Flat Pattern in MOI / Import 3D DXF

 From:  Michael Gibson
3992.2 In reply to 3992.1 
Hi Jose, MoI is designed mostly as a kind of drawing tool for constructing models.

It doesn't really have any functions in it for reverse engineering geometry or flattening out patterns or things like that, your customer would need to use a different tool for doing those kinds of calculations. MoI is focused just on creating the surfaces.

> I ran into a few instances of Alibre not recognizing bends
> from MOI models in our Sheet Metal Conversion Tool.

I'm not sure how the Sheet Metal Conversion tool works in Alibre specifically, but in general it's not really possible to take any kind of surface that has compound curvature (one that is bending in more than one direction at the same time) and make it into a flat pattern without any kind of stretching of the material - that's just a physically impossible thing.

One example of that is a sphere - it's just not possible to unwrap a sphere into a flat pattern without any kind of stretching involved.

So usually if you want to fabricate things with flat panels, you have to restrict the kinds of surfaces you construct to be developable surfaces (ones that only bend along a single ruling line at any spot on them), and not just any arbitrary curved surface.

So I think that's the problem in this case - your customer has created several surfaces here that have compound curvature in them and such surfaces simple do not map to a flat pattern that only bends in one direction.

> I was curious if there was a similar feature in MOI.

No, not currently.

> The Customer also wanted to know if there was any way of
> importing 3D Autocad Models (3D DXF etc.) into MOI.
> He would like to use them as 3D reference figures for future models

Do you know what kind of geometry is contained within the DXF files?

DXF files can contain a lot of different kinds of stuff in them. For example a 3D object in a DXF file can be made up of polygon data where objects are made up of a lot of little planar facets. These are called "3DFace" or "Polyface mesh" entity types in the DXF file.

But DXF files can also contain ACIS solids and NURBS surface information. These are called "3DSOLID" or "BODY" entities in the DXF file.

If they have the ACIS data in the DXF file, they can transfer that data from AutoCAD into MoI by writing out those objets in SAT format from AutoCAD instead of in DXF format. That can be done by using the File > Export command in AutoCAD, and using the File type: ACIS (*.sat).

Let me know if they have polygon mesh data in the file instead of ACIS solids data, that is a much different kind of data and the process of bringing it over is different.

- Michael