Last updated: August 5, 2021

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The random orbital sander is a tool that is absolutely necessary sooner or later during the renovation of various premises. It is considered an effective and versatile tool for polishing and sanding surfaces. When the focus while working is on the quality of sanding, the eccentric sanding is incomparable. This is its main difference from all other types of sanders. It is able to guide the surface to perfect smoothness without sawing and visible scratches.

With our big random orbital sander test 2021 we want to help you choose the right random orbital sander for you. We have compared a classic, a cordless and a compressed air random orbital sander with each other and listed the respective advantages and disadvantages to make your purchase decision easier.




Summary

  • Eccentric machines are universally applicable. They are not only suitable for sanding wood and metal, but also for painted surfaces. They are often used for polishing finished surfaces.
  • Eccentric sanders are only suitable for dealing with flat surfaces. It cannot be used in corners, which means it is not suitable for sanding muntins and shelves.
  • With a total power of 280 watts + an oscillating circuit of 3 mm + 125 mm sanding disc, the random orbital sander is perfectly adequate for a high-quality result and productive work.

The Best Random Orbital Sander: Our Choices

Buying and evaluation criteria for random orbital sanders

In order to make the right decision when choosing an orbital sander, you should first look at the important evaluation criteria.

The criteria you should look for when buying a random orbital sander include:

To avoid spending money on unnecessary features, it is worth taking a closer look at these characteristics.

Oscillating circuit & idle speed

Oscillating circuit is also called eccentricity. Another explanation is the imbalance of the sanding disc. The value varies from 2 to 8 mm. The greater the value of eccentricity, the more productive the sander.

The 2 - 3 mm oscillating circle is suitable for a fine finish.

Productivity as well as the level of finish are directly dependent on this amplitude. A tool with high amplitude and corresponding productivity is required for grinding in materials with high hardness.

When choosing a random orbital sander, you should always pay attention to the idle speed. This is the rotation frequency. This is the number of revolutions of the eccentricity per minute.

  • For machines with a "regulation" option - between 4,000 and 14,000 Rpm
  • For unregulated machines - about 12,000 rpm

Many units have electronic stabilisation that reliably controls the number of revolutions.

Power

For random orbital sanders, this parameter offers from 130 to 900 watts.

The power of 280 watts is sufficient to handle most tasks.

But usually the power of several machines varies between 220 and 450 wat ts. The "strength" of the tool has a direct effect on its power. So it is not surprising that 400-watt machines have a sanding disc with a diameter of 150 mm.

Sanding disc

The 3 main diameters of sanding discs are - 115, 125 and 150 mm. A small disc is usually for amateurs, the medium are semi-professional tools, and large - professional sanders that can easily handle large surfaces.

  • "125 mm" - most commonly used size. There are enough compact, lightweight, relatively inexpensive machines. Many models of this size have a handle. The smaller size makes it easier to work in places with limited access.
  • "150 mm" - these machines are relatively large, are made on a two-handed circuit (with the front and rear handle). However, larger diameters increase the efficiency of grinding as they are equipped with a 300-500 watt motor.
    The size of the sole should always match the power capacity.

Weight

The weight of a random orbital sander can vary between 1.2 - 3 kg.

The more powerful the unit, the heavier and less user-friendly it is!

Sometimes it is necessary to polish the ceiling or elements at height. That's when you need a simple tool to do difficult tasks.

Small machines are better suited for everyday tasks, do not overload the hand and lead to productive work. After all, it is uncomfortable to work with a heavy tool suspended in the air.

Volume & vibration

Many users complain that their hands get tired quickly during work and that they suffer pain from excessive vibrations. To solve this problem, manufacturers equip tools with an anti-vibration system that works on the principle of dynamic counterbalance.

Before buying, it is also helpful to read the reviews of a particular model to consider the vibrations during operation.

Working with a machine that vibrates strongly in the hand is not only uncomfortable, but also not good for your health in the long run. Switch on the machine when you buy it and hold it in your hand - vibrations should be completely absent.

The optimal volume of the machine varies between 60-80 decibels. We would still advise you to use headphones.

Dust extraction

Working with a sander is not possible without creating large amounts of dust and waste. Equipping the tool with an adapter through which the hoover can be connected makes the process of dust removal much easier. Working with the tool becomes much more comfortable.

The high efficiency of dust removal is ensured by holes in the working disc.

The holes in the sandpaper must exactly match the holes in the sanding disc, both in diameter and position. This should be taken into account when buying replaceable sandpaper.

Decision: What types of random orbital sanders are there and which one is right for you?

Let's analyse the 3 different types of random orbital sanders with their advantages and disadvantages:

Type Advantages Disadvantages
The classic random orbital sander Universal:can sand as well as polish Depends on cable length
The compressed air random orbital sander Compact + Lighter weight Depends on compressor power
The cordless random orbital sander Mobility:does not need a cable + Does not depend on a power outlet Battery lasts only a limited period of time (about 1 hour)

The following information will give you the knowledge you need to decide which of these machines is right for you. You will learn what the main differences are, as well as their strengths and weaknesses.

The classic random orbital sander

The classic random orbital sander

This type of random orbital sander works with the help of a cable and socket and is the most commonly used. You can use this corded random orbital sander for both polishing and sanding work.

Advantages
  • Universal use
  • High power
  • High surface quality
Disadvantages
  • Socket dependent
  • Cable length dependent
  • Vibration

What could be a big disadvantage here, apart from the dependence on a socket, is the cable length. With classic random orbital sanders, you should always consider the length of the cable, which will later ensure your freedom of movement. This should be about 3 – 4 metres.

