PETG fine, but bad warping issues with PLA
I am somewhat new to 3D printing. I fell into the Gridfinity trap and have been printing up a storm of bases and bins for my shop. Initially I started out printing in PETG but have recently been trying PLA because I really like the color and appearance of the Galaxy PLA Prusament.
However, when I print larger bins (100mm+) I am starting to experience severe warping and detachment from the build plate. I have tried adding a 3mm brim and printing with the door open and closed but no matter what I am always getting edges lifting that spoil the print. I have also cleaned the smooth plate very thoroughly before each print and am using Prusa slicer with the default Prusament PLA profile (typically 0.25mm Balanced setting).
I was under the impression that PLA was supposed to be the easiest filament but I had zero problems with PETG.
So far I have only tried the smooth build plate. I also have a satin plate and a glue stick if either of those are recommended.
What can I try differently to get better results?
RE: PETG fine, but bad warping issues with PLA
probably worth trying with something like magigoo or 3dlac and a really larger brim...
RE: PETG fine, but bad warping issues with PLA
Yes, glue stick (or "proper" products as above) have the advantage that it sits as layer between print bed and the print.
A possibility is a remaining thin layer of old material (even despite careful cleaning). PLA and PETG are chemically incompatible, they won't stick to each other. I have noticed myself a few times that when switching material, sometimes weird things happen.
Before risking a large print, you could first run a single-layer PLA sheet over the full printbed (use "create box" in Prusa slicer, then scale) and confirm that PLA sticks equally well everywhere (and while at it, check for Z-axis artifacts). It'll also leave residue with the correct material.
RE:
I rarely print PLA but when I do, I tend to have problems: adhesion, warping, clogged nozzles. It's ironic that this is considered a "beginners filament" yet it gives me the most grief. I've successfully printed the so-called "impossible to print" filaments such as POM (Delrin) and unadulterated PC (polycarbonate)... But not run-of-the-mill PLA.
Rant aside, I would use PETG for large gridfinity bins instead of PLA. If using PLA, instead of a brim, try adding mouse ears on each corner. In PrusaSlicer, right click, then Add Shape -> Gallery -> Helper Disk.
RE: PETG fine, but bad warping issues with PLA
So far I did have one success printing this using glue stick on the bed and printing with the chamber closed and set to 30C. I also used a 4mm brim setting.
I don’t know if it made any difference but I also slightly moved the printer to try and reduce any drafts coming from the HVAC as my garage is now in heating season.
I don’t think cross-contamination was an issue because I have only ever printed PLA on my smooth plate and PETG on textured plates. But I did do a very thorough cleaning before anyway.
The behavior I’ve seen with failures is that the first layer appears to go down just fine but starts to lift off during longer prints. Prior to this I’d printed a number of large-ish 125mm parts with no warping, but they are round (ring-shaped, really) and complete in about an hour. It seems like the problems I’ve had started showing up around two hours and especially longer.
As for material choices, I’ve been using PLA here simply because of the much wider range of colors and finishes. For where and how they are being used the mechanical properties don’t really matter.