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Thread: jerky

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  1. #1

    Join Date
    Feb 2019
    Posts
    67

    jerky

    Why does the machine work jerky? Before each line of the program there is such a jerk.

    TNG 2020.02.12

    Attached Files Attached Files

  2. #2
    Moderator
    Join Date
    Mar 2017
    Posts
    611

    Re: jerky

    Your Z speed is limited. And because Z moves it sets maximum permissible speed.

  3. #3

    Join Date
    Feb 2019
    Posts
    67

    Re: jerky

    The speed along the z axis is much lower than the limiting speed. I do not see the logic in such a limited.

  4. #4

    Join Date
    Nov 2015
    Posts
    145

    Re: jerky

    You have set F to 2500 in the program. Your Z axis can only do F2000.
    I suspect that the machine brakes every time.
    Set program F2500 to F2000, also for X. Then the bucking should theoretically be over.

  5. #5

    Join Date
    Feb 2019
    Posts
    67

    Re: jerky

    Yes, if you increase the speed limit it will work fine. But even if the z-axis is stationary, the machine will still twitch, this is wrong. I don’t know how the program algorithm works, but it’s wrong.

  6. #6
    Registered
    Join Date
    May 2008
    Posts
    253

    Re: jerky

    Try including a G64 command at the top of the program. If your machine defaults to G61, then you will get stuttering - check out the difference in the included gcode reference.

  7. #7
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    Join Date
    May 2008
    Posts
    253

    Re: jerky

    Actually, there might be a bug in the G61/G64 code because G64 seems to be ignored if you swap between these two gcodes.
    However, G64 does work straight after restarting TNG, but not after going to G61 and back again.

  8. #8
    Moderator
    Join Date
    Mar 2017
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    611

    Re: jerky

    G64 expects P value to set tolerance. Without P tolerance set, it should default to value in settings. I'll fix this.

  9. #9

    Join Date
    Feb 2019
    Posts
    67

    Re: jerky

    Quote Originally Posted by PlanetCNC View Post
    G64 expects P value to set tolerance.
    where is it set?

  10. #10
    Registered
    Join Date
    May 2008
    Posts
    253

    Re: jerky

    Just try something like G64 P1 and see how it performs.

    Check the Gcode manual the comes with TNG for more info.

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