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Unresolved How to calibrate X and Y steps

Discussion in 'Troubleshooting' started by Terry Reilley, Aug 17, 2016.

  1. Terry Reilley

    Terry Reilley Member

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    Hi everyone!

    I've been running a few test prints lately and noted that my X and Y measurements are off, indicating the possible need to calibrate steps on those axis's (axis, axes, plural of axis?). I used a 140mm square object with a 70mm loop in the middle. Here are the measurements using a digital caliber:

    X-axis - 140.1 mm
    Y-axis - 139.9 mm

    My calipers measure only to the tenth, so that is the max precision I am working with today.
    I used a formula to adjust the steps as follows:

    (Desired Length/Actual measured length) * Current steps

    When I made the adjustments, my square is now actually - well - square AND the circle is actually round on every 90 degree measurement. BUT, the measurement is still 140.1 all the way around. Filament doesn't expand obviously, so I'm thinking I need to repeat the formula until I get it just right but then I had an epiphany:

    Am I really wasting my time with this since filament shrinks as it cools off? Is a 0.1mm tolerance acceptable? To me, it really isn't because it makes the difference whether pieces fit together well of not. For example, I printed a AA battery storage tray (prior to the adjustment) and the darn batteries didn't fit. That's why I decided to check the calibration.
     
    #1 Terry Reilley, Aug 17, 2016
  2. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    Tolerance is whatever you can stand.
    Different types of filaments have different swell and shrink. Trying to get too precise is a 'game'

    The numbers you initially quote:

    X-axis - 140.1 mm
    Y-axis - 139.9 mm

    are not horrible for this type of process. You can certainly 'dial them in' with some adjustments, but you should not be surprised if they are off again for a different filament. ABS, PLA, Nylon, PC, etc. all have different behaviors and different brands will even behave differently (not in general, but in detail they will).

    This is not a CNC machine :)

    P.S. you are not the first person I have had similar conversations with around this behavior.
     
    #2 mark tomlinson, Aug 17, 2016
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  3. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    For what it is worth SLA printers (and DLP) are not going to have the same behavior as FDM.
    Those can be dialed in very tight ...
     
    #3 mark tomlinson, Aug 17, 2016
  4. WheresWaldo

    WheresWaldo Volunteer ( ͠° ͟ʖ ͡°)
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    Please don't try to modify the steps for X and Y to "FIX" this. you can likely get a bit more accurate by double checking belt tightness and some slight messing with extrusion width/overlap/multiplier.
     
    #4 WheresWaldo, Aug 17, 2016
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  5. Terry Reilley

    Terry Reilley Member

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    OK, I understand what you're saying. I tightened the X carriage belt a good bit and it did make a difference. I will check Y axis this morning. As far as the extrusion info you mentioned, are their any recommendations? I'm using S3D with an E3D v6 mounted on Titan and use 1.0 multiplier and 0.48 width. Overlap is 18%.
     
    #5 Terry Reilley, Aug 18, 2016
  6. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    #6 mark tomlinson, Aug 18, 2016
  7. Terry Reilley

    Terry Reilley Member

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    Yes, I left mine as AUTO as well. I'm going to reset the steps back to 80 for both axises (?, lol) and then reduce the extrusion from 1.0 to 0.9 and see what kind of difference that makes. I've read that the recommended factor for PLA is 0.9 and 1.0 for ABS.
     
    #7 Terry Reilley, Aug 18, 2016

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