Tape grinder. Knife maker's grinding machine. Homemade grinder - making a belt grinder with your own hands

At large and small industrial enterprises there has always been a need to have grinding machines in their equipment fleet different types, including tape. In recent years, due to the development of small businesses, handicraft workshops, and simply to carry out minor works For grinding any parts, desktop small-sized belt-type grinding machines began to be produced. The thing is necessary, of course, but everything is spoiled by one nuance: the high cost. And this applies not only to foreign models; prices for domestic analogues also bite sharply. Here, inevitably, many craftsmen begin to think about how to make a tape grinder with their own hands.

How does the grinder work?

Desktop grinding machine belt type or, in simple terms, a belt grinder, is drive device, where the role of the power unit is performed by an electric motor. The tool is intended for processing, finishing and grinding flat surfaces, removing the layer of rust or paint coating present on the workpieces. It is used to process burrs and sharp edges of steel, cast iron, aluminum or non-metallic parts.

Design

There is nothing particularly complicated in the design of a belt grinder. The device consists of a motor, drive and guide rollers. A sanding or roughing belt of the required grain size is passed through them.

When the engine is turned on, the drive roller mounted on its shaft begins to rotate, and through the tensioned working belt, the rotation is transmitted to the guide rollers. By pressing the part to be processed in the working area against the belt, the operator performs the required operation, changing the position of the workpiece relative to the surface of the belt if necessary.

By adjusting the distance between the guide rollers, it is possible to process surfaces with defects of different depths. During prolonged use, the sanding belt may not stretch much. To compensate for possible slack, the design has a tension mechanism. Typically, such a function is assigned to a roller located at the same distance between the leader and the slave.

The grinding machine is supplied with a support table, which also serves as a surface for fixing the workpiece. As a rule, such a table should be able to rotate 90 degrees about one axis. In this case, it is possible to process two perpendicularly located planes without reinstalling the part on the support table.

Although it is necessary to wear safety glasses when working on such machines, it would be a good idea to install a folding clear glass made of acrylic, to avoid eye damage from scale particles, paint flakes or metal dust. For example, you can look at the installed safety glasses on industrial machines where a round emery stone is installed as a working element.

Of course, a grinder control panel is required! For safety reasons, it is recommended to mount it on the machine frame in close proximity to working area operator. Portable machines are equipped with a stand made of durable steel with mounting holes on the base, allowing you to fix the unit on a wooden surface.

If you look at the design details, you can immediately notice some visual instability of the assembled grinding device. The overhang of the side dimensions of the installed rollers significantly exceeds the supporting surface on the base. In addition, the absence of a support table makes it difficult efficient processing relatively large surfaces, and holding the part in a canopy is inconvenient and quite dangerous.

An increased length of the working belt leads to additional losses due to friction. It is necessary to use a higher power power unit in the drive, and this increases energy costs. The tension unit is simple and functional. Adjusting the tension is a matter of seconds. The machine comes with replaceable grinding attachments, with which you can perform grinding even on internal surfaces. Despite this, the cost is 100 thousand rubles. makes me think.

Tape selection

To choose the right belt grinder, it would be a good idea to first determine the overall dimensions of the surfaces of the products to be processed, and then become familiar with the sizes of commercially available sanding belts.

Endless sanding belts differ in three parameters: length, width and grit level. The currently produced size range of sanding belts for such machines is as follows: 610 mm, 915 mm, 1230 mm, 1600 mm, 1830 mm in length; width dimensions are limited to 50 and 100 mm, although others can be found.

In any case, the following criteria must be met:

The tape should be on elastic fabric base.
Maintain maximum angular speeds of at least 1500 rpm.
Possess great abrasive resistance.
The maximum relative tensile strength is at least 15%.
Heat resistance during long-term operation.

When choosing a tape, it is necessary to take into account that the most optimal size sanding belts for a homemade grinder is 1230 mm. Shorter abrasive belts wear out faster because they do not have time to cool sufficiently during idling. As for longer ones, their use will lead to an increase in the dimensions of the entire structure, which is unacceptable; however, this does not provide any improvements.

