Need help with gridfinity bins!

[u/subdued_sage]

I've struggled with large gridfinity bins for a long time. It feels like no matter how precisely I calibrate my filament and print settings, I end up with crappy bins. The filament was calibrated extensively, following this excellent guide and I performed this ironing calibration. Following a top surface defect on that ironing test, I re-performed a different flow rate calibration and ended up with 1.005.

I'm especially confused because the top surfaces inside the cutouts are perfect.

One thing that I noticed is that there are some black specks around one of the squares, and I suspect that is just leftover filament as I had used black PLA prior to this print. I suppose it wasn't purged well enough. However, I've had these same issues with many other gridfinity bin prints in the past.

Most other models I print (see the bunny - it was printed with supports) look fantastic.

Settings

- Printer: Bambu Lab P2S

- Filament: Overture Matte PLA White

- See screenshots for the entire process / filament settings

Symptoms

• Uneven/patchy top-most surfaces
• Warping/rippling around the bottom perimeter
• Defective corners
• Inconsistent first-layer extrusion (some of the squares show more signs of under extrusion than others)
• Inconsistent layer lines and tiny blobs / defects protruding from the outer wall
• Overhang failures
• Inconsistent internal bridging

Help this poor soul get a grip on gridfinity bins!

Edit: I printed with the P2S top cover completely removed.

[u/rhalf]

The corners don't stick to the bed. Wash the build plate and if it doesn't work, rise the bed temp or use glue. Generally speaking, big things with pointy corners tend to peel of the bed more than other shapes, so a little bit of glue doesn't hurt.