Anyone have any idea what might cause this sort of issue on PLA? I run into it frequently, but pretty much only when all of the following points are true:
- the print has multiple parts, so the extruder spends a decent amount of time off of any given part (only one part from this print is pictured)
- the affected part(s), like the picture above, have a relatively steep outward overhang, extending over the build plate
- the outward overhang part is relatively narrow, as seen from a top view
This is from a printer with a 4028 fan (i.e. pretty massive airflow, server type fan) so even the 35-45% (based on layer time) I have it currently set at is more than 100% with single/dual 5015's or etc.
I guess my other option is to try supports, but this doesn't really seem like a situation where supports should be needed. Anyone ever had a similar problem and solved it without just turning the speed waaaayyyyyy down?
How fast are you trying to print? Does it behave differently if you slow down?
One of the reasons prints can shrink like this is that the speed is essentially stretching the plastic as it comes out the nozzle, like a rubber band. As the plastic settles that tension pulls it together.
I doubt moisture is the issue, PLA doesn't actually absorb water very quickly.
Also, have you done a temperature tower and flow calibrarion for this filament?