Weird corner behaviour

Basic Information:

Printer Model: Modified Ender 3 Pro
MCU / Printerboard: SKR 1.4 / Raspberry Pi
klippy.log (1013.6 KB)

Describe your issue:

I have a problem with an “indent” before every corner and slightly overshoot after every corner.
What i did to hopefully solve the problem:
different belt tensions
an different extruder
new TMC2209 drivers on every axis
changed square corner velocity
changed max_acceleration
changed max_accel_to_decel
with or without PA
with or without Resonance Compensation.
No change at all.

BUT. When i do the resonance compensation tuning tower with all the commands in the manual the corners are good - no “indent” or underextrusion before corners and almost no overextrusion after corner.

maybe it ihas something to do with unsynchronized extruder and x/y motion?

tackled this for a very long time now. i dont know what to do.

thank you in advance

Hello @Basti !

Talking about advance: How are your pressure advance settings?

1 Like

Hi @EddyMI3D ,

pressure advance is disabled, thats the weird thing.

1 Like

Not really. This is precisely the sort of thing pressure advance is intended to address.

i agree but its disabled. you can see it in the log.
also reinstalled klipper. i just dont get it

Edit: What can i do to verify that pressure advance is completely off? In my config its disabled


max_extrude_only_velocity = 60
max_extrude_only_distance = 120.0
max_extrude_cross_section = 1.2
instantaneous_corner_velocity = 1.000

These settings are either default or not needed for a common 3d printer

Then follow Pressure advance - Klipper documentation

Since you have no pressure_advance = <calculated_value> in the [extruder] section it is off and this is exactly your problem

Ok i will follow your advice to remove the part in the config. And i will do the pressure advance tuning.

Do you mean the problem is caused by not having a value for pressure advance? So no active pressure advance will cause this dent before corners?

removed the part in the config and also did exactly the pressure advance tuning as you said.

now in the config:
pressure_advance: 0.022
pressure_advance_smooth_time: 0.04

same deal. printed with:
pressure_advance: 0.022
pressure_advance_smooth_time: 0.04

Can you post the corresponding gcode file?

here it is
Test.gcode (494.2 KB)

Ok, compared to the gcode your print indeed looks like s$%…ahmm great :wink:

Have you checked your mechanics?

  • Is x and y running smoothly?
  • Extruder OK not full of dirt?
  • Extruder gears correctly running and smooth?
  • Nozzle clogged?

From your cfg and the gcode, I do not think it is a software problem.

It does :frowning:

Is x and y running smoothly? Yes. Cleaned all the linear rails and blocks and greased them.

Extruder OK not full of dirt? Yes. No dirt. I even used my old Titan Extruder instead of the Orbiter V2.0 - same deal

Extruder gears correctly running and smooth? I think so. The Orbiter V2.0 is almost brandnew. The Titan Extruder is old but back in the days (before some Klipper updates i think or even before Klipper) everything was fine and no dent before corners.

Nozzle clogged? I recently printed with a new one (0.4 instead of 0.6) - same deal

Will recheck everything. Thank you for your help

Edit: I think its a software problem. Even when i rotate the printing object by for example 45 degrees the dent is exactly at the same place. With every Slicer. Its on every printed object. I almost replaced everything. Even the Motherboard.
Its magic i would say :sweat_smile:

Looks like the extruder motion is out of sync at corners

I hope we find the solution here.
The Lochwürfel otherwise looks good. :wink:

What makes me wonder the PA tower seems to look fine.
Did you run it with reduced acceleration?
In your thread on 3DDC we set acceleration and max_accel_to_decel to the same value but still a bit high for a bed slinger.

Did you test it with low acceleration like only 800 mm/s² already or can do so?

I already wanted to suggest turning the object by 45° but you already did it on your own.
This and repositioning the model on the bed should eliminate the rails as root of evil…

Hi LifeofBrian! :wave:

I hope so too…

The PA tower runs as far as i know with a restriction of 500 mm/s² to increase the material at the corners for better visibility of the right PA value. I will test it with 800 mm/s² and 500 mm/s².

But what makes me wonder is the fact that the indent and so on only happens right before and after a corner and the orbiter 2.0 has a max acceleration of 10000 mm/s². So the extruder should be capable of my current 2100mm/s² with the outline speed of just 40mm/s :exploding_head:

There is also almost no ringing with the input shaper values on X and Y and the input shaper results gave me way more acelleration suggestions than 3000 mm/s² on the “slowest” axis. But i use 2100 mm/s².

Even if the 500 mm/s² or 800 will work, i think its just a workaround. Something is not right …

Will post the results with your recommended acceleration soon

Print your model using the exact same slicer and Klipper settings as the PA test object that prints properly. It should look just like the successful PA test object. If so, then start changing your settings one by one until you find the one that causes the corner artifacts.

1 Like

Please share your latest klippy.log

klippy(3).log (1.5 MB)

im printing right now. The corners are looking good for now with the PA settings. Will do more testing one by one

Edit: initial print with the PA settings. Still some slight overshoot after the corner (as it is out of sync) but no dent before the corner

1 Like

Can’t find your PA settings in the config.