Sandblaster with your own hands for a weak compressor
All about sandblasting guns
A variety of techniques can be used to clean contaminated surfaces, one of the most popular is sandblasting. In order to carry out sandblasting, which is cleaning by means of sand, as the name implies, it is necessary to use a specially designed device, namely a sandblasting gun. Such a unit not only cleans the surface on which it acts, but also grinds it. Today in our article we will consider in detail all the distinctive features and unique characteristics of sandblasting devices.
Before going through the process of assembling a reliable and efficient sandblaster yourself, it is advisable to study what structural elements it consists of. So, self-made units are usually collected on the basis of typical schemes, which differ from each other in the technology of sand supply to the treated surface of the base. Despite the fact that different machines have different structural device, for all options are provided with the same “vital” nodes, namely:
- A compressor is a device which is necessary so that the air mass in the machine can be blown out in a timely and trouble free manner;
Regardless of the assembly plan, sandblasting units create an incoming air stream together with the abrasive components. When going to the pressure circuit, the sand under high pressure is sent directly to the outlet pipe, where it is mixed directly with the air, transmitted from the compressor.
For the formation of the necessary vacuum in the paths of the abrasive component in ejector-type equipment is used the so-called Bernoulli effect. The sand is fed into the area where it is mixed under pressure.
Today there are many variations of such equipment schemes. This gives users plenty of options for self-assembly of sandblasting machines. A good machine can turn out even from properly selected improvised materials, which previously seemed completely unnecessary and useless.
Diesel or electric compressor?
Nowadays sandblasters can be equipped with compressor units driven by electric or diesel engines. Which of such compressors to choose depends on a number of factors. It is clear that it is impossible to use an electric compressor if there is no possibility to connect it to the electric network. Autonomy and mobility are not the only advantages of diesel compressors.
A modern diesel compressor is a powerful unit equipped with a variety of systems to ensure efficient operation of any tool
Most modern models of such devices are equipped with an effective system of capacity control, which works as follows: at the moment when the consumption of compressed air by the sandblaster decreases, such a system automatically reduces the speed of the drive motor of the unit; respectively, when the consumption of compressed air increases, the engine speed also increases. Similar systems can also be installed on electric compressors, but because of the design features of such devices they are much more expensive.
The advantages of electric compressors are their simple design, economical operation and maintenance. Among such compressors on today’s market there are stationary and mobile models, which are transported with a special chassis, which they are equipped with. Another limitation for use of electric units is that for efficient operation of the sandblaster, a compressor is required, the motor power of which is within 22-100 kW. Not every electrical system can withstand the connection of such a motor.
Hardly any engines with more than 3 kW output are installed on 220 V machines
When choosing which compressor to buy, taking into account the economic component of its use, it is preferable to choose electric devices.
Main components of a sandblaster
Homemade sandblaster assembles on the basis of typical schemes, which differ in the way sand is fed to the contaminated part. Although there are design differences, the assemblies are the same for both versions:
- compressor. a device for pressurizing the air mass;
- The air receiver, which is necessary to create the necessary air supply;
- abrasive tank;
- the pistol. the basic device intended for giving an abrasive mix on a surface to be cleaned;
In order to increase the duration of continuous operation and to maintain the supply pressure, it is recommended to equip the sandblaster with a moisture separator. When using a plunger compressor, an oil filtration system should be installed in the air inlet.
The apparatus, regardless of the assembly pattern, forms a joint outlet flow of air and abrasive. Pressurized assembly means that the sand is pressurized and fed into the outlet port where it mixes with the compressed air from the compressor. For vacuum formation in the abrasive inflow channel of ejector machines the Bernoulli effect is used. Sand is fed into the mixing zone under the action of atmospheric pressure only.
The existence of many variants of sandblasting schemes is explained by the possibility of creating it from materials that are on hand, often seemingly unnecessary. To understand the essence of the process it is enough to consider the general principles of assembly.
Components for homemade sandblaster
To assemble a sandblaster with your own hands, as mentioned above, it is necessary to prepare all the components of such a device. Some of these can be found in your garage or home workshop, and some can be purchased at any construction market.
One of the important elements of the sandblaster is a container from which the abrasive will be fed into the system. For the manufacture of this capacity is suitable old gas cylinder, which is made of quality metal and perfectly tolerates even significant mechanical stress (from a gas cylinder, by the way, you can make a receiver for the compressor, if the latter is not equipped with them).