The parameters of the mechanical tensile strength of the tape are very important. The use of composite tapes, even glued with the most advanced composition or double tape, strictly not allowed! When the joint is stretched during operation, the tape increases in length and the tension weakens. In this case, the tape may come off the guide rollers or break, and at such a speed this is fraught with serious consequences for the operator and others. Taking into account the high speed of movement of the belt along the surface of the guides and drive roller, the applied specific force on the abrasive surface should not exceed 0.8 kg/cm 2 . Approximately this parameter corresponds to the mechanical strength of an electrocorundum sanding belt: 800-900 MPa.

Advice: before installing the tape on the grinder, it is recommended to hang it on a cylinder with a diameter of about 60 mm. This ensures natural stretching of the abrasive element before work.

DIY grinder: drawings with dimensions + assembly instructions

During development Special attention is paid to the configuration of the rollers, the method of fixing the product and the optimal power of the power unit. More about this.

Making rollers

Particular attention is required in the manufacture of the main, driving roller, acting as a pulley! It must be fairly massive. This will allow you to avoid an unnecessary jerk during the starting moment due to the present inertia of the resting state. The speed is gradually increased to the desired values. If we take into account the use of a standard power unit in the drive design, with a slip not exceeding 9% at a nominal 1500 rpm, the speed will be no more than 1400 rpm maximum.

One more nuance! Steel or cast iron are not suitable for the manufacture of a driving part, because during startup there will be a heavy load on the engine, or it will not be able to turn the too heavy blank at all.

There are two options to solve this problem:

Make a hollow steel roller to reduce mass according to the principle: larger diameter - deeper cavity. Exact dimensions can be calculated using a reference book, although particular accuracy is not necessary.
Second option: making a roller from duralumin grade D16 and higher.

It is advisable to carve an end groove on the pulley, the dimensions of which will be identical to the dimensions of the belt intended for use. This will help prevent uncontrolled belt derailment if the rollers are incorrectly positioned in the plane of rotation.

Of considerable importance surface roughness degree rollers. Featured limit values: Ra1.25-Ra2.5. Increased roughness will lead to premature wear of the belt base, and roughness below the designated limit will contribute to unnecessary slippage during long-term operation.

The rollers must be installed using bearing units closed type based on self-aligning bearings with a fixed outer ring. With this installation, abrasive or other particles cannot get on the roller shaft. When selecting bearings, it is necessary to take into account the correspondence of their load-bearing parameters with the maximum number of revolutions of the power unit.

The rollers can be secured using conventional cotter pins or using a shoulder at one end of the axle, as prescribed by the standard. The drive roller must have a groove for a key common with the motor shaft.

Motor and turntable

If you are going to assemble a belt grinder with your own hands, then you should pay special attention to the choice of drive! Most often, a 0.75 kW engine is used (although up to 1.5 kW is not prohibited) with a speed of 1500 to 3000.

Please note that the belt may not withstand high speeds. As a rule, the engine power is selected depending on the intended operations on the assembled machine. If roughing work predominates, when the load on the drive is large, the power unit is installed more powerful, but with fewer revolutions, and if just surface grinding is required, the parameters remain within the limits mentioned above.

The grinding process is characterized by considerable contamination in the form of microscopic dust particles, so the motor must be a closed type with its own fan for airflow! It is better to ignore the recommendations of “experts” about using a motor from a used washing machine.

To design a homemade grinder, you need drawings with dimensions; in addition, it’s a good idea to think about safety precautions and ease of use on the assembled machine. This requires:

Rotary table.
Pressing plane with reverse side tapes for support.

For the first task, the table bracket must be mobile, with the ability to rotate 90 degrees and fix at extreme points. The recommended table thickness is at least 15 mm, preferably using alloy.

For the clamping plane, a machine frame ground near the support table is suitable.

