Geeetech A20T: Unable to infer active extruder stepper

Printer Model Geeetech A20T
GT2510
PI3

extruder_change.cfg (4.0 KB)
klippy (11).log (22.4 KB)
macros.cfg (871 Bytes)
printer.cfg (6.0 KB)

Hello,

I have a small problem with my Geeetech A20T, when I change the color or change the extruder from T0 to T1 I get this error message:
Unable to infer active extruder stepper

My slicer is the PrusaSlicer 2.7.1, I already found something in the forum, but the SuperSlicer 2.x.x is used here.

In my configuration I have the in the section [delayed_gcode STARTUP_GCODE]
entered the following:
[delayed_gcode STARTUP_GCODE]
initial_duration: 0.1
gcode:
{% set svv = printer.save_variables.variables %}
{% if svv.active_tool != “” %}
{ svv.active_tool }
{% else %}
T0
{% endif %}
{ action_respond_info("Active Tool: " + svv.active_tool) }
set_pressure_advance extruder=extruder advance=0.62 smooth_time=0.08
set_pressure_advance extruder=extruder1 advance=0.62 smooth_time=0.08
set_pressure_advance extruder=extruder2 advance=0.62 smooth_time=0.08

I suspect I have a problem here.
I hope someone here can help me.

Thank you very much

Olaf

That issue is happening when your script is trying to setup presure_advance.
You have that error because your additional extruder_stepper is not syncronized with extruder.
if you are not synchronizing them then you can’t set presure_advance.
So or you set property extruder in your config or synchronize them manually with command SYNC_EXTRUDER_MOTION before setting presure_advance for them.

Hello,
I also tried the following: if I print without a cleaning tower, the print works, but it doesn’t look nice. I don’t have a filament sensor activated on my printer. This would also just be a switch in front of the extruder. Is there a way to use the Sync_Extruder_Motion without a sensor?

If these problems arise in connection with the cleaning tower, is there an alternative for tippers such as the purge bucket process?

I had the same issue with my A20m,
The problem is that during the color change my slicer was adding gcode: SET_PRESSURE_ADVANCE ADVANCE=0

This fails because for a multi extruder setup you need to specify the extruder in the SET_PRESSURE_ADVANCE command.

It seems to be erroneous, as you noted appears to be related to printing the prime tower.
My solution was to filter the command out - how you do this depends on the slicer your using.

someone did try to come up with a solution within klipper : kinematics: Fix "Unable to infer active extruder stepper" errors. by xtoddx · Pull Request #6413 · Klipper3d/klipper · GitHub
but unfortunately that doesnt appear to have progressed.

You might want to check X-In/1-Out Non-Mixing Extruder Config and X-In/1-Out Non-Mixing Extruder - Automate SuperSlicer & PrusaSlicer Filament Swaps

Apparently @jjarosz is successfully running such a setup.

OK, that looks good, thank you, I’ll try it out

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