Is it possible/meaningful to use distortion correction without rotation correction?

Gruess Gott! 
I've got printer with Prusa-like kinematic, mechanic probe with optical endstop (BLtouch self made). I print on not very flat glass. The maximum bed height distortion is 0.2 mm. In the firmware the autoleveling with bed leveling method 1 is enabled with bed correction method 0 and distortion correction as well.
Once in a while, before printing with new bed temperature (ex. 100C for ABS where I expect bigger bump at bed center after printing at bed temp 60 C for PLA) I run the script to renew the rotation and distortion matrix: 
    - M322 S1
    - G33 R0
    - G28
    - M140 S%(bed_temp)s
    - M190 S%(bed_temp)s
    - G28
    - M322
    - G32 S2
    - G28 X Y
    - G33
    - G33 L0
    - M140 S0
    - G1 X100 Y120 Z30 F15000
After that I print with just homing all axes. 
When print starts and printhead goes from Z-max endstop down to the bed X and Y motors make small steps. I think they are correcting the rotation.
My first question is: is it normal?
The second: wouldn't it be better to disable the rotation correction and enable only distortion correction matrix? 
Thank you!


  • The xy moves while changing Z are in deed from rotation and normal.

    And NO - removing rotation and only keep distortion is not a good idea. These are 2 different problems - distortion is disabled after a few mm while rotation needs to stay on so a cube comes out as cube and not with not rectangular axes. It also reduces the amount to correct with distortion.

    If you do not like rotation correction just physically level the bed correctly instead. That you might run without rotation correction.
  • Thank you very much for the answer and for your whole  job developing and maintaining the firmware!
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