Belt grinding machines are used in various applications, often in industry. Grinder is a belt grinding machine designed for dry grinding of a product that belongs to the equipment category under consideration. In this case, the product can be metal, artificial or natural stone or others. You can create a grinder with your own hands using recommendations and certain drawings.

DIY making

When considering the opportunity to make a grinder with your own hands, many home craftsmen have a desire to get the job done, since with the help of this equipment it is possible to carry out various technological operations of grinding parts. In this case, the part can be made of metal or wood, plastic.

Industrial versions usually have a high cost. Also, do not forget that the equipment requires periodic maintenance; a homemade belt grinding machine can be repaired independently without the presence of special tools or equipment.

The grinder can be used to implement the following technological tasks:

deburring;
elimination of minor surface defects;
removing flash;
cleaning the corrosion layer;
eliminating the consequences of laser, plasma or other cutting;
elimination of defects made during the welding process.

Considering the above features, many decide to make a grinder with their own hands.

Features of DIY work

Not everyone can afford even a simple factory-built belt grinder. It's connected with high cost professional equipment. Also, do not forget that the dimensions of the industrial belt grinder grinder are very large. WITH large sizes The belt grinding machine may not fit into the designated room, making its transportation more difficult. The design of the grinder is relatively simple, which makes it possible to create it yourself.

As with any other work, from carrying out preparatory stage a lot depends. In order to create a grinder with your own hands, you need to consider the following points:

First you need to sketch out a drawing that will show the design features. Based on the drawing, it will be clear what materials and tools will be needed to carry out the work.
Next, we find the necessary tools: drill, grinder, electric jigsaw. It is worth considering the point that many grinder drawings determine the need to use metal elements to strengthen the structure, dampen vibration, and so on. Therefore, when choosing a tool, it is worth considering that you will also need to work with metal.
Some parts cannot be created by yourself, as you need a lathe. Therefore, you need to be prepared for the fact that you will need the services of a turner.

When choosing a drawing, we note that the options used to create a do-it-yourself belt grinding machine, with which grinding can be carried out in a horizontal and vertical plane, are very popular. This version, which can also be made with your own hands, will have great functionality, since the part can be processed at the desired angle. As a rule, we take the diagram of an industrial model as a basis, and then change it to suit our needs.

DIY process

When creating power parts, you should use metal whose thickness is 10 millimeters or more. In order to facilitate the work, you can make a kind of marking on the surface according to the drawing. A marker is used to apply markings; the accuracy of manufacturing power parts does not play a big role. Cutting can be done using plasma cutting, but such equipment is extremely rare in the home.

When making the base, it is best to use metal whose thickness is more than 12 millimeters. You can connect the elements using a screw and a nut - you just have to do quite a lot various holes in metal. Assembly is also carried out using electric welding.

Difficulties in the manufacture of a belt grinding machine can be created by the design elements that are responsible for rotating the rotary mechanism to ensure processing in several planes. As a rule, the grooves for turning are made by a milling machine, but you can try and cut them yourself using a drill, file, or drill.

Special attention should be paid to how to make videos. When considering this issue, we note the following points:

When creating a mini grinder with your own hands, you should choose titanium or duralumin rollers. if you cannot find rollers made of these materials, then you can use steel blanks.;
rollers must have precise geometric shape. that is why the work of their manufacture should be entrusted to a qualified turner;
the roller that will be fixed on the shaft of the electric motor used must be made of steel. This is due to the fact that the size of this roller will be quite large, it is quite difficult to find a titanium blank, and other materials may not withstand the resulting load.

It is worth considering that you will need 4 videos:

drive (150 mm);
tension (100 mm);
two small ones for guiding the tape (70 mm).

When assembling the structure, it is worth considering that they must be located strictly on the same line. Otherwise, the tape you are using will constantly come off. The width of the blanks is selected taking into account the width of the tape. In this case, there must be a margin for this indicator of at least 20% of the total width. In some cases, the cylinder is given a barrel shape, for which a small bevel is made at each edge. The cylindrical surface should be smooth, the tape will not slip due to strong tension.

