • Internal grinding.
  • Centerless grinding.
  • Surface grinding.
  • Special machines (for grinding threads, gears).

Grinding process

Grinding is the process of removing the top layer from the surface of the workpiece using abrasives or diamond grit. They are collected in total mass on the working surface and fastened with a binder. They eventually form a grinding wheel or belt.

During operation, the abrasive surface is given a circular motion by means of an electric motor. When the surface of the workpiece comes into contact with the abrasive, the machining process takes place. There is a common belief that grinding with abrasives is friction processing. However, this is not true.

Each abrasive particle has sharp edges, when touched with a material (metal, plastic, wood, stone) it works like cutting tool and removes chips, like a milling cutter or drill. Given the considerable speed of rotation of the grinding wheels, as well as the occurrence of chips as a grinding product, it is necessary to take into account the possibility of injury by this very chip.

Safety measures during work

When working on the machine, the following safety precautions must be observed:

Necessity at work and at home

Today, in production shops, grinding machines are used all the time. Depending on the scale of production, both one machine and all its varieties in terms of complexity and dimensions can be installed.

However, there is always a use for this equipment in everyday life. Some - in the garage there is a bench sander for metal processing. Others have several wood sanders of different design installed in their workshop. The third - in possession is a universal, combined machine. There are power tools for manual grinding: drum type, belt sander, band saw, small machines or large machines. And they are all in demand.

There is a fairly wide range of all kinds of similar equipment from many manufacturers on the market. And their prices are quite reasonable. But these are general purpose machines. And if a person is engaged in his own business, or he has a hobby, then a machine of special specialization is needed. Here the price is already rising several times.

For this reason or based on own desires many craftsmen make homemade products. Mainly for processing wood, plastic and metal, less often for cutting and grinding stone. And, in general, this is correct. After all, even a simple sharpening of kitchen knives is easier and faster to do on a machine than manually using a whetstone. The benefit of creating a home-made machine for wood with your own hands is also its very simple design.

It is not difficult to assemble a do-it-yourself grinding machine for wood. In the people it is also called simply - emery.

The main component is the engine. Surely many in the household have an old washing machine. Its motor is quite suitable for this purpose. If not, a new engine on the market will be quite expensive, but at any flea market you can find a used one in working order. The electric motor must be strong from 750 W to 2 kW, not high-speed from 1500 to 3000 rpm, if it is three-phase, then it can always be adapted to 220 V. You will also need thick plywood, self-tapping screws, PVA glue, and a tool, of course.

The task is simple: to make a hard drive on which sandpaper is glued. To do this, we draw a circle with a diameter of 150-170 mm on plywood, if the plywood is thick enough to hide the clamping nut, one blank is enough. If not, we glue two identical blanks with PVA glue. The clamping nut of the motor spindle must be recessed into the disk flush with its working plane.

From the same plywood 15-24 mm, you need to make several parts:

  • The frame to which the engine will be attached.
  • Feed table with guides for changing the angle of inclination.
  • The design of disk protection.
  • Base for attaching the entire machine to the workbench.

Protection for the disk can be made in the form of an arch with right angles or truncated. She, like the feed table, is attached to the frame. Of the additional devices, you can install an emphasis-protractor on the feed table, which will allow you to feed the workpiece at a fixed, horizontal angle.

Paying tribute to aesthetics, it is desirable to grind every detail before assembly. But this is optional, but with the serving table this must be done carefully. A smooth surface will ensure uniform and continuous movement of the part along the working surface of the disk.

The purpose of this machine is revealed in its very name - surface grinding, that is, for grinding flat surfaces of parts and workpieces. It can be disk, drum (like a thickness gauge) or tape. At the same time, its working surface can be located vertically, horizontally or regulated.

Individual machine designs are made fully adjustable. But this is individual. Everyone makes home-made machines for themselves, so that it is more convenient to work. Fully adjustable designs are more difficult to manufacture. They have an adjustable pressure of the drum or tape, that is, in other words, there is the possibility of a fixed movement of the working surface along the vertical axis. And the tool rest has a mechanism of movement in two directions, like a cutter holder carriage on a lathe.

From the verbal description it is difficult to imagine what it looks like. And even more difficult to understand how it works. But today we have the Internet. There you can find videos where experienced craftsmen share their experience, explain in detail and show how to make such equipment. Detailed drawings and diagrams are provided with exact dimensions and instructions on what material to use for assembly. In general, if there are difficulties with self-design, then you can always just make someone else's copy.

This machine was invented for processing long parts. The abrasive belt is based on a durable cloth fabric fastened into a ring. There are different sizes. It is driven by the same electric motor with similar characteristics. But some craftsmen replace the engine with a drill. A good drill is a versatile tool in many ways. However, this substitution is more relevant for small size desktop machines, as a rule, these are used by modellers.

How is a belt sander assembled with your own hands? The tape is stretched between two shafts or drum rollers. One of which is the master (it is attached to the motor spindle), and the second is the slave (it provides tension to the sanding belt). To prevent the tape from jumping off the drums, washers-stoppers are attached to their ends. It turns out something like a textile coil. With slight distortions, the wear of the belt occurs faster than the edges of the belt rubbing against the lock washers are destroyed. So this idea is quite viable and justifies itself.

Also, between the drums on the back side of the belt, a support screen is installed, which provides a tight pressing of the entire plane of the workpiece to the surface of the belt. To reduce the friction force, the screen is carefully polished. It can be made from both light metal and hard wood.

The drive roller must be rubberized or made of hard rubber. This will ensure that the tape does not slip on the surface of the roller. The entire structure, if necessary, can be positioned in different ways: vertically, horizontally or at an angle. To a common frame, as on all similar machines, a rigid handrest is attached, at an angle of 90 degrees, or adjustable. The distance between the tape and the edge of the hand table should not be more than 3 mm. Due to the fact that the rupture of the tape is not capable of causing significant bodily harm, protection is made only to remove grinding products.

Homemade grinder

A grinder is a high speed belt grinder or general purpose machine. Working surfaces - a disk and a tape. The engine used is the same as on all machines. And high speed is achieved by using pulleys of different diameters. A large diameter pulley is mounted on the motor spindle and is the driving one. Small pulley - tension.

On a universal machine, a disk is also attached to the spindle. You can also install an additional transfer roller, the support mounts of which will be spring-loaded. This is done to quickly change the abrasive belt.

The grinder differs from other grinders in processing speed and versatility. Using interchangeable belts for different materials, even high-alloy steel surfaces can be quickly processed.