Random erratic extruder movements at the beginning of the print

General Discussion
42

See Move exceeds maximum extrusion (AA mm^2 vs BB mm^2)
Most likely a (start-)gcode issue

43

still not explaining why it’s not happening multiple times and then suddenly it does, with the exact same gcode-file. Feel free to analyze the start code. I don’t see any issues with it:
config-202355-82156.zip (6.2 KB)
Umikot_3.gcode (226.1 KB)

44

Your gcode file seems corrupt. Every viewer I try can only (at best) render the first layer.

45

Same for me, but it’s correct - it is single layer print.

46

Yes I only included first layer into the gcode file as max upload is 8MB. The Issue appears always on first layer anyways. Complete Gcode is 43MB. Here is it complete: https://cloud.kalavallerie.ch/s/kXcTAfMrMTnYA2W

47

I just wanna give an update about this issue:

It seems to be tied with bicubic algorithm from bed_mesh.

I reduced probing points to 6x6 and defaulted to lagrange / disabled bicubic. I didn’t have this issue anymore so far.

48

Got it.
I’ll set lagrange on my glitchy Sapphire and set bicubic on my office printer and see if something changes.

49

No, lagrange or bicubic does not make difference, it glitches randomly on both.

50

So I built another printer with Raspberry Pi 4 and Klipper and got same issue with it. Had to use emergency stop because extruder started grinding abrasive filament.

klippy.log.zip (1.1 MB)

51

Hey, short Update from my side:

Since changing to lagrange 6x6 the issue disappeared completely. You wanna compare the settings? Maybe you’ll find the culprit on your end this way. These are my settings right now:

printer.cfg (17.7 KB)

52

Hi!
Sorry, but since there’s no response from Klipper devs I swapped Raspberry Pi 4 to Orange Pi 3 LTS on my Sapphire Plus and issue completely gone.

I still have Ultimaker with on RaspberryPi 4. I’ll try 6x6 lagrange on it.

53

It seems like “performance” CPU governour fixes issue. If RaspberryPi CPU always running on maximum freqency this glich does not occur.

54

I confirm solution. I print for 2 weeks every day 24/7, with “performance” CPU governour this error never happened again.

1 Like
55

Interesting, thanks for sharing.
Seems a strange and rather rare issue. I wonder what the true cause is.

56

It also works with "powersave’ governour.
I guess, error happens when CPU changes freqency.

57

I do not know. It seems special to only very few setups as thousands are using RPi4 setups without this issue.

58

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