Bearings need to be given attention, as they are an important integral part machine They must be exclusively closed. This is due to the fact that the process of using a belt grinding machine involves the formation of a large amount of dust, which, when it enters the internal cavity of the bearing, increases friction and significantly reduces the service life of the structure in question. Also, do not forget about the large load that will be transferred to the axle and bearings - you need to choose them only from the 6th grade.

Drive selection

When making a mini grinder with your own hands, you should select the drive correctly. As a rule, the power of the electric motor should be at least 1.2 kW even if there is a small load. Models that operate on a regular 220 V network are suitable for domestic use. You also need to pay attention to the fact that the electric motor must have a large number of revolutions to increase the processing accuracy. Many models have blades for blowing air through the body, which helps reduce the temperature. Despite the primitiveness of the technology, it is very useful.

Grinder (English) literally – crusher. Meat grinder is a meat grinder, rock (stone) grinder is a stone crusher; stick (wood) grinder – garden crusher of branches and twigs into chips. But there is also a completely unambiguous meaning of the word grinder: in mechanical engineering and metalworking it is a grinding machine. A useful household item. For example, it is impossible to guide a dull meat grinder knife on a whetstone manually. On a manual knife sharpener - somehow possible, having solid working skills. And on the grinder - no problem. The same thing - if you need to polish a part complex shape without disturbing her profile. Or just sharpen scissors or a professional knife. It is best to edit various types of wood and metal cutters on a grinder. It is quite possible to design and assemble a grinder with your own hands, without having complex equipment and skills to work with it. In terms of money, this will mean savings of 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 external turning at all. For example, how to make a simple grinder literally out of trash, see the video below:

Video: DIY belt grinder made from trash

Or another option, how to make a stronger and more durable grinder from scrap metal:

Video: scrap metal grinder

Disc or tape? And drive

There are almost more types of grinding machines used in industry than lathes. The emery known to all craftsmen - a motor with a pair of grinding wheels (or one wheel) - is also a grinder. For yourself at home, it makes sense to make either a disk end grinder (plate grinder) or a belt grinder. In the first, the abrasive is applied to a rotating hard disk; in the second - on an elastic band running around a system of pulleys and rollers. The disc type is more suitable for grinding simple wooden parts and coarse or medium clean metal parts. Using a belt grinder, it is also possible to produce precise and clean finishing of profiled parts of complex shapes, incl. large-sized, see below.

A disk grinder is very easily obtained from the same emery or a motor of suitable power, see below. You need to order an adapter from the electric motor shaft to the disc shank grinding wheel on a metal base. Or under a clamping chuck, then on the same motor it will be possible to build a mini lathe, see figure:

A worn-out “plate” is suitable: a disk made of thin (4-6 mm) fibrous plastic is glued to 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 disk and tape grinder is not only in the possibilities of use. If we take ordinary household crafts, then for a disk grinder a drive power of 250-300 W on the shaft is enough. For small wooden parts - and 150-170 W. This is a motor from an old washing machine, a straight (ordinary) drill or a screwdriver. But for a belt grinder you will need an engine from 450-500 W: three-phase with batteries of starting and operating capacitors. If you plan to process large items, then the motor power is from 1-1.2 kW. Moreover, capacitor batteries for both will cost not much less than the engine itself.

Note: a 100-200 W drive uses a mini-belt grinder (see below) for precise knife dressing, 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 movement of the abrasive (see below) using a standard speed controller. You just need, firstly, to make a holder for the drill that rigidly fixes the tool. Secondly, an elastic transition coupling from the drill to the disk shank, because It is difficult to achieve their precise alignment without special equipment, and runout will negate the accuracy of processing and can damage the drive tool.

