Do-it-yourself sandblasting from a high-pressure washer

A DIY sandblasting attachment used for installation on a standard Karcher machine will allow you to turn such equipment into a full-fledged sandblasting unit, useful in many situations. Most Karcher washing machines operate under high pressure, so their technical capabilities are quite sufficient to supply sand through such a nozzle. The difference between such a homemade device and a classic sandblaster will be that sand will be supplied through its nozzle along with water, but this is not critical for many situations.

Kärcher wet sandblasting kit

How does a sandblasting nozzle work?

The operating principle of any sandblasting installation is that abrasive material from a special hopper enters the nozzle under the influence of an air flow supplied under high pressure. In serial installations, a separate compressor is used to create such pressure, due to which a significant amount of kinetic energy is imparted to the sand stream emerging from the nozzle. In the case of a Karcher washing machine, the pneumatic equipment built into it will be used for these purposes. As a nozzle for such equipment, you can use a serial gun, specially designed for equipping pneumatic treatment plants, but in order not to spend money on such a device, you can easily make it yourself.

In order for your homemade sandblasting nozzle, which you will use for installation on a Karcher device, to be effective and not malfunction, you must use high-quality materials for its manufacture.

Operating principle of wet sandblasting rust cleaning machine

Of course, equipment assembled in this way can, with great stretch, be considered as a full-fledged sandblaster, but it is quite suitable for cleaning various surfaces with a stream of water mixed with sand. When using such a sandblasting device, it is very important to adhere to two recommendations:

It is better to use distilled water as the working fluid, which will avoid corrosion of the metal elements of the nozzle;
the sand that will be used as an abrasive must be of a very fine fraction and carefully sifted.

Diagram of a sandblasting nozzle (click to enlarge)

A self-assembled sandblasting machine, the basic elements of which are a Karcher mini-washer and a homemade nozzle, will work according to the following scheme.

When you press the start button on the nozzle gun, water under high pressure created by the compressor flows past the opening of the intake hose, the other end of which is placed in a hopper with sand. This creates a vacuum in the intake hose.
Under the influence of vacuum, sand is sucked from the hopper into the main hose, where it is mixed with the water flow.

In order to minimize sand consumption and bring this parameter to a value of 30 kg of abrasive for processing a surface area with a diameter of 70–80 cm, the design of this equipment must be supplemented with taps and dispensers.

Homemade mixer from water taps and tees

How to make a machine from a pressure washer

You can also use a Karcher sink or a similar unit of another brand as a compressor for sandblasting. The device, whose original purpose is to wash cars, is capable of creating high water pressure with low water consumption. The task comes down to modernizing efficient, dust-free equipment. For Karcher you only need to make a special attachment for the outlet pipe.

The following materials will be required:

ceramic nozzle, purchased in a store or made by yourself;
reinforced hose;
mixing unit (tee with a nozzle of suitable diameter);
cylindrical dispenser, supply control unit;
a tube for collecting abrasive with an air supply channel into a sealed tank.

The sandblasting installation from a high-pressure washer operates according to an ejector scheme. The injected liquid, passing through the mixing block at high speed, forms a vacuum in the sand supply channel. It enters the cleaning zone along with water under high pressure.

Making a homemade nozzle

In order to turn a Karcher mini washer into an effective sandblasting unit using a homemade nozzle, you will need the following structural elements:

a nozzle through which a mixture of water and sand will be supplied to the treatment zone;
trigger;
reinforced hose that will be able to withstand high pressure;
dispenser necessary to make the consumption of abrasive material more economical.

Nozzle diagram: 1 – thread; 2 – low pressure chamber; 3 – nozzle; 4 – fitting for sand supply; 5 – junction of two parts of the nozzle; 6 – smooth tapering transition

For the nozzle, if you intend to use your sandblaster regularly, it is best to purchase one that is made of ceramic. This type of attachment, which is constantly exposed to abrasive material, will last you much longer than its metal counterpart.

