Issues while generating skin in Lattice Commander

[Anonymous]

Hi, 

Generating skin in the lattice commander creates extra triangles above the surface. Refer to the image. 
The original file is a STEP file converted into STL and then brought into Lattice Commander. 

Thanks, 
Mayur

[steffen_anders_adsk · Accepted solution]

Hello, @Anonymous,

Welcome to the Netfabb forum!

Skin creation seems to trip over narrow passages and intricate geometries. I recommend that you create the skin separately by means of either hollowing (Modify > Generate shell) or 3D extrusion (in repair) plus fix of self-intersection. You may also want to consider hollowing in LC on a mesh that doesn't have those through holes, and inserting the holes (+ hole wall thickness) later on.

Kind regards,

Steffen

[steffen_anders_adsk]

One more thing:

What helps with this is to make sure to work with parts that have a regular mesh, a mesh whose triangles are reasonably equilateral. Long and narrow triangles, or worse still, self-intersections and degenerated triangles, can trip up Hollowing quite nastily. You can use Repair to address these requirements. (Remesh, Detect/Split off/Delete Self-intersections, Remove degenerate faces)

Optionally, once satisfactorily skinned and latticed, replace the enveloping shell with the original, un-remeshed one. 

Kind regards,

Steffen

[Anonymous]

Hi Steffen, 

Thanks for your feedback. Hollowing a solid part (without holes) worked. But trimming lattice from the mesh afterwards is a bit of a task. 

Considering remeshing the whole part, as well as each individual surfaces. While remeshing entire part at once, it distorts the edges drastically. (Tried both the meshing approaches - Uniform as well as Adaptive. It is slightly tricky to find the exact mesh settings). Also, selecting each individual surface is a little difficult. Since you have to figure out the edge angle while selecting the surface.  In this case, it is creating a lot of problems as there are uneven and narrow triangles. 

It will be great if can you please tell me how to exactly to replace the enveloping shell with the un-remeshed one. 

Additionally, as an alternative approach - I tried to import the model into optimization utility directly as it was a STEP file. But found out that in 2020 update you can no longer import CAD format in Optimization Utility. Had to download the 2019 version. 

Thanks, 
Mayur

[steffen_anders_adsk]

Hello, Mayur,

Here are the steps to replace a shell in a mesh:

1. Take your original part …
   
2. … and enter Repair.
3. Remesh the part (and repair as needed) to make it suitable for skinning and latticing. The part should have mostly regular triangles, should be closed and oriented.
   
4. Click Apply Repair and choose Keep original part.
5. Take the remeshed part and perform skinning and latticing as usual.
   
   Ignore irregularities in the outer surface.
6. Click Generate component to take the mesh result from skinning and latticing back to the original build platform.
   
7. Select it and enter Repair.
8. In the context view, select the Shells tab.
9. Select the shell that envelops the whole part …
   
   
10. … and hit Delete.
    
11. In the project tree, click and drag the original, unremeshed, solid shell and drop it into the repair section of the latticed part.
    
12. Click Apply Repair.
    

You now have merged the original solid shell with the latticed cavity.

Best regards,

Steffen

[Anonymous]

Hi Steffan, 

Thanks, this was really very helpful. 😀

Can you please let me know, why can't I import STEP file into 2020 Optimization Utility?

Thanks, 
Mayur  

[jtomasd]

Hi, I have been following this steps, and the part has improved their quality. 

But its not 100% perfect. When I am repairing the part, in the shell section I don't have 2 options. I have one that deletes the whole part.

After droping the original part, I just finish with the original one. 

[steffen_anders_adsk]

This means that there is some connection between the outer, undesirable hull section and the inner one that holds the lattice, so you will have to find that connection and manually separate the two sections so that you can discard the one you don't want.

In repair, try the Overlap command. This selects any triangles that are coplanar to a tolerance. So, following the example above, first drag the good shell into repair, use Overlap, delete anything that was selected, then drag the good shell into repair again, and work from there.