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

Since shock and irregular alternating loads on the drive in a grinder are an order of magnitude lower than, say, in lathe, the drill holder for it can be made of 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 advisable to use a drill without an impact mechanism and with a steel shell on the neck (for installing the front handle).

coupling

For the adapter coupling, you will need a piece of steel rod (not necessarily turned) of the same diameter as the shank of the grinder drive shaft, and a piece of PVC-reinforced hose (garden irrigation) with a clearance such that it stretches tightly over the rod and the 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 reliable clamping in the drill chuck. After assembling the coupling in place, the hose on the shank and rod is tightened tightly with clamps; can be wired. Such a coupling completely counteracts the misalignment of the drive and driven shaft up to 1-1.5 mm.

Tape is still better

A belt grinder allows you to do everything a disk grinder can do, and much more. Therefore, next we will focus on how to make a belt sanding machine with your own hands. Amateurs, focusing on industrial designs, sometimes make very intricate grinders, see figure:

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

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

Kinematics and design

As mentioned above, there are many designs of grinders. When considering what and how to build a grinder for yourself, it is better to focus on industrial designs designed to be fully mechanized for precise and clean grinding of large-sized profiled parts: once it “sands” the blade of an airplane propeller or wind turbine properly, it can handle any other work.

Kinematic diagrams of grinders for the specified purpose are shown in Fig.:

Basic kinematic diagrams of belt grinding machines (grinders)

Pos. A is the most complex and perfect, with three rocker arms. If the length of the tension roller rocker arm is approx. 2 times less than the working one, then by adjusting the tension of the springs, it is possible to achieve 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 belts of different lengths. Secondly, in the same way you can quickly change the belt tension for different operations. The working branch of the belt 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.

The scheme with a coaxially swinging rocker arm (item 2) is simpler, cheaper and in terms of processing accuracy is not inferior to the previous one, if the length of the rocker arm between the axes is at least 3 diameters of the workpiece. To reduce the profile by grinding, the stroke of the rocker arm is limited by stops within 10 degrees up and down. The pressure of the belt to the part is most often gravitational, under the weight of a rocker arm with a bypass pulley. The tension of the belt can be quickly changed within certain limits by pulling the rocker up with a weak adjustable spring, partly compensating for its heaviness. 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 working surface of the belt will run around the bypass pulley. For example, the fairly popular BTS50 grinder is made using a coaxial rocker design. The disadvantages of the scheme are, firstly, the technologically complex rocker arm joint, which is coaxial with the drive shaft. Secondly, the need for an elastic band: if you make the idler pulley sliding and spring-loaded, the processing accuracy decreases. This drawback when processing small parts is completely eliminated by an additional tension roller, see below.

The scheme with one misaligned rocker arm is used quite rarely in industry, because in principle, it does not allow achieving uniform tape tension. However, it gives 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 circuit from the point of view of an amateur master. And then we’ll try to figure out how to make a grinder belt ourselves and do without custom-made turned parts.

3 rocker arms

Competent amateurs build their grinders exactly according to the scheme with 3 rocker arms, on the left in Fig. below. Not all propeller blades can be ground, but in this case another advantage of this scheme applies: if the grinder is used as a vertical grinder, then the working branch of the belt 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 design is also widely used (in the center) for the same reasons. Repeating them yourself in most cases is quite possible. For example, the drawings of the KMG grinder, popular abroad, can be downloaded.

The dimensions are, however, inch - the machine is American. For the drive, in any case, it is possible to use an angle drill-grinder (on the right in the figure, 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 an unusable washing machine with a horizontal tank. Its advantage is low speed. This makes it possible to make a large-diameter drive pulley and thereby eliminate belt slippage. A belt slip during operation is almost certainly a damaged part. Most washing machines have 2-3 speed asynchronous motors for 220 V - Spanish. Shaft power – 600-1000 W. If you come across one, don't forget about the standard phase-shifting capacitor bank.

Coaxial rocker

Amateurs do not make pure grinders with a coaxial rocker arm. A coaxial hinge is a complicated thing; you can’t make an elastic band yourself, and store-bought ones are expensive. Grinders with a coaxial rocker are most often used at home in the version for small precision work from a table, i.e. with a rigidly fixed horizontal rocker arm. But then the need for a rocker arm as such disappears.

