Overstepping/Understepping Error



  • Hi,

    Don't know if anyone has ever come across this:

    0_1526612639037_stepper_driver_problem.jpg

    While controlling the printer manually from the web interface or from Repetier it seems to function normally. Sending GCODE moves the printer the desired distance in all three axes. Once a print is loaded and it begins running GCODE it turns circles into ellipses and misplaces almost entirely the infill/bottom layers within the brim.

    This printer (running on Duet3d Wifi) has moved from England to the US and the Y-axis runs on an external stepper driver due to the power requirements of the corresponding steppers. Besides a transatlantic move the only other real change is updating the firmware from 1.20 to 1.21 but as I've not seen any other similar issues I've tentatively ruled out firmware.

    Any help or thoughts welcome.

    Thanks

    Nate


  • administrators

    It could be that your M569 timing parameters are not right for your external stepper drivers. Firmware 1.21 allows you to set 4 different parameters, whereas previous firmware provided a single value. Check the direction-to-step setup time in particular.



  • @dc42 said in Overstepping/Understepping Error:

    It could be that your M569 timing parameters are not right for your external stepper drivers. Firmware 1.21 allows you to set 4 different parameters, whereas previous firmware provided a single value. Check the direction-to-step setup time in particular.

    Sounds like this might be the case.

    Is there any documentation you can direct me towards that might clarify parameters like these:

    "Taa:bb:cc:dd (firmware 1.21RC5 and later) Minimum driver step pulse width, step pulse interval, direction setup time and direction hold time, in microseconds"

    Would it be the within the stepper driver chip information (Toshiba6600) ?

    thanks


  • administrators

    Yes, it will be on the datasheet for the driver or for the chip on which the driver is based. But to see if that is the problem, temporarily try T10 in your M569 commands for the external drivers. If that solves the problem, refer to the datasheet to find a more optimum setting.


 

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