Possible glitch in an STL file

[KevWhite65]

Cura Version

5.11.0

Operating System

Windows 11

Printer

Anycubic Chiron

Reproduction steps

I have the attached file that I have run through the Cura slicer. It did not give me any errors. What I did was rotate the piece 180 degrees so that the smaller part of the top of the piece was on the print bed. I did this because I wanted to print it without supports and this seemed the easiest way. I started the printing and since it was going to take over 4 hours, I left but occasionally came back to check on it. Twice it ended up in a big glob of melted filament. I tried printing a third time but stayed to keep an eye on it. After about 5 minutes, only 1% of the print, the printer pushed out a small glob of filament which immediately caused the part already printed to come off the print bed as the glob caught on the nozzle.
I am concerned that even if I try printing it without rotating it and using supports, it will still mess up. Can you please check the coding on this and let me know if there is a problem? Thank you.

Actual results

During the print, the extruder pushes out a large glob of filament that causes the nozzle to catch on the print and release it from the print bed.

Expected results

A clean print

Add your .zip and screenshots here ⬇️

BloodGod_Bottom.zip

[Asterchades]

First off, this will not print successfully without supports no matter the orientation. That floating collar in the middle has 90° overhangs that extend a considerable distance and will have no chance of resolving without supports underneath regardless of being flipped, and those skulls on the outside are similarly going to have dropped edges without them.

Further to this, by flipping it over you're giving the whole model an extremely small footprint. Just a single line is all that's going to be holding the print to the bed unless you're using a Brim, which is going to make it much easier for it to detach and ultimately cause a blob.

That being said, I cannot find anything which would directly lead to the behaviour that you're describing. The chamfer at the top is behaving unusually (or at least differently to what I would expect) but nothing which would be directly leading to it pushing out a blob of filament while stationary. Without the requested Project File or Support Package when submitting the issue I cannot test it with your settings, however, so it's possible that something you have set could be causing that. As such I would request again to provide one of those files for further inspection.

---

Tangentially, @HellAholic, I would like to ask you to double-check something here for me as well. Note the behaviour of the skin generation around the chamfer at the top of this model, which I've currently got flipped by 180° (the behaviour similar either way, it's just easier to see like this). This seems extremely inconsistent given the geometry, and also feels like it shouldn't be there at all with the Skin Removal Width being set to the same as the Wall Thickness. Decreasing the Skin Expand Distance to 0 will remove it but seems a less-than-ideal solution.

(Image is created using the default Custom FFF Printer definition, set to 0.4mm line width.)

It's possible this inconsistency is a contributing factor to the original issue.

[HellAholic]

@GregValiant Sorry
Asterchades,
It's complicated, set the top/bottom thickness to 1mm for example and those areas change to skin walls.
The default angle for skin expansion is 90 which means all skin will be expanded. The setting guide has some depictions for the feature. We've been looking into them for weeks 😛 Probably some changes will come in the future.

[GregValiant]

Not me this time. @Asterchades.

I do get some odd surface expansion (or whatever it is) when I slice it. I don't see a failure there, but there is a lot of motion going on.

I would print this "threads up" and with Normal supports. If it is printed "threads down" then it needs to be sunk into the build plate by 0.20 or 0.40.
(Since I wrote it and since it's sitting here, I would use "Support Interface Material Change". A single large flat interface is what it's perfect for.)

"During the print, the extruder pushes out a large glob of filament that causes the nozzle to catch on the print"
@KevWhite65 are you sure it's making a blob? That sort of behavior has not been reported here. It is far more likely that the nozzle is catching on something and breaking the model loose from the plate (mechanical failure due to low bonding on the plate). Settings like "Connect Infill Lines" can help with that as can enabling "Z-Hop on Retraction" which can mask it.

Please zip and post a project ("File | Save Project").
Without knowing your settings it's hard to tell exactly what might be going on.

[HellAholic]

Sorry (Greg), shows that I'm always thinking of you 😛 (As the first responder to the users' issues - Clarification)
There is a fail for Top Surface Skin being generated inside if you have top surface expansion value, we're busy to get that patched up for the 5.12 🚀 Hence my lack of brain function.

[GregValiant]

"...shows that I'm always thinking of you..."

St. Paula the Patient is starting to show some concern.

[github-actions]

This issue has been automatically closed because there has been no response to our request for more information from the original author. With only the information that is currently in the issue, we don't have enough information to take action. Please reach out if you have or find the answers we need so that we can investigate further.