What are wall trowels and how do they work

If we have gone through the arduous experience of sanding or smoothing walls, ceilings and even floors with a sheet of sandpaper or even with a conventional electric sander, we know well the work that task is required, and once it is finished, we also know the aches and pains our body feels.

Fortunately, that burdensome task is being left behind thanks to the increasing use of wall planers, which allow us to sand, polish and smooth walls, ceilings and floors quickly and with very little effort.

These useful machines introduced on the market some 20 years ago, are similar to conventional electric sanders, except that they are equipped with a long extendable (or “telescopic”) handle so that we do not have to keep our arms above our head throughout the day. of work. This may seem unnecessary to a home user, but it is highly welcomed by painters, setters, drywall or drywall, plastering specialists and many other similar duty workers who must sand walls or ceilings / floors around the clock, both in new construction and remodeling.

Furthermore, in addition to sanding large surfaces, the heads of many of these machines also allow convenient sanding of edges and corners without the need for ladders or scaffolding, allowing not only a direct finish of these small and confined areas, but also contributing to worker safety. And as if that were not enough, although they are ideal tools to work on drywallThey can also be used on other surfaces such as cement, paint coatings, screeds, natural and artificial stone, tile adhesive and many other materials on walls, ceilings and floors.

Given all these advantages, let us then know the tool to which we are referring. The figure below shows a typical model of wall planer with its main components.

Like any power tool that generates large amounts of dust, it is very important that the tool wall planer It comes equipped with a dedicated port for its removal, which allows it to absorb up to 85% of the dust produced, guaranteeing a cleaner, healthier and safer work environment. Certainly, this detail was not ignored by the manufacturers. Some models, for example, incorporate this port in the upper part of the handle, as we can see in the figure above, and this port can be connected by means of a hose to a dust collection bag provided by the same manufacturer, as shown in the image following.

Although the variety of accessories depends on the manufacturer and model, in general, a wall planer sold with the following parts:

• A kit of various types of sanding discs
• A hex wrench
• A dust collection bag
• A telescopic handle extension
• A replacement brush

The operation of the straightener It is very simple and does not differ much from its conventional pairs, since a motor (generally, with brushes) attached to the head rotates a sanding disk at different speeds that are achieved by means of a corresponding controller located in the handle of the tool. In turn, dust can be easily removed from the workplace, either, as just noted, by connecting a manufacturer-supplied bag to the dust collection port, or by using a vacuum cleaner designed for this purpose.

Therefore, one of the key components of the tool is the sanding disc / carrier head unit. The disk It is mounted on a backing pad and, as indicated above, the manufacturer generally supplies a series of discs of different grades to suit the needs of coarse, medium or fine sanding. Changing the discs is done in a simple way, as shown in the generic figure that follows.

Sanding discs

That is, with the hex wrench supplied, the screw E is unscrewed and the washer is removed, then the sanding disk is placed on the pad and the back of the disk will be firmly adhered to the pad by a system velcro. Finally, the washer is replaced and the screw is screwed in with the help of the hexagonal wrench.

Another important component is the switch / regulator module speed. This module allows a soft start, maintains the nominal speed almost constant up to the nominal power and provides an overload protection by current limitation in case of overload of the motor, whereby the motor stops and restarts when reducing the work pressure.

The switch is usually of the self-locking type, meaning that when the switch button and the lock button are pressed, the switch is locked, no need to hold the switch for the entire time the machine is used.

The electronic speed regulator allows the speed to be adjusted in different positions in an adjustment number that, depending on the make and model of the machine, ranges from 1 to 5 or from 1 to 6, that is, the machine can have 5 or 6 speeds different. This speed selection is an important resource according to the finish we want to obtain and the type of surface we are sanding.

Technical characteristics of wall trowels

A good one straightener The mid-range range has a power rating between 600 and 800 W. This will ensure that the toughest sanding jobs are carried out quickly, always leaving a professional touch on every surface you work on.

The no-load speed varies between 800 and 1700 rpm, while the disc holder pad accepts sanding discs of a variable diameter between 200 and 225 mm, depending on the model.

Since sanding jobs are strenuous, the weight of the tool is an option to consider. However, if it is a very light machine, it may not be able to handle large, time-consuming jobs. A suitable average weight of a straightener that provides excellent performance varies between 3.5 and 5 kg.

Another interesting feature is the possibility of offering smoothing in corners and hard-to-reach areas. For this, some manufacturers present models equipped with partially removable heads, allowing a part of it to be removed, as we can see in the following figure, to facilitate sanding the corners.

Being an operation that produces high levels of noise and vibration, the sanding of surfaces must be carried out with tools that minimize these levels, even when hearing protectors must be used. The wall planers commercially available generally have the following noise and vibration parameters: acoustic pressure of 90 dB, acoustic power of 103 dB and vibration acceleration of 2.9 m / s.

Finally, the length of the telescopic arm is also another aspect that will add versatility to the tool. In this way, walls and high ceilings (for example, of sports or commercial institutions) can be easily reached with straighteners provided with extensions between 1200 and 1800 mm, or even more.

Tips for using a straightener

Drive a wall planer It is not complicated, but it is always advisable to follow a series of guidelines that will reinforce the quality and productivity of the work carried out, as well as the safety of the user.

To do this, let’s try to follow the following steps in a task of dry sanding.

• Once we start the machine, we lightly support the head against the work surface and apply enough pressure so that the abrasive disc is always parallel to the work surface.
• We use a constant and wide movement, maintaining it whenever the disk is in contact with the work surface.
• Do not allow the disc to move over screws, nails, sharp protrusions, grooves etc., as it may be damaged. In that case, we must first mark those conflict areas with a pencil, then remove the nails and screws with a pliers, and apply a layer of joint compound if it is about drywall, or mix / putty / plastic filler on other surfaces.
• Let’s limit the work pressure. The tool always gives indications of its extreme working limit by uncontrolled vibrations of the transmission cable due to pressure, revolutions or the wrong type of abrasive for the surface being worked. In this case, we must remove the head from the work surface for a few seconds and then start the work again, moderating the pressure or regulating the speed of the tool.
• We must not force the machine. Excessive pressure can cause stalling, engine overheating, work surface burns, and kickback.
• Let us use suitable discs according to the surface to be polished / sanded and according to the desired results. Fine sandpaper does not leave marks, but grade 80 or less can leave undesirable marks on ceilings or walls.
• If our straightener It does not come equipped with means to work in corners and confined places, let us always have a sheet of suitable sandpaper at hand to carry out the manual polishing of those sectors.
• Let’s avoid over-sanding and if it occurs in one spot, we simply fill it in with joint compound or plastic filler / putty / filler and then give it time to dry before sanding again.
• Let’s use a flashlight to sand each area effectively. Some manufacturers of straighteners They incorporate an LED light in the handle, as we see in the first figure of this article, which perfectly serves this purpose.

In conclusion, when faced with the task of having to sand a surface located in a complicated place, the best and most practical option is the use of a paper straightener.