Re: Bedlevelling (all types) is always slightly off.

Quote
glopglop

kFZD9Dy.jpg

Here the tilt seems to go the other way, so that the "virtual" bed is effectively higher on the left (well front left).

It almost feels like the levelling code is over-compensating?

No... More likely, it has to do with the Z-Home position. Are you homing the Z axis at the center of the bed? It is best to do that just because that is where most people print.

Also, That minimizes the amount of error as the nozzle moves away from the home position. Homing at the center means the nozzle can only travel 1/2 as far compared to homing in a corner.

Quote
glopglop
This is the output from the `G29 T` stage :

Recv: Bed Topography Report:
Recv: 
Recv: (0,9)                                                                   (9,9)
Recv: (10,185)                                                                (180,185)
Recv:      .          .          .          .          .          .          .          .          .          .
Recv: 
Recv:      .          .          .          .          .          .          .          .          .          .
Recv: 
Recv:  -1.190   -0.938   -0.675   -0.445  [-0.215]   0.057    0.242    0.432    0.607    0.802
Recv: 
Recv:  -1.160   -0.903   -0.648   -0.435   -0.185    0.070    0.307    0.465    0.687    0.822
Recv: 
Recv:  -1.098   -0.865   -0.628   -0.355   -0.098    0.115    0.307    0.487    0.667    0.865
Recv: 
Recv:  -1.050   -0.807   -0.563   -0.335   -0.098    0.122    0.332    0.538    0.717    0.903
Recv: 
Recv:  -1.025   -0.743   -0.533   -0.302   -0.098    0.142    0.367    0.558    0.742    0.945
Recv: 
Recv:  -0.995   -0.730   -0.508   -0.263   -0.033    0.190    0.380    0.592    0.760    0.952
Recv: 
Recv:  -0.970   -0.720   -0.498   -0.260   -0.070    0.153    0.397    0.570    0.770    0.992
Recv: 
Recv:  -0.893   -0.705   -0.480   -0.265   -0.033    0.190    0.395    0.595    0.820    0.957
Recv: (10,10)                                                                    (180,10)
Recv: (0,0)                                                                     (9,0)

That is a lot of tilt. UBL can handle that. But still... You will get the best results if you minimize the tilt.

Quote
glopglop
Actually, just a thought, is it possible the levelling code is making assumptions about INVERT_X_DIR & INVERT_Y_DIR?

No... That is all factored in at the lowest levels. UBL is doesn't need to know about that. UBL just tells the Stepper routines what coordinates it wants the nozzle to move to.
My suggestions are:

• Physically level the bed as well as possible
• Home the Z-Axis at the center of the bed
• Re-validate you can print a small object at the center of the bed (Very important since we may be changing the Z-Home numbers Do a G29 D to insure UBL is deactivated prior to the print.)
• Regenerate the mesh with G29 P1 (and save with G29 S1 )
• Fill the mesh with G29 P3 (and save with G29 S1 )
• Activate UBL (G29 A) (and save with M500 Now UBL will be active when the printer powers up)
• Do the same G26 pattern
• Post a picture of the G26 Pattern
• You may want to mark your glass (and your bed) so you know where left and right and top and bottom are. You always want to put the glass back on the bed at the same location with the same orientation.
• We will edit the mesh based on that picture

It will go surprisingly quick once we have the next G26 pattern printed.