Power Restoration bug

Bambu Lab H2 Series Bambu Lab H2D
1

Lemme tell you a story:
While printing with the H2D, I was given this error: HMS_0700-2000-0002-0004: The AMS slot1's filament may be broken in the toolhead. | Bambu Lab Wiki
This stopped the print and prompted me to do the insane task of disassembling the H2D’s toolhead, so I shut off the printer and waited the next day. Later, I turned the printer back on although not doing anything with the toolhead or even the print still seated on the bed and the printer wasn’t giving me the error anymore, problem solved right? When it then prompted me to continue the print it was performing before said error and I continued it, the Z-offset was massive and for some reason didn’t calibrate even though it never needed to since the bed didn’t move a single bit during the time it was off. It then started air printing and I had to abort print.
This has never happened on my A1 during a power outage (a real one btw) which had perfectly resumed printing afterwards even though being off for much longer than the H2D was, allowing more room for the A1 toolhead to sink.

How do I fix Z-offset after a power outage?

2

The neat thing is, you dont. It’s not a feature that is guaranteed to work. Power loss recovery is a quite tricky function and it’s often not working because the printed doesn’t really have a internal backup power supply to execute the “working scene preservation” procedure. What I mean here is that when executing a line of gcode, and the power loss strikes, then you’re not guaranteed to have the correct outcome of that gcode. This is especially true when it happens while your nozzle is on travel and your bed is on z hop. Then after the power loss the bed’s position is completely unknown for the printer.

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