GcodeCNCDemo incomplete movements

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  • #6087
    AvatarAnonymous
    Inactive

    Hi,

    The movements made by the stepper motors when adressed via GcodeCNCDemo6axisV2 in my test case are incomplete ( fewer steps made than sent via serial monitor). Please make suggestions for the possible cause and remedy.

    Thanks

    #6969
    AvatarAnonymous
    Inactive

    – stepper motor steps-per-turn differs from firmware setting.
    – faulty wiring to stepper motor
    – damaged H bridge IC.
    – low power (not enough amps)
    – high torque (something fighting motor)

    … that’s all I can think of at the moment.

    #6970
    AvatarAnonymous
    Inactive

    Hi,

    I tested a bunch of stuff but did not yet find the bug :

    changed number of steps in the lists of costants – no effect
    changed the motors (2) to those sold by adafruit (bipolar serial wiring) 12V 0.35 A and 35 Ohms per phase
    varied stepper speed via speedrate and motor->setSpeed() : speed changes, number of steps moved seems the same
    Power supply :12 V , 90 W (8V, 5VA before)
    There is no load on the motors
    changed the onestep command from interleave to double

    When entering e.g. G00 X200; it does one turn as it should
    G00 X-200; will result in two turns in the other direction, not just one

    I need to search for an explanation of this behaviour, hints are welcome

    Thanks

    #6971
    AvatarAnonymous
    Inactive

    x200 and x-200 are absolute values. from +200 to -200 is |400| steps. that is correct number.
    if you want relative movements it’s… g90? g91?

    in relative move g0 x200 will be absolute 200, then g0 x-200 will be abs 0.

    #6972
    AvatarAnonymous
    Inactive

    Hi

    After opening the serial monitor, I entered a single command G00 X200 Y200; . With steps per turn set to 200, it should do one rotation independent from the mode selected.Now I observe it actually does about a half rotation in both cases, also for -200. M114 yields as position the number of steps entered, +-200 for both steppers. Whether it is exactly half I cannot tell. Both steppers always do the same numbers of steps (equal number of steps in the command). The movements made do not, as far as I can tell, differ from test to test. Changing steps_per_turn has no effect on the behaviour. O.K. I did not pay attention to the different modes, but this obviously is not the cause of this trouble.

    Tomorrow, I will review the wiring, but I dont think that’s it.

    #6973
    AvatarAnonymous
    Inactive

    consider absolute mode:
    g0 x200 is 0+200.
    g0 x-200 is 0-200. from the previous position, +200 to -200 is -400.

    consider relative mode:
    g0 x200 is 0+200.
    g0 x-200 ix 0+200-200, or 0, back to starting position.

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