Budget belt sanding machine. How to make a belt grinder for metal with your own hands? DIY belt sanding table

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Installation

Grinder (English) literally – crusher. Meat grinder is a meat grinder, rock (stone) grinder is a stone crusher; stick (wood) grinder – garden crusher 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 applies if you need to polish a part of a complex shape without disturbing its profile. Either just sharpen the scissors or 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. Disc is more suitable for grinding simple wooden parts and coarse or medium purity - metal. 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 shank of a metal-based grinding disc. 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 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 design 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 drive pulley large diameter and thereby prevent the tape from slipping. A belt slip during operation is almost certainly a damaged part. Most washing machines with 2-3 speed asynchronous motors for 220 V are 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 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 textile-based emery cloth. 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 workpiece 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

The generatrix (side surface in cross-section) of the grinder drive pulley must 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 production. 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 due to the complete absence of real opportunities for the average citizen to receive one.

5,00

You can make a very convenient manual belt sander from an angle grinder with your own hands. With the help of such a tool it is good to sharpen an ax, knives, etc. Treat the surface at any angle, giving it a flat plane. In general, anyone who works with iron or wood will appreciate this mini machine.
Sharpening the cutting edge of the ax:

With this sharpening, the corner will not float away.

How to make a belt sander from an angle grinder

The mount for the angle grinder will be made from a piece of thick steel, about 10 mm thick. We drill a hole for the neck of the angle grinder.

We cut a wide slot.

Using a grinder we cut off the fastening.

Next, we clean and polish so that everything looks beautiful and safe.

With paws clamping device drill a hole.

Then cut a thread on the wide side.

As a result, this mount can easily be put on the angle grinder and clamped so that everything is held tightly.

Let's try it on.

Now you need to make a roller that will rotate the tape from sandpaper. We take chipboard and use large diameter bits to cut out round pieces. To obtain a wide roller, we glue the round pieces together.
Then use a feather drill to drill a hole in all of them at once.

Then we clamp it in a vice and use a triangular file to make an internal hole for the hexagon.

Like this.

We take a wide nut and make notches on the planes with a file.

They are needed to help the nut stay in the wood better.

We dilute two-component epoxy glue and glue the notched nut into the wooden roller.

After the glue has dried, clamp the roller into the lathe.

We sew under the ellipse. This is necessary so that the tape does not fly off. Then sand it with sandpaper until smooth.

It came to the second video. It is made of three bearings pressed onto the main line.

Let's make two such ears.

We put it on the edges of the protruding shaft.

Let's weld the plate. The result was a U-shaped part holding the roller.

To prevent the shaft from flying out, we fix it by welding

Now let's make the frame. It will take two steel pipes different diameters so that one fits into the other.
A flat overlay is welded onto a larger diameter pipe. It is needed in order to press on the tape while sanding.

We weld a roller of bearings to a thin pipe.

We take a ring of sandpaper (sold in hardware stores), insert the pipe into the pipe and estimate the approximate size of the entire device.

We saw off the long ends of the pipes. We make a wide groove in a thin pipe, and a hole in a thick pipe.

We weld a nut to the hole.

I have been making knives for several years now and always use 2.5 x 60 cm and 10 x 90 cm belt sanders in my work. For a long time I wanted to buy another one, with a tape width of 5 cm, as this would simplify my work. Since such a purchase would be expensive, I decided to make it myself.

Problems when designing a future machine:
Three limitations had to be overcome. Firstly, there was no 10 cm wide tape available locally; it could only be ordered online. This didn't seem like a very viable option to me, as there is no greater disappointment than finding out that the tape has worn out and needs to be replaced, and you have to wait a week or two for a new one to arrive. Secondly, there was a problem with the rollers. I searched but couldn't find any tape suitable for 10cm. Thirdly, the motor. A belt sander requires a fairly powerful electric motor, and I didn't want to spend too much money on this project. The best option for me was to use a used motor.

