Infill printing before perimeters despite "infill before perimeters" unchecked!
 

Infill printing before perimeters despite "infill before perimeters" unchecked!  

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ccamp88.rupk
(@ccamp88-rupk)
Active Member

I'm having a strange phenomenon that I've observed on a few different prints (but not all) which has stumped myself and the unofficial facebook group. 

TLDR: Some layers seem to be printing before infill despite "infill before perimeters" the setting, causing an inconsistent horizontal bulge in the perimeters. Read on for my troubleshooting context.

On both the Calibration-Castle and 3D-Benchy I've noticed this bizarre banding that at first I thought was a mechanical issue due to its consistency. But then I realized that the artifact is not present when slicing and printing with my Cura profile. I decided to watch the prints with my own eye, since they're not long, and what I saw was very strange. Before I describe it, I should add that I had "solid infill threshold" on so for the Calibration Castle, several of the layers were totally solid, including the layers in question.

With Calibration Castle, for every layer beneath and above this banding, Perimeters print as expected, before the infill. However, right at the point where the banding begins, I noticed that the infill printed BEFORE perimeters. And just a couple layers up, where the banding ends, perimeters began printing first again. I then checked, and "Infill before Perimeters" is most definitely unchecked. With Benchy, the layers that print before perimeters are technically top-layers, but they should still be printing after as well.

So I then turned off the "solid infill threshold" for the cali-castle model, and as expected, the layers with the bulge still print before the walls, but there is no sea of plastic forcing the walls outward and the bulge is almost completely gone.

Can anyone explain this? I've tried to document my best and include pics. Let me know if more info needed.

Posted : 26/10/2020 5:43 am
ccamp88.rupk
(@ccamp88-rupk)
Active Member

It seems like some of my images got cut off. Some corrections:

  • In the 1st image Solid Infill Threshold is set to 70, and remarks that flow tuning and other adjustments removed other artifacts but the band remains
  • In the second image Solid Infill Threshold is off
  • In the third and 4th and 5th images Solid Infill Threshold is set to 70
  • The 5th image also shows a cube printed with Cura that has no such artifact.
Posted : 26/10/2020 5:49 pm
Neophyl
(@neophyl)
Noble Member

Have you read https://help.prusa3d.com/en/article/the-benchy-hull-line_124745   The Benchy hull line is a well documented phenomenon.  

Also why would you want to use the solid fill option without good reason ?  Iirc its set to zero on the prusa profiles.  Its there for when certain parts need it, which in reality means almost never.

Posted : 26/10/2020 6:39 pm
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 -2
(@-2)
Illustrious Member

Bulging is a known issue with Prusa Slicer - but I think you may the first to notice the perimeters on bulging layers are being printed AFTER infill.  A bug report over at github is in order.

It is always wise to get more than one opinion... as for trusting Prusa? No way man....
Posted : 26/10/2020 6:56 pm
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 -2
(@-2)
Illustrious Member

Well - I was curious so I downloaded and printed that cube using 100% defaults at 0.20 Quality on my Mk3. It prints without bulges. 

It is always wise to get more than one opinion... as for trusting Prusa? No way man....
Posted : 26/10/2020 7:53 pm
ccamp88.rupk
(@ccamp88-rupk)
Active Member

@tim-m30

I definitely don't doubt it. I have just switched over to PrusaSlicer from Cura, and after porting over most of my settings this is the result. But after pouring over everything available in PrusaSlicer though, I can't imagine which one could be causing my issue. It also doesn't help that PrusaSlicer doesn't label which features are which in the g-code like Cura does so I can't just upload my g-code to prove that the infill gets worked on before the perimeter.

Posted : 26/10/2020 8:45 pm
ccamp88.rupk
(@ccamp88-rupk)
Active Member

@neophyl

Yes I'm aware of the hull line, however in other slicers I've been able to tune the artifact out mostly and I'm also aware that I don't need to be printing with solid infill normally. This issue persists across other models beyond benchy though. I've listed just two examples. But the core of the issue here is that I'm saying I have observed, with my own eyes, that the infill is intermittently printing before the walls which is certainly not the desired result, regardless of if I "need" to be printing with solid infill or not. Maybe I should try to capture this on video, a timelapse would definitely not do it.

This post was modified 4 weeks ago by ccamp88.rupk
Posted : 26/10/2020 9:03 pm
Neophyl
(@neophyl)
Noble Member

I’m not giving any reasons for or against, just trying to help.  Like the fact that there’s an option in the print settings to turn on verbose gcode, which iirc does label the parts of the gcode.   That might help you with whatever investigation you want to do. 

Posted : 26/10/2020 9:50 pm
ccamp88.rupk
(@ccamp88-rupk)
Active Member

@neophyl

:O that is hugely helpful, thank you. 

Posted : 26/10/2020 10:20 pm
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 -2
(@-2)
Illustrious Member

By the way - there's another complete thread on bulges - search for "buldges" ... lol.

https://forum.prusaprinters.org/forum/original-prusa-i3-mk3s-mk3-how-do-i-print-this-printing-help/buldge-when-print-reaches-solid-layers

It is always wise to get more than one opinion... as for trusting Prusa? No way man....
Posted : 26/10/2020 10:28 pm
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