Concrete grinders are a very handy tool that can perform a range of grinding, polishing and surface removal tasks.
Furthermore, whether you are using a handheld machine, or walk-behind grinder, the principle action is much the same; both tools use rotary action rather than impact to remove material.
This leads to a smoother finish, which is perfect for preparing or polishing the surface depending on the disc attachment you are using.
How to use a walk behind concrete grinder
The video above is a good introduction to using a walk behind grinder.
It is worth remembering that walk-behind models differ in speed and power when compared to a handheld machine.
There is also a range of options available. For instance, single-disc models are suitable for working in small or restricted areas.
For larger, (normally commercial) jobs, the walk-behind grinder comes in dual, triple and even four-disc configurations, meaning more surface can be covered in less amount of time.
How to use a handheld Concrete Grinder
As demonstrated in the video above, smaller, handheld machines are excellent for home projects as well as industrial work where space is tight.
The grinding diameters normally ranges between 5 to 12 inches, which also makes them the top choice for use on concrete countertops.
As with the walk-behind models, handheld tools have a wide range of disc attachment options. They can also be hooked up to an industrial Vac for better dust control on the job.
Concrete Grinder Disc Attachments
Essentially, the more you invest in attachment options the greater versatility you will have when using your tool.
The three most common grinding disc attachments you will come across are as follows:
- silicon-carbide grinding stones,
- tungsten-carbide inserts,
- and diamond-segmented grinding tools.
Choosing which attachment to use is completely dependent on the material and finish you wish to achieve. Let’s take a closer look at the functionality of each.
Silicon-carbide stones come in various grits for coarse or fine polishing. They are a cost effective way of smoothing out imperfections in the surface.
That being said, silicon-carbide stones can clog very easily as you work. This can prove very frustrating on commercial jobs, as the stones are inefficient at removing surfaces over a large area.
Tungsten-carbide inserts are more expensive to buy than silicon carbide stones, however they do remove surface coatings with greater speed and efficiency.
The inserts feature carbide-tipped blocks. These are designed with beveled edges so that they are able to strip thicker coatings without scratching the concrete. (note: the inserts are best used on materials thicker than 1/16 inch)
The main uses for tungsten-carbide inserts includes removing adhesives from surfaces, scraping through layers of paints, resins and tar.
Diamond-segmented abrasives are best used for profiling work and removal of thin-film coatings. This more delicate approach also lends itself to fine polishing and the removal of small surface imperfections.
During the grinding process the abrasive gradually wears away to expose new diamonds beneath.
As with the aforementioned attachments, diamond-segmented abrasives come in various grit levels, ranging from fine to coarse. You can also pick up different bond hardnesses with varying diamond concentrations to suit the surface you are working on.
When attempting to choose which add-on it is recommended that you discuss your needs with the workshop owner. With the correct advice you will be able to match the correct attachment to the job at hand.
- Related Content: Buying the best concrete grinder (Top picks for 2017)
Top tips for better grinding results
Know the limits of your hand-held grinder
It is good practice to remember that hand-held grinders aren’t designed for aggressive profiling jobs. In fact, no matter the attachment you use, there will be some types of coating that your grinder will not be able to remove.
The best use of a hand-held grinder is for the removal of thin coatings and paints, as well as cleaning and minor surface imperfections.
A handy tip on knowing what blade attachment to use
When choosing which attachment to use, (i.e carbide or diamond abrasives for instance) the main issues to consider are the type and thickness of the surface material, and where applicable the strength of the bond if you are removing material.
A good rule of thumb to determine this is as follows: If the material to be removed can be cut with a knife, use a tungsten carbide attachment. And as we mentioned above, a diamond segment should be used on thinner coatings no more than 1/16 inch thick.
Ballast weights with walk-behind machines
When using a walk-behind grinder you should consider the weight of the machine and the impact it can have on the grinding process.
Heavier units place more weight on the discs which leads to greater traction with the ground, the end result being faster and deeper grinding.
To achieve the same with a lighter machine you can always opt for ballast weights; these will create better contact with the ground and are ideal for tougher surface removal jobs
How to select the correct bond hardness
Finally, if the diamond abrasive is the correct attachment for the job, you can determine the correct bond hardness by once again analyzing the surface.
When faced with soft materials, use a hard bond. When grinding hard materials opt for a soft bond. This is because softer materials will wear away at the matrix and the different layers of diamond much more quickly.
Image Credits: Bosch.com