Gap between wall and infill when using settings modifier

[krikru 1]

Hi,

 

I have a model in which I want to fill in some parts completely, i.e., 100% infill density. To achieve that, I use extra models which I set to "Modify settings for overlap," place them over the regions I want completely filled, and choose "Infill Density" 100%. However, when I preview the first layer that is not a bottom layer (see inserted image), I notice that there is a small gap between the wall and the infill, which I suspect will weaken the model (which is the opposite of what I want!).

 

Where does this gap come from and how can I get rid of it?

 

There is no such gap between the wall and the bottom in the bottom layers (which are just below the layer currently being previewed).

 

Edited February 25, 2022 by krikru
Rephrased

[krikru 1]

Hello? Can anyone in this community please explain this behavior? And how to remove the gap? I have also marked this as a bug, so I think that some developer should at least take a look at it if no one can explain why this happens!

 

I'm using Cura 4.10.0.

Edited March 18, 2022 by krikru

[GregValiant 1,248]

Open that model in Cura and set up Cura as you did to create the problem area.  Then use the "File | Save Project" command and post the 3mf file here.

[krikru 1]

Gap.3mf

I created a minimal working example and uploaded that. I attached an image showing a gap where there is supposed to be no gap IMO and that would weaken the print considerably.

 

[krikru 1]

What do you think? Is this a bug or desired behavior? (I don't see who would want to have this behavior, though.)

[GregValiant 1,248]

Sorry.  I forgot about this.

I did play with it and I couldn't get the gap to go away.  Go over to GITHUB and post a bug report.  Do a complete write up and post the project file.

As a work-around did you try using a Cutting Mesh set to 100% infill?

[krikru 1]

Why should I do that work? Doesn't Ultimaker care about Cura enough to do it themselves? I have taken the time to describe the issue completely here and you were able to reproduce it. Going to Github and reporting the bug there shouldn't be a problem for any Ultimaker developer.

Edited April 21, 2022 by krikru

[GregValiant 1,248]

I'm not a developer, I'm a Cura user.  If a bug report isn't made then how would the Ultimaker Team know there is a potential problem?

Furthermore, on a personal level I don't see that .2mm gap as a problem and I don't agree that it would  "...weaken the print considerably".  In an actual print the gap may not even be there.

And thirdly, the situation doesn't occur with Cura Arachne and so maybe it has already been addressed.  Cura 5.0 Beta is out today.

 

[krikru 1]

Okay, I apologize but I assumed that either you were a developer or that at least the developers would read the threads that had been tagged as "Bug" here, since this is Ultimaker's own forum.
 

About the gap in the model, I'm not a structural engineer, but I think a 0.2 mm gap between lines that are only 0.4 mm wide themselves can potentially have a quite large impact. Similar to how Cura ensures that a support comes off easily by adding a vertical gap between the model and the support, I think the bonding between the two extrusion lines is likely to be compromised if there is a horizontal gap between them and act as a weak spot should the model need to take some load (if the two lines wouldn't even touch physically, there wouldn't be any bonding to speak of at all). When watching some of CNS Kitchen's videos (this channel investigates how different print settings and methods affect model strength; I can recommend it if you haven't seen it), it becomes apparent how much different things can affect printing strength.

 

Hopefully you're right though and that it's fixed in Cura Arachne.