Metal grinding machine with their own hands
It is difficult to find metal surfaces, those or other products that are not subjected to machining and maintain an even surface after the metal casting. Almost everything that is made of metal is ground. This is done to achieve a smooth and flat surface of all planes of the iron product. Previously, there were only hand tools (sandpaper, abrasive wheels, lathes). But, since such work is heavy, they decided to invent automated machines that do all the work automatically. In addition to them created and machines for home processing of metal products.
Any grinding equipment has one, direct purpose. it is to process the surface of the metal, in order to achieve evenness and smoothness of all sides of the workpiece or workpiece. This equipment can be used for roughing, finishing and final machining. Grinding. Various abrasive elements of different sizes and shapes are used in the assemblies. Each of them is designed for certain operations. With the help of this equipment, it is possible to perform the following operations on metal processing:
- Grinding both external and internal surfaces of the metal product, which, in turn, have a complex shape and different purpose.
- Grinding tools of various shapes and types.
- Implementation of machining parts with serrated plane, as well as products that have threaded areas.
- Cutting of metal castings as well as roughing and grinding of complex profiles.
- Production of grooves on the surface of metal bars with a spiral and longitudinal shape.
Below we will look at what types of sanders, designed for processing metal surfaces, there are.
Existing types of grinders
Industry produces several types of machines, differing both structurally and by purpose. These are the main ones:
- Eccentric or orbital, in which case the tool head simultaneously rotates around its axis and along a certain orbit. In this way, it passes over a slightly different area each time, so that scratches and burrs are scuffed up more and more with each pass.
- Vibrating model. Here the working sole performs reciprocating movements with a frequency of about 20000 movements per minute. It is through these movements that the grinding takes place.
- Angle grinder, which is commonly called “angle grinder”. With the help of this tool is carried out rough processing of parts, large logs, etc.п. For processing, grinding wheels of the required grit are used.
- A belt sander, which is usually used for work on large surfaces. Structurally, it represents the rollers, driven by an electric motor, on which the sandpaper belt.
Materials will be needed:
Next, we look at the photo of the grinding machine manufacturing.
First of all, cut blanks of wood chipboard, for the manufacture of the body of the future grinder.
Next? we need a motor from a washing machine. Let’s install the drive roller on the motor shaft, for such purposes we pick up the coupling for plastic pipes of such a diameter that it can be firmly seated on the sheave shaft. To adjust the shaft pulley to the right size, turn on the engine and work with a file like a lathe. Next, the clutch is accurately pressed on the pulley, it should hold firmly, as an additional fixation you can use glue.
In the sleeve inserted a piece of plumbing pipe, which serves as a leading roller. For a better grip on the grinding belt, the roller can be covered with rubber from a bicycle camera.
Assemble the housing, also install the motor, tighten it securely with bolts and nuts. There will be two holes in the table top, one for the idler pulley and one for the drive pulley.
We make the driven roller also from a piece of sanitary pipe, it is necessary to press two bearings into the pipe. We will use a long bolt or threaded rod as an axis. The axis of the driven roller is attached to a special platform of plywood, this platform can move under the table top in the horizontal direction, resulting in the tension of the grinding belt.
For convenient belt tension, you can adapt, a long threaded rod with a nut that pulls the platform, thereby tightening the grinding belt. As for the alignment of the belt, there is no such a function. It’s important to fix the rollers so that they don’t come together, but move apart a little when you look from above, then the belt won’t fly off.
Fixing the base plate for the sanding band.
Homemade belt sander, completely copes with the processing of wood, an excellent DIY for the home workshop!
Also, attached is a video, which shows in detail the process of making a belt sander with their own hands.
The process of developing the belt-disc machine
I started by making rollers from plywood, 16 mm thick, using a 60 mm BIMETAL bit. As 16 mm plywood was used, 7 blanks were necessary for making each of the rollers.
After making the blanks, they were assembled on the glue in 2 packages of 7 pieces, tightened with a threaded rod and screw clamps, and left to dry for a day.
Then, as a donor of sheet steel were used side panels from the hull of some EU-soviet computer equipment, long ago gave up and decommissioned due to moral and physical obsolescence. From this metal, 2 mm thick, were cut out (according to the drawings) blanks of the body of the belt grinder and the rest of the machine elements.
I signed all the elements with care, in order to avoid mistakes later on (I must say right away that it did not help much, there were mistakes and some things had to be reworked). According to drawings made blanks of the drive roller bracket with tensioning unit. In the driven pulley was made (by Forstner’s bit) a cutout with diameter of 300 mm and depth of 11 mm for pressed-in bearings. Subsequently a similar groove with diameter of 40 mm was made in the drive pulley faces.
Elements of the drive roller bracket joined by electric welding. I noticed that with age, there are problems with vision (I see worse in shaded areas), before welding, I get a stable arc, hit the electrode in places completely not intended for this (this is an apology for the appearance of welds).
