Hello everyone.
I have an issue with leveling the bed. Even if I tighten all the screws, use,A4 paper, and try various options for Z-switch, I have a feeling that its not leveled, and the back part of the bed is always higher than the front one, no matter what I do. When printing pretty large objects (like iPhone case) the first layer sticks to the bed unequally: sticks well in some parts, in others the bed is too high or too low. So its impossible to print. I somehow printed with PLA before even with not perfect first layer, but now I have switched to ABS and its totally impossible. The first layer is spoiled and further layers are printed in the air. I can print some smaller objects though, like ultimaker robot, because its printing square is not so large. So, may this be some mechanical problem? I have a heated bed, but the problem was on non-heated bed as well. Maybe someone could upload a good bed level testing object with rounded corners and so on? I so far had no success in printing the perfect first layer, but first PLA prints were pretty ok. Every help will be much appreciated.