Solutions to design problems:
The first problem with the tape had a simple solution. Since a 20 x 90 cm belt was available for sale in hardware stores at a reasonable price, I could make two 10 cm ones from it. This imposed restrictions on the size of my machine, but due to price efficiency, this option was the best. The second problem was solved using a lathe. To do this, I watched a video on the Internet and realized that I could make the videos I needed myself. With the engine the task was more difficult. I had several electric motors in the garage, but for some reason I had to give them up. Finally, I decided on an old tile cutting machine that had a 6-amp electric motor. At that time, I realized that this power might not be enough. But since the work was at the experimental stage, I decided to first achieve a working version of the machine, and the motor could be replaced later. In fact, the motor is suitable for small amounts of work. But if you're going to be doing more intensive sanding on it, I'd recommend the 12 amp minimum.

Tools and materials

Tools:

Angle grinder with cutting discs.
Drill and drill bits.
Wrenches for 11, 12 and 19.
Lathe.
Vise.

Materials:

Electric motor (6 A minimum, or 12 A recommended).
Various bearings.
Nuts, bolts, washers, lock washers of various sizes.
Metal corner.
Sanding belt 20 cm.
10 cm pulleys.
Powerful spring.
Steel strip 4 x 20 cm.
Beam 2.5 x 10 x 10 cm made of wood or MDF.

Electric motor for machine

I had a choice of several motors, but the electric motor that was on the tile cutting machine had a more suitable casing. To some extent, working on the machine was like an experiment, because I was not sure that the motor had enough power. Therefore, I settled on a modular solution with the frame for the belt mechanism as a single element, which can be removed and rearranged on a more powerful base. The rotation speed of the motor suited me quite well, but I was worried that 6 A would provide weak power. After a little testing, I saw that this electric motor was suitable for simple work, but for more intensive work, you need to choose something more powerful. When designing your machine, pay attention to this point.

As I mentioned, the motor casing was very suitable as it allowed the creation vertical machine, which will be easy to move.

First you need to free it by removing the work table, saw, protection, water tray, leaving only the electric motor. Another benefit of using this motor was that it had a threaded core with a nut to hold the saw in place, allowing the pulley to be installed without using a key (I'll explain what a key is later).

Since I had a pulley that was too wide, I decided to use the large clamp washers that are usually used to secure the saw, turning one over so that there was a wedge-shaped groove between them. I found the space between them to be too narrow, so I put a lock washer between them to widen it. Advantage in this method is that the pressure washers have a flat edge that locks with the flat edge to rotate simultaneously with the core.

Belt

I used a 7 x 500 mm drive belt. You can use a standard 12 mm, but a thin one is more flexible and will put less strain on the motor. He doesn't need to rotate the grinding wheel.

Device of a belt grinding machine

The device is simple. An electric motor drives a belt, which rotates a 10 x 5 cm “main” pulley, which drives the abrasive belt. Another pulley 8 x 5 cm is located 40 cm above the main one and 15 cm behind it and is mounted on a bearing. The third 8 x 5 cm pulley rotates on a lever and acts as a tension roller, holding the abrasive belt tightly. On the other side, the lever is attached to the frame by a spring.

Determining the drive type

The main question was to rotate the main pulley directly with an electric motor or with the help of an additional pulley and drive belt. First of all, I chose a belt drive because I wanted to have the option of replacing the engine with a more powerful one, however, there was another reason. When you do intensive metal processing, there is a risk of encountering some problems. The belt drive will slip in such cases, while the direct drive will create big problems. With a belt, the device will be more secure.

Frame manufacturing and installation

It is important to mention that using a metal corner as a frame can have both advantages and disadvantages. The obvious advantage is that it is convenient to assemble, like a construction set in childhood. But the main drawback is that it is strong only in two directions, but weak when twisted. This means that we need to take this weakness into account and calculate what torque can be transmitted from the pulleys to the frame, and compensate for it using additional jumpers.

Cutting:
You can use a hacksaw to cut the corner, but an angle grinder with cutting disc they will do things faster. After cutting all the pieces, I would recommend sanding down all the sharp edges to avoid cutting yourself during assembly. Holes can be drilled using conventional drill and cutting fluid.

