Some more food for thought - For arguments sake, your machine is all set up and homing limits work and your soft limits work. You hit Ref Home, your machine moves all axis to its home position, again for arguments sake X-0,Y-0 and Z-0, if you decide to move say the X axis past the limit switch, if it is all set up correctly, there is a limiting speed factor built into the set up that will only allow the axis to move at that speed, say 20% of normal operational speed, this will give you time to think and see that if you keep your finger on the jog button it will reach a solid stop, now at 20% speed this will not cause much, if any damage, most it will do is cause the motor to stall, but hopefully the operator will notice this and stop before this happens. Also some folks add a second limit switch after the homing switch to prevent this from happening, also the limits are normally an inch or so from the end of travel to allow for any unexpected failures, i.e. E stop can be pressed before failure occurs. Again this is all documented in the manual. You can also add limit switches on the other end of axis travel and this will give a further measure of protection over and above the soft limit set up. Again all documented.