(Weird asymmetric) z banding problem

Discussion in 'Calibration, Help, and Troubleshooting' started by fpex, Jul 10, 2016.

  1. fpex

    fpex Well-Known Member

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    I have now moved back to nGen (first time on hybrid) a wonderful material, which breaks easily I know.
    I am printing test figures for calibration in the centre and I notice some weird asymmetric z banding. It is present left of the centre but not right ...
    My feeling is that it is related to retraction as I can always see a tiny blob on the left side followed by something which could be banding which disappears towards the end on the right side of the print.

    I never saw this so I am doubting. Any other possible explanation for Z banding on one side and not the other?

    I will try with a negative "extra retraction distance" to see if the problem is over extrusion instead of banding. Thanks for any other suggestions I could try to get to a perfect print.
     
  2. fpex

    fpex Well-Known Member

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    I inspected also my prints in PLA and it looks like this behaviour is typical only of the titan direct. nGen shows it more.
    Strange.
     
  3. fpex

    fpex Well-Known Member

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    Sorry to bump this up, but I keep seeing this strange banding on the left that is not present on the right and I have no idea what to do to fix it any longer. One side prints amazing the other is not that impressive.
     
  4. Dr Jeep

    Dr Jeep Well-Known Member

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    something on one side (left to right) might also be cooling related ?

    have you tried messing with the settings in the slicer that adjust where each layer starts (shortest path, random etc) at least that would prove it's retraction related by moving the start points.
     
  5. fpex

    fpex Well-Known Member

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    I have tried several things resulting I much bettere result, especially tuning the layer thickness and retraction. But banding stays. Today I will try a long print and also checking for wobble, even if this happens only on one side and is mostly visible with sides parallels to the Y axis
     
  6. fpex

    fpex Well-Known Member

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    I am now doing another tall print. First inspection shows some wobbling on both axis. I have had worse with no impact in prints and normally I would expect wobble to show on the overal perimeter.
    I tried to remove the wobble but it seems rather impossible. :-(
     
  7. Dr Jeep

    Dr Jeep Well-Known Member

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    Can we see a photo ?
     
  8. fpex

    fpex Well-Known Member

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    Once the print is finished (9 hours to go) I will take some photos to show what my issue is
     
  9. fpex

    fpex Well-Known Member

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    Printer is still busy, but I managed to ... obtain the same banding on the entire print now. I reduced wobbling and changed settings further.
    As the printer is busy I could only take a photo with my phone, so sorry for the bad quality photo.
    Print is at 0.2475 layer with nGen, banding can be seen with the light at a angle (so it is not that bad). I will try to see if reducing extrusion and playing with temp further will have any effect as I feel that nGen also makes it worse (while softer materials like ABS+ make it better).

    [​IMG]
     
    #9 fpex, Jul 18, 2016
    Last edited: Jul 18, 2016
  10. Eviltoy

    Eviltoy Well-Known Member

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    @fpex did you manage to resolve this?
     
  11. fpex

    fpex Well-Known Member

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    Yes, it was combination of less extrusion, tightening few things and (most of all) adjusting the layer thickness to a value not the standard round ones.
     
  12. Eviltoy

    Eviltoy Well-Known Member

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    bleh so I have a different issue then. Tried all sorts of layer heights. I used the prusa calculator and it said to use 0.24 but I still get that. Thanks for the reply dude
     
  13. fpex

    fpex Well-Known Member

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    what material are you using? I am surprised that the calculator gave you such a nice number .... normally it is a weird one.
    In my case I has to also recalculate the pitch from the z steps (which i set based on calibrating the actual movement) and then the layer thickness
     
  14. Eviltoy

    Eviltoy Well-Known Member

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    ABS and PETG.
     
  15. fpex

    fpex Well-Known Member

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    Check my settings and see if that helps. Check my layer thickness
    Just note that not all ABS and PETG are born equal.
     
  16. Eviltoy

    Eviltoy Well-Known Member

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    Will give it a shot. Note that I have 8mm leadscrews with 8mm pitch so my steps are set to 400. Do you have a different value calibrated?
     
  17. fpex

    fpex Well-Known Member

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    I set up the steps according to calibration. I measures movements and extrusion and changed steps in order to get as close as possible.
    I did this by printing 20x20x20 mm cubes. Then I use the step to calculate the effective pitch and I use this value instead of the real pitch to calculate the layer thickness.
    Also of you are using socks, ditch them. They can generate what seems banding and make a mess of the heater blocks. After several prints I think they are to be used only when necessary and mostly never
     
  18. R Design

    R Design Well-Known Member

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    @fpex I've never done any of these Z axis layer height calculations and would love to improved the look of the sides of my parts. ;-)

    Can you talk me through the science and how to perform the calculation?
     
  19. mike01hu

    mike01hu Well-Known Member

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    You are wrong here. Provided you have fitted the nozzle correctly the socks have no effect on extrusion other than holding the temperature well and insulating the sensors from the cooling air blast. All those I know that use them are very happy.
     
    PsyVision likes this.
  20. fpex

    fpex Well-Known Member

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    I am not happy with them. With some material it s fine, with flex they are a pain.
     

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