Abstract: The combination of a rotary tool and a drive therefor, the tool having a conical taper between 60.degree. and 120.degree. to chamfer or remove burrs from machined workpieces. The tool comprises a casing containing a motor for rotating the tool, the motor having a drive shaft connected for rotation to the tool, and the tool having a shaft coaxial with the drive shaft. The drive shaft and the tool shaft are elastically connected for axial sliding movement of the tool shaft relative to the drive shaft against a force urging the tool shaft in a direction away from the drive shaft. The drive shaft is splined, and the tool shaft has thereon a splined member surrounding and engaging with the splines of the drive shaft.