Stop Print Crashed into Purge Block
I had a MMU 2.0 test print detach, so I selected "Stop Print" from the menu, and the hot end crashed into the purge block. Judging by the amount of grinding, I think it was trying to get to the "home" Z height.
I have used this feature to stop a lot of prints before the MMU 2.0 upgrade/firmware and the Z axis has always gone up, but it went straight down this time.
Debugging info:
Printer: Prusa i3 MK2S, MK2.5 upgrade, MMU 2.0 upgrade
Printer firmware: 3.4.2
MMU 2.0 firmware: 1.0.2
Other deviations from the norm:
The extruder cables are blocking the extruder block from triggering the X axis end stop button. I am currently working on fixing this. I have ran into this issue in the past, but I was usually able to squeeze the cables to get an extra millimeter of clearance. I am about to add 3mm of PETG to the part that is supposed to press the button to fix it permanently.
The line of filament that gets laid down in the negative Y axis before a print crashed into the end stop of the X axis. At the time I wasn't worried about it, because I normally can't use the rightmost ~3mm of my print area anyway due to the same fat cabling issue as the left side has. In my experience, if this happens at the beginning and doesn't get too close to either side of the X axis during the print it will be fine. Thinking back on the amount of grinding, it was probably trying to go 20+ mm outside of the printer's maximum width. My fat cabling problem would only account for ~ 4mm.
Once the actual print started everything worked fine for about 3.5 hours before I needed to stop the print. No layer skipping or shifting occurred. I will try to eliminate some of the variables and post an update.
Re: Stop Print Crashed into Purge Block
I added a 3mm extension to the X axis end stop. The extruder still crashed into the right side while priming the extruder, but using the "Stop Print" function while printing into the purge block did not cause the extruder to crash into the purge block.
It seems unlikely that the X axis calibration was the problem. I suspect that I stopped the print during a different phase (like while the MMU was swapping filaments) and that was the difference. I don't have a reason to test this anymore.
Re: Stop Print Crashed into Purge Block
I reduced the width of my bed to 240mm in Slic3r and the priming phase no longer runs into the right side of the X axis.
Re: Stop Print Crashed into Purge Block
The extruder still crashed into the right side while priming the extruder, but using the "Stop Print" function while printing into the purge block did not cause the extruder to crash into the purge block.