I'm not having a lot of luck exporting what I'd like to be a smooth object as a .stl for printing. I get different combinations of gnarly areas where there a zillion triangles generated and visible oval rings on the flattened curves, but haven't found a magic combination of settings to export either really smooth curves, or evenly-distributed facets.

I did fix an area at the "peak" of the flattest curve, where lots of triangles converged, and gave me a small lumpy area. Putting a small flat on the "peak" seems to have kept MOI from using the point as an attractor.

However, with different settings, I still get either visible oval rings, small stray bulges, and/or oddly-place grooves. Very frustrating when you don't know what you are doing...

I've attached the model, if anyone wants to take a whack at good settings for printing it at high resolution on an FDM printer.

What gives you grieve is the inner, lower surface of the egg. Everything, the isocurves to be precise, converges to two points, as you can see on the screenshot (made in Rhino v4). I'd guess that once you recreated that surface, all will be fine when exporting. I have no idea, though, how to display isocurves in MoI.

I downloaded Mac Rhino, and while it's like Photoshop with a million options, I just imported the .3dm file and exported it as a .stl, and it made a much better quality .stl than I've been able to get from MOI. Printing now, but it looks pretty good so far.

I'm using Moi for 3D printing a lot. Never had any real issues.
The setting you are looking for is: Divide larger than.

My usual settings:
Angle 1 - 3 depending on the printer i'm using
Divide larger than: 1 mm
Avoid smaller than: 0.1mm

I always check the stl in Netfabb.

I hope this helps.

Dinos

Hi Rick,

> However, with different settings, I still get either visible oval rings, small
> stray bulges, and/or oddly-place grooves.

Is there a particular setting and also area that you can show me so I can see these? On an initial quick look just loading your model and cranking up the slider towards the "more polygons" side, I get a result that does not seem to have anything like that visible, it looks like this:



Are you seeing something different than that or is there a specific area of the model where you're having a problem?



> <...> evenly-distributed facets. <..>

The best way to get more evently distributed facets is to use the "Divide larger than" setting in the expanded dialog. You can put in a distance value there and any polygon larger than that size will be further subdivided, that tends to help make a more uniform dicing up of polygons. For example here I've set Angle = 5 and "Divide larger than" = 1 unit:




- Michael

MOI still generates z zillion long triangular regions with those settings, vs. Rhinocerous, which creates much more uniformly-sized facets that don't seem to interact with the slicer to create odd artifacts.
My first print with Rhino export is finishing printing now, and it has fewer visible surface artifacts than MOI.

Hi Rick,

> MOI still generates z zillion long triangular regions with those settings, <....>

Where in particular are you seeing them, can you indicate any in the above screenshot I posted?

If you mean on planar surfaces, then try adjusting the setting here:




Switch that to say "All". By default with the setting of "Curved" it means the Divide larger than setting will only apply to curved surfaces and not to planar surfaces. If you switch it to "all" it will apply to all surfaces and force a more uniform dicing everywhere.

If you are still seeing any problems after that, it would probably help if you would indicate the specific area where you have the problem.

- Michael

I don't have pix, as I toss the not-so-good prints, but the issues appear in a couple of areas.

- Until I put a small flat on it, the "peak" of the flattest side had an area about 6mm that was all rough and lumpy. It's where there was a couple of hundred triangles all coming to one point. there's a name for this issue, although I can't recall it.

- Sometimes I get 10mm long narrow indented valleys that run from the juncture of the round barrel at the bottom and the "egg" toward the center of the flattest curve.

- I've also seen a 4mm wide patch of rough surface running up to the lower center of the flattest curve.

- Other times there are fairly obvious oval rings around the center of the flattest curve.

Bottom line is that MOI feeding a slicer seems to do a mediocre job when you crank up the resolution on the .stl. I've seen the same issue using Cura and Kisslicer.

Hi Rick,

> Bottom line is that MOI feeding a slicer seems to do a mediocre job when you crank up the
> resolution on the .stl. I've seen the same issue using Cura and Kisslicer.

Do you mean you saw these results using the settings I just posted a minute ago?

If not then the bottom line is that you just needed to just adjust a few settings to generate a denser mesh.

- Michael

> - I've also seen a 4mm wide patch of rough surface running
> up to the lower center of the flattest curve.
>
> - Other times there are fairly obvious oval rings around the center
> of the flattest curve.

It's hard for me to really follow the specifics of this - if you want more help getting better results in MoI it would be a lot clearer if you could post an image with these particular areas circled.

Just in general with a simple look (and in the screenshots I posted above) I was not able to see any of the problems that you are mentioning so that makes it a bit difficult to give you very good feedback about what you should do to improve it. My best guess though is that you want to use "Divide larger than" with a setting of "All" to force more even divisions throughout your mesh.

- Michael

I would say it will be a combination of settings.

So it appears he is having issues where "poles" are created for the stl mesh.

Poles are not necessarily bad and don't specifically make something "not smooth", but they can create effects when combined with the other settings that have to do with generating a path for the printer.

Although you have a high resolution printer, there will be settings that determine the print resolution. Various step/size settings for the print. Nozzle stuff etc.....

These combined with the sizes/counts of the polygons will affect the end result.

Hi Michael,

> Just in general with a simple look (and in the screenshots I posted above)
> I was not able to see any of the problems that you are mentioning so that
> makes it a bit difficult to give you very good feedback about what you should do to improve it.

Ricks problem is referring to the finished product from the 3d printer the mesh from MoI is fine it's when the mesh is put through the 3d printing software which slices the model to create paths for the printer according to what resolution is set for the specific printer so it's the resulting slices that are the problem.
Like Dinos I've had no such issue with my 3d printer exporting stl files from MoI.

-

Hi Danny,

> it's when the mesh is put through the 3d printing software which slices the model to create
> paths for the printer according to what resolution is set for the specific printer so it's the
> resulting slices that are the problem.

Yeah when your mesh is not dense enough it's possible for some aspects of the mesh structure to come through in the final print...

In order to avoid that you need to adjust some settings to produce a dense enough mesh to avoid seeing individual polygons.

The main settings to use for that are set an Angle fairly low, but then also use the "Divide larger than" setting to force a more uniform dicing of the mesh. From what I can tell from what he wrote, Rick has not used "Divide larger than" for the output he had difficulty with. It's hard to say for sure though without more specific information from him.

- Michael