inconsistent extrusion on top layers?

[robust gorge]

Hey everyone,
Got a new VC 4.1 here running RatOS 2.1. This is my second VC (both 500s).
Yeah, I've already been through plenty of pain with first layer issues and all that on the first one. But this one I just can't get a handle on…
On most layers I'm just not getting consistent extrusion. Sometimes under, sometimes over. Just not even. I've gone through flow, Z offset, beacon calibration, etc. But it keeps coming out pretty much the same.
Anyone got a general idea which direction I should keep digging?

[robust gorge]

New tests with full surface first layer. Its strange to see the lines, which are perfect and the next again are underextruded. The bed also looks not ideal for it 🙁

Tested with 0,2 Layer Height First and Second Layer
First Layer 0,5 width other 0,45 width
Flow Calibrated to 1,0075
PLA Matt Filament at 220°
In the UI of Mainsail i dont see a change in the flow rate while these different lines are happening.

Its an open VC4.1 500 with adaptive heatsoak and this beacon settings:
variable_beacon_scan_compensation_enable: True
variable_beacon_scan_compensation_profile: "auto"
variable_beacon_contact_start_print_true_zero: True
variable_beacon_contact_calibrate_model_on_true_zero: True

Attached the Bed Mesh and the Beacon Compensation Mesh
the wave on the left of the bed is also visible with a ruler on the clean bed without magnetic sheet etc. On the Linear Rail of the printhead not.

[still current]

The symptoms would suggest a hw issue. My first suspects would be a partial blockage in the nozzle or a failure of the hotend mounting.

Very few of the filaments I use have an extrusion multiplier of >1, so I’d first try a cold pull to try see if there is blockage. After that I’d check that all the hotend/mounting screws and nozzle are properly tightened.

[robust gorge]

when the current print is finished i will double check again.
here another example of a current print. i wonder about these dots with different surface ?extrusions?
but if i look more detailed i see different exstrusions every layer. under, under, over, under.

[robust gorge]

@still current could the waves in the heightmap (see above, like these https://discord.com/channels/582187371529764864/1479434741701673010) in combination with the compensation mesh result in this extrusion pattern of these dots? If I look on both it looks like the same. Ever seen?

[still current]

We’ve seen similar wavy patterns, they seem to stem from the magnetic leak from the magnetic mat. Mine has those too, but i do not see the extrusion/height issues you see. I would be surprised if those were causing your issue, as there is quite a large change in the diagonal lines next to each other, whereas the waves are in x direction.
Were you able do a cold pull with a cleaning filament/nylon? Are the small screws between the heatblock and the heatsink tight?

[robust gorge]

i've done many tests 🙂
here my results:
-> avoid the wavy patterns caused by the magnetic leak, with double pei or in my case some layers of paper, removed the wavy patterns from the heightmap. Not from the Print. -> not the cause 🙂
-> Checked every screw on the toolhead, including the 3 mini screws of the hotend and the 4 screws securing the phaetus -> all tight -> not change 🙁
-> Cold Pull and changed nozzle -> no change

I still see these dots pattern in extrusion and even some times the extrusion between the diagonal lines changes. like something changed the z offset while line change. (its not visible changed, it just feels like)

Current running test: move to contact bed mesh, lets see if there is a change.

will post an update when finished

[robust gorge]

ok...
i also tightend every z screw. motor mounts, lead screw adapter etc.

i made one mistake run with to much z offset and very very much underextrusion, but it probably gives a hint. It looks like my mesh?

after another calibration run (felt like the 20th...) i have a quite good one.
but in the top i get the same pattern with under extrusion and two diagonal lines again.

and the top layer of this two layer test also attached. I think its just perfect. I will give an update if it fails again 🙂 looks promising so far!

these are the current settings:

variable_beacon_adaptive_heat_soak_layer_quality: 4
variable_beacon_scan_compensation_enable: True
variable_beacon_scan_compensation_profile: "auto"
variable_beacon_contact_start_print_true_zero: True
variable_beacon_contact_calibrate_model_on_true_zero: True
variable_beacon_bed_mesh_scv: 25
variable_beacon_contact_true_zero_temp: 165
variable_beacon_contact_expansion_compensation: True
variable_beacon_contact_prime_probing: True
variable_beacon_scan_compensation_probe_count: 11,11

any wrong or useless settings?