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Planetary Grinder vs. Rotary Grinder: Which is Best for You?

When you're newer to the concrete floor game, various tool options can be confusing and overwhelming. It can take some time to get used to your workflow and learn what techniques work best for your business.

In general, there are some hard and fast rules for which tools to use in certain situations. Concrete floor grinders are the key to success, but there are so many options for sizes, discs, blades, and more.

In this guide, you'll learn the features of a planetary grinder vs. a rotary grinder and how each one should be used. That way, you can decide which one to buy for your next project.


Types of Grinders

Concrete floor grinders come in many different categories. There are handheld grinders that are compact and portable, used mainly for tight spaces and light jobs. Then, there are walk-behind grinders that are moderately sized and pack a good punch.

There are also ride-on grinders, which are best for massive projects that require covering a large area as quickly as possible.

The most popular category of concrete floor grinders is walk-behind grinders because of their moderate size, power, and ability to link together for larger jobs. Contractors that focus on residential projects and moderately-sized commercial projects rely on these, while contractors who work on malls, corporate buildings, and factories require ride-on models.

When you're choosing a concrete grinder, you aren't just thinking about the size of the project. You also need to consider the condition of the concrete you're working on. 

A new concrete floor covered in mastic will require a different tool than a new old concrete floor. This means you also need to consider power and weight. You'll also want to think about dust control options and disc options. 

Rotary grinders and planetary grinders have different gearbox and disc configurations, which changes their efficiency and success with different types of projects.

Rotary Grinder Features

Rotary grinders have a fixed gearbox that does not rotate with the discs. There are several discs attached to the gearbox that rotate to grind the concrete. These discs are all on the same plane, so they make contact with the concrete floor together.

Planetary Grinder Features

A planetary grinder differs from a rotary grinder because the gearbox moves as well. The discs attached to the gearbox also move but at a different speed and direction than the gearbox. The gearbox doesn't make contact with the floor. It spins to benefit the movement of the discs on the floor.


Planetary Grinder vs. Rotary Grinder

The movement of the gearbox on these grinders makes the difference in the type of job that is accomplished. Under the same power and conditions, these grinders perform very differently. 

Rotary grinders gain more stability from their fixed gearbox, while planetary grinders can shake badly on the uneven ground due to their moving gearbox. Because planetary grinders also have discs that move at a different speed than their gearboxes, going at a higher rate of speed than 1200 rpm/min can cause the machine to favor one direction.

Rotary grinders can be heavier than planetary grinders, making them harder to transport and maneuver. Planetary concrete grinders are much lighter and more flexible and are often favored for portability. 

However, many rotary grinders now come with removable weights that can make them heavier or lighter according to the type of job. This can help when a tougher job requires more power because adding weight can increase the grinding power of the rotary grinder.

Uses For Planetary Grinders

Planetary grinders are much easier to be trained on because they have an ease of use that the rotary grinder lacks. Because they are lightweight and flexible, they are great for lighter jobs.

The best uses for planetary grinders are jobs where less power is needed to achieve a polished finish. You might want to use them for softer concrete and polishing jobs.

If you need to prepare a garage floor for an epoxy coating, a planetary grinder is the way to go. If you just need to smooth out a concrete floor, these machines are perfect.

Benefits of Rotary Grinders

Rotary grinders are your powerhouse machines. You should choose these machines if you have jobs that require aggressive grinding. They are already heavy-weight machines, and you can add or remove weight based on the job or if you encounter an extra tough spot.

Because of their weight, you can achieve a higher rate of rotational speed for the discs without losing control of the machine. This speed and weight make a rotary grinder the perfect choice for removing tough materials like mastic and thick paint. However, it is advisable that more skilled operators take charge of these machines.

When operated by an experienced employee, rotary grinders can provide a superior polish on a concrete floor like no other machine.

Final Thoughts

With all things considered, you can really accomplish most jobs with either a rotary grinder or a planetary grinder. Machines are so flexible now that they come with several solutions that allow you to modify them for different jobs.

For example, getting a model that has removable weights can help with flexibility. Additionally, you should pay attention to buying the right concrete diamonds and attachments like vacuums or water supplies.

It comes down to skill level and preference. If you're dealing with a lot of tough jobs and are confident in your experience, then a rotary grinder may pack the punch that you need. If you're just getting started and want to take it easy, planetary grinders may be for you.

Ace Your Next Project

Onfloor Technologies supplies contractors with all the tools they need to be successful at every job. If you're on the market for a new concrete floor grinder, check out our online store to compare models and prices.

Still battling out the planetary grinder vs. rotary grinder question? Why not try both? Shop our floor grinders today.

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