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Different filament creates stringing issues

Discussion in 'Troubleshooting' started by niko001, Aug 25, 2013.

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  1. niko001

    niko001 New Member

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    Hi,

    I've printed a test print (5mm cube) with the blue PLA that was shipped with the Robo3D, and the print came out perfectly. I've since changed the filament to some green PLA (same specs, i.e. 1.75mm), and with the new filament, the print looks really bad (stringing issues, uneven layer density, etc.). Both were printed with the default settings provided in the "Getting started" guide (180°, 30mm/s perimeter speed). There's a sticker on the green PLA saying "170°-240°".

    From reading other threads on this board, I think I should do the following:
    - Increase retraction length to e.g. 4mm
    - Lower retraction speed to 10mm/s
    - Increase (?) the temperature to 190°

    Have I missed anything, or have you got any other tips&tricks?

    I've checked that the bed is level and re-checked the leveling of the z-axis.

    Thanks!
    Nick
     

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    #1 niko001, Aug 25, 2013
  2. niko001

    niko001 New Member

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    Thanks, Polylac, I'll try it out and will report back :)! I just didn't want to "waste" a test-print (for example by needlessly increasing the temperature when the right approach would have been to decrease it). I'll try it with a higher temperature.

    Edit: Yes, I believe the "not following the correct shape"-issue is due to the layers not sticking together. I watched the print-head during printing and the paths looked ok, the gcode-preview is also fine.
     
    #2 niko001, Aug 25, 2013
  3. polylac

    polylac New Member

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    Hmm... just try it out, some little prints where you can if it strings or not.
    I guess a increase in temperature yould solve it, because it gets more liquid.
    It's a know issue that different colors behave a little bit different.

    on the other hand it looks like sometimes the printhead doesn't follow the round shape?
    Is this only becaue the layers don't stick togehter? (is the preview in repetier ok?)
     
    #3 polylac, Aug 25, 2013
  4. polylac

    polylac New Member

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    to be honest I'm not 100% sure, but I really think is something like that. If the temperature is lower then you extrude less and the layers don't bond so good (because it has to melt the old layer just a little bit to melt togehter).
    And strings are caused by a high viscosity (honeay does, water doesn't) so i guess it's this.

    Also you won't waste much filament, you need to print mabey 5mm high and you see if it does or not.
     
    #4 polylac, Aug 25, 2013
  5. tesseract

    tesseract Moderator
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    Welcome to the fun world of 3d printing things can change with the humidity in your area how long the filament is exposed to air before being used depending on where you live you may have to preheat it to dry it out before using. I am in CA so our humidity is relatively low but there are lots of issues I did almost the opposite of what you show in your settings for retraction and everything thing seemed to be doing just fine then I opened up my BLACK ABS and the strings are back but for my other materials the settings I have seem to work fine

    Currently mine retraction is set to
    0 length which may disable the whole thing but the other settings are as follows
    .3mm lift
    25 speed
    0 extra on restart
    0 minimum travel


    sorry if this confuses you even more but basically it is a try and find out what works for where you are and the material you are using
     
    #5 tesseract, Aug 27, 2013
  6. Printed Solid

    Printed Solid Volunteer Admin
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    Hi Nick,
    Turning up the temp should work just fine. It is quite normal for different colors or brands of material to require slightly different temperatures for optimal printing.

    Just to clarify terminology to help troubleshoot other issues, the picture you posted is not a stringing issue. The extruded filament is too cold to stick to the previous layer so the hot end is actually pulling filament off the part as it moves around the diameter.

    Stringing looks more like little hairs (or even big plates if it's bad) coming off of the part. If that was the issue then I would actually say turn up the retraction, turn down the temperature, and increase the speed of non-print moves.

    By the way, I know if hurts, but get used to the idea that you're going to throw some prints away. You're learning how to use a new machine. The best way to learn is by failing sometimes.
     
    #6 Printed Solid, Aug 28, 2013
  7. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    Good advice. Just had to T/S some stringing on one roll of ABS we had. Same vendor and all as others, but that roll liked it 5 degrees C cooler.
     
    #7 mark tomlinson, Oct 27, 2013
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