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Engraving is not symmetrical

Discussion in 'CNC Mills/Routers' started by tsopkow, Apr 17, 2021.

  1. tsopkow

    tsopkow New
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    I have a very simple engraving (See attrached picture) and you will notice that one side of the engraving is wider than the other. The distance between the lines in each closed vector should be the same.

    This is a router that I built based on the workbee design and is running belt drive for x and y axis. The controller I am using is an openbuilds blackbox.

    I have checked the play in both the x and y direction of my machine. I have made sure the calibration in the x and y are the same. I have machined the edges of a sample board and checked that the corner is 90 degrees.

    I am hoping somebody can offer some advice on how I can correct this problem.



    engraving problem.jpg
     
  2. Rob Taylor

    Rob Taylor Master
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    Does it happen everywhere across the machining area? Odd that the lines are spaced differently, but the terminal serifs are equal lengths in the exact same axis. Seems to rule out uneven screws. Maybe Y axis racking based on cutting direction? The right hand motor is leading the left hand motor, but not when it's a Y-only movement?
     
  3. Christian James

    Christian James Journeyman
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    Quote: "I have made sure the calibration in the x and y are the same."
    Not sure what you mean, but both axes should be calibrated independently - they will not necessarily have the same setting in grbl after calibration is complete. Looking at those slopes in the pic, it looks like one of the axes is moving at a different "rate" to the other.
     
  4. tsopkow

    tsopkow New
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    Sorry that was my poor wording, each axis was calibrated independently.
     
  5. Peter Van Der Walt

    Peter Van Der Walt OpenBuilds Team
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    Can you do a couple more test pieces. Like the classic circle, diamond, square. Other, more predictable, test cuts. It may help is with some more insight into which axis is misbehaving. Also give all your shaft coupler grubscrews a tightness check
     
  6. tsopkow

    tsopkow New
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    Attached is a picture of a square, diamond and circle. It looks like the circle is not quite round.

    cnc shapes.jpg
     
  7. JustinTime

    JustinTime Veteran
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    I think that what Peter meant was something like this

    Test.png
    It will give a better indication where the problem is.
     
  8. Alex Chambers

    Alex Chambers Master
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    Your attachment doesn't work for me @JustinTime.
    Alex.
     
  9. JustinTime

    JustinTime Veteran
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    I was editing it and you must have looked at it while I was editing.
     
    Alex Chambers likes this.
  10. Rob Taylor

    Rob Taylor Master
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    Yeah shows for me.
     
  11. tsopkow

    tsopkow New
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    Ok, I can do this tonight when I get home from work.
     
  12. Peter Van Der Walt

    Peter Van Der Walt OpenBuilds Team
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    Called the “Circle Diamond Square” test. It’s real name is “B-NAS 979; Composite cutting test 4.3.3.5” (;
     
    Giarc likes this.

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