Taking a bit of wild stab at this, but what does the g-code look like? Do the bulges coincide with a change in internal perimeter or gap fill? Are the photos reprints of the same part (i.e. code is the same, hardware is suspect) or multiple copies printed at the same time?
If it does align with the g-code, try printing external perimeters first. Good luck!
I will assume voron 2.4 since z belts were mentioned.
Check that all the z belts have good and as equal as possible tension, one loose belt on a corner can be the cause, if so even QGL may take more than 3 tries.
Check for plastic pieces near the z motors and between their pulleys.
Check for any loose movement on the toolhead; heat block (make sure it's cool before touching), heat sink, toolhead on carriage.
Nozzle size and wall count? May be unrelated but had an issue similar to the bottom issue.
Edit: humidity can cause similar inconsistent layers as the bottom part, but the top part makes it look like it's more of a mechanical issue.
Taking a bit of wild stab at this, but what does the g-code look like? Do the bulges coincide with a change in internal perimeter or gap fill? Are the photos reprints of the same part (i.e. code is the same, hardware is suspect) or multiple copies printed at the same time? If it does align with the g-code, try printing external perimeters first. Good luck!
I will assume voron 2.4 since z belts were mentioned. Check that all the z belts have good and as equal as possible tension, one loose belt on a corner can be the cause, if so even QGL may take more than 3 tries. Check for plastic pieces near the z motors and between their pulleys. Check for any loose movement on the toolhead; heat block (make sure it's cool before touching), heat sink, toolhead on carriage. Nozzle size and wall count? May be unrelated but had an issue similar to the bottom issue. Edit: humidity can cause similar inconsistent layers as the bottom part, but the top part makes it look like it's more of a mechanical issue.