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

Its features are, firstly, an overhead bed for the tape (item 7), which significantly expands the possibilities of use. For example, the plane iron is straightened on this grinder with an angular stop literally by itself. In this case, the grinder works, so to speak, like a self-propelled whetstone (emery block). Having removed the bed, we get a grinder with an elastic band for precise grinding/polishing of rounded small parts. Secondly, the tension shaft (item 12). By clamping it to the groove with nuts, we get a relatively fixed tension of the tape for working with the bed. And after releasing the nuts, we switch the grinder to the gravitational belt tension mode for fine work. Drive - not necessarily through a pulley (pos. 11). You can screw it directly onto the drive shaft shank (item 16) from the drill through the adapter coupling, see above.

A specialized tool grinder (for example, for guiding and straightening turning tools) generally loses any semblance of the original design. A high-speed motor is used for it (200-300 W is enough power). The drive pulley is, accordingly, of small diameter. The bypass pulley, on the contrary, is made larger and heavier for inertia. All this together helps reduce tape runout. The tension roller for the same purpose, plus for greater uniformity of belt tension, is moved further away and spring-loaded with a long, not very strong spring. How to make a grinder for processing incisors, see the video below.

Video: grinder for making cutters

One rocker

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

In this case, the original scheme is also modified: the rocker arm is turned 90 degrees, moved up and spring-loaded, on the left in Fig. It turns out to be a simple vertical grinder. And, importantly, it works without problems with homemade non-stretchable tape. A tension spring (in the center) or a compression spring can provide tension to the tape. Its strength is not so important, as long as the tape does not bend excessively during operation. No adjustments are required during use.

Consumables and parts

The only consumable material for a belt grinder is a tape (not counting grease for bearings and hinges. The tape can be ordered to the desired length (see at the end), but you can also make it yourself from sandpaper on textile based. It is highly desirable - flexible, unimpregnated. In general, the procedure for making a grinder belt with your own hands is as follows:

We cut the workpiece - a strip of the required 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 outline the mandrel with the workpiece inside out.
We bring the ends of the workpiece exactly end to end and securely fasten them.
Place a piece of glue stick for a hot glue gun on the joint.
Heat with a construction hairdryer until the glue melts.
We apply a patch of thin fabric to the joint.
Press with 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 for the patch. It is very durable, but just try running your finger across a PET bottle. Not very slippery? Rough PET film cannot be stretched under tension even over polished metal. And instead of a patch, it is better to seal the back of the tape with a continuous strip of PET film with an overlap of 2-3 cm. The runout 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 blank skin.

Second, insert the finished tape into the machine and grind something indecent with it without strong pressure. The scar on the seam will be sealed, and the tape will become no worse than the branded one.

But the most important thing is elasticity best glue for gluing the grinder tape, it is not expensive and difficult to use thermo- or mounting, but ordinary PVA. If the tape is covered with a lining along the entire length of the back, then its PVA strength will be more than enough. How to glue PVA grinder tape, see video

Video: gluing grinder tape with PVA glue

Pulley

Formative ( side surface cross-section) of the grinder drive pulley should be straight. If you use a barrel pulley, the belt will bend like a trough along its entire length. The rollers prevent it from slipping, see below, but the generatrix of the pulley must be straight.

A pulley for a grinder that is not intended for particularly precise work, firstly, does not have to be turned. In a scheme with 3 rocker arms, the beating of the belt from its misalignment will go out on the rollers before it reaches the working branch. In a simple vertical grinder, the beating of the belt 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

Secondly, the pulley, rollers and, in general, all the parts of a home grinder can be made from plywood. In production, this is certainly not an option, even if a 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 it and itself. But you won’t be running a grinder at home every day in 3 shifts. And no tape slips along the plywood pulley. Incl. homemade. So you can safely make a grinder pulley from plywood:

Video: pulley for grinder made of plywood

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

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

Video: what wheel is needed for a belt grinder

Rollers

The rollers of the grinder, oddly enough at first glance, are its most important parts. 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 grinder for incisors. Only barrel rollers can cope with this task, see below. But the “trough” of the belt after any roller must straighten before it reaches the working area.

