Warping problems

I’ve been working on printing a box. The lid is about 4" across each side and has walls about 1" high. We’ve gotten the print pretty good, but still has a few problems. I am using the default slic3r configuration (though with a brim added), no support, ABS filament is from lulzbot. We’re using PET tape on a glass bed with a Taz 4. I’m also applying hairspray before printing.

The two problems might be related. The first is that the boxes tend to warp. The corners tend to lift off, though not as badly as when I first printed it. Even with the corners pretty flat, the bottom warps so it is not flat. Also, as you can see in the picture attached (hopefully), the layers tend to lift off one another and the box cracks along the layers.

I’ve tried walls 2mm and 4mm thick, the thicker walls seem to make the problem worse. I put slits in the box, and that seems to help some, but does not eliminate the problem.

Any suggestions?

Add a 7mm brim layer to the first layer of the box in Slic3r. Also run a filliament calibration to ensure you are extruding the correct amount. Also consider using an enclosure of some sort. Large Turkey roaster bags taped around the frame actually work really well for that if you just need a quick one. That will minimize the layer separation. Also make sure your filliament diameter is set right. Separation of layers like that can be due to slight underextrusion.