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"Capping" infill to support the next layer


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Posted (edited) · "Capping" infill to support the next layer



I have been researching this idea but can't find anything that seems to accomplish it.


Consider the following: you have a layer skin that reaches beyond the perimeter/wall of a previous layer's wall, but you have infill. However, the next layer's wall pattern includes geometry that can not reliably be printed in open, unsupported space due to turns, etc. Essentially, it's not technically overhang since it's inside a solid model but with infill it becomes overhanging. Simply bridging between infill lines isn't sufficient since the walls aren't perfectly straight lines. Is there a way to "cap" or skin the infill between the infill lines on the layer just prior to the layer that will need the support? I realize that I could easily solve this by doing 100% infill but that's major material waste.  "Gradual Infill Steps" is better but still has issues with very shallow angles resulting in still unsupported areas. I've poked around all the Cura settings, but can't find something that does the trick.


Here is a visual breakdown of the idea. For simplicity to reduce visual noise, I'm showing only the 2 layers in question, but these would be in the middle of a print. In the case of this example, they are layers 31 and 32. At this point in the model underneath this particular feature, layers 1-30 are just infill.


Layer 31: includes the infill lines with open spaces.



Layer 31: wall and skin "overhang" the infill's open space. While the skin lines would attach to the wall, at this point the wall is already collapsed in some places.



Here's another look but with "x-ray" to see the layer 31 infill lines underneath:



There are some sections that would basically be ok since they are fairly straight lines.

However, while not extreme, there are sharper turns that would stretch out straight - losing detail - or droop when adhered to the next infill line it contacts - causing more serious degradation if not outright failure of the print.


"infill capping" concept idea and outcome


Layer 31, but now with infill "caps" (solid yellow would be skin lines):



Layer 32, fully supported on top of the caps:



And again, layer 32, but "x-rayed":



Does such a concept or feature exist in Cura?

How challenging would this be to realize in a plugin?


Looking forward to the expert's and community's feedback.



Edited by peterlanoie
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    Posted · "Capping" infill to support the next layer

    This isn't something that you will be able to pull off with a plugin, since this behavior is handled by the slicing engine (which doesn't have plugins).


    Ensuring that the skin is properly supported is something that is on the backlog, but it's not something that we got to (yet). There are obviously also multiple ways to do it, so if you do have some tests / insights as to what works, we would be interested!

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    Posted · "Capping" infill to support the next layer

    Thank you for the reply and info. I haven't come up with any ideas on how to do this but will keep hunting.


    For a "capping" solution, I would imagine in the slicer that you could look at the print locations of a layer and see if they fall on an x/y location that is in between infill lines. Or examine all the spaces between infill lines, and see if there's lines above it on the next layer, then compute a skin fill in those infill spaces. I wonder if (depending on the approach) the process would end up in some kind of weird recursive situation: if you add a skin in infill space, does the process logic then think the layer below it should also have a "cap" support skin? Then you'd end up with 100% infill. :-(

    Not knowing the details of the slicer algorithm I obviously can't appreciate the complexity of it all.



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    Posted (edited) · "Capping" infill to support the next layer

    Just a bump for this post since it's very old. Has there been any progress on this? 

    This also applies to gradual infil, where we might have situations where the infill percentage changes creates infill lines that are unsupported. Gradual infill should also have some sort of knowledge of how the underlying infill lines are located as it steps between percentages.


    Edited by ThingWizard
    Clarification and added picture
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