Why is counter-clockwise "forward" when a workpiece is being cut on a CNC lathe?

Question

I was at work, and a co-worker told me for "homework" to come in at tell him why that when using a CNC lathe, when the piece is being cut, that counter-clockwise is "forward" and that clockwise is "reverse".

I think it has something to do with the placement of the cutting tools, but i don't know much about the CNC lathe, and I'm learning as much as I can about it before I go off to college.

Answer 1

It probably has to do with the way the chuck is attached to the driving mechanism and/or the direction the clamps on the workpiece in the chuck is rotated.  Cutting forward puts a torque in the same direction as the chuck and/or clamp so, the piece will not loosen, nor will the chuck itself loosen from the driving mechanism.

For cutting "in" (reverse) the cutting torque is in a direction that would tend to unscrew either the clamp or the whole chuck from the driving mechanism so, there is a small chance either the piece might come loose in the clamp, or the chuck itself might unscrew.  If that happens the force on the cutting tool is 'in' toward the chuck so, the piece won't fly  out, it will just stay in-place.

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Answer 2

That is because your cutting tool is on YOUR side and in order to cut anything you must rotate the workpiece counterclockwise. I hope this helps you - lifelong Lathe operator- when cutting on the other side of the workpiece your tool has to go in upside down