Weird leveling result

[Nightreaver]

Hello

I bought a new CoreXY, upgraded to a Duet2Wifi + BLTouch... and started bed leveling. (thats short version of what i did )
Earlier I used capacitive sensor and had some weird results, so now that I have BLTouch I thought... the leveling would become better, but its not really.

I'm leveling with 49 Points total... with around 30mm distance which think is a good count for my print bed.

But what i am seeing doesnt make sense to me. I have and idea what it might be, but I'll be waiting for your experience opinions before doing andything else.

Here is the picture:

Mean error: 0.161 mm
RMS error: 0.090 mm
Maximum deviations: -0.081 / 0.386 mm

Side Question: I enable the leveing on Duet Wifi still with sending "M420 S1" during start ?

Thanks for your help

[Veti]

please test your repeatability

https://forum.duet3d.com/topic/6962/m48-measure-z-probe-repeatability-and-print-to-serial-output

[Nightreaver]

I used the Macro in the Thread you've posted:

G32 bed probe heights: 0.176 0.171 0.171 0.176 0.171 0.161 0.176 0.165 0.153 0.153, mean 0.167, deviation from mean 0.009

[dc42]

Are you probing with the bed heater on or off? If you are probing with it on, then you may want to try adding the B1 parameter to your M558 command, in case magnetic field from the bed heater is affecting the BLTouch.

[Nightreaver]

I'm probing with cold bed all the time and with

M558 P9 H5 R0.3 F120 T2000 A10 B1
G31 P30 X5 Y54 Z1.5

[Veti]

what is your bed and surface?

[jaurand]

I have something similar on my bed leveling. My coreXY has wheels, and I was told that the wheels get a slight flat spot on them. I'm guessing it is a flat spot on the wheels that you are seeing the rise and fall. Working on upgrading to linear rails

[Nightreaver]

The bed is 4 point aluminium, with an 12V MK3 heater.
And the surface is kind of fiberglass sheet, around 3mm thick?

[Nightreaver]

@jaurand The was one of my Ideas, as the pattern seem to be repeating. I will check my wheels