Setting Z Height on Rostock Max v2 has weird behavior

[RobertM]

When homing with the option under the Advance Settings the cheap skates correctly move to the top, tap the end stops and settle, I then move to the menu to manuall decend the hotend with the turn knob, slowly but surely I reach the bottom and find my new Z=0 point. I back to the previous menu and hit 'Set new Z=0'. At this point I move up the menu to Home again and while it's in transit I jump back in to the menu that shows the Z value and it reads a number much higher than expect, something around 550mm, the real travel distance should be something like 390mm. When the cheap skates get to the limit switches they stop, as usual, and then the Z value pops back to a value that I'd expect (~390mm). This behavior seems odd, but doesn't cause me any issues.

The problem I've run in to twice (in about 4 days) is that sometimes after a Home (one time it happened with MatterControl and the other from the LCD) the Z value reads the 550mm number, trying to then lower the hotend manually (either in MC or the LCD) it sits there and sounds like its just grinding, I can flick the endstops to make it stop. If I give it a move that will move it back in to the print area (like G1 Z200 F3000) it moves correctly and doesn't grind (I enter this thru the MC terminal). I looked over the EEPROM settings and saw that the build envelope for Z was set to the sane value of ~390mm and I measured my 'steps per mm' and that was correct too.

Where is it storing this 550mm home value and should I do something about it? It feels like the machine loses it's world space sometimes and then things get 'wacky'. Worst case I can just validate my Z after a home and make sure it's reasonable.

Anyone else run in to something like this?

[derzaubererer]

When homing with the option under the Advance Settings the cheap skates correctly move to the top, tap the end stops and settle, I then move to the menu to manuall decend the hotend with the turn knob, slowly but surely I reach the bottom and find my new Z=0 point. I back to the previous menu and hit 'Set new Z=0'. At this point I move up the menu to Home again and while it's in transit I jump back in to the menu that shows the Z value and it reads a number much higher than expect, something around 550mm, the real travel distance should be something like 390mm. When the cheap skates get to the limit switches they stop, as usual, and then the Z value pops back to a value that I'd expect (~390mm). This behavior seems odd, but doesn't cause me any issues.

The problem I've run in to twice (in about 4 days) is that sometimes after a Home (one time it happened with MatterControl and the other from the LCD) the Z value reads the 550mm number, trying to then lower the hotend manually (either in MC or the LCD) it sits there and sounds like its just grinding, I can flick the endstops to make it stop. If I give it a move that will move it back in to the print area (like G1 Z200 F3000) it moves correctly and doesn't grind (I enter this thru the MC terminal). I looked over the EEPROM settings and saw that the build envelope for Z was set to the sane value of ~390mm and I measured my 'steps per mm' and that was correct too.

Where is it storing this 550mm home value and should I do something about it? It feels like the machine loses it's world space sometimes and then things get 'wacky'. Worst case I can just validate my Z after a home and make sure it's reasonable.

Anyone else run in to something like this?

sometimes my zmax gets fucked up aswell i then calibrate the noozle down to the piece of paper and home afterwards when it hits the endstop screws the value should jump from 500 to the value you expect

[RobertM]

Yeah, it seems like something is a skew, but then again its not really harmful, just seems like it's method to Home is something like "Move up 150% Z-max length, then on endstop trigger set absolute position to {0,0,Z-max length}.

I've been working with MC bed leveling to get a slight slope out of my bed and Ive been seeing some weird Z values after completing the Auto bed leveler routine (like a negative Z-max, which is SUPER BAD when you home since 0 is now below the machine), but that's likely something between me and MC, not the Rostock nor Repitier firmware.