Troubleshooting bad PLA warping

After many successful prints on my roughly 1-year old Lulzbot Mini, I am suddenly experiencing terrible warping problems on every single print. The image below shows one example printed using Protoparadigm PLA, but I’ve seen the same behavior with other brands as well. Every corner of every print is warping like this, despite using the identical models, filament and Cura settings as before. I also know from other users online that many people are successfully printing the same models with no warping, even on lower-end printers.

Things I’ve already tried which didn’t help:

  • Replacing the PEI surface
  • Cleaning PEI with alcohol
  • Changing various settings, especially the temperatures
  • Reverting the z-offset back to the original factor setting (which I believe squishes the first layer significantly to improve adhesion)
  • Replacing the nozzle
  • Even printing with a brim doesn’t solve this problem, even though a brim definitely shouldn’t be needed with this type of model and material

At this point I’m out of ideas on how to troubleshoot the problem further, but there certainly seems to be something wrong with my printer. Any advice would be appreciated!

Assuming everything else is normal and good, I would suspect the bed heater. Have you monitored the bed temp during printing? Does it make significant changes while printing? Also, if you haven’t tried it, try turn the cooling fan off during printing and see if that helps.

The bed temp reported in Cura during the print is very consistent (+/- 1 degree). I’ve ordered a laser temperature probe and will independently verify the bed temp as soon as it arrives.

I did try printing with the cooling fan turned off completely. This caused the print to fail as soon the first bridging occurs (at around 4.5mm in this model), but it did significantly reduce the warping. I suppose I could try only turning on the fan later in the print job (say at 4mm in this case), though that doesn’t really explain why the behavior suddenly changed. Any other suggestions?

Is the barrel cooling fan still operational? They do have a somewhat higher than hoped for failure rate. The warping is wierd though, given its PLA. Can you post the model STL so we can see if there is something wierd going on with it please?

The barrel cooling fan is still spinning at least - I’m not sure how to evaluate whether it is operating as expected. I’ve been planning to upgrade it to the larger TAZ 6 design anyway to mitigate heat creep, though I’m not sure how that could be related to the warping issue? I assume heat creep would manifest by producing a clog that causes the print to fail partway through?

I don’t know whether it would be appropriate for me to post the model STL directly since it is also part of a commercial product, but it is available for free at (the earlier photo showed the 2x2" tile, though the warping behavior is consistent with other STLs as well). That being said, I know from their product forums that many people are successfully printing the same STL, including with low-end printers without heated beds.

Regarding the earlier poster’s suggestion, I did try repeating this print by keeping the fan off until around 4.5mm height (shortly before the first bridging begins), and while that change didn’t completely eliminate the warping it at least helped significantly. Hopefully that helps in the diagnosis. I’m still at a loss for why the behavior would have changed with the same STL, material and Cura settings as before.

When I have seen this issue there was something on the surface that the PLA can not stick to. It might be something that the IPA can not break down, or require a number of attempts to remove.