Main video

The main video is the most important detail project, since it receives torque from the motor and transmits it to the tape. I used an old bushing to secure it, but I recommend using a bearing instead. The bushings do their job, but they constantly overheat and require regular lubrication. Moreover, they can scatter dirty lubricant, which can be annoying during operation.

Shaft:
There are threads on the sides of the shaft with different directions so that the mounting bolts do not unscrew when rotating. If you cut off one threaded side like I did, leave the one that goes counterclockwise, otherwise you'll have to make a locking bolt (I'll describe how to make that later) and a cotter pin. The main pulley will be placed on the cut edge.

Pulley:
Continuing with the theme of reuse, I found an old pulley from another project. Unfortunately, I prepared it for the threaded pin that it was supposed to be held on, but, in fact, this is not a problem. I made a rectangular cutout in this pulley. I then used an angle grinder to cut a groove on the end of the shaft. By placing the key in the hole formed by the shaft groove and the rectangular cutout of the pulley, I securely fixed them relative to each other.

Making rollers for a grinding machine

I made the rollers from several pieces of 2.5 cm thick hardwood. But you can use MDF, plywood or other material. When laying layers, you need to make sure that the fibers are perpendicular, this will give the rollers additional strength and the layers will not crack.

It is necessary to make three rollers: the main roller, the top roller and the tension roller. The main roller is made of two 13 x 13 cm pieces of 2.5 cm thickness. The top and tension rollers are made of two pieces of wood measuring 10 x 10 cm.

Process:
Start by gluing together pairs of 13 cm and 10 cm pieces of wood, clamping them together with clamps. After the glue has dried, trim the corners using miter saw, then find the center of each part. Mount them in the lathe and turn them until they measure 5 x 10 cm and 5 x 8 cm.

Upper and tension rollers:
Next, you need to install bearings in rollers measuring 5 x 8 cm. Choose a core or spade drill, and drill a recess in the center to the width of the bearing. The inner race of the bearing must rotate freely, so you need to drill a hole that goes through the roller through the inner race of the bearing. This will allow the bolt to go through with a minimal hole.

Main video:
This part is done a little differently. There are no bearings on it, but if the shaft extends less than 5 cm from the roller, you will need to grind the roller down to width. Measure the diameter of the shaft and drill the same hole in the center of the roller. Try to insert the shaft, it must hold tightly, otherwise the roller will shake.

Bolting the rollers

Next, you should fasten the two halves of the rollers with bolts; do not rely only on glue. Remember that the bolt heads need to be recessed into the wood, since the roller rotates in close proximity to the frame.

Tension lever

The lever is made of a metal strip measuring 10 x 30 x 200 mm with rounded edges. It needs to be drilled large holes, so I recommend using for this drilling machine and lots of lube. A total of 4 holes are needed. The first is at the pivot point. It is not in the center of the bar, but 8 cm from its edge. The second hole will be located on the edge closest to the rotation point. It will serve to attach the spring. Two additional holes need to be drilled at the opposite end, approximately 5 cm apart. They need to be a little wider in diameter as they will be used for tuning, which I will talk about next.

When all the holes are made, you can attach the arm to the vertical angle between the top roller and the base. The end on which the spring will be attached is directed towards the main roller. It should rotate freely, so I recommend using two nuts for fastening, not tightening the main one completely, and using the second one as a locknut.

Installation of rollers

The upper roller is attached statically and must be clearly in the same plane along with the tension roller and the main roller. You can do everything by eye, but I recommend checking everything well with a level. To align the roller, you can add a washer, or, if it is not enough, a bolt. They are inserted between the frame and the roller.

There is no need to install the tension roller completely. We still need to make a stabilizing device.

Belt stabilization

Wear on the rollers or uneven surfaces can cause the abrasive belt to gradually come off during operation. The stabilizing device is a device on the tension roller that allows it to be at an angle that keeps the abrasive belt centered. Its design is much simpler than it looks and consists of a locking bolt, a slightly free-playing tension roller and an adjusting bolt.

