I have been using mach3 and the maxnc15 for over a year - 2D cutting with no problems. I am beginning to experiment 3d cutting with cut3d. My problem is - my maxnc seems to loose track of 0 height on the z axis. All other axis' seem to be fine, but the z axis seems to go too deep after a while. If I stop the program, and return the cutter to 0, mach3 says it is at 0, but my bit is below my original 0 surface. It starts out fine, and cuts fine for a while, then seems like it looses track of itself. Any suggestions?