# Bed leveling issues.

The z probe data is:

15:47:43.351 : X:0.00 Y:0.00 Z:487.638 E:0.0000

15:47:52.715 : Z-probe:10.36 X:-70.00 Y:-70.00

15:47:57.491 : Z-probe:11.05 X:-70.00 Y:0.00

15:48:02.350 : Z-probe:11.27 X:-70.00 Y:70.00

15:48:08.060 : Z-probe:11.19 X:0.00 Y:-70.00

15:48:13.013 : Z-probe:11.56 X:0.00 Y:0.00

15:48:18.006 : Z-probe:11.88 X:0.00 Y:70.00

15:48:23.746 : Z-probe:10.78 X:70.00 Y:-70.00

15:48:28.620 : Z-probe:11.64 X:70.00 Y:0.00

15:48:33.651 : Z-probe:12.38 X:70.00 Y:70.00

According to these data, there is an inclination, but instead of correcting it, he accentuated it, making the low side even lower and the high side even higher.

This is on a Delta with 0.9.2.9.

This is the configuration.h file

https://drive.google.com/file/d/1BcltVdDvll5PSo5jo05wOuEeB3V0RiTf/view?usp=sharing

## Comments

G30 P0

on one point does the height returned change significantly or does it stay swinging around an average number?

And another one - why do we measure a rotation if you say without autoleveling the paper method shows it is flat. That is a contradiction except if at that point G32/G33 was active adding to the correction.

So with a and b positive this means bed goes down with increasing x and y.

Looking into measured values you see that this is in deed what you measured, so computation of this correction matrix seems correct.

For example x 70, y 70 you get z = 0.0048 * 70 + 0.0194 * 70 + 18.0146 = 19.71 compared with 19.98 measured. So at that edge an error of 0.2mm is to be expected.

At 0,0 it is easy 18.0146 compared to 18.02 measured.

These differences will be there and come from imperfect geometry of course. What you get is a regression plane that minimizes the mean error over all measured points. With 3 points you get an equation where the 3 points measured would fit exactly, but all other points you would manually measure will be different.

What I see is also that the difference is nearly 3.7mm which is a lot. Did you adjust the end stop offsets to have same distance to bed after homing? That should be the second stage in delta calibration right after checking bed is also as perpendicular to the z axis as you can. This should reduce the starting error a good part.

How many extruder does the printer have? If you have extruders with offset different then 0/0 you might need to go lower after homing then the 4mm I saw. Problem is that activating the extruder could trigger an endstop and then position is already wrong at the top since xy motion is limited at top to only a few mm with 4mm space left to end stops.

a curious fact is that, the lower the area that claims to be the highest, the more difference there is between it and the lowest.

G33

23:18:42.070 : Z-probe:16.48 X:-63.88 Y:78.12

G32

If you look into your marked part

you see z goes first up then down. That is not from rotation and no flat bed would do that. So this is not correctable with G32 rotation. This comes assuming bad is flat in reality - from geometry errors in your delta. And that is also why you shoudl first calibrate geometry parameter using e.g. escher delta calibration tool for 6 parameter and then start correcting the remaining errors using G33 so the regular error is at minimum possible.

Since that error will exist until the top you might also want to correct it for complete Z and not only until Z=1 which is the default.

I can't think what else to try to get this working

From my experience these values look like errors from delta geometry. This does not mean xy size will differ that much and the error is not very big. Changing an tower angle by 0.5° might change it more.

What bothers me more is that the values do not swing around 0 for G33 which they should if run after G32 S2.