Rotary cutting tool comprising two cutting portions having opposed cutting directions

A method of machining a workpiece, said method comprising:

• providing a rotary cutting tool with a first cutting portion including a plurality of first helical teeth having a helix direction, each of said first helical teeth having a first cutting edge oriented so as to cut in a first direction of rotation of the rotary cutting tool, said rotary cutting tool further comprising a second cutting portion offset from the first cutting portion and including a plurality of second helical teeth having said helix direction, such that said first and second helical teeth have a same helix direction, each of said second helical teeth having a second cutting edge oriented so as to cut in a second direction of rotation of the rotary cutting tool, wherein said second direction of rotation is opposed to said first direction of rotation;
• mounting said rotary cutting tool on a machine tool with a sleeve;
• performing a first machining step on said workpiece with said first cutting portion by cutting said workpiece with said first helical teeth along said first direction of rotation;
• and
• performing a second machining step on said workpiece with said second cutting portion of the rotary cutting tool by cutting said workpiece with said second helical teeth along said second direction of rotation,
• wherein said first and second machining steps are performed successively while keeping said rotary cutting tool mounted on the machine tool.