A machine tool for machining a workpiece, comprising: a machine base; a workpiece holder supported by the machine base for holding a workpiece, the holder being rotatable about an axis; a workpiece rotary drive (M W) for rotating the holder about the axis; a tool mount supported by the machine base for carrying a tool to be engaged with a workpiece held in the holder; a drive arrangement for moving the workpiece holder and the tool mount relative to each other in a plane which is transverse with respect to the axis, by moving at least one of the workpiece holder and the tool mount relative to the machine base; and a control arrangement configured to control the workpiece rotary drive and the drive arrangement so as to carry out first and second discrete machining operations, wherein a surface profile is machined on the workpiece in the second machining operation which is non-equidistant from the axis in a plane which is transverse with respect to the axis, wherein the axis is a longitudinal axis of the machine tool, the tool mount is movable in a plane which is transverse with respect to the axis, the drive arrangement comprises a tool mount drive for imparting the transverse movement to the tool mount, and the control arrangement is configured to control the workpiece rotary drive (M W) and the tool mount drive so as to machine the surface profile on the workpiece, characterised in that a tool mounted in the mount and the workpiece are moved clear of each other by the drive arrangement after the first machining operation and then brought back into engagement to commence the second machining operation whilst the workpiece is being rotated continuously by the workpiece drive, the control arrangement is configured to bring a tool carried by the tool mount into engagement with a workpiece held by the holder to commence the second machining operation when the point of contact on the workpiece is accelerating away from the tool mount, and the control arrangement is configured to accelerate the tool mount towards the point of contact on the workpiece until the component of the velocity of the tool mount in a direction towards the point of contact is greater than the velocity of the workpiece in that direction, and then to decelerate the tool mount in that direction such that it matches the velocity and acceleration of the workpiece in that direction as it engages the workpiece. a machine base; a workpiece holder supported by the machine base for holding a workpiece, the holder being rotatable about an axis; a workpiece rotary drive (M W) for rotating the holder about the axis; a tool mount supported by the machine base for carrying a tool to be engaged with a workpiece held in the holder; a drive arrangement for moving the workpiece holder and the tool mount relative to each other in a plane which is transverse with respect to the axis, by moving at least one of the workpiece holder and the tool mount relative to the machine base; and a control arrangement configured to control the workpiece rotary drive and the drive arrangement so as to carry out first and second discrete machining operations, wherein a surface profile is machined on the workpiece in the second machining operation which is non-equidistant from the axis in a plane which is transverse with respect to the axis, wherein the axis is a longitudinal axis of the machine tool, the tool mount is movable in a plane which is transverse with respect to the axis, the drive arrangement comprises a tool mount drive for imparting the transverse movement to the tool mount, and the control arrangement is configured to control the workpiece rotary drive (M W) and the tool mount drive so as to machine the surface profile on the workpiece, characterised in that a tool mounted in the mount and the workpiece are moved clear of each other by the drive arrangement after the first machining operation and then brought back into engagement to commence the second machining operation whilst the workpiece is being rotated continuously by the workpiece drive, the control arrangement is configured to bring a tool carried by the tool mount into engagement with a workpiece held by the holder to commence the second machining operation when the point of contact on the workpiece is accelerating away from the tool mount, and the control arrangement is configured to accelerate the tool mount towards the point of contact on the workpiece until the component of the velocity of the tool mount in a direction towards the point of contact is greater than the velocity of the workpiece in that direction, and then to decelerate the tool mount in that direction such that it matches the velocity and acceleration of the workpiece in that direction as it engages the workpiece.