How to hollow out a 3d Mesh object. I am trying to make a "shell" of an organic shaped object prior to CAM

[StageCrafter]

I am going to fabricate a "flat packed" or sliced model of some animals using a CNC router.  I first want to hollow out the inside of the model prior to slicing it in Slicer for Fusion 3d.  This will reduce the weight of the final model.   For example I have a .stl file of this dolphin that I am then slicing and exporting the sliced files as .dxf files.  I could offset the 2D lines in the .dxf file prior to machining, but the part numbers and dowel placement would not be optimized. 

 

Any help would be greatly appreciated. 

[VIRTUALENVIRONS]

Is the dolphin model a solid?  I would think an imported .STL file would be a surface model, please confirm

[StageCrafter]

It is a mesh so I don't believe it is truly a solid.  I tried to convert it to a generic solid and it crashed Vectorworks. 

[VIRTUALENVIRONS]

A mesh and surface model are essentially the same to Vectorworks.  I can see the triangles in your Dolphin.   

 

I see they supplied the cross sections of the Dolphin.  You could use those to rebuild it in Vectorworks, but it would be very difficult and unless you were very familiar with NURBS, not really a solution.

 

Some programs like CINEMA 4D can add thickness to a mesh.  I would assume Blender (need help here) could do the same.  Blender is free, perhaps someone can confirm this.

 

good luck

 

 

 

[rDesign]

@StageCrafter I have not tested to confirm, but the open source software MeshLab says that it can hollow out 3D models for 3d printing (screen cap from website below). That dolphin looks like it has a high mesh density (many triangles), MeshLab could also handle the mesh optimization, which might keep it from crashing Vw.

 

 

A link below to a page with instructions on how to hollow out a model in MeshLab:

Hollow out model for 3d printing

[Claes Lundstrom]

A mesh is indeed a solid provided that the shape is closed and leak free, and that all normals are facing the correct direction. You can use it for solid subtractions just like ordinary solids. 

 

To check that it's valid and leak free, check the volume. If it's OK the volume should be bigger than zero, like it is in the picture. 

 

I imported the mesh in the picture, and converted the parts (in this case four meshes) into a single mesh. I then added a smaller version inside the original, and ran Subtract Solids, and it worked ok. It still had a volume and the clip cube showed an edge as a solid. 

 

 

[VIRTUALENVIRONS]

@Claes Lundstrom

 

Nice work on the boat hull.  Good info on the volume, did not know that.

I have used the method you suggested before to create a thickness. but did not see that happening with the Dolphin, too thin at the edges.

 

It is interesting the provided the cross sections.  If someone was willing they could simply take the time to recreate them and loft themselves a Dolphin.  I would do it the other way, tip to tail.

 

 

 

 

[Claes Lundstrom]

Here are a quick simple examples I generated in the fly of meshes being after processed with solid subtractions. Seemed to work as expected as far as I can tell.

[VIRTUALENVIRONS]

@Claes Lundstrom

 

Really nice work.  What are you rendering in?  

The boat.  Just interested.  Why are the hull subtractions for.  Although I have never built a boat, I have rebuilt two.

[VIRTUALENVIRONS]

 

I don't know why I did not think of this before, I used this method last week to build a 1938 BMW.  I often extract a surface and shell.  It seems work better.  I don't know if this would work with imported geometry.

For the BMW below shell would not work on some parts of the car in both directions, but after extracting a surface it worked.....mysteries of Vectorworks.

 

[Claes Lundstrom]

3 hours ago, VIRTUALENVIRONS said:

@Claes Lundstrom

 

Really nice work.  What are you rendering in?  

The boat.  Just interested.  Why are the hull subtractions for.  Although I have never built a boat, I have rebuilt two.

I usually use Keyshot for product renderings as delivers results very quickly with its high quality realtime rendering. It works very well with my main freeform modeling program (OK with VW too), as I seldom spend more than a few minutes in it to generate a quick visual on a simple model.  I would perhaps not use it for architectural renderings though. 

 

The models where just examples of fairly complex closed but hollow mesh based shapes being trimmed afterwards with solid subtractions in VW. The discussion started with meshes from Rhino and whether they could be used as solids. I don't use Rhino but have a similar situation from the program used.

 

Here is a practical example, where I imported a "solid" mesh, and divided it into two parts in VW using solid modeling, and to be used for 3D printing. The result was a 523 mm long scale model printed in one session, which took just under five hours. 

[Benson Shaw]

@StageCrafter  You might like the Vectorworks Create Contours tool and the Shell tool.  The shells can be hollowed out via PushPull (Sub Face Mode) or Solid Sectioning.  I contoured from the center axis. Perhaps better to offset the start plane to avoid a dbl thick center element. Use Extract tool, Face Mode, Create Planar Objects to get the full scale edges for CNC.

This can all be scaled down for the 3d print.

-B

 

Mesh to Contour v2024.vwx

Edited January 14 by Benson Shaw
No time like the present.

[Piotr Karczewski]

To continue this subject I'm wondering if there is a way to fill in the mesh shape?

Or transform mesh to generic solid (Which will be working every time in every situation)?

• I do have a lantern form .fbx file which I wanto to simplify and convert to few generic solids.

But the only thing that I could done was transform mesh to 3d polygons which is not useful at this time.

Edited February 20 by Piotr Karczewski

[VIRTUALENVIRONS]

Can you post the file

[Piotr Karczewski]

41 minutes ago, VIRTUALENVIRONS said:

Can you post the file

Sure:
street lamp.vwx

[VIRTUALENVIRONS]

HI Piotr,

There is a way to shell a mesh, but the mesh has to be what they call "water tight" In 3D printing.  The model is not.  Imported I am assuming.

 

If the mesh was generated by Vectorworks, it can be processed to use "Shell" giving it a thickness.

 

Sorry I am of not help on this problem

[jmcewen]

3 hours ago, Piotr Karczewski said:

To continue this subject I'm wondering if there is a way to fill in the mesh shape?

Or transform mesh to generic solid (Which will be working every time in every situation)?

• I do have a lantern form .fbx file which I wanto to simplify and convert to few generic solids.

But the only thing that I could done was transform mesh to 3d polygons which is not useful at this time.

The classic workaround here is to select a single face, use the push pull tool to move it 1" (or any fixed distance that is easy to remember and type quickly), then use the push pull tool to move it back to where it was originally-- again, only if the mesh is watertight to begin with.  I do not know how this changes meshes to solids, but for some reason it does most of the time.  on a really intense mesh it migh tstilll crash  for you though.

[VIRTUALENVIRONS]

I did mention a workflow for VW.  I suppose I might as well finish It off.  This might also work for a good mesh from Blender.

 

1 Take a sphere and convert to NURBS 

2 Ungroup and remove the bottom half to make it easy to see.

3 Then Stitch and Trim.

4 Extract a Surface

5 Shell

[Piotr Karczewski]

Thank a lot anyway!
I just wanna ad some street lamps external libraries.
Finally I was able to transform skp file but it wasn't short&easy