Left extruder retract bug

[errolt]

Hi everyone.

I'm having a problem with the left extruder. I use the left extruder only for infill, right extruder for perimeter. I don't know if the bug is related to this.

The problem is that when the left extruder is done for the layer then the gcode zeroes the E, then it retracts 5mm as it should, leaving E at -5mm.
But when the left extruder starts up again then the first thing the gcode does is to zero the E again, without restoring the retract, leaving the extruder retracted by 5mm. Then the gcode starts printing from there, meaning that there is 5mm of filament printing lost.

If I disable zeroing of E then the gcode still does not restore the retract before printing, but the filament isn't "lost". The snag is that the extruder tries to restore the retract along with the first print move, which means that it tries to move filament at movement speeds, such as F3000, then the stepper motor skips.

I contacted support about this. They just told me to turn zeroing back on. I did, and sent them a gcode file showing my problem, but I got no further support from them.

Attached is the sample I sent them.
At line 1305 there is a retract on T1 of 5mm.
Then T0 is used.
Then at line 1457 T1 is zeroed, while still retracted 5mm.

You will see that at line 1311 there is a command to restore the retract for T0, but no such command is issued for T1.

Any insights?

Thank you,
Errol

[bubbasnow]

Im not seeing that issue, i added a second extruder t1, and chose that for infill.

i do have additional tool change .gcode, but you can see that each time it retracts the amount i set in add extuder setting page in processes first before the custom gcode is placed.

i do have all ooze control behavior disabled, allow zeroing enabled

testdual.gcode

(1.46 MiB) Downloaded 286 times

[errolt]

Hi bubbasnow,

Thank you for your help. I went through all your settings, changing my settings one by one to match your settings.

I think I found the setting that causes this bug.

Can you please do me a favour and enable "Only retract when crossing open spaces" under advanced. Reslice and see if you still get good code.

With that setting enabled, like it was the whole time, I get this bad code:

T1
; tool H0.3 W0.4
G0 X49.049 Y87.731 F4800
G92 E0
G1 X52.722 Y84.058 E0.2592 F1500

With it disabled I get this good code:

T1
; tool H0.3 W0.4
G0 X49.049 Y87.731 F4800
G1 E0 F1200
G92 E0
G1 X52.722 Y84.058 E0.2592 F1500

Note the "G1 E0" to rewind the retraction.

Thank you,
Errol

[bubbasnow]

yes that enable retract across open spaces causes bugs in dual extrusion.. that's why i disable all ooze functions. You wont miss it.