If you’re using a rotary machine to grind or polish a concrete floor, you may be surprised to see the manufacturer recommends maneuvering the machine in a side-to-side motion rather than straight forward. This action is more commonly seen with floor burnishers and buffing machines, but it’s necessary for rotary floor grinders, too. To help you get the best results, we’re breaking down why the rotary machines have to swing side-to-side and how to perform an s-curve.

How Do Rotary Grinders Work?

While planetary grinders use belts and pulleys to move the discs, rotary grinders utilize geared construction. In a rotary floor grinder, there may be two, four, or eight heads that are rotating from a fixed position and only one or two large discs that rotate and directly grind the floor. Other styles may have smaller discs that are on one plane or overlapping planes.

As each head rotates, the center of the cutting pattern is continually overlapping. If you are to move in a straight forward path, there will be clear lines and rows in the surface. On the other hand, if you swing the machine from one side to the next, the machine will make passes in different locations, so there’s no double cut and the scratch pattern is more feathered and subtle. This sideways motion creates an “S-Curve” in the path.

Benefits of a Rotary Machine

Rotary grinders are generally a lot heavier than the planetary style grinders, so they can be used for more intensive, heavy-duty tasks, like removing thick coatings, layers of paint, or to polish a floor more quickly. However, the heaviness doesn’t fatigue the operator because the grinding heads rotate in opposite reactions and makes it easy to operate. The user may need a bit more of a learning curve in order to get the best results, but once they are familiar, they’ll find it as easy to operate and less exhausting than a planetary option.

How to Perform an S-Curve

The only time you can use your rotary machine in a straight line is when you are polishing against a wall or barrier. Then, you have to operate the machine in a straight line that’s parallel to the edge as you move forward. When you move out from the wall, you have to walk backwards and implementing the s-curve method.

If you’ve never used a rotary grinder, you may think the s-curve involves swinging the machine from one side to the next is creating a wide arc, but that’s actually not the case. The machine is simply moved side to side at around a 20 degree angle from the right and left side of the cutting path as you move forward or backwards. It’s very fluid, yet controlled motion.

Find the Right Rotary Machine for Your Next Project

If you would like to see if a rotary grinder is right for you or learn more about our selection of equipment, reach out to a member of our customer service team today at (815) 278-1308 or by filling out our contact form to get started!