Stepper motors strange toolpath generated


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Thread: Stepper motors strange toolpath generated

  1. #1
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    Default Stepper motors strange toolpath generated

    Hi Tom, I have a machine with 3 Steppers motors Nema 34, configured for 1600steps/rev, each axis has installed a quadrature encoder with 1024 ppr.
    The Input Gain configured in Kmotion is 1600/4096 = 0.390625.
    In X, Y and Z I have installed Zero backlash ballscrew, step 5mm, so in KmotionCNC the axis are configured for 8128 counts/inch.
    If I move 1inch of each axis using G0 or G01, it moves exactly 1inch.
    The problem is when I run the attached GCode, in someway it generates a strange toolpath like you can see in the attached picture.
    Do you have any Idea of what is happening?
    I dont have any Geo file configured.

    The trayectory planner is configured like this:
    Break Angle: 15
    CL Tolerance: 0.0005
    Corner Tolerance: 0.001
    Facet Angle: 0.5

    Thank you very much!

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    Default Re: Stepper motors strange toolpath generated

    What you are seeing is mechanical slop or backlash in your machine. The zone is full of posts with pictures with the same defect. It is caused by lost motion when reversing on the motors. It is always very pronounced while cutting circles.

    Ben

    Sent from my HTC6525LVW using Tapatalk



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    Default

    Quote Originally Posted by bhurts View Post
    What you are seeing is mechanical slop or backlash in your machine. The zone is full of posts with pictures with the same defect. It is caused by lost motion when reversing on the motors. It is always very pronounced while cutting circles.

    Ben

    Sent from my HTC6525LVW using Tapatalk
    Thank you very much for your answer. I have already configured a backlash compensation but I'm thinking now that maybe is a mechanical issue in the nut, because is very big the backlash, almost a milimeter, and maybe the velocity is limiting the amount rate and it never apply the compensation, I will to check it out.
    Thank you again.



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    Default Re: Stepper motors strange toolpath generated

    Backlash compensation is a sticking plaster solution at best.
    Once you involve cutting forces, backlash compensation can make things worse, as the cutter will pull/push the workpiece around.



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Stepper motors strange toolpath generated
Stepper motors strange toolpath generated