The Content Of The Article:

First and foremost for finishing surfaces, flat or not, this "eccentric" has more than one trick in his bag. From roughing to polishing, the sander knows how to be as aggressive as it is delicate. It remains to discover these various features, and to make the most of them.

Use an eccentric sander

An eccentric and efficient machine

With its circular sanding plate combining orbital and rotary movement, this machine combines eccentricity and efficiency. In competition with the other sanders, she quickly carved out a large place, demonstrating beautiful skills in areas as different as the work of wood or that of the bodywork. The vibrating and the triangular are reluctant indeed to tackle the big jobs, while the tape is confined to it almost exclusively.

A particular operation

The plate is not fixed directly at the end of the motor shaft. It is eccentric, via a ball bearing, on an intermediate plateau. Equipped with fins, the latter also acts as an integrated suction turbine. Thus, when starting, the sanding plate is first animated by an elliptical movement. Then it's the only centrifugal force that throws it into a rotation faster and faster. The combination of these two movements gives the abrasive grains a spiral stroke. They only occasionally iron in the same place, resulting in sanding similar to good quality manual work.
Both the efficiency and the aggressiveness of sanding depend on the frequency of the oscillations and their amplitude. But also the size of the abrasive, the pressure exerted on the machine, the capacity of the suction system. Not to mention the state of the support!

Shapes and diameters

There are two types of eccentric sanders: the classic, with two handles, and the "palm" sanders. More compact and of medium power, the latter are particularly reserved for sanding while finesse or polishing in hard to reach places. "Two-handed" sanders are more suitable for large surfaces, but they are very accurate as long as they are handled flexibly.
Initially offered with a plate of ø 115 mm, eccentric sanders are today mostly equipped with 125 or even 150 mm, like our machine. This allows for a larger work surface, a more powerful engine and a better comfort to use.

Essential functions

The power. The motorization of the sanders on the market ranges from 200 to 500 watts. Since sanding at full speed is not easy, high power is not required. A 350 to 400-watt motor has a sufficiently wide adjustment range to suit both roughing and finishing and working quickly, without excessive fatigue.
The drive. Most machines have a speed control knob. A most useful function, which changes the speed of rotation of the plate and, therefore, the frequency of oscillation, depending on the medium to be sanded. Slow speeds are used to roughen, polish and sand heat-sensitive materials such as paints or plastics. Fast speeds are reserved for finishes and resistant materials such as hardwoods or metals.
The speed limiter. All eccentric sanders have a "braking" system which prevents the plate from reaching the maximum rotation speed too quickly and limits empty revs. Simple rubber crown, ABS pad or electronic regulation, these brakes make it possible to approach the support gently, without the risk of digging it as soon as this first contact.
The sanding tray. The abrasive sheet is attached to a sanding plate with a "Velcro" self-gripping coating. The one fitted as standard on sanders has a medium flexibility for universal use. Other options are offered with different densities. The softer ones make it possible to sand or polish surfaces with pronounced curvature. The harder ones offer important abrasion capabilities and facilitate flat work.
To save time during its change, the attachment of the plate on the flange is usually reduced to a central screw. On those with multiple screws, the maneuver is not much more complicated and the risk of loosening during work are zero.

Choose your abrasives

The disc, on the back of which is glued a flocking, is fixed with one hand on the self-gripping coating of the plate. Standardized, the perforations of the discs fit on the suction holes of the sanding pads. The family of abrasives available is wide. Corundum discs (normally red in color) are rather reserved for "dry" materials: non-resinous wood, unpainted metals, etc. The anti-fouling discs are coated with a substance resembling talc. Thus, the materials (paint, resin...) do not adhere to the abrasive, which remains usable longer.
Side grain size, abrasives are on their reverse side the indication of the number of grains per square inch (40 to 600). The lower the number, the greater the abrasion, the higher it is, the finer the finish. The grains 80 and 120 cover the uses the currents.

The accessories

Apart from conventional abrasives, it is possible to mount sheep wool polishing discs, felts or polishing sponges on the tray. This allows to revive the painting of a body, repolish tarnished marble, polish a wax, etc.
There are also non-woven nylon abrasive pads. These thick discs are particularly well suited to fragile surfaces, ginning between two layers of varnish or paint, etc. The abrasive sponges give the wood a rustic appearance and make it easier to pick up the lacquers by "matting" them.

Dust evacuation

Effective suction delays the fouling of abrasives. It clears the surface and allows the user to better follow his work. During sanding, the integrated turbine sucks dust directly under the tray to reject it to the outlet nozzle. The latter receives as standard a salvage bag made of paper or canvas. But you can also connect a suction hose, via a fitting often sold as an option. The efficiency of the vacuum cleaner is higher than that of the bag, even if the pipe is sometimes annoying.