Drilling holes in bolts:
For this purpose, I made a device in the form of a wedge-shaped cutout in the board, which will help hold the bolt in place during drilling. You can do this manually, but I don't recommend it.

Fixing bolt

The retaining bolt is a simple bolt with a hole drilled in it and is installed on the bar through a wide hole that is located closer to the pivot point of the lever. Since it is located between the lever and the roller, its head must be ground off so that the roller does not catch it. The bolt must be secured as shown in the picture.

The bolt on which the roller is attached

It needs to be loosened a little so that the tension roller has a slight play. But to prevent it from unwinding, you need to make a castle nut. To do this, you just need to make cuts on the edges of a regular nut so that it looks like a crown. There will be two drilled holes in the bolt itself: one for the adjustment bolt and it will be lined up with the locking bolt hole, and another for securing the castle nut with a cotter pin.

Bolt for setting:
Once the tension roller is in place, you can install the adjusting bolt, which will pass through the holes of the retaining bolt and the bolt on which the tension roller rotates. The system works when you tighten the adjusting bolt, causing the axis of rotation of the tension roller to shift its rotation angle outward, thus causing the belt to move closer to the mechanism. A spring at the other end of the lever adjusts the tension in the opposite direction. I recommend securing the adjusting bolt with a locknut as vibrations can loosen it.

Note: You can add a spring with reverse side tension pulley, but I haven't found any reason why this should be done. A small advantage will be that in this way the roller will have less play. But I will add that I did not do this, and I did not have any problems.

Completing the work of making the machine yourself

When everything is done, you need to check all the bolts again and make sure that the stabilization mechanism is assembled correctly. Then you have to turn the device on for the first time, which can be scary. It's like driving a car where the steering wheel and transmission don't work. I recommend turning the motor on and off for very short periods of time to prevent the machine from spinning at full speed.

In fact, the hardest part for me was adjusting the spring. If it is pulled too tightly, the tape will not be able to rotate... Too loosely and it cannot be held, it will fly off, which in itself is dangerous.

Ready!

That's all. You should end up with a decent, medium-power belt sander that can be converted to a more powerful one if desired.

I hope you enjoyed this master class. Thank you for your attention.

I decided to assemble this device to simplify cleaning the legs of radio components and other surfaces that need to be prepare for soldering.

This is actually the detail that gave me this idea:

You can get it from a Soviet cassette recorder.

Glue it to it fine-grained sandpaper:

Working part sanders ready, let's get started creating a drive. We need any motor with a shaft diameter of 1.5 mm; it will fit perfectly with the nozzle.

And a button like this:

We bend the button fastenings for subsequent fastening to the engine:

And solder it to the electric motor in any place convenient for you:

One of the button pins is also soldered to the body.

We bend one leg of the motor and close it with solder to the body:

Now we need to deal with nutrition. I used network adapter at 7 volts:

We begin to connect the adapter to the motor. We solder one contact of the adapter to the free leg of the switch, the other to the free leg of the electric motor:

That's all! The machine is ideal for cleaning solder joints and other small work. By the same principle you can do small drill using a collet chuck. If you already have a drill bit, you can leave the attachment on the original shaft and simply clamp it into the chuck.

During construction and repair work Men often need to process wood, stone or metal. For quality work It is advisable to purchase a belt sander. But what to do when finances do not allow you to make such a purchase? To do this, it is enough to build a belt sanding machine with your own hands.

Purpose of a belt sanding machine

Wood is widely used in a wide variety of manufacturing organizations. Many different parts and products are made from wood. In order to properly process a wooden blank and give it the appearance of a finished product, it is customary to use various equipment, including belt sanders.

Belt grinding equipment is typically used in the final stages of production, when parts are subjected to finishing machining. Such devices are convenient to use in the production of furniture and various consumer wood products. Depending on the material used, belt sanders work with wood or metal.

