Arduino CNC design. How to limit stepper motors?

Question

Arduino

There is an arduino CNC design. Everything works, I control the machine through the keyboard. But you need to stop the stepper motor at the edge. How to set coordinates or the like, how to stop??
https://www.dropbox.com/s/avnbx5kdr09thgn/IpMedZac... - photo

Answer 1

Count steps - you will have to regularly calibrate to a certain starting point, - the reference point will float away
In any case, at the edges there is a mechanical stop + sensors that cut off the installation