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Partially Solved Blobs and stringing on prints - searched, calibrated, still no solution

Discussion in 'Troubleshooting' started by theman00011, Jan 1, 2016.

  1. theman00011

    theman00011 Member

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    So I have been facing this problem for a while and have been searching the forums and calibrating, everything I can find, to no avail. The problem is that on small to medium prints (large prints have pretty much no issue) there's large blobs and stringing all over it. (See pictures) I have lowered the temperature for the filament I am using which is 195 for PLA/PHA from Colorfabb to the lowest recommended temperature. The one on the left is at 210 degrees and on the right is 195. It helped a tiny amount but it isn't the source of the problem. I have double checked the E steps per mm and it extrudes to the 100mm mark perfectly every time. I am using Cura if that matters much. Any help would be greatly appreciated because I am at a loss for ideas and I really want to print small objects. Thanks[​IMG]
     
    #1 theman00011, Jan 1, 2016
  2. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    Either lower the overall print speed or set a minimum print time per layer.
    Also make sure the fan is running 100% after the first couple of layers.

    I suspect on small objects you are not giving the previous layer time to cool and harden before laying a new layer over it.

    This also explains why larger objects are better. The layer is cooled before it starts putting more plastic on top.
     
    #2 mark tomlinson, Jan 1, 2016
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  3. theman00011

    theman00011 Member

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    I have the minimum time per layer set to 10 seconds and the speed to 60 mm/s but I will slow it down and try again.
     
    #3 theman00011, Jan 1, 2016
  4. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    10 seconds is pretty fast for a smaller layer. Try 30... you need to give the plastic time to set.
     
    #4 mark tomlinson, Jan 1, 2016
  5. theman00011

    theman00011 Member

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    I tried at a slower speed and it helped a tiny bit but not much. I will change the layer time to 30 seconds and try again. Could it be a retraction problem or a stepper motor skipping or stalling?
     
    #5 theman00011, Jan 1, 2016
  6. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    Retraction can help to a point -- in this case it might reduce the stringing.
    Retraction helps you prep a non-print move by removing the filament so it doesn't string.
    Not seeing this as a stepper issue either if your larger prints work. If the larger prints had the same issue then something more fundamental would be at issue.

    No, I think it is just a scale problem. As you scale down the print other factors are affecting the heat management.
     
    #6 mark tomlinson, Jan 1, 2016
  7. theman00011

    theman00011 Member

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    That is true. It turned a 6 minute print into a 30 minute print but I will let you know how it turns out and if it's any better after it finishes. Thank you for the help.
     
    #7 theman00011, Jan 1, 2016
  8. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    You'll want to experiment with the minimum layer time ... if 10 was too fast, 30 might be overly slow :)
    Good luck.
     
    #8 mark tomlinson, Jan 1, 2016
  9. theman00011

    theman00011 Member

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    There appears to be less strings but the blobs are still there. The crack on the wall is from taking the print off the bed, probably poor layer adhesion from the low extruder temperature. I am still at a loss for how to fix these blobs and it is killing me.[​IMG]
     
    #9 theman00011, Jan 2, 2016
  10. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    Have you checked the eStep calibration? Given that it is smaller minor variances in extrusion will have more effect.
    It is easy and fairly quick to test.

    EDIT: Yes, I re-read you said you did this...crud ;)
     
    #10 mark tomlinson, Jan 2, 2016
  11. theman00011

    theman00011 Member

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    Yep, E steps extrudes exactly 100mm when told to. Maybe it is the USB connection. My computer has been slow lately and maybe it is causing it to pause briefly. Can you use a SD card without the LCD controller?
     
    #11 theman00011, Jan 2, 2016
  12. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    Yes, you can. Copy the GCode to the SD card and load it in the card reader (under the printer -- PITA without an LCD).
    Then launch the print from the SD card (which I can show you how to do with Simplify3D and one picture, never tried it with the others).
     
    #12 mark tomlinson, Jan 2, 2016
  13. theman00011

    theman00011 Member

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    Yeah, I found how to do it. But the more I thought about it, it probably isn't the USB because it would have showed up on 5+ hour prints.
     
    #13 theman00011, Jan 2, 2016
  14. WheresWaldo

    WheresWaldo Volunteer ( ͠° ͟ʖ ͡°)
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    So many things it could be, and it's frustrating, we know. It's not really a printer it is a small manufacturing plant, so you have to think differently. Try adding a bit of retraction and retraction hop, play with extrusion multiplier, try a different manufacturer of filament. There is no one answer, sorry I can't be more specific than that.
     
    #14 WheresWaldo, Jan 2, 2016
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  15. theman00011

    theman00011 Member

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    I understand it could me a multitude of problems. I just needed some suggestions on things to try because I was out of ideas. I will give those a shot and see if they help.
     
    #15 theman00011, Jan 2, 2016
  16. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    Retraction is a really good one.
    I have struggled with this sort of thing on ABS, but not so much with PLA.
     
    #16 mark tomlinson, Jan 3, 2016
  17. theman00011

    theman00011 Member

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    Right now my retraction setting in Cura is

    Speed: 40 mm/s
    Distance: 3mm
    Minimum Travel: 15mm
    Minimal extrusion before retracting: 0.02mm
    Z hop when retracting: .5mm

    Does everything seem about right with those?
     
    #17 theman00011, Jan 3, 2016
  18. Trama

    Trama Member

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    Not sure if this applies to cura but I found that with matterslice that the extruder retraction speed is also used for re-extrusion at the start of the next line. So if the speed is to high it just dumps out a large amount of filament at the first pass. Check and see if that is the case. When I reduced the retraction speed it went away completely


    Sent from my iPhone using Tapatalk
     
    #18 Trama, Jan 3, 2016
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  19. theman00011

    theman00011 Member

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    That seemed to have helped quite a bit. There are still some blobs on the corners but reducing the retraction speed appears to have eliminated a lot of them. Thanks
     
    #19 theman00011, Jan 3, 2016
  20. Trama

    Trama Member

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    The matter control web site has a calibration block file and is a real quick print to use when checking settings


    Sent from my iPhone using Tapatalk
     
    #20 Trama, Jan 3, 2016

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