Rollers with flanges (sides, edges) will not hold the tape. The issue here is not only and not so much with the misalignment of the roller axes: the grinder belt, unlike the drive belt, must withstand the loads from the parts being processed without slipping. If you make videos with flanges, then if you barely touch the tape with something, it will creep 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 for turned steel and not less than 35-40 mm for plywood. The tension roller (the probability of the tape slipping from it is greatest), if the working branch of the tape does not come off it, can have a diameter of 0.7-1.2 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 processed cleanly, see e.g. track. video:

Video: barrel roller for grinder

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

And another option

All critical parts of the grinder - a solid belt, pulleys with a coating that prevents it from slipping, rollers - can be purchased separately. They won’t be that cheap, but still not thousands of foreign ones and not dozens of native leather jackets. The remaining parts of the grinder, either flat or from corrugated pipes, are made using a regular tabletop drill or drill. Here's where you can order parts for the grinder:

//www.cora.ru/products.asp?id=4091 – tape. Lengths and widths are made according to the customer's wishes. Consult on abrasives and processing modes. Prices are reasonable. Delivery time - questions to Ruposhta.
//www.equipment.rilkom.ru/01kmpt.htm – spare parts (components) for grinding machines. There is everything, the prices are divine. Delivery - see previous page.
//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 ones suitable for grinding.
//dyplex.by.ru/bader.html, //www.syndic.ru/index.php?option=com_content&task=view&id=36&Itemid=36 – spare parts for grinders. They do not make ribbons to order - choose from the catalogue. Rollers without axles; axles sold separately. The quality is impeccable, but everything is very expensive. Dispatch - within 2 weeks to the border. Then - their customs, our customs, Rusposhta. Total approx. 2 months It may not arrive if some local bureaucrat considers the product sanctioned. In this case, there are no problems with the return of payment, completely absent for the average citizen real opportunities get one.

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Grinder is a belt grinding machine used for dry grinding of products made of metal, various alloys, wood, artificial stone, plastic and other materials.

The question of how to make a belt grinder with your own hands is asked by many home craftsmen, because with the help of such equipment you can perform various technological operations with products made from various materials. Using a belt grinder, you can remove burrs, eliminate surface defects, remove rust, remove flash, eliminate the effects of plasma and laser cutting, and clean welds.

Making your own grinder

It would seem that it is much easier to purchase branded equipment and use it in your workshop for many years than to make it yourself. However, not everyone can afford to pay a decent amount for a serial machine from a well-known manufacturer. Moreover, it is not at all difficult to make such a machine yourself, which will have the required functionality.

Main parts of the machine body with dimensions (click to enlarge)

In order to become the owner of a homemade belt grinder, you should first sketch out a drawing, and also stock up on a drill, grinder and jigsaw. Some parts for the belt grinder will need to be ordered from a turner, but this is not a problem these days. It is better to immediately focus on making a grinder that will work in the vertical and horizontal plane: such equipment is highly functional and allows you to process parts at the required angle. You can take the diagram of a branded machine as a basis and use it to make homemade equipment.

If you need a simpler grinder made from scrap materials, then you can see this option in the video below:

Manufacturing process

For the manufacture of power parts of the machine it is necessary to use sheet metal 10 mm thick. To draw the contours of such parts for their further cutting, you can refer to the drawing. There is no need to follow the dimensions exactly, since only the dimensions of the parts that you are going to process on the belt grinder will depend on them. You can draw the outlines of the parts on a sheet of metal with a marker, and use a grinder and a jigsaw to cut them out. It is much easier to cut out such parts using a plasma cutter, but not everyone has such equipment at home.

Base, machine body parts and engine before assembly

To make the base of your homemade grinder more reliable, it is better to use a 12 mm thick sheet of metal for its manufacture. To assemble the grinder base you can use screw connections, but then you will have to drill a lot of holes, which will significantly weaken the entire structure. It will be much easier and more reliable to assemble the base of your machine using electric welding.