Axes were turned without using lathe. I clamped a blank of suitable diameter in the chuck of an electric drill rigidly fixed horizontally), the opposite end of the blank was fixed in the bearing of suitable diameter, aligned with the chuck of the electric drill, and then using an angle grinder with cutting (scraping) discs (primary processing) and a simple file and emery (finishing) ground to the required size. I am not the author of this technology, I found a similar one on the Internet and applied it to my needs. The task was done, and that’s the main thing.
made cages for bearings of drive roller and swivel unit from water pipe of suitable diameter. The tube was cut lengthwise, a “surplus piece” of the diameter was sawed off, the tube was bent (on a mandrel from an old, faulty bearing) to the inner diameter of 30 mm and the joint was welded. Then rings of 10 mm in width were cut from the workpiece. From blanks to size (as per drawings) I made the side panels of grinding table, swivel node (which is also the drive belt tensioning node) and bracket for flange motor mounting and drive belt tensioning node.
In the cut rings of the future ring the bearing (used) was inserted and the ring was welded to the side plate or rotary knot. To ensure alignment, the panels (via the bearing) were tightened before welding with a bolt of 10 mm diameter. Before welding, for subsequent extraction of the bearings, 3 mm diameter holes were drilled under the bearing at the level of the outer ring.
From the garage stocks was successfully selected a flange on the engine for mounting the base of the grinding disk and drive pulley.
Then, after fixing the flange on the motor, and, alternately, the master and slave pulleys, as well as the blank grinding disk base with chisels and improvised undercarriage (chisel stop) made a master and slave pulleys, spacer under the master pulley and grinding disk base with a recess for the slot mounting.
From workpieces, using welding, made the base of the belt tensioning unit. The same node is central in the assembly of the belt table, it is screwed to the side panels.
After testing the holes for fixing bolts were marked. A drive roller axis was installed prior to drilling to check for misalignment and alignment. Side panels are temporarily secured with clamps. After drilling the holes, fastened the side plates to the base of the belt tensioning assembly with M6 screws.
Proceeded to fabricate the swivel unit. According to the drawing, there is a marking for the stud of fixing the angle of rotation.
Drill a pilot hole of 3 mm according to the markings.
Using the control hole marker marked and began making the arc slot (kerf) for the stud fixing the angle of rotation.
Springs are installed on the grinding belt tensioning assembly
How to make rollers for the grinder with your own hands
Preparation of rollers for the grinder is one of the most laborious stages of work. For the grinder, most often, make four rollers with different sizes. from 70 to 150 mm. Steel, titanium or duralumin is generally used. It is also possible to cut out parts from wood.
The drawing of a home-made grinder “turn-key”
Important! When turning it is necessary to give rollers a “barrel-like” form, so they do not fly off the strip.
The mounting surface (lateral sectional view) of the grinder pulley must be straight. If you use a pulley pulley, the belt will curve with a trough along its entire length. The pulleys will prevent it from sliding, see “The sheave should be straight”. further, but the pulley should be straight.
A sheave for a grinder that is not made for precision work does not have to be turned. In the 3-arm diagram, the runout of the belt from its alignment will be eliminated on the rollers before it reaches the work area. A tensioning spring will sufficiently reduce belt runout in a simple vertical grinder. For this reason it is possible to make a grinder pulley without a machine tool.
It is much more important to correctly calculate the diameter of the pulley according to the speed of the motor and the required speed of the belt. A belt that runs too slow will tear the material; a belt that runs too fast will tear itself before it has processed anything. In which case what belt speed is needed is a special conversation, and a very tricky one. In general, the finer the abrasive and the harder the material, the faster should the belt move. How belt speed depends on pulley diameter and motor speed, cm. Figure.:
Fortunately, for most abrasive-material pairs, the allowable belt speed limits are quite wide, so the grinder pulley can be more easily selected:
Second. the pulley, the pulleys and in general all home grinder parts are quite acceptable to make from plywood. It is definitely not an option in production, even if a plywood Grinder is offered for free with extra payment: the grinder needs a salary, and a wooden Grinder in the shop will be completely worn out before it and itself pay for itself. But you are not going to drive the Grinder day after day in three shifts at home. And no belt slips over the plywood pulley. In t.ч. homemade. So you can safely make a grinder pulley out of plywood.
The size of the grinding belt
Grinding belt size is usually linked to the parameters of power and speed. The wider is the belt, the slower it should run on the pulleys. Accordingly, the power of the device for wide ribbon should be higher.
Usually for grinders are produced in width of 75-76 mm, 100 mm, 115 mm. The length can be 457 or 533 mm. It turns out that if the tape is longer, it will last longer.
Materials will be needed:
The following photo shows the process of making parts of the grinder.
This homemade machine uses a motor from a washing machine for 14k. rpm. Connect it to the mains through the speed regulator.
Here is a scheme of connecting the regulator to the electric motor.
Machine body, made of pieces of wood chipboard, and fasten with furniture screws. Its dimensions are determined by the specific motor.
A stop for the sanding belt is made from a mounting angle, the edges of which are rounded to prevent the belt lock from catching.
We make the master roller from two propylene pipes of diameter 20 and 32 mm.
Choose a larger pipe also with an inside diameter of 20 mm.
In addition, in the inner hole of the double pipe we put the tin pipe bent out of sheet metal.
