Until a while ago, air conditioning and / or heating installers, electricians, technicians from telephone or cable TV companies, plumbers and many other professionals whose job involves the frequent opening of slots or channels in walls did not have alternative tools to perform that task.
Only a suitable chisel and hammer were the commonly used items for decades and are still very popular when it comes to small jobs, or on soft surfaces and / or in hard-to-reach places such as wall corners. However, when the walls are covered with more resistant materials or when the task becomes voluminous and / or systematic, these hand tools become impractical from every point of view.
To this end, power tools such as an angle grinder equipped with diamond masonry discs, or a rotary hammer with suitable chisels can cut channels in the walls much more quickly and comfortably. However, these tools generally present a problem: the significant production of dust, which not only can form a fog making it difficult to see the work area, but can also spread to the entire room, if it is interior spaces, and generate harmful effects on the health of the user.
Fortunately, modern technology has advanced with the development and commercialization of a power tool specially designed for making grooves and channels in walls of any type. That is why in this article we will present the grooving machine or, as it is known in Spain, the strawberry chaser.
Function and main components
Basically a grooving machine is similar to a angle grinder, but it presents two fundamental differences:
one. It is equipped with a different cutting system, which allows the simultaneous mounting of two discs, generally with a variable number of spacers between them, to create a pair of slits parallel to each other and spaced at will of the user. The spacers are offered in sets of washers, usually six, which depending on the manufacturer may or may not be the same width. In the following figure we see a typical diagram of the mounting unit of the discs and spacers.
two. It includes a displacement system, which allows the tool to slide with great precision on a wall, cutting the indentations to the desired depth and facilitating, at the same time, the extraction of dust through a dedicated port.
These two characteristics, added, in fact, to the system to extract the dust is what makes the grooving machine into the ideal power tool that vastly outperforms a angle grinder (since it can double or even triple productivity) to make grooves in brick or plaster walls.
Since the dust removal system is a key feature for the benefits offered by a grooving machine, it is important to determine which type of vacuum cleaner is the most convenient to use. For example, if we are working on a drywall wall, the dust generated will quickly clog the filter of any household vacuum cleaner equipped with that element. For this reason, some type of cyclonic aspiration is generally preferred, such as that provided by a cyclonic vacuum cleaner, or the ash vacuums used for cleaning chimneys, ovens and grills, specially designed for very fine dust particles (see figure down).
On the other hand, chip collectors used in woodworking shops are usually not suitable for this case, since they often do not provide adequate filtration and do not work properly with the small bore hoses used by a grooving machine.
The figure below presents a typical model of grooving machine with its most common parts.
- Main handle
- Additional handle
- Protection cover
- Depth stop
- Depth gauge lock lever
- Suction adapter
- Cutting disc
How to use a grooving machine
In addition to observing the safety precautions detailed below, the proper use of a grooving machine It involves following a series of steps that we can summarize as follows.
Step 1: With a pencil or other element we clearly mark the channel that we want to open on the wall.
Step 2: With a wall scanner we examine the entire marked surface to make sure that there are no pipes or cables already embedded and that we could damage when opening the channel.
Step 3: We establish in the grooving machine the width of the channel we want to open. On most models, this includes removing the discs and changing the order of both the discs and the spacers. The more spacers between the discs, the wider the cut will be.
Step 4: We select the depth of cut. Generally this is accomplished by moving the depth gauge lock lever (see figure above) to set the depth gauge. The greater the depth chosen, the more the protective cover discs will protrude.
Step 5: We connect the tool to the vacuum cleaner that we have chosen. Although the use of dust extraction is not mandatory, it is in fact highly recommended, even for making small channels.
Step 6: We begin the cutting work, following the following guidelines:
- First we turn on the dust extractor and then the grooving machine. We support the grooving machine on the wall and begin to slide it through the marks previously made. The rollers or wheels of the displacement system that the tool has make it easy to travel along the wall in a fairly straight line.
