Downhole machining system and method

A downhole machining system for machining a casing in a borehole in a well having a top, comprising:

• a first tool part having an axial extension and an anchoring section to fix the first tool part relative to the casing,
• a second tool part adapted to rotate and move axially in relation to the first tool part, the second tool part comprising a machining bit which is movable in a direction radial in relation to the axial extension,
• a first actuator comprising an electrical motor for axially moving the second tool part in relation to the first tool part,
• a second actuator comprising an electrical motor for rotating the second tool part in relation to the first tool part, and
• a third actuator comprising an electrical motor for rotating the bit,
• wherein at least one of the first, second and third actuators comprises a gear for changing a rotational speed of a rotor of the motor, wherein the bit is moved radially in a bit housing, the bit has a sharp end facing the casing and a piston end, and the bit is moved radially in relation to the axial extension via an electrical motor driving a hydraulic cylinder which is in fluid communication with the bit housing pressing onto the piston end.