SOLVED: Voron 2.4: offset one x-axis while moving y-axis only - and vice versa

[koira]

I operate a Voron 2.4r2 since almost 2 years and just recently one of the main A/B-belts broke - fair enough after some intense use in a hostile environment as I am living on an island in the ocean with high temp and high humidity. 

So I ordered new belts and installed them and as I was at it I also decided to exchange the z-belts as well and replace the standard X/Y-idlers with the ones developed by chaotic labs (https://www.aliexpress.com/item/1005006147407981.html). the latter looking good, sturdy and identical for left and right mounting.

ever since, though I experience the printhead displacing itself inconsistently a few mm left and right on the x-axis (if I move only the y-axis for 350mm) or vice versa displacing itself a few mm back and forth if I move only the x-axis.

I double checked the A- and B-belts are running fine and being well seated in their repsective idlers. i made sure the belts are exactly the same lenght and mounted symmetrically. I tried with strong or weak tension of the belts. I de-racked the gantry and it's running absolutely smooth in every direction, left and right side of the gantry hitting the endstops and the other side of the frame at exactly the same distance.  at the same time no changes whatsoever have been made to the stepper-motors, the controller or the voron's configuration.

yet, the displacement in the axis that should not move at all while moving on the other axis remains the same. looking at the attached video you can easily see what I am talking off if you concentrate on the notches of the belt to the right - the y must hnot move as I moved the y-axis only. but they do

where else do I need to search to find the reason for this? what could cause this behaviour?

thanks a lot for any input pointing me into the right direction to fix this - I ran out of ideas what to look for.

Edited March 30 by koira
solved the problem.

[koira]

 

ha! I just found the solution by myself: for whatever reason I cannot explain the rotation_distance for X and Y where set to different values. after I corrected this everything seems to run smooth!