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Homemade water sand blasting nozzle

Nozzle details: 1 – pistol; 2 – nozzle; 3 – nozzle holder; 4 – sandblasting nozzle

The efficiency of the sandblasting machine with a homemade nozzle, which you will equip your Karcher sink with, is greatly influenced by the quality of the nozzle. It’s worth starting to create such an element yourself only if you have the opportunity to drill an exact hole in a metal rod, the diameter of which is at least 15 mm. But if this is not possible, then it is better to purchase a factory nozzle, the quality of which will determine the operation of the entire device. The advisability of purchasing a serial nozzle also lies in the fact that some models of such products are already immediately equipped with triggers.

When choosing a hose, the length of which must be at least 2 meters, you should pay attention only to reinforced products. This is explained not only by the fact that such a hose will work under high pressure created by the compressor, but also by the fact that its internal walls will be constantly exposed to abrasive, which will quickly render the unreinforced product unusable.

When starting to assemble and attach the nozzle to equip the Karcher washing machine, you should adhere to the following algorithm of actions:

a ceramic or metal tip must be fixed to the nozzle of your homemade nozzle using a threaded connection;
the dispenser, with which you will regulate the flow of the water-sand mixture coming under high pressure from the nozzle, should be attached to the metal or ceramic tip of the nozzle;
the hose through which sand will be supplied from the hopper must be secured to the back of the nozzle, for which a fitting and a clamp of the appropriate diameter are used.

Scheme of operation and example of manufacturing a nozzle for collecting sand

When assembling and installing a nozzle for Karcher, you should take into account the fact that all elements of such a device will operate under high pressure created by the compressor of the device. That is why all formed connections must be ensured with maximum tightness and reliability. It is not difficult to fulfill this requirement if you make such connections using a special fum tape.

There is one more trick that will allow you to save abrasive material. It consists of the following: cleaning must be performed over a special container with a grid into which the waste mixture of water and sand will be collected. This mixture can be reused by lowering the end of a reinforced hose into it, which is connected to the nozzle of the device. There must be a grate on the top of this container; it is necessary in order to hold processing waste and prevent it from getting into the water-sand mixture.

Karcher sink with sandblasting nozzle in use

Assembling a sandblaster from a gas cylinder

The simplest design for self-assembly is a homemade pressure-type sandblaster from a gas cylinder. The following elements will be required:

ball valves – 2 pcs.;
gas cylinder;
a piece of pipe from which a funnel is made for filling the chamber with sand;
tees – 2 pcs.;
hoses with a passage of 14 and 10 mm, respectively, used to transfer air from the compressor and remove the mixture;
clamps for attaching sleeves;
fum tape intended for sealing threaded connections of apparatus parts.

In order to assemble the sandblaster, you must perform the steps in the following order:

Preparing the tank. Remove all contents from the container, clean the inside surface using non-abrasive detergents and wait until it dries.
Making holes in the cylinder. The top one will be used to fill in sand - its size should correspond to the diameter of the selected pipe. The bottom hole is for connecting a tap.
Crane installation. The regulator can be tightly welded or screwed through an adapter pipe.
A tee and a mixing block are installed behind the tap. Fum tape is used to seal the threaded connection.
A tap is mounted on the cylinder valve, behind which a tee is installed.

At the final stage, you should take care of the mobility of the device - weld wheels or handles for moving. To increase resistance to do-it-yourself sandblasting, supports from corners, pieces of reinforcement, and tubes are welded.

Then the elements are connected to create channels for supplying and discharging the mixture:

fittings are placed on the tee located below and the balloon valve;
a sleeve with a 14 mm passage for air flow is placed between the mixing block and the tee;
an injection unit is connected to the unoccupied branch of the tee with a fitting;
a hose for the finished mixture is connected to the remaining outlet of the lower tee.

What can you use a homemade sandblasting machine for?

The effectiveness of using a sandblasting unit with a homemade nozzle, assembled on the basis of a Karcher apparatus, is ensured by the fact that sand mixed with water is supplied from a nozzle under high pressure, which is created by the built-in compressor of the device. Possessing significant kinetic energy, such an abrasive jet is capable of effectively cleaning various surfaces.

