alright, I have been trying every post processor and setting I can find in bobcad, and it is not stopping the output of negative X values for the grooving tool. Actually, I am testing with the drills and the parting tool removed from Bobcad so I can just see what changes the grooving toolpath to positive x values.
I have now also tried all four tool orientation settings in Bobcad and they dont fix the problem. This makes no sense. They should change the front or rear toolpost positions at least, the way I look at it they should, but, its as if changing to the other three orientations does nothing (at least to the visual toolpath representation in mach)