Ever figure it out? Don't quote me on this but Im pretty sure should be able to run a 4th axis with a new breakout board. The one that shipped with my vortech had barely enough I/O to connect the minimum stuff. Matter of fact they had the Estop switch connect in series with an axis limit switch so that the machine would only run if the E stop was PRESSED. :-/ If you setup a new break out board you should be able to add a 4th axis without disconnecting anything.