- We must take into account that, depending on the material of the wall and the depth of the cut, the grooving machines they can be very fast. For example, a channel in a plaster wall, from the ceiling to the middle of the wall can be done in less than 10 seconds. The important thing is to take care of the speed so as not to exceed it and, therefore, not to cause premature wear of the blades and of the tool itself.
- It is also important to consider that the discs of the grooving machine They make the cut on the edges of the canal, that is, on the marks that we previously made in Step 1. Therefore, afterwards we will have to remove the remaining wall fillet with some other instrument.
Step 7: When we finished the channel, we turned off the grooving machine and we remove it from the wall. If it is plaster, we can remove the fillet with a wide and thin chisel that electricians use, for example. To do this, we place the chisel in one of the grooves and slide it to the side, prying to remove the fillet. This way we will tear off a good piece of the fillet, leaving a very neat channel with clean edges. If it is a more resistant material, we can use a narrower chisel with a drill.
The grooving machines They are fast tools that handle cutting discs; therefore, they are dangerous and caution should always be exercised during their use. In addition to the usual safety measures applicable to all electric tools and those recommended by the manufacturer, in the case of a grooving machine We must respect other additional measures that particularly concern the use of cutting discs.
- First of all, wear personal protective equipment: dust mask, ear protectors, gloves and apron that can stop small abrasive or wall fragments being thrown. Eye protection must be able to stop the fired debris that is generated in different operations. The dust mask or respirator must be capable of filtering the particles generated in the operation performed. Prolonged exposure to high intensity noise can cause hearing loss; hence hearing protection is essential.
- We should always use diamond blades and never use them from the side, as they are designed for peripheral cutting and could disintegrate if lateral forces are applied to them.
- The specified speed of the cut-off wheel must be at least equal to the maximum speed indicated on the tool. Discs used above their specified speed may break and be thrown.
- Always use disc flanges that are not damaged and that are the correct size for the selected disc, since only in this way do they properly hold the discs and prevent their breakage.
- The hole size of the discs and flanges should fit properly on the tool shaft; otherwise they will become unbalanced, vibrate excessively and may cause loss of control.
- Never use damaged discs. Therefore, before use, we must inspect them for nicks or cracks. If we don’t find any visible defects, we can run the tool at full speed with no load for one minute. Normally, damaged discs will break during this test time.
- Be very careful with kickback (sudden reaction that occurs when the blade disc becomes trapped or stuck) and other related hazards, which generally occur when the tool is misused. In order to avoid the sharp setback, we must proceed as follows:
- Keep a firm grip on the tool, positioning your body and arm to resist the forces of sharp kickback. Let’s make good use of the auxiliary handle, if provided, to have maximum control over the sharp kickback or twisting reaction produced during start-up.
- Never align our body with the cutting disc, since at the point of jamming the abrupt recoil will propel the tool in the opposite direction to the movement of the disc.
- Be extremely careful when working on sharp corners or edges, as they tend to jam the disc and cause loss of control or sudden kickback.
- Do not use saw chains, wood carving wheels, segmented diamond blades with a clearance greater than 10mm, or serrated saw blades, all of which create kickbacks and loss of control.
Advances in Grooving Technology
The main advances that today the technology of the design of the grooving machines They target a number of vital factors, such as minimizing the amount of dust generated, as well as greater versatility and productivity.
Attentive to this, some manufacturers have designed models of grooving machines that replace diamond discs with burs, generally disc burs. This practically eliminates the formation of dust and, therefore, the use of vacuum cleaners, since the cutters rotate at a slower speed than diamond discs and therefore do not polish the material, but instead granulate it.
The use of burs also allows channeling in materials such as solid brick and cement, in which diamond blades are generally not appropriate. In addition, it is possible to open vertical, horizontal, oblique, flush with the floor and even curved channels, which opens up new possibilities for optimal productivity.
However, the technology of grooving machines Based on mills raises the cost of the tool and its accessories, so the user will have to carefully evaluate the type and frequency of use to decide whether this new technology will ultimately pay off the expense.
In a future article we will provide some considerations that will help us acquire a grooving machine with diamond blades capable of fully satisfying our needs.