Eccentric sander: features and principle of operation

Features of eccentric sanders

The main goal of finishing work is to bring surfaces to perfect condition. This cannot be achieved with mechanical devices. Grinding units will help you do this job quickly and efficiently.

There are several types of such devices, differing in functionality, operating principle, and class. For delicate finishes, an orbital sander is recommended.

Thanks to the soft rubber sole, the device will allow you to accurately perform the following types of work:

• level the primer;
• make grout;
• prepare surfaces for coating.

The main feature of these machines is that in addition to the eccentric rotation of the sole, there is also a radial rotation. This ensures high-quality polishing of planes of various slopes and curvatures.

Design and principle of operation

Orbital sanders provide good surface finishing due to their design features. The structure of the unit is shown in the photo:

The rotary-circular and translational movements of the abrasive wheel allow you to perform not only rough, but also filigree polishing of various surfaces.

The operating principle of the tool is not complicated and is represented by the following points:

• the working circle is mounted on the sole;
• the drive is attached to the base;
• when the device is turned on, the abrasive rotates around its axis;
• An impulse is applied to the sole, causing it to vibrate.

Note! Both movements occur in parallel, which is why the trajectory of the abrasive elements does not repeat. Due to this, the quality of polishing is ensured.

Types of Grinding Tools

Manufacturers offer several options for eccentric sanders. They are classified according to various parameters, which allows you to choose the appropriate model.

Grinding tools are also divided according to other criteria:

• power supply – from the electrical network, battery-powered or running on compressed air (pneumatic);
• according to the processed material - metal, wood, plastic;
• by layout - one- and two-handed;
• the diameter of the sole is 125 and 250 mm.

Some models are combined, designed for finishing various types of materials.

Kinds

ESMs are classified according to several criteria:

• machines with which you can work on wood or metal;
• ESMs that operate from an electrical network or from batteries;
• professional models and devices for household needs;
• miniature units with speed control and large pneumatic ESM.

ESMs are capable of making surfaces perfectly smooth. The quality of the “orbital” is achieved through the translational-rotational movement of the canvas itself. At high speeds (more than 10,000 thousand per minute), a large amount of energy is generated, which is transmitted into vibration. It is transformed into a force impulse, thanks to which the polishing process occurs. The eccentric needs a counterweight, which is necessary to smooth out excess vibration.

Let's look at the most popular ESM manufacturers.

• produces inexpensive and compact units.
• Bosch produces high-power (more than 650 watt) and medium-power models. The company's products are of good quality and have many different additional options (rotation adjustment, speed, etc.). This type of equipment is most often purchased by professionals. It is quite expensive, but is very reliable and also has a long service life.
• The quality of EShMs is not inferior to German units from Bosch. The devices are ideal for use in service stations and garages. The dust removal system is especially effective on the models. Each model has its own design features. Some ESMs are equipped with a speed controller (up to 6 positions).

Now let's look at some of the distinctive details and functions of the devices.

• “Orbitals” for professionals are equipped with special relays that control a constant rotation speed during operation. In this case, the torque automatically switches to afterburner mode, and the engine's reserve power is used.
• The starting current limiting block is used for several reasons: when it is necessary to reduce the load, and also to avoid noise when the engine starts. This device is found exclusively on professional models.
• Adjusting the sole brake is necessary for quick stopping.
• 90% of ESHs have a socket that allows you to connect a vacuum cleaner (sometimes the vacuum cleaner is replaced by a special container made of a PVC bag or paper bag).
• Professional tools are often equipped with a casing around the eccentric assembly.
• The D-lever allows you to work more comfortably.
• A switch with a lock is most often found in expensive professional models.

Also, the EShM cannot be installed permanently. This is usually necessary when you need to work with small-format products. If there are voluminous depressions or depressions on the workpiece, then the ESM will not penetrate there; there is also the possibility of damage to the edges by the rotating element of the machine.

Areas of application of ESM

The orbital sander has found its application not only in the professional sphere - such tools are also used in everyday life. The main purpose is to level surfaces for further finishing. EShMs are used:

• during construction and repair work - for grinding plastered surfaces;
• in the manufacture of new and restoration of old furniture - preparation of surfaces before applying varnishes, paints, primers;
• during car repairs at service stations - to level the primer applied to the car.

The tool can polish natural stone, plastics, and glass. For each type of work, a different abrasive is selected and the wheel rotation speed is set.

Specifications

The quality of a tool's performance is determined by its parameters. Before figuring out how to operate an eccentric sander correctly, you need to study its technical characteristics.

Important! The greater the amplitude, the worse the quality, but the higher the productivity.

Eccentric orbital sanders have to work not only on horizontal surfaces. That’s why another parameter is so important – the mass of the tool. The more powerful the machine, the heavier its engine, the more uncomfortable it is to operate the device in weight. The weight of household ESM is about 1.5-2 kg.

What parameters should you pay attention to when choosing a grinder?

The most important technical parameter for any tool is its power. An orbital random orbital sander can have a power from 150 to 1000 watts. Depending on the model and purpose, this machine can be used for domestic or professional purposes. Tools with a power of approximately 400 W are ideal for cleaning various parts.

