A device that forms smooth cylindrical surfaces along a log being moved longitudinally past a cutting station. The device includes a feed conveyor that moves successive logs longitudinally past a cutting station. A planetary cutting head drive is situated at the cutting station. The drive rotates a cutting head about a first planetary axis spaced from the log axis. It also revolves the cutting head about a stationary second axis that is coaxial with the log axis. A smooth cylindrical cut is thus made about the periphery of the log as it is moved longitudinally parallel to its axis.