At work !

Like other power tools, it is not recommended to work in a wet environment. Only dry sanding is possible, which limits a little the use of this machine body. Some manufacturers also advise against sanding plaster and plaster. Despite serious suction, their fine abrasive dust is likely to damage the engine and mechanics.


With regard to start-up, two schools compete. Should we put the machine on the support before starting it, or start "in the air" and then put it gently? In fact, in use, everyone chooses his method. The air starting is predominant for heavy work while on delicate surfaces, it is better to press the pad before squeezing the trigger.


Conventional sanders have three gripping areas: the rear handle, an auxiliary in the front and the so-called "palm" above the crankcase. The first is just to keep the machine flat. The second is used to direct the sanding that can be done in all directions, even against the wire on the wood. This handle folds or disassembles sometimes to work close to an obstacle. The one at the top of the housing, allows a catch of one hand, to polish for example.


It is the pressure on the machine that decides the more or less free rotation of the sanding plate. With a little training, his dosage is learned quickly. For roughing, use only a small amount of pressure on the tool. Driven by centrifugal force, the disc rotates at a high speed and removes as much material as possible. Conversely, for fine jobs, slow down the rotation by pressing on the machine cover. The eccentric movement then predominates and reaches its maximum efficiency.

The interview

It is reduced on these machines, whose sensitive parts (bearings and motor) are in principle hermetic. At most, from time to time, disassemble the tray and perform a quick cleaning with the gun to remove dust from the fins, and under the flange. On the other hand, refrain from greasing them. This would favor the amalgam of dust and the opposite effect of that sought would be obtained. A jet of compressed air into the engine's ventilation openings will preserve its cooling.

Anatomy of the machine

Anatomy of the machine

A: removable front handle
B: speed variator
C: "palm" handle
D: trigger
E: rear handle
F: dust bag
G: suction nozzle
H: blocking button
I: sanding tray

Accessories

Accessories

A: corundum discs for wood;
B: anti-fouling discs for paints;
C: sheepskin lambswool;
D: polishing pad;
E: abrasive nylon mesh.

Adapt sanding speed

Adapt sanding speed

The electronic variator makes it possible to adapt the speed according to the material. Choose a slow one for fragile surfaces or paints, a quick one for hardwoods or rust removal of metals.

Set up the abrasive disc

Set up the abrasive disc

The installation of an abrasive disc requires a small knack to align its perforations with the suction holes of the pad. Fold the sheet, and align it with two holes.

Adjust speed

Adjust speed

Before putting the machine on the surface, set the speed, start the engine and wait until it reaches its maximum speed. Then gently put the pad on the material to avoid digging.

Sand in circular, back and forth

Sand in circular, back and forth

Most of the work, with this sander, is done by printing it circular motions and back and forth. Never park in the same place to even out abrasion.

Getting started

Getting started

Some operations, such as sanding this song, require a very precise grip. It is sometimes better to hold the machine with both hands to "feel better" than to use the front handle.

Dust and residues

Dust and residues

The dust bags are of limited effectiveness. A fitting adapted to the machine, to which the pipe of a vacuum cleaner is connected, collects infinitely better the residues and releases better the work zone.

Refine sanding

Refine sanding

To refine a sanding, or insist on a more resistant area, you can tilt the machine and work with the edge of the tray. But beware, in this way, the abrasive wears irregularly!

Keep the machine flat

Keep the machine flat

The front and rear handle, widely spaced, serve to keep the machine flat on the surface. Press down slightly to slow down the rotation and benefit from the orbital motion.

Sand with finesse

Sand with finesse

In the hollow of the concave pieces, it is still the edges of the plate which are the most solicited. Move the machine regularly to sand finely and judge the progress of the work.

Sand the painted materials

Sand the painted materials

Sanding of painted metals is within the reach of the machine. Make large circles to allow the room to cool between two passes. Use an anti-fouling abrasive, otherwise the disc will quickly stain.

Polish bodywork

Polish bodywork

The polishing pad, made of soft foam, makes it possible to apply polishes or polishing pastes on the bodywork. Set the drive to slow speed, and spread the product evenly.

Clean the sanding tray

Clean the sanding tray

The sanding plate is fixed to its bearing only by means of a central Allen screw. It is therefore easy to disassemble, for replacement or to perform regular cleaning.

Take off the dust

Take off the dust

From time to time, a "blow gun" blow inside the body of the machine will take off the dust. These agglomerate on the suction fins or bearings, and limit its effectiveness.

The settings

The settings

Specific to this machine (SXE 450 Duo Metabo), a setting allows to have an eccentric stroke of 3 mm for fine work (left) and 6 mm for more abrasive sanding (right).


Video Instruction: SKIL Learn Which Type of Sander to Use