An Introduction to Hand-Held Concrete Grinders

A hand-held concrete grinder has a wide range of applications, from renovation work, to leveling and remediation, as well as supplementing the work of a large, walk-behind floor grinder, since the hand-held tool can easily grind edges, corners, and other hard-to-reach areas, leaving the walk-behind grinder to handle the large areas. A well-designed concrete grinder will make a difficult job much easier. Although there are a lot of budget concrete grinders on the market, these are simply metalworking angle grinders with a diamond cup wheel mounted. Those do not have the important features and characteristics that make purpose-built concrete grinders such as the AGP machines so effective.  

Applications

Concrete grinders have many uses for tasks in renovation of old construction, such as grinding off old screed, plaster, grout, or concrete. They are also great for grinding off crests and generally levelling uneven concrete surfaces. This grinding operation may be needed for any number of reasons, such as preparation for painting or for repair of damage, etc.

Types of Cup Wheels

There are three main types of cup wheels available to be used for specific tasks. Cup wheels for grinding hard concrete will have diamond segments designed for this purpose with softer bond, allowing more aggressive diamond exposure. These diamond segments will stay sharp grinding hard surfaces but will not last as long. Cup wheels for grinding abrasive materials such as soft concrete, screed, tile mortar, etc. will have diamond segments made to resist the abrasiveness of the work material, thus lasting longer. PCD cup wheels are suited to aggressively scraping away adhesives and soft coatings such as bitumen and elastomeric roof coating without smearing, leaving behind a rough surface.

Dust Containment

Since these tools are grinding dry, dust containment is very important because of the dangers of exposure to silica.  Therefore, the dust skirt must be as effective as possible. The dust skirt also provides the additional function of keeping the cup wheel properly aligned to the surface. Therefore, it needs to have the ability conform to the surface shape by way of a spring suspension. In addition, to allow grinding up to the edge, the skirt needs to have a half-moon door which can be temporarily opened, but this door should be kept closed at all other times.

Constant speed

Since the grinding of vastly different surfaces is possible, it is important that the rotation speed may be adjusted to best suit the application. In addition, having constant speed electronics allows the set rotation speed to be kept consistent during operation, which will result in a much more even surface. Unlike most of the concrete grinders in the market, AGP grinders are all equipped with variable constant speed.

How to Choose Your Concrete Grinder?

AGP has a full line of concrete grinders and so one can find the exact tool needed for the job. There are 3 main criteria for choosing a concrete grinder: handle style, cup wheel size, and motor type.

Handle designs

There are 2 main handle designs: angle style, and vertical style. It is a matter of operator preference which type to use. The technique employed with either involves a light touch, with the operator guiding the tool quickly over the surface to grind a small depth at a time. The vertical style, such as used on the G5, G7, and BG5 models, puts the weight of the motor directly over the cup wheel, making them especially suited to grinding horizontal surfaces like floors. These are also suitable to be used with the floor grinding trolley. The angle style, such as used on the G125, G180, and BG125 is more general purpose and works well in a variety of situations.

Cup wheel size

The most common sizes for cup wheels are 125 mm (5”) and 180 mm (7”). 125mm usually have a wider variety of consumables available and tend to be more economical. 180mm, such as the G7 and G180, are more suited to grinding larger areas.

Motor type

Universal motors use the conventional carbon brush design used in most power tools. These motors offer good power-to-weight ratio, simplicity, reliability, and economy of operation. The motor’s carbon brushes are a wearing part and thus maintenance involves replacing them when worn. Brushless high-frequency motors, such as used on the BG5 and BG125, have the advantage of having much higher efficiency and thus output, as well as not needing to replace brushes, thus making them virtually maintenance-free. Although their initial cost is much higher, they tend to last many times longer than universal motors, have higher efficiency, and have a higher ingress protection rating.

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