Stuff the whole assembly on the splined motor shaft. The connection is reliable with minimal runout. For the driven roller pick up two bearings and depending on the outer diameter. a polypropylene pipe with exactly the same inner size.
If it turns out to be less, it can be drilled with a feather drill of the necessary diameter.
We flatten the bearings with a steel tube to relieve the side load. On the inner end of the roller put a ring cut out of a coupling of the same size, which will serve as a stopper.
Assemble on the stud the resulting assembly and screw, using washers and nuts, to the base.
The home-made grinding machine is almost ready, now put on the sandpaper. It may shift to the left or right side of the rollers as it rotates. To eliminate this phenomenon, we rotate around its axis by both nuts of the driven roller, until the belt will not shift to one or the other edge. Thus, we find the position when the belt is in its place. That’s it, the homemade grinding machine is ready to work.
A short video review of this homemade machine:
How to calculate the diameter of the drive roller.
To calculate the diameter of the drive roller, we need to know the belt speed at which the Grinder will work and the number of motor revolutions.
The belt speed should be chosen according to the recommendations of the belt manufacturer. For example, the 3M Cubitron steel belt should have a speed of 22-25 m/s, while the same manufacturer recommends 30-35 m/s for aluminum zirconate belts. Belt speed depends not only on the type of abrasive, but also on the grit size. And on the average it is recommended to drill carbon steel at 32. 38 m/sec, alloy and stainless steel at 18-30 m/sec, Titanium.15 m/s, non-ferrous metals 35-45 m/s, plastics 10-30 m/s, malleable iron 38-34 m/s, gray iron 35-45. As for the wood, it is recommended not to exceed 20 m/sec. It is also necessary to know that different wood will burn at different speeds.
The formula for calculating the belt speed
where D-diameter of drive wheel in mm, N-rpm of motor.
Formula to calculate the diameter of the drive wheel:
where V- belt speed in m/s. N-motor revolutions per minute.
Calculation example. We need to calculate the diameter of the drive roller for steel (22-25 m/s). Electric motor 2800 rpm.
The belt speed for different materials can be adjusted by changing the diameter of the drive roller or by adjusting the motor speed. Also understand that as the diameter of the drive roller increases, the load on the motor increases, and if it is of small capacity, such as from a washing machine, it will often stop even from a small load.
Machine tool design and diagrams
Any assembly of homemade equipment begins with the construction of the bed or base of the future machine tool. This can be done with metal material, or with wood material. The standard size of the bed is 500mm x 180mm with a thickness of 2cm.
After making the base, you can move on to the next steps. Asynchronous motor can be installed in several places, so that its work was full-fledged. To prepare the plane on the bed itself or to make a platform under the motor, which will be attached to the end of the bed. The other side of the bed is designed to locate the shaft, with a pulley for the belt and rollers for the abrasive belt. Belt itself is installed with a slight incline. It is done for the abrasive to smoothly and accurately contact with the workpiece surface.
Tip: Before installing the abrasive strip on the rollers, you need to wrap a thin strip of rubber around them. This will reduce the slip of the strip during operation.
As we can see from the diagram and drawing, the design of the grinding equipment is quite simple. All varieties of these machines are assembled according to the same scheme.
Tip: In the process of assembling your future unit for grinding, it is necessary to observe all the necessary dimensions, as well as to make calculations of all parameters should be extremely serious.
When we are familiar with the design, we can move on to the assembly process.
Assembly process of the grinding machine
The following items will be needed to assemble the grinding tool:
- Wood board.
- Wooden bars or metal profile tube.
- Ball bearings.
- Electric motor.
- Rubber belt.
- Rubber belt.
- Metal pulley.
- Self-tapping screws, fasteners.
- Abrasive element.
- Working tool (drill, angle grinder, screwdriver, jigsaw, etc.).д.).
- Welding machine (if the bed structure is made entirely of metal).
Once we have decided on the materials and working tools, we can proceed to the assembly of all parts and elements into one mechanism. This is done by assembling a frame. It can be made of metal (consisting of a metal pipe) or wood (consisting of wooden bars and solid wood).
When the frame is ready
You can proceed to install the motor. The power of the motor must be at least 2.5 kW and no more than 3 kW, with a motor speed of 1200 to 1500 rpm. A pulley for the belt is installed on the motor shaft. The motor is mounted on one side of the frame. Often the motors are used from washing machines used in the household.
On the other hand
The shaft with bearings is positioned, on one side of which is fixed the pulley, and on the other side the roller, on which in future will be put the abrasive belt. Shaft pulley and motor must be positioned on a level horizontal plane. The belt tensioning mechanism should also be located in this area.
Next, made of wood
Or from plywood, or metal, a stand is constructed, on which the rest of the rollers will be placed and the sanding belt will be worn. There should also be a tensioning mechanism. In addition, the presence of the working bar, which will produce a rubbing abrasive tape.
On the bed, usually at the end, is installed start-up button. The machine‘s electrical circuit must be grounded.
When everything is done, the first run can be done and the machine can be set up properly. When the adjustment is made, the first workpiece is run through and the result is checked. If everything was successful, it means that you have done everything correctly.
For visual clarity and full understanding of the entire assembly process, you can download video instructions.