The semicircular grooves on the parts of the belt grinder, which ensure the rotation of the platform on which the rollers are placed, will require a lot of time. To make such grooves yourself, you will need to tinker with a drill, cutters and a file, and also use a drill. You can make your task much easier if you entrust the making of such grooves to a qualified milling machine operator.

Model of the machine made of plastic: thanks to the rotating unit, the grinder can be in a vertical position...

To make the rollers of your homemade mini-machine, it is best to use titanium or duralumin (D16). If it is not possible to find blanks made from these materials, then steel can also be used, but then the rollers must be made as light as possible by choosing metal from their inner part. To make rollers for a homemade machine, you will need the help of a qualified turner, just make sure to prepare a drawing for it.

In any case, the largest roller of the belt grinder, which will be fixed on the electric motor shaft, will need to be made of steel, since a titanium blank of this diameter is very difficult to find, and duralumin may not withstand significant loads. For the entire homemade machine, you will need to make 4 rollers, the dimensions (diameter) of which are: drive roller - 150 mm, tension roller - 100 mm, two small ones - 70 mm. If you are going to make a mini-machine, then the diameters of the rollers may be smaller.

...as well as horizontally

When you collect your homemade machine with finished rollers, it is very important that they are positioned strictly in one line. Otherwise, you will constantly experience the tape coming off. The width of the rollers depends on what size sanding belt you intend to use on your equipment. When you make a drawing for the manufacture of rollers, be sure to keep in mind that they must be barrel-shaped, this will ensure that the sanding belt is securely held on them during operation. In order to give the rollers this shape, a small bevel is made from each edge: 1–2 mm.

The finished rollers of your homemade belt grinder should have a smooth surface; you need to tell the turner who will make them about this. The bearings on which they will rotate must only be of the closed type, otherwise they will quickly become clogged with dust generated during operation. In order for your homemade equipment to work for a long time and without failures, you must choose bearings for it that have a class of at least 6. The rollers rotate at high frequency, so the bearings for them must be of very high quality.

Working belt

You can always see a spring on a belt grinder, which is necessary to ensure automatic tension of the sanding belt. If you use such a spring, then changing the tape will be very convenient, and its tension will be adjusted automatically. It should be said right away that it will be necessary to change the tape several times even when processing one product. Processing any metal part It is necessary to start with a tape with a coarser abrasive, gradually changing it to a finer one.

Very important attention should be paid to gluing the tape. There are options for proper gluing on the Internet, and you can also watch this process on video. To make it, you need to use sandpaper on a fabric basis. The seam on the tape is made only end-to-end and it must be reinforced, for which a strip is used thick fabric, placed on the back side of the area to be glued. To glue tape sandpaper, you must use only elastic glue, and it must be of very high quality.

For high-quality and reliable gluing of tape for sanding tape, you will need it proper preparation. You can glue the tape using a glue stick for a hot-melt gun: this method can be clearly studied in the video above. For heating, you can use a regular technical hair dryer.

If you wish, you can make your homemade grinding machine even more versatile; to do this, it should be equipped with an additional table placed on the side of the largest pulley. This will allow you to process parts on a belt grinder, pressing them against the sanding belt from the side of the largest pulley. If you decide to make such a table, you will need to provide for the possibility of changing the direction of movement of the sanding belt, which should always move towards the work table, and not away from it.

A simpler design of the grinder can be seen in the video below:

Selecting a drive for a homemade machine

It is very important to choose the right electric motor to equip your grinding and sharpening equipment. Even if you are assembling a mini-machine, the engine for it should have a power of 1.2–1.5 kW. It is advisable to choose an engine that runs on electrical network 220 V, because when using a three-phase device and connecting it through a capacitor, you will lose 30 percent of its rated power. For your sharpening and grinding machine to be effective, you need to choose an electric motor for it with big amount rpm The drawing of a homemade belt grinder shows that the electric motor for it must be selected with a cantilever type of fastening, which provides for its fixation in the front part of the body.