Abstract: Tool chatter during a pipe threading operation is reduced by positioning a pipe end to be threaded alongside a threading tool, positioning a radially expandable mandrel inside of the pipe end, securing the mandrel by expansion, threading the pipe end with the threading tool, and removing the mandrel. A preferred mandrel comprises a housing, an elastomeric sleeve, a piston, and a cylinder head. The elastomeric sleeve covers the outside cylindrical surface of the housing. The device is filled with hydraulic fluid and the piston is actuated to expand the sleeve against the inside of the pipe. Vibrations from the cutting operation are absorbed by the hydraulic fluid after being transmitted into it via the elastomeric sleeve.