SOLVED Z banding (?)

Discussion in 'Calibration, Help, and Troubleshooting' started by Alex9779, May 22, 2016.

  1. Alex9779

    Alex9779 Moderator
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    I need some opinions please...

    1) Is there Z banding in this prints?
    IMG_0012.JPG

    2) And in those?
    IMG_0013.JPG
     
  2. Alex9779

    Alex9779 Moderator
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  3. Stefan

    Stefan Well-Known Member

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    ... No problem with 100mbit/s :D

    I do not really see any issue, compared to google searching for "Z banging".

    But I'm no expert so.. other should comment too.

    bye
     
  4. Alex9779

    Alex9779 Moderator
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    Funny... I have 50mbit, upload took seconds, if I open it again I see every line of the image coming slowly, like at the time when I used a 28.8Kbit modem...

    It is called "head banging" :p
    I talk about "Z banding"... :rolleyes:
     
  5. Alex9779

    Alex9779 Moderator
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    Anyone else a comment?
     
  6. GeoffS

    GeoffS Member

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    I had a similar appearance on tall parts I was printing but ti turned out to be loose/worn belts on X and Y. Replaced the belts and problem solved


    I do have a spiral effect on prints that I can't sort out, not that it helps you :)
    [​IMG]
     
  7. Alex9779

    Alex9779 Moderator
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    @GeoffS thanks for the answer but I wanna know what you see on both prints. I made no assumption what there is so please describe what you mean when you say 'a similar appearance'. Is that z banding what you see?
     
  8. GeoffS

    GeoffS Member

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    Similar - having a resemblance in appearance, character, or quantity, without being identical

    When I had a 'similar' issue with my printer, I assumed Z banding but replacing the threaded rods with ACME screws made no difference, the belt replacement did.
     
  9. JohnEsc

    JohnEsc Well-Known Member

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    From what I've learned here on the forum, the G+ community, and my own research, I would say your @Alex9779 prints do not show signs of Z banding. I have learned though that a number of people are accusing Simplify3D of not handling curves all that well. I hear Slic3r smoothens curves much better than S3D, maybe they'll decide to do an update someday to improve some of their known bugs!

    Z - banding sample: https://ultimaker.com/en/community/17720-z-banding-when-ever-i-use-infill-whats-wrong
     
  10. Stefan

    Stefan Well-Known Member

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    Oh John's link... That's what I really call Z Banging :D
     
  11. Alex9779

    Alex9779 Moderator
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    Ok so how would you rate 1) and 2)?
     
  12. Tom De Bie

    Tom De Bie Well-Known Member

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    Doesn't look like z-banding to me. Z-banding mostly has a patern in it. ie, every 4mm the same line that jumps out. This has mostly to do with the quality of the z-axis rod. When using leadscrew this effect disapears...
    What I see on your pictures is a wobbely effect of the z-axis. This can be remedied by adding an extra bearing on the top and bottom of the leadscrew. Also think that fully inserting the leadscrew in the coupler isn't the way to go as this will amplify any movement from an uneven steppermotor shaft. In the wiki they say you have to fully insert it, but when you insert it until you can screw it in place the coupler will have more movement and will do it's designed work. ie, keep the leadscrew stable.
     
  13. JohnEsc

    JohnEsc Well-Known Member

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    I like the cylinders in image #1 but wasn't sure if it was a light reflection. What difference did you make to these 2? Layer height, temp, print speed...
     
  14. Alex9779

    Alex9779 Moderator
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    Just rate it, details maybe later...
     
  15. R Design

    R Design Well-Known Member

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    OK the first picture looks much better than the second.

    (Caveat it could just be the same cylinders rotated and / or in with a different lighting!)

    First of all I'd say there are vertical lines of the kind that seem to come when printing a bit fast. My interpretation is that they come from some kind of resonance that occurs when the nozzle moves in circles, possibly making many much smaller direction changes that correspond to the mesh. In other words the nozzle might be making a series of straight lines that are 1mm long to create the circle, but the resonance appears every 5mm... that kind of thing.

    If the cylinders were (hypothetically) printed again at a slower speed we could then concentrate on the horizontal bands.

    In the worse of the two images they seem to have an astounding regularity, there seems to be a pattern repeating itself all the way up the part.

    That is not what I experienced with bad bearings (that was much more random).

    But it might be lead screw related.

    (Turn the lead screw and see how much vertical movement one revolution corresponds to...)

    I think I've noticed that when I turn my BigBox on it's side to do something underneath and then put it back the right way up again, the bed / leadscrew mechanism can be unbalanced and start doing strange things a bit like that. A few prints later and it's kinda gone. Next time after turning on it's side plan to wind the bed all the way up and down a few times before printing.

    Well, that's just a few thoughts since you asked1
     
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  16. Alex9779

    Alex9779 Moderator
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    That's a
    That's a good idea! Didn't thought of something like that... maybe I should try the same with Slic3r and see if the arc feature kicks in...

    Good, I just rebuilt the whole motion system, cleaned all bearings and lubricated them with soap-based lithium grease as recommended.

    I was thinking the same, the lead screw is still "running in" the grease, cleaned them also, rubbed all the old grease away and when I reassembled I had the squeaking I had when they were new. So I think they were super clean again. Also the nuts...

    Very much appreciated!!!

    A problem I have is that I have nothing to compare since I know anybody doing the same 3D printing stuff in person... I lack the possibility of comparison...
     
  17. R Design

    R Design Well-Known Member

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    Yes, I think that's a problem that many of us have: the problem of points of comparison.

    I'm only printing in pale gray XT and, with the light held overhead, it's possible to see all the defects.

    My point of comparison is: what would it look like if it were perfect?

    Then I try to understand what's going on and come up with a plan of action.

    And then I try to forget about it all and get back to what I'm actually trying to use the printer FOR.

    The great hope being that eventually, at some point in the future, both my creations and my printing will be up to a level worth showing!
     
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  18. Alex9779

    Alex9779 Moderator
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    Yeah for me too but I have a problem that I want to optimize maybe too much. Comparing with shots Colorfabb or E3D makes on the filament promotion page are not a good base to start comparing...
     
  19. mike01hu

    mike01hu Well-Known Member

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    I'm with @R Design here. There are many variables here, as he knows I found out today:(, but the relatively even distribution of the patterns seems to point to a mechanical issue. For my input I might suggest that the repetition pattern will be a leadscrew effect but, assuming auto-leveling is turned on, you may also get an effect of Z-axis adjustment during X, Y, transitions, not from the actual Z movement but from the stiction effects of the leadscrew nuts and bushings. The BB design really needs longer support bushings on the Z-axis, say two shorter ones in each corner spaced futher apart in the Z plane, and better support at the top and bottom of the pillars and lead screw; press down on the front of the bed and it will move without much pressure, showing there is flexibility in the structure that should not be there. I'll stop here as I could go on for ever but @Henry feldman picked up on the bushing issue when comparing it with his CNC machine.
     
  20. Alex9779

    Alex9779 Moderator
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    I just wanna get a feeling so please don't try to analyse as much but just tell me how your parts look like: worse? better?
    And maybe which prints you'd say that's ok...

    We discussed the lead screw in a few posts, I still think the wobbling isn't that much of an issue because my lead screw has a lot of play. Though I don't think this is a problem because it is just the pitch that counts. The bed is quite heavy so only the upper thread pitch of the screw has contact to the lower thread pitch of the nut, that is always the case either if moving up or down, gravity "presses" the bed in that direction.
    Lubrication prevents sticking, but the bead is lead by the four corner rods, if those are stiff enough, and I think they are, the wobbling of the screws does not produce such effects...
     

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