Bed mesh problems

Basic Information:

Printer Model: ZAV mini
MCU / Printerboard: SKR1.3 + EBB42 + Eddy USB
Host / SBC RPi3B+
klippy.log
klippy (2).log (1.9 MB)

Hello.
I installed BTT EDDY USB to my CoreXY(100x100) printer. Following the instructions at BTT GitHub i made all calibrations and config setup. It’s works. Eddy scans surface, klipper makes bed mesh and z motor spins when XY axes moves.
But when at Y0 first layer become perfect then at the Y100 nozzle become too close to the bed. At the same time X axis work normal.
I tried tens different values of bed_mesh parameters. Recalibrate Eddy several times. But nothing helps. What i need to do to resolve this problem?
The best result on the first photo.



My opinion
considerations
my bicubic_tension: .2 ,
filament is not showing much variation?
your table is aligned with a variation of +/-0.1 without the probe it already prints beautifully
what is the height of the print?
try box test pot mode with thickness set to calibrate the extrusion multiplier.

I tried from 0.2 to 0.8. 0.5 gives the best result

Filament has nothing to do with it. I made more then 10 test prints and all has the same problem.

your table is aligned with a variation of +/-0.1 without the probe it already prints beautifully

That’s true. But not enough as you can see. And also I’m doing it for experience. I have a bigger printer where bed is much worse. I want to install eddy there too. But experimenting with small printer is much easier and more convenient.

On the photo? 0.2mm

try box test pot mode with thickness set to calibrate the extrusion multiplier.

All calibrations on my printer has done and it prints well.

Look, I’m being kind, I read your log, I saw your pictures, I chose good words to suggest possible improvements, but your printer prints very well. And your filament has already been tested more than 10 times with the same problem. So I’m sorry.

over extrusion :wink:

No negative in my words man. I just answered to your considerations. My english not very good that’s why i’m trying to answer maximum short and accessibly.
There is no overextrusion on my printer. May be even a bit underextrusion. It can look like overextrusion, but it my experiments with Z-offset. With normal Z-offset print looks like on the last photo.
As you can see on first photo “overextrusion” appears only close to Ymax of print. Most of print is normal. But still a bit underextrusion at Y0.

1 Like

I think i found where is the problem.
This is Eddy scan mesh:

And this is mesh done with simple pressure sensor on the nozzle:

As you can see there is a big difference between them exactly near Ymax.

This is an interesting result. I cannot explain the differences since both sensors should at least return a “similar” topology and not something completely different.

You should keep in mind that:

  • An Eddy current sensor likely is a bit unpredictable at the edges of the bed → Probably makes sense not to go the absolute extremes
  • The influence of the probe’s X and Y offsets can be quite significant, especially if the axes have some twist or other offsets → A probe that uses the nozzle effectively cancles all such offset errors