These calculations are relatively easy for any 3rd-year mechanical or civil engineering student, by hand. That being said, you have more problems than (presumably) not knowing how to do these calculations.
What support will the two X-axis beams have? Are they lying on a floor, supported only at the ends, supported with some kind of welded frame? If you expect calculations or finite element analysis to be predict better than 0.1mm, the information you feed in gets very important. Material properties, exact section properties, loading conditions, support conditions, etcetera, etcetera. The precision to which you know these properties will dictate the precision to which FEA can predict deflection.