GUYVER,
0.05M is not that bad for backlash. See if you can tweak your axis and maybe reduce it some.
I just replaced the screw mounting support bearings in my machine and varying the bearing preload can make a difference.
If you don't have that option then I quess you have what you have.
PLay with 50 50 50 rule as the values seem to be a good starting guideline.
RICH