It takes no more than 5 minutes to clean a propane tank from rust and paint.

A homemade sandblaster, assembled on the basis of a Karcher sink, can be successfully used to solve the following problems:

cleaning surfaces from various types of contaminants;
removing old coatings from surfaces: paint, glue, building mixtures, etc.;
removing areas susceptible to corrosion from metal surfaces;
cleaning metal surfaces before further processing.

Despite the simplicity of its design, a homemade nozzle for Karcher devices, designed for sandblasting, is highly effective in cleaning various surfaces.

The fact that such a nozzle is a convenient and effective device is well demonstrated by the video of its use. Such a video, as well as videos on the manufacture and assembly of such a device, can be found on the Internet without any problems.

Sand for hydrosandblasting

It’s worth starting with the choice of consumables, since the principle of sandblasting itself is trivial. Unless the flow of sand is supplied directly from the compressor unit, but is captured from the tank by a flow of water, which has a sufficiently high kinetic energy for these purposes. This is precisely the subtlety of using sandblasting nozzles for Karcher

The instructions for use recommend that the user only use sand supplied by the nozzle manufacturer. And this is no coincidence. Those who did not pay attention to this detail then pay with a sharp decrease in the speed of the cleaning mixture, and, accordingly, a decrease in the efficiency of sandblasting. There are plenty of reviews on the problem that has arisen.

Sand used in sandblasting nozzles has a number of features:

Extremely uniform in fraction - 0.3...0.5 mm, no more and no less (a finer fraction will only produce grinding; the disadvantages of larger fractions will be discussed later).
The particles have a rounded shape in plan, without sharp protrusions and corners.
The sand must be strong enough so that it does not crush and disintegrate into smaller fractions after the first use.
The supplied material must be completely dry before mixing with water.

Sandblasting with a high-pressure washer can be used to clean relatively small surfaces of a simple, flat shape (the sand consumption coefficient when working with more complex configurations will be several times higher). The sand itself cannot be recycled or recycled after processing. This is explained not only by the difficulty of collection, but also by the need for particularly thorough cleaning, since waste sand contains particles of materials torn off from the cleaned surface.

The technology for preparing “branded” sand from kärcher is characterized by a high degree of purification of the starting material – river or quarry sand. After grinding in high-precision ball mills, the semi-finished product is additionally calcined. This increases mechanical strength and makes it possible to use the abrasive for sandblasting not only relatively soft non-ferrous metals and alloys, but also steels. During the preparation of sand, larger fractions with a diameter of more than 0.6 mm enter the container: the grains of sand become noticeably heavier, and the kinetic energy of the water flow is insufficient to capture them and deliver them at the required speed (at least 350 km/h) onto the surface to be cleaned.

Principle of operation

The operating principle of a sandblasting machine or device is to supply sand into a special nozzle. The abrasive comes from a special container using high-pressure air . To create such a powerful air flow, the sandblasting machine is equipped with a compressor, which imparts kinetic energy to the sand. For Karcher-type devices, equipment with pneumatics is typical.

At low cost you can make a nozzle for sandblasting; your original gun will work perfectly. The main thing is not to skimp on the quality of materials. The operating efficiency will be much higher, and the device will work without failures or complaints. Use decent and high-quality materials.

It is a mistake to believe that such a sandblasting nozzle can fully replace a professional device. But it is quite capable of cleaning different surfaces Some recommendations should be taken into account when working:

use distilled water - this will protect metal parts of the structure from corrosion;
The abrasive must be fine-grained and sifted.

A part made independently will function according to the following principle:

Water under the influence of high pressure created by a compressor will flow along the intake hole of the hose, which at the other end is placed in a special container with sand. This circuit is necessary to create a vacuum in the intake hose.
The vacuum helps the abrasive move into the main hose, where the sand is mixed with the water flow. Thus, sand is supplied along with water.

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For better functionality and productivity of the unit, you need to improve the design by adding dispensers and taps. These additions will reduce sand consumption. The best values would be thirty kilograms of abrasive per surface area of 0.8 meters to be cleaned.

