Actuators and methods for controlling tools

A cutting system comprising:

• a first motor operable to rotate a first threading extending in a first helical direction around an axis;
• a second motor operable to rotate a second threading axially spaced apart from the first threading and extending in a second helical direction opposite the first helical direction around the axis;
• a cutting tool comprising a shaft having a first mating threading extending in the first helical direction configured to mate with the first threading, and a second mating threading extending in the second helical direction configured to mate with the second threading;
• and
• a controller in communication with actuators for the first and second motors and linear actuators for controlling position of a workpiece relative to the cutting tool, and
• a memory coupled to the controller and configured to store data representing a series of movements of the cutting tool corresponding to a desired cut or series of cuts on the workpiece, the controller configured to control speed and direction of the first and second motors to effect a desired pattern of axial and rotational movement of the cutting tool while controlling movement of the workpiece relative to the cutting tool, including:
• a) moving the cutting tool in the first and second opposite axial directions, including withdrawing and advancing the tool to or from a resting location, to or from an axial base cutting location, or axially shifting the axial base cutting location;
• b) rotating the cutting tool;
• and
• c) creating a sawing motion of the tool, including while at the axial base location, while rotating the tool, or while axially shifting the axial base location.