A tool called a spinner is interposed between a rotary driver and a flexible shaft that is being rotated and moved axially when a duct or chimney is being cleaned by a whip head at the end of the shaft. A tubular shape collar has a home position on the body of the spinner. Grasping and holding the collar at its home position, while the driver rotates, helps steady the driver as the body moves within the collar. To dampen oscillation of the shaft, the collar is moved lengthwise from the body, and along the shaft to a working position where it is held manually. The collar is retained on the body by frictional means. A user can overcome the retaining force and, without using a second tool, slide the collar off the body and along the shaft to the working position, while the spinner is rotating or stationary.