I think I need to explain this better:
In CM4 you only get the choice of SO3, SO3XL, or SO3XXL for configuration. In my case X of 830 crashes the gantry because my dust boot is slightly wider than the Z plate:
So I went to the MDI window and set X at 800 using $130=800
I then verified this in the log using $$:
And X is indeed set to 800:
Then I try to rapid position using CM4 and Crash!!!
Then I look at the actual position in CM4 and it shows 815 (I hit my Estop button so as not to kill my belt, don't know if it would have gone further):
I am still a newbie, but this suggests to me that even though the machine knows it has limits, CM4 does not know when to stop and/or it still thinks the bed is wider than it is? Or maybe I lost the plot and just need a nap?