Simplify3D User Forum

I've experienced what I think is an S3D "glitch" today and it's about made me pull my hair out trying to troubleshoot the problem. This part is designed as open frame, and I've used S3D to print it probably hundreds of times. Today when I went to print it, S3D wants to suddenly fill in the open frame area. I've run the part through just about every repair utility I have access to, including:

Meshmixer
netfabb
Microsoft 3D online repair service
Sketchup's Solid Inspector (Sketchup was used to create the part in question)
S3D's repair tools

All of the above find no problems with the part, and yet S3D insists on filling in the open area. It's never done this before, which tells me it's some sort of software glitch or perhaps I nudged some tiny S3D setting without realizing it and doing so caused the problem. I'm uploading several files to see if anyone else would like to take a stab at this.

Change the layer thickness to 0.2001. It'll slice correctly then....

That's all it takes? I'm away from my computer and can't try it for a couple of hours. If it works, that's awesome. Can you explain to my brain why this would happen and why changing the layer thickness by such a minuscule amount would "fix" this? If my brain can understand it, maybe I can avoid this happening in the future.

I'm firmly convinced there is a subtle bug in the slicing logic that occasionally causes one of two results...either a missing layer, or a partial or full solid layer instead of the correct layer profile.

This must be something to do with something like rounding or suppression of a number of decimal places in one of the many calculations that the slicing routine must have to do. Making a tiny change....like altering the layer thickness by 0.0001....makes the result of the calculation very slightly different...and the bug is not there.

If anyone from S3D happens to read this...there are several examples of both types of issue that have been reported over the past few months.

Well, regardless of the "why," I'm just glad somebody quickly knew the answer. Thank you! I literally lost 5 hours of my day trying to fix this. Should have just come here first.

I get this all the time and I definitely wish they'd fix it. It Seems to occur when the layer height is an even divisor for the height of a vertex, such as when features change significantly right at a vertex in the STL file.

Well if we ever see another update to the software in this century maybe they will fix it.

V3.1.0
This is a persistent problem with a particular model i have.
I have changed layer height value - no effect.
I have re exported STL with different cord setting - no effect.

Cannot say it is an endearing feature - but definitely is a bug.

Taking the "open frame.stl" from the first post all I have to do is to play around with the slicing behaviour, Setting it
to "Merge all outlines to a single solid model" will indeed print it solid.

On the other hand I know I had problems with seemingly perfect stl files which went away after changing layer height. But in my case it
was 99,9% the stl files fault. And the remaining 0,1% are just so hard to reproduce...