Confirm your rotary blades are balanced for smooth, vibration-free cutting. These balancers are often used after your blade hits something or is sharpened. Originally designed for lawn mower blades, you can use them with any high-speed rotary blade, such as circular saw and rotary tool blades, with a center hole. To inspect, simply place a blade onto the pointed spindle. If your blade tilts to one side, it’s not balanced.