Unlike similar tools, a pneumatic orbital sander has a round sole. The sole diameter of different models may vary significantly. Tools with a plate diameter of 125 mm are considered universal. The speed of a tool is the most important indicator of its performance. It is most convenient to work with models that have a soft start function, which allows you to gain speed without jerking. You can achieve ideal grinding results using models that have a speed controller.

Additional functions

Some models are equipped with additional functionality, which significantly improves the quality of work and increases its productivity. Often these options are important when deciding which tool to choose.

Additional features affect the cost of the grinding machine. But such costs are justified - productivity increases, quality improves, and ease of use is ensured.

How to choose an eccentric sander

Considering the above information, it will be easier for the master to make the purchase of the tool. It’s not enough to know how an eccentric sander works; you need to decide on the selection criteria:

• Budgeting. For household needs, when the device is used from time to time, it is not rational to buy an expensive professional machine.

• Class. First, the accents are determined:

— for productivity, choose a disk diameter of 150 mm with an amplitude of 5 mm and above;

— for finishing quality – 125 mm with an amplitude of 3 mm.

• Weight. It depends on convenience. If you have to work a lot on vertical surfaces or sand the ceiling, then the tool should be lightweight. It is better to give preference to a device of medium power.

The choice of manufacturer also matters. In order for the ESM to last for a long time, it is recommended to pay attention to brands that have managed to prove themselves in their work on the positive side.

Accessories and spare parts

Regardless of the specific model of the polishing machine, its auxiliary equipment plays an important role. Among the attachments, the bag stands out in its role. It allows you to collect maximum debris, dust and waste. As a result, the work is done as cleanly as possible.

Backings formed on an adhesive base allow grinding discs to be secured in holders. Special flexible shafts help to work in hard-to-reach places. For the grinding itself, brushes or rollers made of nylon, metal and special composites are used. Polishing machines are equipped with main and additional handles. But when selecting such components, you need to carefully check that they make the work easier and not complicate it.

The sole for a vibration machine, as already mentioned, can be made in the form of a triangle or a rectangle. The first type works better in limited space, the second - in cases where you need to process a maximum area. If the power cord is initially short, you will have to continuously use an extension cord. Of course, all spare parts and auxiliary components must be purchased only from official manufacturers.

Rating of eccentric sanders

On the working tools market you can find many interesting options for OHM, both Russian and foreign manufacturers. Some of them (judging by the ratings) are more popular among consumers and professionals, others less so.

If you choose a tool from the professional category for personal use, this review recommends paying attention to models from Metabo and Bosch. They are easy to use, equipped with a large dust collector, and provide high quality grinding.

How to use a sander correctly

Features of using a belt sander

A belt sander is best suited for processing large, flat surfaces.

First of all, you need to put on the tape. The easiest way to do this is when the car is lying on its side. Having first snapped off the fastener, put on the tape, taking into account the direction of movement - indicated by the arrow both on the tape and on the rollers of the machine. This is necessary so that the seam on the tape is positioned correctly. Otherwise, the tape may either break or damage the surface instead of sanding. After this, snap the fastener into place.

The belt in the machine always moves in one direction, so you also need to work in one direction with the tool - pressing it tightly to the surface, moving it towards you. The wood must be processed along the grain with a belt sander. Otherwise, deep furrows may appear. There is no need to press unnecessarily on an already heavy tool - instead of increasing productivity, you can overheat and thereby damage the tape.

To expand the functionality of the belt sander, you can use a frame, stationary mounts (vices), and corner stops. It is the band tool that can be fixed permanently with a vice and moved not by it, but by the surface being processed (for example, a board, a block). This type of tool mount is especially important for grinding small parts. Also, when the machine is stationary, it is very convenient to sharpen notches and curves.

Another way to use the belt tool is when the machine is lying on its side. Its advantage is that in this position a right angle is formed.

Video: how to use an eccentric (orbital) machine

When preparing the machine, you need to pay attention to how dusty the job is expected to be. And if there may be a lot of dust, it is better to connect the vacuum cleaner right away, fortunately many models have this option. The work is relatively clean - a dust collector will do

A respirator will keep you healthy

The work is relatively clean - a dust collector will do. A respirator will help you stay healthy.

Important! During operation, you need to periodically check the dust container and prevent it from overflowing. Otherwise, dust will come out from all the holes. The abrasive disc is attached to the round platform of the machine with Velcro - you simply apply it and press it with your hand

You just need to make sure that the holes on the disk coincide with the dust holes on the platform

The abrasive disc is attached to the round platform of the machine with Velcro - you simply apply it and press it with your hand. You just need to make sure that the holes on the disk coincide with the dust removal holes on the platform.

When processing a plane with a machine, you need to press the platform tightly against it. You need to hold the machine level so that the platform is not pressed against the surface by the edge - otherwise there is a risk of damaging the surface with scars. In order not to remove excess, this is especially true during body work, it is better to check the surface more often with your palm for roughness.

As you work, check the dust content of the nozzle, change it on time so that the work does not go in vain when the grain is “clogged” and the roughness is no longer torn off.

Video: how to use an eccentric sander for body work

There are many ways to use grinding machines. This includes preparing for painting the body, treating floors, sanding wooden parts (even children's toys), and even polishing. The result of work, of course, depends on the skill and perfection of a person’s skills

But no less important is the quality of the tool, as well as how correctly it is selected and used correctly.

Good luck with your work!