I was running table surfacing program made in cut 2d which was about half way through when all of a sudden the gauntry stopped when it should be going in the x- direction paused, then when the Yaxis made its stepover the X continued in the X+ but thinking it was at X zero. Luckily I was standing there watching and stopped it from running off the tracks.( Note to self stop being lazy and hook up the dam estops!) Thinking this my have been just a fluke I re ran the program from the beginning after re-zeroing the X axis. However it seems it wasn't a fluke on the next run it did the exact same thing. Im not sure that it was in the exact same spot but if not it was dam close.
What could have caused this not only to happen but twice?
Some info on my machine. It was made with buildyourcnc electronics ie. ps, bob, driver, and steppers. It is a steel welded frame with with CNCRouterParts linear motion on all axis, R&P on X and Y, and Acme on the Z.