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Bridges with ABS

Discussion in 'Troubleshooting' started by supercazzola, Apr 5, 2018.

  1. supercazzola

    supercazzola Active Member

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    I'm having a bugger of a time trying to print the digital sundial that is up on thingiverse. In particular, the thin bridges while using ABS. I've tried some very low parts cooling fan to help the filament cool quickly, I’ve tried the lowest hotend temp and quicker print speeds, but I still can't quite get it right.

    What I see is the failure of the filament to span across the entire length of the gap. If the bridge has several layers, it will eventually make it across, but the bottom layers will show an arch, With the narrowest section being at the center of the bridge.. bridges with less height will actually never make it across the span.

    Tried with S3D and Cura for Robo.

    Any ideas ?

    [​IMG]


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  2. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    Well, been a long time since I messed with ABS, but I do remember that this specific use case (bridging) is one where you need to make sure the fan speed is set correctly and movement speed (for bridging) matters. Those are your knobs to tweak.


    We moved over to other filaments for heat resistance and abandoned ABS a long take ago so hopefully someone else (like @Geof ) can add more value.
     
  3. drbanks

    drbanks Active Member

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    I've done several kg of ABS printing, albeit on another printer, and while most of my prints were successful, anything that had any significant bridging was not. ABS likes a pretty warm build environment, meaning that the print cooling fan tends to be turned off, which in turn leads to an awful lot of sagging.

    I s'pose you could always turn the fan on and off around the bridging bits, but then you're going to be dealing with the cooled bits shrinking and possibly warping, so it just seems like you'd want to be using a different filament instead.
     
  4. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    That is in fact exactly what you need to tweak. Fan off (or very low speed) in general and boosted settings for bridging moves only.
     
  5. supercazzola

    supercazzola Active Member

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    How kick ass it would be if any of the slicing programs had the ability to flag sections (automatically or even manully) as bridges and then I could go back and turn fans on and off around them... with fans even at 10% for whole part, had significant warping and no additional help to the bridge


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  6. WheresWaldo

    WheresWaldo Volunteer ( ͠° ͟ʖ ͡°)
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    Cura, SLic3r and S3D already do this.
     
  7. supercazzola

    supercazzola Active Member

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    Really? I don’t see it jumping out at me.
    For example, where is it in S3D?


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  8. WheresWaldo

    WheresWaldo Volunteer ( ͠° ͟ʖ ͡°)
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  9. supercazzola

    supercazzola Active Member

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  10. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    Don't mind the crotchety older guy -- although pretty much my age :)

    He just gets tired of typing the same things over and over (I just cut-n-paste)
     
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  11. supercazzola

    supercazzola Active Member

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    The problem was I was looking at older posts where, apparently, this feature was not yet implemented in slicers, and was seeing it was too complicated... the forums are nice here, and I don't mind Waldo pointing out my memory issues... I’ll probably ask the same question again sometime. I still get intimidated by S3D...


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