The main purposes of using wood grinding machines are the final leveling of the surface, bringing their roughness level to the required value, obtaining even and smooth surfaces of wood products and wood materials before veneering or after coating with varnish and other finishing materials, removal of local irregularities in the form of depressions and elevations, peeling off burrs and removing local deposits of varnish and primer, deburring, internal grinding and grinding of curves.

Belt grinding machines for metal work with various materials and formats that are common in metalworking: plain and alloy steel, non-ferrous metals in the form of quadrangular, round and flat workpieces. Grinding machines allow efficient and effective minimal costs time to grind round timber and large diameter pipes.

Depending on the type of processing and type of feed, belt grinding machines are intended for:

for grinding curved surfaces with a free sanding belt;
for processing flat surface with a fixed table, manual movement of the iron and table, as well as mechanized movement of the work table and manual movement of the iron;
for processing panel and block parts, their ends and side edges;
for intermediate sanding of paintwork.

Belt Sanding Machine Design

Belt grinding machines are produced by modern foreign and domestic manufacturers in wide range. Grinding machine prices vary widely. They also differ in possible performance and design. However, they also have something in common. They are united by the fact that absolutely all machines have an abrasive belt as a working element, which is most often connected into a ring and placed between rotating drums.

One drum is the master drum and the other is the slave drum. This means that the first of them is equipped with a mechanical transmission, which is most often based on a belt drive, through which torque is transmitted to it from electric motor. Any belt sanding machine is designed in such a way that the speed of movement of the drive drum, and therefore the speed of movement of the abrasive belt, can be changed, providing different modes of surface treatment.

The abrasive belt can be positioned vertically or horizontally. In addition, equipment modifications are available for sale in which the working element is installed at a certain angle. The abrasive belt is mounted on a frame, on which the workpieces are usually located. Workpieces can be held by the operator manually or with the help of special devices that make the work easier for consumers and make the processing procedure more efficient and safe.

The machine table is made of metal sheets or thick boards. If the design provides for the table to be made of metal, then it will be possible to sharpen more complex products. The length of the working part of the belt grinding machine and the grinding belt itself primarily depends on the length of the products that will be sanded on the machine.

If the part is shorter than working surface machine, it will be much more convenient to process, and the processing will be of higher quality. For example, with a sanding belt length of 4.5 meters, you can easily process wooden blanks, which are 200 centimeters long.

Belt grinding machines are divided into equipment with a fixed and movable work table and devices with a free belt. A special group is wide-belt grinding machines, in which the caterpillar-shaped table is also a feeder. For machines with tables, the belt is placed horizontally; for designs with a free belt, it is installed in different ways.

Since the grinding process inevitably generates a lot of dust, all belt grinding machines are usually equipped with special powerful hoods that remove most of it during the technological process itself. Grinding machines are powered by an electric motor, which has a power of about 2.8 kilowatts. With a high-power motor, the normal speed of the belt reaches 20 meters per second.

Abrasive belts for grinding machines

The cutting tool of belt grinding machines is a sanding belt, which consists of a fabric or paper base and abrasive grains that are attached to it using adhesives. Abrasive belts are manufactured using two methods: mechanical and electrical. The first method consists of uniformly pouring abrasive grains onto a base that is covered with glue, and the second method occurs in electric field, which orients the grains upward with their sharpest edges to improve the cutting properties of the grinder.

Abrasive grains are poured onto the base in a bundle tightly or sparsely. The most effective is considered to be an abrasive belt with a sparse backfill, when the grains occupy less than 70% of the area, because wood dust generated during the grinding process is not able to get clogged between their grains. Can be used as abrasive material natural minerals or artificial materials, which have high hardness, for example, green and black silicon carbide, white and normal monocorundum, as well as normal electrocorundum.

For the purpose of gluing grains, synthetic resins and hide glue are used. As a base, fabric such as calico and twill, or special grade paper is used. The size of the abrasive grains is indicated by a number that corresponds to the size of the sieve cells in which these grains are retained, and is displayed in hundredths of a millimeter.

