Need Help! Circles not round, 6040 laser machine


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    Default Circles not round, 6040 laser machine

    Hello all, I recently purchased a 6040 laser machine from China, after many tests I started noticing circles made on the machine don't come out round, the come with a slight oval shape which is more noticeable the smaller the circle is, can anyone offer some insight on the problem? I have tried tightening the belts, tightening the bearing holder screws, tested the steps per pulse unit, various speeds, changing the start point and the circle always comes out with the oval shape in the same spot as shown in the photo I've attached.
    Id really appreciate some help as this machine is my only income at the moment and I cannot make round our even small square shapes because they all come out crooked and wrong.

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    Default Re: Circles not round, 6040 laser machine

    You may need to examine your X & Y axis for calibration. Will each axis correctly travel a long calibrated distance?
    Any backlash?



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    Quote Originally Posted by KOC62 View Post
    You may need to examine your X & Y axis for calibration. Will each axis correctly travel a long calibrated distance?
    Any backlash?
    Yes, both are accurate



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    Default Re: Circles not round, 6040 laser machine

    To get an oval shape, one axis must be traveling a different distance than the other, for a given command. So, what can cause this difference?

    mechanical assembly not true?
    Friction?
    dynamic behaviour?
    i.e. acceleration not correct for the speed used.
    missing steps?
    CAD dimension error? ...



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    Default Re: Circles not round, 6040 laser machine

    Quote Originally Posted by KOC62 View Post
    To get an oval shape, one axis must be traveling a different distance than the other, for a given command. So, what can cause this difference?

    mechanical assembly not true?
    Friction?
    dynamic behaviour?
    i.e. acceleration not correct for the speed used.
    missing steps?
    CAD dimension error? ...
    i don't know what's causing this, it's very strange, the oval shape occurs always in the same direction no matter what i do, i can try it in all corners and with different speeds and all, but it always comes out with an oval shape that´s diagonal to the circle. Squares also come out crooked, like a leaning tour of pizza



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    Default Re: Circles not round, 6040 laser machine

    How did you verify the mechanical squareness of your X & Y axis?
    If you make a rectangle, say x=6", y=8" then then the "hypotenuse" should be 10", or some other test for accuracy.



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    Default Re: Circles not round, 6040 laser machine

    i have made several medium to small squares but never a bigger square, if that's the problem how to i fix the squareness of my axis? and wouldn't that only be noticeable on larger prints? i can make a 4mm circle on the edges of my bed and all come out the same



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    Default Re: Circles not round, 6040 laser machine

    I don't know your machine so I can't say how it should be checked for alignment.
    I'm going by theory and trying to help you find the answer.
    A circle has the formula X^2 + y^2 = r^2. To get it to be an oval means that one axis was not asked to be the same length as the other axis.
    By making the largest circle, or square, on your machine and then measuring each axis, may help to determine which axis is not working properly.
    You appear to get consistent errors in the same direction (axis?), correct?



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    Default Re: Circles not round, 6040 laser machine

    yes, but i have tried many tests in which i would change the steps per pulse unit and the circles would change yes, but the diagonal oval shape would still remain



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    Default Re: Circles not round, 6040 laser machine

    OK, I hear you trying steps per pulse.
    What is not clear to me is if you command the X-axis to move 10 inches, do you actually measure 10 inches? The longer the better in case of accumulating errors.
    Then a similar test for the Y-axis.

    Can you measure the exact error of a large "oval" circle in percent? And on which axis do you see the error? on one or both? e.g is oval diagonal?



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    Default Re: Circles not round, 6040 laser machine

    Is that a new machine? and you have tried tightening the belts and bearing holder screws, but still can't solve this issue.
    I am afraid it's very hard to solve it.
    this issue is caused by x, y axis calibration, a very slight error will make a big difference when you try to cut or engrave something.
    it is a very important working procedure when they build this machine, and they must test it before sell it.
    maybe you can ask your supplier for help? do they give you any good suggestions?

    E-mail:nolan@thunderlaser.com facebook:https://www.facebook.com/ThunderLaser
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    Default Re: Circles not round, 6040 laser machine

    Quote Originally Posted by KOC62 View Post
    OK, I hear you trying steps per pulse.
    What is not clear to me is if you command the X-axis to move 10 inches, do you actually measure 10 inches? The longer the better in case of accumulating errors.
    Then a similar test for the Y-axis.

    Can you measure the exact error of a large "oval" circle in percent? And on which axis do you see the error? on one or both? e.g is oval diagonal?
    i have tried about 10cm (4 inches) and it was short by about half a millimeter ( about 0.019685 inches), and this happened on both axis ( not surprisingly since they have the same steps per pulse unit) thus that doesn't seem to be the problem because it would not show as much on such small circles.
    As i stated and is shown in the pictures, the oval shape is diagonal yes, so it's even more strange... i'm running out of ideas :/



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Circles not round,  6040 laser machine

Circles not round,  6040 laser machine