For the backfill hole can adapt the cover of the old fire extinguisher
In order to fill the container for the abrasive material, it is necessary to weld a piece of pipe to the metal cylinder, at the top of which for the convenience of filling a special neck is fixed, used as a funnel.
Particular attention should be paid to the choice of compressor when making the sandblaster yourself. High-quality and reliable compressor units, which may be suitable for equipping such a device, are quite expensive, so if you want to save money on their purchase you can make a compressor with your own hands, using inexpensive components.
In particular, for the manufacture of mini-compressor, the power of which will be quite enough to perform sandblasting at home, you can use ready-made compressor heads from the brake pneumatic drive of cars ZIL (130-157) and MAZ. Such heads must be equipped with a receiver (it can be made from an old gas cylinder), the drive motor, as well as the frame on which all elements of the design will be mounted.
Homemade compressor on the basis of the brake compressor from the car ZIL-130
To equip a homemade sandblaster, the assembly process of which is well demonstrated by numerous videos on the Internet, you will also need:
- ball valves, which should be highly reliable and durable (that is why it is better to choose such products from proven manufacturers);
- reinforced rubber hose (at least 14 mm in diameter), capable of withstanding high pressure and constant exposure to abrasive material;
- gas hose, which will supply compressed air, not yet mixed with abrasive material (the diameter of such a hose must be at least 10 mm);
- fittings, which will be used to connect the hoses to the elements of the system, as well as collet-type clamps;
- FUM-tape, which is needed in order to ensure the tightness of the connection of all elements of the construction of a homemade sandblaster, working under high pressure.
A complete set of parts for assembling the system: from the nozzles to the desiccant
Sandblaster with his own hands
Making a sandblaster by your own hands from the author of a makeshift sandblaster: photo of making with a detailed description.
How to make a simple sandblaster
To begin I want to show the circuit of my self-made sandblaster.
So, a compressor was bought (in the garage needed thing, but this powerful took for sandblasting) 2-piston with a receiver for 100 liters, belt drive, forced cooling pistons and motor capacity of 3 kW and a performance of 500LM. the most powerful single-phase compressor from those represented in our market.
I want to clarify. For the normal productive sandblaster this compressor is weak, and on this if you will do sandblaster powerful who sandblasted candles, the minimum compressor capacity should be 500 l / min and above!
Another important point is the diameter of the hose should be 3-4 times the diameter of the nozzle, the hose should have as few as possible connections and bends, all bends should not reduce the inner cross-section, the length of the hose should not exceed the required.
If you need a long hose, you need to pay off the lengthening of the air part, not the one in which the sand will be transported, I made it only 3 meters, and the air part. about 8 meters, which allows the compressor to be away from the sandblaster, and to pull in less dust. Hose should be 18 mm inside diameter. At the same time, the hose connections approached 1/2 (16mm) and 3/4 inch (20mm).
A large cross-section should be maintained throughout the piping from the compressor to the nozzle. For this reason, the quick connectors used for the spray gun, etc. inapplicable for sandblasting due to the fact that the inner diameter of the quick-disconnect couplings is only 5 mm.
On this had to unscrew the plug on the receiver and screw in its place a ball valve, since the cross section of the plug 16 mm. On faucet sets a union nut, called at plumbers amerikanka that it was possible to disconnect easily a sandblaster from the compressor. Again we pick up faucets so that not to reduce the flow area
The air supply is organized, but I faced another problem. when the tank runs out of sand, the bulk of it remains on the edges of the vessel, and in the center is empty.
The solution is simple. it is necessary to make a cone at the bottom. Here we go: I cut off the old bottom, make a cone from a plaque 1 mm and weld it to the tank, from below I welded a thread of 16 mm, rewelded legs on a cone.
Now it is necessary to make hooks for hoses so they can be coiled up conveniently. In addition I want to say that giving air into the cylinder from above was superfluous, in fact without it all works even better, so left only a valve by which you can drain the pressure from the tank, in case if the cone is clogged with sand.
