Cura generates geometry not present in the original file

[GregValiant 1,245]

Yeah.  If it isn't reproduceable (and I can't) then the Cura team won't be able to do anything with it.  I think there is something going on with the model and maybe with your install of Cura.  Not being able to put a finger on the problem makes troubleshooting impossible and we're left with what I'm doing which is guessing.

[gr5 2,167]

So if I remember right, I asked you to publish a project file and you still haven't done that.  It's been many weeks.  If you can post a project file then I can probably duplicate the problem and if I can duplicate the problem then so can the cura team and we can create a github issue and get this fixed.

 

To create a project file, in cura, do "file" "save project as".  Then post the file it creates.  It will contain your machine settings, etc.

 

Oh wait - you *did* create a project file.  however the object was too big.  Cura wouldn't let me print it because the object exceeded the build plate.  Please scale down the part so it isn't so close to the edge of the printer and then duplicate the issue and *then* save the project file.  I still think the issue is related to your floating point processor.

[baltic 1]

23 minutes ago, gr5 said:

So if I remember right, I asked you to publish a project file and you still haven't done that

You remember it wrong 😉

[gr5 2,167]

Yes, I realize that now.  But could you please publish a new project file that gives the problem but where the part is a little smaller?  Somehow even though your project file had most of your machine settigns - somehow you modified the keep away zones or something.

[baltic 1]

It doesn't happen on smaller ones. Even if i scale that model down, it stops happening.

[GregValiant 1,245]

Just thinking here.

IdeaMaker reported "14 non-manifold edges".  If we consider them gaps where triangles come together, then scaling the model down narrows those gaps.  Maybe it narrows them enough that the gap falls below some threshold in Cura and they become too small to notice?

 

I did a quick test and scaled the original model up by 140%.  I still can't reproduce the extra surface though.  It was a nice theory until reality got in the way.

[baltic 1]

51 minutes ago, GregValiant said:

If we consider them gaps where triangles come together,

But the artifacts are not at triangles intersections.

I think ill find time to file the bug with all the info. Maybe other luckers, who also have it, could add something to it. And so we find how to reproduce it.

It's definitely a Cura problem, since it doesn't happen with 4.7 Only 4.8 and upwards.

[gr5 2,167]

On 4/29/2021 at 9:57 AM, baltic said:

But the artifacts are not at triangles intersections.

I disagree.  Several times.  In my posts above.  Please please please post a project file so I can try to duplicate your issue.  Again - your part was too big but in theory you can just scale it down to 90% (that's an option in cura - you don't have to do anything in cad).  I did that myself but then I didn't get your triangle issue.

 

So please duplicate your issue on a smaller part (or the existing part scaled down somewhat) and then post the project file and then lets see if greg or I can duplicate your issue.  If so then we can all 3 post in gitub issues and they cura software guys will likely take a look at the issue.

 

Oh and let's do this in Cura 4.9 (the latest) otherwise they'll just ask for you to get it to fail in cura 4.9 before they'll even look at it and if you don't reply it autocloses after a few weeks.  I speak from experience.

[GregValiant 1,245]

To update this thread...

There was a recent bug post on GitHub that appears to be this same problem.  The poster there was also exporting their model from Solidworks.

@burtoogle (SmartAvionics) has posted a patch HERE (which I am not Cura savvy enough to understand) but it would seem that he's confident it addresses this problem.