Model pulls up on one corner during printing

While trying to print a large model, one corner lifts as the print progresses (see attached images). When the raft is printed (right before the bottom of the model is started), it lays flat against the platform. I tried a different PLA from a different manufacturer. Same results. I tried shimming the back of the platform with some success (lifting is not as bad). I touched up the fine offset to bring the platform closer to the nozzle. I'm not sure if that helped.

Questions which come to mind: Is the platform warped? Would adding more shim be the best solution? I'm not sure printing at the bottom of the temperature range for the filament would help - a bit concerned about layer to layer adhesion.

Oh gurus of this forum, What to do?

 

Testing is the only way to sort what is actually "bottom of the temperature range"
I have one printer that prints PLA best at 175c another at 190c yet another at 185c... you get the idea.
Leveling the bed (with shims) is the best approach.

I no longer auto-level any of mine since they are already leveled manually.

You can check the plastic base is warped by removing it and using a straight-edge. If so they will send you another.

 

Thank you Mark. Good point about checking the base with a straight edge. The problem is aggravating as it only occurs in the one corner and only with large prints.

 

Tape or something similar on top of the magnetic posts for the base of the bed works for manually leveling.
Put a strip or two or ten when needed Rerun a single layer print with NO autoleveling (remove the G29 from the startup GCode while testing). Attached is one such single layer STL, size it to fit the bed.

Restore G29 when done if you want to return to auto-leveling (not a bad idea for most cases)

 

You can leave autoleveing on if you want. You may need to tweak the z offset with autoleveling disabled and then restore it if you do disable it while testing. I just find it easier to remove it from the equation while doing manual leveling.