Inconsistent Z ribbing/Banding

Discussion in 'General' started by Eviltoy, Sep 4, 2016.

  1. Eviltoy

    Eviltoy Well-Known Member

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    Hi Guys

    I am having a weird issue with my current setup. It is a wilson 2 running a e3d v6 and titan extruder. It would seem that I am getting inconsistent layers somehow. I switched leadscrews and belts already as well as ensured that everything is square. I have tried PID tuning the hotend and bed as well. Even tried printing with no heated bed and using different filaments. Everything seems rigid without play now but I still get the inconsistent banding. I recalibrated the esteps and get to 417 steps and that gives me a constant output of 100mm of filament. I will be switching to toothed idlers as a next step but then I would have exhausted all options. What could it be?
     

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  2. GeckoBox3D

    GeckoBox3D Well-Known Member

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    Is this with PLA or ABS? or both? what resolution does it occur at? Does it happen at lower printing speeds / acceleration / jerk settings?

    Ribbing / banding is a complex issue, affected by many variables. Even a slight deviation of 10 microns will cause banding. If the lead screws are not true, than it can force the plate side to side as it raises causing this issue, even if the machine seems rigid. In a similar vain, if the rods / screws are not true, binding friction may cause the motor to lose steps.
    Are your belts tight? if the belt is not tight,it will cause variation in print head placement. Switching to toothed idlers will not cure banding, but it will solve noise. If these bands appear regularly, and have a repeating pattern, especially across multiple prints it is most likely a mechanical issue.

    OR, it could be an extrusion issue. insufficient cooling will cause the print to curl on the edges, resulting in it being squished with the next layer, causing a bulged band. The top of your cube does appear to be curled. solve this by printing slower, increasing fan output (PLA only), or printing multiple items at once.

    It could also be over extrusion..... material has to go somewhere, right? Similarly, your retraction settings might need tweaking. long travel moves may cause the nozzle to ooze and be insufficiently primed for the next print move, or a retraction may skip steps causing too much / too little material to be deposited. This can be corrected for in some slicers, such as S3D with an 'extra length on restart' setting. This is often a fix that is hiding a mechanical issue in my eyes... if your extruder is missing steps regularly, you may have upped the steps per mm to account for this unwittingly. When you retract, it may or may not be losing steps now (depending on speed of retract), and so now you may be under or over extruded, depending on the time since the last retraction.
     
  3. Eviltoy

    Eviltoy Well-Known Member

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    Tried with PETG and ABS. Used .24 layer height for this specific example but I have tried .1, .12, .2. I am using a .4 nozzle. I tried printing with 4 cubes at once too with the same result although the bands are inconsistent. The wilson 2 is similar to a i3 just more rigid as it uses aluminium extrusions for the frame. I have played with the extrusion multiplier and retracts with the same type of issue. I will try realigning my Z leadscrews again but as it stands I cannot see any wobble on them. I used 2mm retracts on this specific cube but I have printed the same with 1 mm retracts as well and the pattern still persists. The belts are quite tight.
     
  4. Eviltoy

    Eviltoy Well-Known Member

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    I also tried printing from 50mm/s all the way down to 20mm/s with the same results. PRinted a single wall calibration and the inconsistent layers were present as well
     
  5. Eviltoy

    Eviltoy Well-Known Member

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    Update i realigned my z motors and tightened the extruder idler now i have a semblance of consistency image.jpeg
     
  6. GeckoBox3D

    GeckoBox3D Well-Known Member

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    'no wobble' does not equal consistency, you also need to ensure that all rods and screws are true 90 degrees. If for example they were at 89 degrees, this would give you inconsistent bands.

    There is no single answer unfortunately, just make sure to watch prints closely to rule out causes. If you believe build quality is still an issue, I suggest investing in a dial gauge
     
  7. Eviltoy

    Eviltoy Well-Known Member

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    They are all true i believe after the realignment and tightening of the idler i am now overextruding so i will recalibrate and report back
     
  8. Eviltoy

    Eviltoy Well-Known Member

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    Ok looks like i am not overextruding. Still getting the consistent bands not related to the pitch of the leadscrews. I have switched to flex
     
  9. Eviltoy

    Eviltoy Well-Known Member

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    Switched out stepper drivers and the same issue persists im at a loss
     
  10. Eviltoy

    Eviltoy Well-Known Member

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    Well i looked at everything i cannot see any wobble on the leadscrews whatsoever. I think you were onto something when you mentioned the extrusion as if i set my multiplier to .9 the ribbing is barely visible however it is under extruding at that point as top surfaces have gaps. I recalibrated the extruder as i noticed that i can extrude 100mm of plastic consistently but 50mm for some arb reason had big variances. I suspect i have a dodgy hobbed gear in my titan as it was of the first batch of extruders.
     
  11. GeckoBox3D

    GeckoBox3D Well-Known Member

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    How do the top surfaces have gaps? Pictures speak a thousand words... You may not be underextruding just based on top layers, it may be bad retraction settings, not enough top layers, not enough infill etc....

    Do you have microstepping on Z enabled? If so, perhaps consider switching to full steps. Full steps are normally adequate enough for the Z Axis. If you are missing steps, you will know straight away with full Z steps as they will be much more obviously squished. This will at least let you rule one more thing out.
     
  12. Eviltoy

    Eviltoy Well-Known Member

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    Ok will switch to full steps on the Z. I have 3 top layers running there is slight gaps in the top layers Ill try that. Could it perhaps be the stepper motor or driver going? Also I have turned off all retraction for the testing. Infill is set to 20% rectilinear.
     
  13. Eviltoy

    Eviltoy Well-Known Member

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    Left is .9 extrusion multiplier right is 1 with the same layer height of .2
     

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  14. PsyVision

    PsyVision Moderator
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    Try one at .85. Where are the gaps on the top, around the edge or between infill lines ?
     
  15. Eviltoy

    Eviltoy Well-Known Member

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    On the top and the infill looks stringy but its s3d and the rectilinear infill always is stringy in my experience. I'll give .85 a shot
     
  16. Eviltoy

    Eviltoy Well-Known Member

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    Ok tried that and same ribbing and parts are flaky
     
  17. Eviltoy

    Eviltoy Well-Known Member

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  18. Eviltoy

    Eviltoy Well-Known Member

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    Could it be that i got flakey stepper drivers? I have some decent drv8825 drivers that i can test
     
  19. PsyVision

    PsyVision Moderator
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    Maybe, it could be worth swapping them, nothing to lose.

    However, your top doesnt look that bad and the sides are probably the best yet... 80% FR :p
     
  20. Eviltoy

    Eviltoy Well-Known Member

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    Did i mention i have the first gen hobbed gear section on my titan not sure if that changes anything. I'll install tmc2100 drivers on x and y and 8825 on the extruder. I think z should br fine with the 4988 for now
     

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