And this is a general view of the sandblaster assembled. it turned out quite compact, despite the long and thick hose)
Now there is the most important thing. the nozzle. Firstly you need to have a crane for comfortable work, secondly a nozzle holder, and the nozzle itself made of hardwearing material. The crane was taken on 3/4 inch (20 mm), because its inner section of only 18 mm. The complete handle and nozzle looks like this:
The holder nozzle made from a coupling nut on 3/4 and adapter socket with 16 mm to 12 mm, which screwed to the faucet with a coupling nut.
In the resulting holder ceramic nozzle is inserted, and its discrepancy in diameter is eliminated by selection of the rubber band of the correct diameter
Regarding the nozzle. it is not difficult to make it from the spark plug. I took a spark plug from a chainsaw, because it has a thinner electrode, and the diameter of the future nozzle. 4 mm. From the spark plug from the classic, you get a nozzle of 5 mm, which for my compressor is very much. too rapid drop in pressure and the compressor does not have time to make up for it.
To make a candle into a nozzle, you need to take off its skirt and all metal. Then using a diamond disc (stone disc, ceramic tile disc, etc.).п.) to saw off from ceramic insulator of plug the bottom part, which was in skirt. Then you need to unscrew the electrode from the future nozzle, and if it is not unscrewed, you need to drill it with a drill of the same diameter. In the presence of drills with a diamond tip would not be bad to make a cone on the nozzle, the crane side, but in principle, and so it works.
Homemade sieve also was uncomfortable, and the stones slipped through it, because it was found a metal sieve for flour, which has proved itself perfectly)
When sandblasting the dust is opaque, so you need to use a respirator, preferably with the exhaust downwards.
To protect your face and eyes can use a mask of plexiglass, but it quickly fogs up. this is the second By the way, the exhaust is down in order that this mask does not sweat.
Checking the work of the sandblaster on the cup of the rear spring.
Well and I want to say that the sandblaster system is complex, and in case of discrepancy at least one part of it normally will not work. Here we can draw an analogy. the strength of the chain is determined by the strength of its weakest link. Therefore, for those who decide to do sandblasting with their own hands to summarize what you need to pay attention to create a working machine:
Compressor with a capacity of 500 l / min or higher, with forced cooling, large air tank (50 liters minimum) and preferably with belt drive, as they are not as warm, and when sandblasting compressor does not turn off.
The diameter of the inner cross-section of all hoses and nozzles, ranging from the compressor to the nozzle should not be less than 16 mm, or at least be 4 times the diameter of the nozzle, but there porridge is not spoiled oil) Just as possible (and it is possible) to avoid the bends on the pipes and hoses at work already.
The cylinder should have a tapered bottom, with as sharp an angle as possible.
The nozzles should be as hard as possible, for example a hardened steel nozzle should last about an hour or two. Of ceramics, about 100. Of tungsten carbide. about 900-times. The lateral cross section of the nozzle can be both conventional straight and cone (Venturi nozzles). The latter give an increase in performance, because accelerate the particles to about 700 km / h (in a straight nozzle speed of about 300 km / h), but the Venturi nozzle is probably not made at home, because there is nothing to handle ceramics.
Sand. It should be sieved, preferably twice, or even three times with a sieve in which the mesh size is smaller than the diameter of the nozzle. In addition, the sand should be completely dry, so that it spills out of the fist. Sand can be river gray, or yellow, or quartz, or any, as I understand it, the main thing that the sandblaster was red, and abrasive dry and sifted) Also use electrocorundum, cast iron chips and other abrasives, but I think in the garage can do without them.
Here are some indicators of the already working machine, which I think will facilitate the construction of a new one. And so: compressor capacity. 500 l / min, the receiver. 100 liters, the nozzle diameter. 4 mm diameter hoses. 18 mm, the pressure when sandblasting. rapidly falling to 8 atm. to 1.5 and stays in this range /-0.5 atm. depending on how long you open the nozzle tap. Even at such low pressures successfully sanded paint and shallow rust. For heavier cases, you have to turn off the crane and wait a little bit until the pressure is higher, but in principle you can work.
Budget. If we learn from others’ mistakes, and do not step on the same rake, you can make a machine for about 50 u.е., if you do it yourself and already have a cylinder and a welder with a compressor. If the price includes a compressor, then of course the price will be different, but I did not include it because in any case would buy it in the garage, and more powerful, in order to use the future pneumatic tools.
Well, that’s it, I threw out everything I knew, but now there is an article with everything you need to assemble the machine in the garage.