Anycubic Kossel Linear Plus and "periodic surface marks"

Hi guys!
im having a big issue with my new anycubic kossel linear plus delta printer... i assembled it with some upgrades i printed with my orter cartesian printers...
The Kossel Linear plus gots now a tmc2208 stpper driver in spreacycle mode... standard belts, motors, mainboard...

The issue im having is that on just one face (the y face of a test cube) i get some periodic marks no matter what i tryed....
That marks are just "periodic marks" on Y face, not the "classical U marks" on the front face (that is perfect)....

Here some pictures:
[imgur.com]

What i tryed:
- changing speed (from 10mm/s to 150 mm/s);
- changing layer height (following this guide: [forums.reprap.org] - i tryed every layer height);
- belt tension, more tension - less tension;
- adjusting voltage on stepper driver (from 0.8 to 1);
- replaced with original a4988 stepper driver;
- PID calibration both on hotend and bed;
- different firmware (original anycubic firmware, marlin 1.1.8, marlin 1.1.8 bugfix with new linear advace 1.5);
- checked assembled integrity for some miss allignment/ mechanical problem...

Nothing changed....

Any tips to fix my issue?

thanks,

Andrea

Edited 1 time(s). Last edit at 04/27/2018 03:49AM by Andriee.

The Z-tower is perpendicular to the Y-axis. If it's linear rail or the carrier has some issues, like flat spot on a ball bearing or dirt in the rail, it could lead to those "hiccups".

did you lubricate the linear rails with some thin machine oil? The prints on my anycubic got ugly after few hours because the rails are not lubricated, but only corrosion protected.