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Thread: circles

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  1. #1
    Join Date
    Apr 2015
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    11

    circles

    HI Guys Me again.When I send code to cut a circle. it cuts a oval or if i send code for a square it cuts square on a angle.Don't know how to fix it.
    Could it be the drivers. I am using 4 axis tb6560 with Mach3 Help!!

  2. #2
    Join Date
    Mar 2009
    Posts
    533

    Re: circles

    You will need to calibrate your X-axis and Y-axis.
    Are your you using the same lead screw TPI for both X & Y axis?
    Are you using micro-stepping?
    I don't have your driver board, so I can't tell you how to set them up.

  3. #3
    Join Date
    Apr 2015
    Posts
    11

    Re: circles

    Thank you for your reply. Yes I am using the same lead screw on all axis its 1/2- 10- 5 start.I used mach 3 set steps per minute.on all axises I have A axis set as slave to Y axis. I am using 1/8 micro-stepping.Thank you

  4. #4
    Join Date
    Mar 2009
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    533

    Re: circles

    Have you tried moving 1 axis, say 5" very slowly, to see if it moves 5"?
    Then the other axis 5"?
    The reason I'm asking "slowly" is that acceleration could mess with the movements if it isn't setup properly.
    Somewhere something doesn't look like it is adjusted properly.

  5. #5
    Join Date
    Apr 2015
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    11

    Re: circles

    I will try that in a little while.And let you know what it does

  6. #6
    Join Date
    Apr 2015
    Posts
    11

    Re: circles

    I tried that and the Y and A axis together moved 4" exactly .I used G1 very slow And the X axis 4" exactly I even tried the Z axis moved exactly 1" .Also I have been using a feed rate of 25 is that to fast or to slow?

  7. #7
    Join Date
    Sep 2010
    Posts
    717

    Re: circles

    Also check back lash. Both the screws/nuts (pulling/pushing hard on the axis for starters) AND the mach3 back lash setting.
    Current build: http://www.cnczone.com/forums/diy-cnc-router-table-machines/264838-new-machine-desing-quot-cnm13-quot.html

  8. #8
    Join Date
    Apr 2015
    Posts
    11

    Re: circles

    I am using anti-back lash nuts. I found in mach3 in motor tuning step pulse it says 1-5 and dir pulse 0-5. mine is step pulse 0 and dir pulse 0. could that be my problem?

  9. #9
    Join Date
    Apr 2015
    Posts
    11

    Re: circles

    I also see in general config. A axis is set to angular instead of linear is that wrong

  10. #10
    Join Date
    Sep 2010
    Posts
    717

    Re: circles

    No I don't think so. 0 is the default, I have mine at 0 too, works fine.
    Double check the backlash with some force, it could explain the ovals...
    And also check that you have back lash comp. turned off in Mach3? If there is no back lash.

    - - - Updated - - -

    Quote Originally Posted by oldcoalminer View Post
    I also see in general config. A axis is set to angular instead of linear is that wrong
    Yes, that's wrong in your case.
    That's your problem I'm pretty sure.

    Hub
    Current build: http://www.cnczone.com/forums/diy-cnc-router-table-machines/264838-new-machine-desing-quot-cnm13-quot.html

  11. #11
    Join Date
    Mar 2009
    Posts
    533

    Re: circles

    Yes, as hub said, it is wrong. A-axis should be linear.
    However, if it moves a different distance than say the X-axis, it could jam your gantry.

    I think that the step pulse should be greater than 0. Some drivers require a minimum pulse width.
    Also, make sure that the pulse polarity is correct for the driver.

  12. #12
    Join Date
    Apr 2015
    Posts
    11

    Re: circles

    Well guys tried every thing you suggested and still no circles

  13. #13
    Join Date
    Jan 2007
    Posts
    1795

    Re: circles

    can you cut or draw a 5x5 in square with your router, and post the picture?

    it is definitely the two axis moving differently..

    the couplers on the two side.... might slip one of them..
    if it saved as slave axis, then mach sends same pulses for both side..
    so virtually they moving same distances..

    what ovality you measured?
    and what degree that inclined side approximately?

    if gantry has flex, then that also could cause it..
    but if gantry flex, or router can ""wobbling"" then difference small..

    a photo could help a lot more..


    when I used mach, I set 5 ns the timing on pulsewidth..

  14. #14
    Join Date
    Mar 2009
    Posts
    533

    Re: circles

    To refine our analysis, we would need more information.
    For example, if you could make a perfect square in G-code, what are the actual dimensions of the final result?
    Are the errors consistent every time? In other words, it's not lead screw slipping on motor shaft.

    When a circle is cut where does the oval appear? Along a X-axis?, Y-axis? or on a diagonal?
    And how much is it out?

    It needs to be determined where the error is coming from; faulty mechanics?, faulty Mach 3 settings? faulty driver settings?

  15. #15
    Join Date
    Sep 2010
    Posts
    717

    Re: circles

    Quote Originally Posted by KOC62 View Post
    Yes, as hub said, it is wrong. A-axis should be linear.
    However, if it moves a different distance than say the X-axis, it could jam your gantry.

    I think that the step pulse should be greater than 0. Some drivers require a minimum pulse width.
    Also, make sure that the pulse polarity is correct for the driver.
    A setting "0" is not zero.. It wouldn't work if it was zero -> no pulses at all.. It's the minimum pulse with, about 3us if I remember correctly. You can increase it if the driver needs by setting a value of higher than 0.,
    Current build: http://www.cnczone.com/forums/diy-cnc-router-table-machines/264838-new-machine-desing-quot-cnm13-quot.html

  16. #16
    Join Date
    Sep 2010
    Posts
    717

    Re: circles

    As the setting was wrong, you have distorted your gantry (more or less)..
    Try to disconnect screws from gantry and square it up again. Hopefully nothing is bent too much...
    Adjust until everything is square & straight.
    Then try again.

    Hub
    Current build: http://www.cnczone.com/forums/diy-cnc-router-table-machines/264838-new-machine-desing-quot-cnm13-quot.html

  17. #17
    Join Date
    Apr 2015
    Posts
    11

    Re: circles

    Well Guys i got it working. I rewired the motors per driver instructions and removed the terminals blocks I had motors connected with and hooked them up straight . And also changed enable pin for A axis. The only thing I need to fix now is Z misses steps going to set height at end of code. I think lead screw is a little out of line. Thank you all for your help. I really appreciated It.

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