weird extrusions

Hello,

Please see the picture below.

I believe to have calibrated my printer since when I print the 20mm cube I am within 0.15mm of the target. However for larger prints, I have been noticing this issue under extrusion in 1 area leading to a slight over extrusion just following it. I think I have the steps/mm as a correct approx value for my printer. I am printing abs on kapton tape + abs juice. Could anyone help me out as soon as possible (so I can get back to printing . By the way printer is a custom built p3steel ?

Thanks,

Edited 1 time(s). Last edit at 07/27/2016 06:06PM by blahhh10.

It looks like your bed is not level, or your auto level bed correction is not working. The under extrusion is probably when your nozzle is in direct contact with the glass, and the over extrusion blobs are probably when the pressure build up wins and pops out for relief.