Missing Layers After Slicing ~ v5.1.1

[hunter.schoonover]

I have four parts on the print bed in SImplify3D... when slicing, I can see missing layer lines in the previewer.

What's even stranger is that the missing layer lines....

> are not always in the same part.
> are not always at the same height in the same part.
> are not always present. Sometimes, the preview does not show any missing layer lines.

The variations listed above can be achieved by the following:

> translating the parts on the bed surface. Part placement can result in all 3 variations above.
> scaling the parts uniformly.
> changing print layer height.

Can someone please advise?

As of right now, I do not believe this is an issue with the models. For reference, I am using Onshape to create my models.

[hunter.schoonover]

New development....

This issue seems to be related to part placement.

Here's a recent test I did:
1. I removed all other parts except one that had a single missing layer line.
2. Resliced.
3. Still had missing layer line in same exact spot.
4. Clicked center and arrange.
5. Resliced.
6. Missing layer line gone.

I just found this issue in a previous print I sliced as well. I never saw these issues in versions prior to v5.

Any advice? Is this a known bug? Is S3D working to resolve it?

[S3D-Jason]

Can you share a factory file for the print (File > Save Factory File As)? Hard to give suggestions without being able to experiment with the actual model.

Also, if you haven't seen it, there's already a good tutorial on our site that explains the best practices for working with problematic models:
https://www.simplify3d.com/resources/ar ... sh-errors/

Trying the different region repair modes at the bottom of that article can work wonders for really stubborn parts.

[hunter.schoonover]

Can you share a factory file for the print (File > Save Factory File As)? Hard to give suggestions without being able to experiment with the actual model.

Also, if you haven't seen it, there's already a good tutorial on our site that explains the best practices for working with problematic models:
https://www.simplify3d.com/resources/ar ... sh-errors/

Trying the different region repair modes at the bottom of that article can work wonders for really stubborn parts.

Thanks for the reply Jason.

The Factory File is too large to attach, so I added it to Dropbox. Please find it here:

https://www.dropbox.com/s/boldbc687troc ... ctory?dl=0

Thank you for suggesting that article.. before posting, I did try the steps outlined in the "Identify the Source of the Problem" section, but S3D found no Non-Manifold Edges, nor any Self-Intersections. I also did a cross section view in both S3D and in Onshape, and all of the parts appear fine.

I also noticed after making my post that S3D isn't printing Top Layers where the missing layer line is, but is printing Bottom Layers above it.

[hunter.schoonover]

I imported the models into Simplify3D V4.1.2 and have been experimenting there. So far, the problem cannot be replicated.

This is looking more and more like a bug introduced into Simply3D V5.0 and above.

Just moving a single model around the print bed and rotating it can change how many layers are missing after slicing, the height of the layer(s) missing, and even get rid of the missing layers issue all together (all layers present).

Is this some kind of roundoff error? Perhaps when the model is moved, not all of the points along the same z axis, or not all of the points for a triangle along a specific axis, are lining up exactly as they should, causing breaks in the mesh....?

Is the Simplify3D dev team aware of such a problem?

[S3D-Jason]

I tried the region repair mode I recommended above and it sliced the file fine on my end. Can you confirm if you already tried that suggestion? Alternating fill worked fine for me, which is usually the first one we recommend trying for stubborn parts if positive fill didn't work.

[hunter.schoonover]

I tried the region repair mode I recommended above and it sliced the file fine on my end. Can you confirm if you already tried that suggestion? Alternating fill worked fine for me, which is usually the first one we recommend trying for stubborn parts if positive fill didn't work.

Yes, that works. Thank you for finding a setting that lets me print that model successfully.

But why is Simplify3D V5.0 having so many issues with what I would consider to be a relatively simple model, especially when I am unable to successfully replicate the issue in V4.0 (so far)?

Why does moving the model around the print bed make the problem worse or better?

Do you have any recommendations for how to handle this moving forward, besides having to look at every sliced print in the previewer, and hoping that I notice every time the slicer misses a layer?

Also, are there any down sides to using Alternating Fill that I should be aware of? Would it be a bad idea to leave it on all the time?

For context: I love S3D, have been using it for years, love the new features released in V5.0, and recommend it to everybody... but this is a little perplexing to me.

[S3D-Jason]

V4 used something that was closer to alternating fill, so if your only goal is to match V4 then this is a safe bet. We have seen many files that V4 could not slice correctly which are solved by positive fill, so that is why this is the new default in V5. We continue to offer both options, since some parts may slice better with different modes. The article I mentioned above shows examples of some parts which may require different modes, so depending on how it was modeled you may need to choose a different repair mode.