Nozzle manufacturing process

A homemade nozzle for Karcher can turn a washing unit into a functional sandblasting unit for home use. You will need the following set of consumables:

a hose that can withstand high water pressure;
trigger hook;
dispenser to save abrasive consumption;
a nozzle into which a mixture of water and sand will come out.

Advice: if you plan to regularly use a sandblasting attachment for a Karcher, it is best to give preference to ceramics. This is due to the fact that the abrasive acts on the metal nozzle more aggressively and its service life is much shorter than that of its ceramic counterpart. The productivity of the device will depend on the quality of the nozzle.

Do not experiment with making a homemade nozzle if you are not a professional in this matter. It is necessary to accurately drill a hole with the required diameter . The market is saturated with ready-made parts and consumables of decent quality at reasonable prices, so it’s better to purchase them. In addition, the finished parts already have a trigger mechanism in the kit - a hook.

The hose you will use must be at least two meters long, durable and reinforced. A stream of high pressure water will pass through it , which will be created by the compressor. Strength is also important because the unit will work with abrasives, so a product of dubious quality will not last long.

Algorithm of actions

Using a thread, the tip is fixed to the nozzle.
A dispenser is also attached to the nozzle, which regulates the supply of sand-water mixture.
The container with sand is connected via a hose; for this, a suitable clamp and fitting are used.

Please note: the Karcher compressor creates high pressure, which will affect all elements in your structure. Therefore, they must be secured and installed securely and correctly. All parts and connections must be ensured with maximum tightness. For any connections, it is best to use sealing tape.

To save the most sand, you should prepare a special container with a grate. Above it, you need to carry out the necessary cleaning of the surface using a sandblasting nozzle . The water-sand mixture will accumulate in this container. This mixture can be used again if a reinforced intake hose is lowered into it. The grate covering the container is needed to keep waste from being cleaned so that it does not contaminate the sand and water mixture.

Areas of use

The high pressure created by the Karcher compressor allows a jet of water mixed with sand to be thrown through the nozzle, thus effectively and quickly cleaning many surfaces.

The sandblasting nozzle will easily allow you to cope with some tasks in a very short time:

cleaning various surfaces from complex contaminants;
removal of building mixtures, glue, paint, varnish;
cleaning metal from rust and corrosion;
carrying out stripping of metal products for subsequent processing.

The simplicity of the design and the ease of self-production can significantly facilitate and increase the quality of the work you perform. This attachment will save your time and effort.

Upgrading a blow gun to sandblasting

Sandblasting, made from a blow gun, is small in size. The performance and efficiency of the device depends on the power of the compressor used.

To create a mini sandblasting machine you will need the following materials:

blow gun;
tee;
ball valve designed to regulate the supply of abrasive;
outlet nozzle with clamping nut.

You can use a small fire extinguisher or a regular PET bottle as an abrasive tank.

Precautionary measures

When working with a machine on which a sandblasting attachment is installed, certain precautions must be observed. A water-sand mixture can cause injury.

When working with the device, wear special clothing, it will protect against injury;
use closed and comfortable shoes;
carry out cleaning work outdoors.

Since contaminated surfaces are processed and cleaned using sand and water, there is no need to use a respirator.

Safety precautions

Even despite the fact that sandblasting is done using a special nozzle, basic safety rules should be applied. Since the flow of abrasive material is supplied under fairly strong pressure, injury can occur if you are careless. To prevent this from happening, the following rules should be applied in practice:

work only in closed protective clothing;
shoes must be closed;
It is better to clean outdoors.

As for face and respiratory protection, in this case they are optional. You can get by with overalls and closed shoes.

Building a sandblasting machine with your own hands is not difficult if you approach this matter correctly. Moreover, this is easy to do if you already have special nozzles and a washer with good pressure. In this case, you can save on buying a compressor.

If you don’t want to make such a device with your own hands, or for some reason it’s not possible, you can simply purchase a ready-made sandblasting nozzle or the device itself. But it will be much more expensive than if you assemble it yourself.