I make my g code in sheetcam.  Basic shapes right now....I'm just getting started.  Occasionally, right when my torch fires on my plasma, the motor torques go to zero, the torch arc turns off, the fault light comes on on the back of my Gecko driver.  Mach 3 still thinks that I am moving along the path....  I can hit "feed hold" and catch it quick enough to cycle the power on the CNC controller.  Sometimes the torch fires and it will cut the remainder of the path.  Other times the arc immediately dies and the fault light comes back on.  It only happens immediately when the torch fires or if my path goes off of the sheet of metal (which makes sense because it cannot complete the electrical circuit).

Any thoughts?  Is it my starting Z height?  Thanks,

Sounds like your picking up some wicked bad noise, EMF.  I think you will need to do some shielding.

http://www.machsupport.com/forum/index.php/topic,23827.msg167896.html#msg167896

Brett

Thanks,  I'll check that out!