If you are interested in how to make a belt sanding machine, then you should pay attention to the following sizes of grinding powders and abrasive grains and their classification: grinding grain - from 2000 to 160 microns, grinding powders - from 125 to 40 microns; micropowders - from 60 to 14 microns, very fine micropowders - from 10 to 3 microns.

Sanding paper is supplied to woodworking enterprises in sheets or rolls. On the non-working surface of the skin there is a marking with the specified characteristics of the skin and the manufacturer. For a belt sanding machine, skins are used in rolls and cut into strips of a certain length and width. The length of the cutting tool is determined depending on the method of its connection - lap or butt at an angle.

The ends are cut off when gluing end-to-end at an angle of 45 degrees and then glued onto a canvas lining with a width of 80 to 200 millimeters. At one end of the tape, when gluing with an overlap, the abrasive grains are removed with hot water over a distance of 80 to 100 millimeters, then the other end of the tape is applied to the exposed base lubricated with glue. Compress the joined ends and dry them using a special device or a size press.

Sheet sandpaper is used for combined belt-grinding machines. For grinding discs It is customary to cut the skin in the form of a circle according to a template, the diameter of which is 60 - 80 millimeters larger than the diameter of the disk. Using a rectangular template, blanks are cut for the reel. After cutting, they have smooth edges without tears. The presence of unglued ends or seals when gluing tapes can cause premature rupture of the tape.

The skin is cut into sheets using wide-belt sanding machines according to a template made of plywood or aluminum sheet. The skin is cut in such a way that the edges are smooth and the difference in the length of the side edges is no more than 1 millimeter. One of the beveled edges is cleaned, removing abrasive to a width of 20 millimeters. The cleaned edge and longitudinal edges are covered with a strip of tracing paper, 40 millimeters wide, which protrudes beyond the edge of the sandpaper by about 10 millimeters.

Lubricate the beveled edge with tracing paper with glue and leave it in the air, depending on the viscosity and type of glue. Then the beveled edges are joined and a strip of sandpaper is applied to the joint, the joint is compressed and held in a press. It is customary to hang finished endless belts on special brackets and keep them for at least a day in a dry room before installing them on a grinding machine.

Operating principle of a belt grinding machine

A belt sanding machine consists of a table top with a work table for mounting the cutting tool. This table is fixed in different positions relative to the tabletop. The material for the countertop is usually laminated chipboard 25 millimeters thick. The worktable on rollers is moved manually or laterally by a mechanical drive along round guides that are attached to supports.

Above the table there is a working belt mounted on non-drive and drive pulleys. The sanding belt is tensioned and adjusted using screw device with pneumatic cylinder. Double belt sanders have two identical sanding tools that are placed in series on a bed and have sanding belts that move towards each other.

Grinding is carried out by the transverse movement of the work table and the longitudinal movement of a short iron, which presses the belt to the material being processed. The sanding belts are driven by an electric motor via a belt drive. The waste generated during grinding is collected by a dust collector, which is connected to the exhaust network.

When assigning a grinding mode, it is recommended to select the grain size of the sandpaper, the feed speed and the pressing force of the belt to the product based on the specific roughness and properties of the material being processed. The grain size of the skin is usually chosen depending on the hardness of the materials being processed and the required surface roughness. The clamping force and feed speed are interdependent quantities. With little force and high speed of feeding the sandpaper, some areas of the surface may not be sanded; high pressure and low feed rates, burns and blackening of the material are possible.

Before installing the tape, check the quality of its gluing. Do not use incorrectly glued or torn sanding belts with uneven edges. Using the handwheel, you can reduce the distance between the pulleys and put on the belt. The gluing area is placed so that the outer end of the seam on the abrasive side is directed against the working movement of the sanding belt.

The belt tension can be adjusted by moving the tension roller for the belt grinder or the non-drive pulley. It is not advisable to tighten the tape too much, as this will cause it to break. But the sanding belt, with low tension, slips along the pulleys and heats up very quickly. The tension force is set depending on the strength of the base of the cutting tool and is determined by the arrow of its deflection with slight pressure on it.

