LV8729 on extruder strange behavior

[DzzD]

I just tried to replace the extruders stepper drivers with LV8729 using 64 microsteps.

Now something strange is happening , it does not change direction when it perform a retractation/repush filament.

It is doing a retractation, but rather then pushing back the filament it act like if it was doing a second retraction. It does not happen allways just sometimes.

After retractation, rather than pushing back the filament it push it away ?!

Any idea ?!


I have defined this in config :
#define X_DRIVER_TYPE TMC2208_STANDALONE
#define Y_DRIVER_TYPE TMC2208_STANDALONE
#define Z_DRIVER_TYPE TMC2208_STANDALONE
#define E0_DRIVER_TYPE LV8729
#define E1_DRIVER_TYPE LV8729
#define E2_DRIVER_TYPE LV8729


Also I have read about :
#define MINIMUM_STEPPER_POST_DIR_DELAY 650
#define MINIMUM_STEPPER_PRE_DIR_DELAY 650

But that dont help.

[William]

Hi, I find this: https://www.youtube.com/watch?v=lDljLaXWg4E
I hope this can help you.

[DzzD]

I hope this can help you.

Unfortunatly not that much

I think the stepper motor does not change direction well, but dont understand why, also I have trouble to find good documentation on how to configure marlin 2 for LV8729 both extruders and TMC2208 on X,Y,Z.

what is strange is that I ve search for the constante E0_DRIVER_TYPE into the whole source code of marlin 2.0 and I did not found where it was used ?

[DzzD]

Not finding a solution for the moment, I ve replaced the two extruders stepper drivers with the originals A4988

Maybe I will try also TMC2208 for extruders, because the video you linked to, suggest it should works even if some say they have not enought power.

If someone find a solution for LV8729 on extruders with Marlin 2.0, please, let me know...

[psxsnake]

many users did report to me that TMC drivers has issues with torque on M variants but its a direct cause of the anti back flow disks and people that removed them where able to use TMC drivers with the reduced pressure inside the bowden.

so remove the anti back flow is suggested on A20M... (I have to print first time with that printer in next days)

[psxsnake]

Which kind of issue if removed?

[psxsnake]

I just tried to replace the extruders stepper drivers with LV8729 using 64 microsteps.

Now something strange is happening , it does not change direction when it perform a retractation/repush filament.


But that dont help.

which vref you set up for this drivers?

[DzzD]

I ve tried 0.55v and 0.85V, both give the same result, it works 50% of the time and sometime it produce a double retractation rather than retracting and pushing back the filament, the motor does not change it direction after retractation and so it retracts twice.

[DzzD]

I finally sent back the LV8729 and I use TMC2208 instead, it works nice, only problem is that with linear advance they stop at mid print, I suppose stepers drivers overheat ?