Hi,
you need to reference your machine, that is go to a particular location, repeatably, on each occasion you fire Mach up.
When you first turn on Mach doesn't know where it is UNLESS you tell it, usually specifying that location as 0,0,0. Note
these are machince co-ordinates. Mach does a very good job of tracking where it is at any given moment from that starting point
but you do have to tell it where the start is.
If you confirm the start position then you can tell Mach 'the left hand boundary is 9.5 inches to the left of 0,0,0' and likewise other
boundaries. Boundaries make no sense unless the machine has been referenced.
You may be able to wangle a way of using your limit switches to signal a location but I would recommend independent home switches.
They need to be good quality microswitches or similar to repeatably and accurately reference your machine. Does your controller have
spare inputs? Three would be ideal....you can combine them into one circuit with one input pin but one input per switch is preferred.
Craig