Please see the discussion here FluidNC running 2d Contour too high - #13 by CesarH Maybe this is a post processor issue. I am using Beta 3. When doing 2d contour FluidNC seems to put the bit too high by the thickness of my stock. Everything looks OK in Fusion when running the simulation. I have the hobbyist version. When I put a G92 Z5.0 (thickness of my stock) at the top of the gcode, it worked.