The Roomba comes with a tool that easily cuts the threads from the rollers. It's a plastic tool, with claws on one side and a hidden razor blade on the other. You slide the razor blade down the brushes once, and then use the claw side to make quick work of removing the threads. Of course, I've never used mine. My quilting room never has threads on the floor. (cough, cough... gasp, coughing more)