How correctly the belt runs can be checked by turning the pulley manually or briefly turning on the electric motor. When the belt slips, the pulley axis is turned by a handle at a small angle and secured with a locking device. After setting up the belt grinding machine, the dust suction system is turned on, a trial processing of the parts is carried out and their quality is checked.

A manual feed belt grinder can be operated by one worker. By moving the product relative to the cutting tool in the longitudinal direction and rotating the part around its axis, the operator sequentially brings into contact with the tape all areas that form the surface to be processed. If you slow down or move carelessly, sanding may occur.

It is customary to grind individual sections of a part in several passes. High-quality leveling can be achieved by properly regulating the pressure applied to the handle of the iron and the speed of movement of the table and iron. The pressure must be reduced as you approach the edges to prevent them from being sanded off. To increase the quality and productivity of grinding, small bars are placed on the table in a row, several pieces at a time.

Belt grinding machines with mechanical feed of products are serviced by two operators. One of them places the part on the conveyor, orients it along the width of the work table and directs the product under the clamping elements of the machine. When being picked up by a conveyor, parts must not be moved laterally.

It is not allowed to feed into the machine workpieces that have unequal thickness and parts with gross surface defects. The feed rate and pressure of the clamping beam, as a rule, are not regulated during processing. The second operator is receiving finished parts and ensures that unacceptable edge rounding and sanding does not occur.

Making a Belt Sanding Machine

The price of belt grinding machines from an industrial manufacturer is quite high, so when they are used infrequently, craftsmen involuntarily think about whether to buy the equipment or not. An alternative to buying an expensive machine is to assemble it yourself. The main parts of the machine are the frame, rollers and engine.

The motor can be removed from an old washing machine. Cut the frame from thick iron measuring 500 by 180 by 20 millimeters. Cut one side straight milling machine for metal, it is required to attach the platform with the motor. The dimensions of the working platform are approximately 180 by 160 by 10 millimeters. Make markings and drill three holes in the end of the evenly cut frame. It is necessary to tighten the platform to the frame with three bolts.

Remember that the longer the work table is, the more options you will have when choosing a technological method for grinding and processing the product. If the length of the workpiece is less than or equal to the length of the work table, then you can achieve a perfect grind much easier than when moving a large workpiece.

The engine must be placed tightly on the frame. It should have a power of approximately 2.5-3.0 kW and a rpm of about 1500. If you choose a sanding belt speed of approximately 20 m/s, then the diameter of the drums should be about 200 millimeters. Thus, if the engine speed is sufficient, a gearbox for the grinding machine is not required.

One of the two drums will play the role of a drive drum, which should be firmly fixed to the engine shaft, and the other tension drum should rotate freely around a fixed axis on bearings. The table on the side of the driven drum should have a certain bevel, which will ensure smooth contact of the sanding belt with the surface of the work table, this is especially true for a glued joint.

You can make a tension drum and a drum that guides the sanding belt from chipboard. To do this, you need to saw blanks from the slab overall dimensions 200 by 200 millimeters and from them assemble a package of 240 millimeters. Square tiles or their package should be folded on an axis and machined to a diameter of about 200 millimeters.

Remember that in the center the diameter of the drum should be 2-3 millimeters larger than at the edges. With a similar surface geometry, the flexible sanding belt will be located in the middle of the drum. The optimal tape width is 200 millimeters. From a roll of emery cloth that is 1 meter wide, you can easily glue 5 similar tapes together.

Glue cutting tool necessary end-to-end, placing a thin one underneath dense material, for example, tarpaulin. It is recommended to use the highest quality glue you can get. Be sure to stretch rubber onto the rollers, the width of which reaches 30 millimeters. Rubber can be taken from the inner tubes of a moped or bicycle.

On a homemade belt sanding machine, in addition to grinding wooden products, for which it is actually intended, it is very convenient to sharpen tools with cutting surfaces - chisels, knives, axes, pruners. Another advantage of this grinding machine is the ability to work with parts that have a curved surface - to do this you need to grind the workpiece with the back side of the work belt.

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