Strange slicing in S3D

I went to print a new effector for my He3d K200 so I had a spare to try to create a new blower type part cooling duct, and when the print finished , I could see through it in one line across the part. I used Simplify 3d 4.0. Up to now, it had performed flawlessly on the few prints I made. Looking at the slicing later by layer, you can see that it creates rectangle where none really exists. I have a side by side comparison of S3D on the left, and Cura 2.7 on the right. You can see the continuous seam top to bottom. Does anyone know what settings I can change that will change the slicing behavior?

Top Layer - You can see the rectangle exists in S3D, but not Cura
Attachment 11091

Mid layer, you can see the seam continue (layer 25 of 40 )
Attachment 11092
First Layer, you can see that it starts at the very bottom.
Attachment 11093

Thoughts?

Consider to open the STL file in a program such as meshmixer and slice it with Edit, Plane Cut to see what the internal section of the STL file shows. The layers in S3D appear to present a construction artifact, indicating that the file creator did not use union or merge to join the entities. S3D also has an error utility that may clear those artifacts. If the STL file is not proprietary, consider to post it with your message. I would like to see the insides.

fred, I open the file in meshmixer as you suggested and did a plane cut. Here are 2 screen shots, one with no fill and one with a mesh fill to highlight the construction. I did not create the stl, but it sure looks like construction artifacts.
First no fill:
Attachment 11096

now, with mesh fill.
Attachment 11097

The stl is on thingiverse here -> https://www.thingiverse.com/download:3896657

So even if they are construction artifacts, what can be done in S3D to make a good print?

s3d does things like that, some of it is preparation for adding stuff in later layers.

For example, If you have text you'll notice it starts the text quite a few layers before it actually surfaces. I think it just adds things like that to make the part stronger below or around certain parts.

And for that particular stl. John cut the centre out of the original effector, resized it and then plugged the original centre back in - which is why it shows the rectangle.

It shouldn't effect the print - I've printed that part a couple times with no issues.

How many top and bottom layers are you using ?

I brought the stl file into my meshmixer and used Edit, Generate Face Groups. Accepting the defaults results in different colors. The rectangle in question then shows up clearly as being at least one layer higher (or maybe lower) than the rest of the part. Meshmixer sees it as an entity of its own because of the abrupt change in elevation.

I also used Edit, Plane cut, rotated the cutting plane to vertical referenced to the major face of the part and did not remesh/fill. The resulting slice shows clearly there is an internal double wall to the construction rectangle.

These are design flaws that some slicers may ignore or otherwise repair, but sometimes not.

I wish I was more skilled in meshmixer, as I would expect one could collect these components and merge them into a single entity, ridding the part of the glitchy sections.

I just tried something else.

Using Edit, generate face groups, then use Separate Shells to create two independent objects.

By playing around with scaling, I was able to determine that the inner rectangular structure is larger than the enclosing part. I was able to scale the inside portion to 0.995 uniform (although I should have left Y alone) and make the double wall disappear, but only to the eye. I'm unable to tell if the two walls are close enough together to call a single wall.

Unfortunately Meshmixer's skill with Boolean Union is miserable. It distorts the shapes beyond use.

I exported the individual parts, then used OpenSCAD Import() to see what I could do with that program. It previews fine (F5) but fails as expected with the rendering. I don't understand everything I'd like to in OpenSCAD, either. If I was more capable in Blender, I could probably bring either the main file into Blender and fix the double walls, or bring the two parts into Blender and properly merge them.

Since I have all these wonderful tools with which to manipulate models, I popped the stl into Fusion 360. It really shows clearly where the double wall falls. From what little I know of F360, the next step is to perform a mesh to Brep action. At this point my F360 goes belly up. That's not a good sign at all!

CA, I used 0.2 layer with 5 top layers, 3 bottom and 40% infill. The attached photo shows that the print has a clear seam, that passes light thru it ( thats how I noticed it). I already printed mine with my first printer ( da Vinci Jr ) and there was no issue. Also, Cura will have no issues.
Attachment 11103

fred, That's a lottta work to try to get this stl working. Like I said earlier, I just printed it for a life size mode to do some design work. If I need another, I'll just slice in Cura. It sounds like the origin of the issue is the way the part was stitched together, but I do not know how to do it any better.

weird, it's the file i'm using.
40% infill, why ???????????

with that number of shells, 10-15% infill is more than enough.

you see a lot of people using heavy infill. totally not necessary, it's the shells that do most to determine a part's strength and rigidity.

Quote:

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Originally Posted by curious aardvark

weird, it's the file i'm using.
40% infill, why ???????????

with that number of shells, 10-15% infill is more than enough.

you see a lot of people using heavy infill. totally not necessary, it's the shells that do most to determine a part's strength and rigidity.

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Good to know about infill. I thought it would add strength

I just created a thread in the S3D forum. I will post a link here, assuming they approve my post.

For what its worth ( and apparently not much my the S3D group ) here is the thread I opened at S3D https://forum.simplify3d.com/viewtopic.php?f=9&t=8639

We will see..................