The compressed air random orbital sander

The compressed air random orbital sander

The procedure for this type is similar to the classic one, but instead of a socket, cable or battery, you need compressed air. Here there is the need for a compressor, which makes the use of this device much more complicated for us.

Advantages
  • Compact
  • Lighter weight
  • Cheap
Disadvantages
  • Limited mobility
  • Compressor dependent
  • High energy costs

On the other hand, the pneumatic random orbital sander has some advantages. Since this tool does not need a motor, it affects its weight and price. It is relatively light and convenient to use. At the same time, it makes it much cheaper than the other models.

The battery-powered random orbital sander

The battery-powered random orbital sander

The cordless random orbital sander is valuable for repair work in places where there are no power sockets, such as in the garden. You can use your cordless random orbital sander flexibly and are not tied to a socket. You only need a charged battery for full use.

Advantages
  • Mobility
  • Compact
  • Independent of power supply
Disadvantages
  • Limited use time
  • Replacement battery required
  • Lower power

Such a cordless machine clearly comes with disadvantages. The limited usage time is unfortunately one of them. You should always consider the level of remaining battery life. A solution to this would be the replacement battery, which of course causes additional costs again. Another minus that has to be taken into account is the power. Of course, it does not produce as much power as a corded random orbital sander.

Guide: Frequently asked questions about random orbital sanders answered in detail

In the following section, we would like to answer the most frequently asked questions in detail.

What is a random orbital sander suitable for?

Eccentric sanders are universal in their application. They are suitable for sanding not only wood and metal, but also lacquer coatings, natural stone and glass. They are often used to polish the finished surfaces.

The Universal Power Tool handles a wide range of tasks. Typical jobs for which a random orbital sander can be useful:

  • Careful sanding and polishing of metal, wood, plastic, etc.;
  • Cleaning the surface of paint and varnish;
  • Finishing walls and ceilings;
  • Refinishing of plastic and plexiglass.

At the same time, this type of sander is only suitable for dealing with flat surfaces. It cannot be used in corners, small grooves and recesses, which means it is not suitable for sanding glazing bars and shelves.

Advantages
  • Works on uneven work surfaces
  • High removal rate due to the additional rotary movements
  • Used for a perfect fine sanding
  • Suitable not only for rough and fine sanding, but also for polishing
  • The high-quality machining
Disadvantages
  • No machining of corners possible
  • Limited in its area

What should a good random orbital sander cost?

You should ask yourself right at the beginning what you need a random orbital sander for and how often you will use it. If you use such a tool only rarely, it is probably not worth buying one of the expensive tools, and you will be very well served by an inexpensive model.

The prices for a random orbital sander start at 40 €. The appropriate price for a random orbital sander can best be determined according to the following 3 consumer types:

Craftsman type price range
The occasional user €40-100
The do-it-yourselfer €100-300
The professional €300-600

How does a random orbital sander work?

Polishing and sanding are possible through a combination of rotary and eccentric movements of the soleplate. The sanding pad rotates in orbit and scrolls around its axis at the same time. Such a complex movement allows you to grind effectively with a minimum number of errors.

The special structure of the movement path prevents small particles from damaging the surface.

In oscillating movements, the vertical axis, which passes through the centre of the sole, shifts relative to the other axis of the motor. The displacement is indicated by the amplitude of the eccentric oscillations. (Oscillating circuit)

What does eccentricity mean on an eccentric sander?

Eccentricity means vibration amplitude. This usually varies from 2 to 8 mm. With this function, you can change the mode, i.e. select coarse or high-quality finish.

The greater the eccentricity value, the more productive the sander.

On the "slow speed", when the vibrations are concentrated on a smaller area, the sanding will be finer. However, this does not mean that machines with low eccentricity should not be considered when buying. They are quite suitable for small volumes of work where speed is not as important as the accuracy and quality of the grinding and polishing.

What should the power of an eccentric sander be?

The power of several sanders varies between 220 and 450 watts. As a rule, 280 watts is quite sufficient to handle most tasks. The most suitable option for productive work is a machine with a 150 mm sanding disc, a 5 mm oscillating circle and a power of at least 300 watts.

For everyday use at home, 5,000 to 8,000 revolutions are sufficient.

To roughly finish metal surfaces or to sand seams after welding, you need about 12,000 revolutions. Soft wood or plywood needs a specific average speed.

Random orbital sander or orbital sander: What are the differences?

Both sanders are capable of fine polishing the surface with sandpaper. They basically do the same job, but there are actually a few differences. The following table contains a few differences:

Orbital sanders Eccentric sanders
1. Has a square sanding plate 1. Has a round sanding plate
2. Has a circular oscillating motion 2. Has an eccentric oscillating motion + a circular motion
3. Has a lower stock removal rate 3. Has a higher stock removal rate
4. Are good for small work surfaces and narrow edges 4. Are good for finishing large flat work surfaces

They differ both in shape and working principle.

The sanding discs: What should I look out for?

When buying, make sure that there is a mechanism for braking the sanding disc.

Exzenterschleifer-1

The random orbit sander can handle a wide range of sanding and polishing tasks on a variety of materials.
(Image source: Studio Ócular / unsplash.com)

Typically, there's a plastic disc that fits tightly against the soleplate on top. This mechanism helps to make the rotation of the sole around its axis smoother, which in turn affects the quality of the sanding.

The advantage is that work breaks are reduced and the likelihood of spoiling the surface is reduced.

Image source: Kovtunenko/ 123rf.com

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