I have two very similar models. The one on the right printed first and printed beautifully. The one on the left was a total failure. I glued both down and used a brim. In both cases, when I pulled them off the plate, they were fully adhered to the bed.
The first print used a brand new .4mm nozzle. (The second print was printed soon after.) These are big - pretty close to full-plate size, and the base layer is 5 mm. I used 30% infill cubic and 4 wall loops. ABS GF. Same filament.
I don’t understand why the second one failed. If you look, you can see the top layer of the plate looks really rough. And then the protrusions broke off, then spaghetti. And when I pulled it off the plate, it warped massively. That front left corner is now 7mm off the table top.
I did not dry the filament before this, but that first print was perfect, as have been other, smaller prints. And its stored in the AMS with plenty of dessicant and a meter that registers 10% humidity.
Fans all turned off for ABS? Its best to bring the temp down very slowly in the chamber after the print to prevent corners curling up. Differential cooling will result in warping. Looks like the print head contacted topmost layer after warping. Keep the chamber hot. Cool slowly.
I’ve had similar issues with large parts. When the surface gets that bad, you know it was pulling up somewhere during printing. If it was still fully stuck to the plate, it’s possible the plate itself was lifting off the bed. Were they both centered as well as possible on the plate?
I was printing a plate full of 2" diameter keychains made with the image to keychain tool. It wasn’t an adhesion issue, as they were stuck very well. I noticed that only the ones on the perimeter ever had a bad top finish. I made a few clips that hold the edges of the build plate onto the bed and the problem disappeared. I only use them when I’m printing something that really fills the bed and has a large contact area.
Print a tall object like a skull and open your door at the end. You’ll hear it cracking as layers delaminate. Then prinr a flat sheet and do the same. Open the door straight after, or worse, turn the auxilary fan on to cool your plate and you can watch it with your own eyes as it lifts. After printing. It’s well documented. My point is-> preheat the chamber, no draughts or fans during printing, and cool the chamber temp slowly. Some even write the gcode to bring it down incrementally once printing is complete.
I have not tried them myself, but you can find “bed clamps” on makerworld. I can not guess at their effectiveness though. In one reported case, the plate was still bent but into an M-- rather than a U-shape.
Other anti-warping features I use for PETG, PA6-CF and PPS-CF (on a Plus 4) are a lower printing speed and layer height to reduce the heat input per layer, reducing the warping volume per layer significantly.
Note that with respect to the layer height effect on ABS, contradictory observations have been made in the forum. Since I do not print ABS, I bow to actual experience.
