I have a Hardinge SV200 CNC Lathe equipped with a Fanuc SV control. I have six months using this machine without a problem until yesterday. I notice that when I was running a program, all of a sudden the machine added or substracted 0.394" randomly on the Z axis. I started doing some testing and notice that every time I did the zero reference return, the machine stopped in a 0.0001 coordinate or in a 0.394 coordinate. This way it didn't matter how often I adjust my Z tool offset, this kept changing randomly. I don't know how to fix it and I would definetly appreciate any help.
Update: I was able to fix it. Luckily I had an extra limit switch for the Z axis, I change it and problem solved. Still, here is a link to a video showing the problem I was having.
I hope this helps someone else.