Things to try:
- Clean the build plate really well, hot soap and water, dry it, and keep your fingers off the surface. This really does help.
- Add a brim via the slicer. I’ve got a few models that like to warp, and adding a brim minimized or eliminated it. If you use Orca Slicer, add mouse ears.
- Minimize drafts around your printer, With large parts, you want cooling to happen slowly and evenly.
- Get a smooth PEI (high temp) plate or an aftermarket plate (I have a Wham Bam PEX plate) These have much higher adhesion.
- Pre-heat the bed. Before sending the print, tell the printer to bring the bed up to the target temp (typically 65C for PLA, 70C for PETG) and once it reaches temp, let it sit that way for 15 minutes or more. This allows the temperature to stabilize on ALL areas of the bed. It’s not uncommon for the edges and corners of the bed to be five degrees or more cooler until the bed stabilizes.
- On a case-by-case basis, change the cooling/fan parameters. In the filament profiles, on the cooling tab, Increase the “No cooling for the first” X layers, or decrease the fan speeds. Note, you can be more or less aggressive with this depending on the specific model. Parts with overhangs need cooling. Parts with heavy bases may not need cooling for more initial layers, etc…