https://cadexchanger.com/

Its a bit spendy, $650 for a one user perpetual license, but I was considering it. As a home hobbyist/model designer, I get a lot of STL and OBJ files that aren't easily converted for use in MOI or Alibre, my two CAD programs. I'd love to be able to modify these files, create new designs from them, etc. It seems like everyone uses a different file format and even when we agree on a common format, there's always one program that can't read what another has written, even in a cad neutral format. Cad Exchanger might be a way to alleviate these issues.

Any ideas or experiences?

Many thanks,

Bob

Hi Bob, it's a useful converter but it's main focus is converting from one CAD format to another CAD format.

Your STL and OBJ files are going to be containing polygon mesh data, not CAD data. It's not easy to take something that's been diced up into a hundred thousand little triangle fragments and try to reform large smooth CAD surfaces from it. CAD Exchanger will not do that type of conversion, it says:

https://cadexchanger.com/formats

They have a good page giving more details:
https://cadexchanger.com/blog/the-challenge-of-the-polygonal-to-brep-conversion

So the problem is that the data that you are wanting to load is just fundamentally in a different representation (polygons) than what a CAD program is designed to work on (NURBS).

You can go from NURBS to polygons pretty well, that's done by dicing up smooth surfaces into small polygons. Think of that as similar to taking apples and smashing them up into applesauce. But it is not easy to start with small polygons and reform analytic surfaces from those, that would be like starting with applesauce and trying to form it back into apples.

So it's not an issue of just file format translation, it's that the base model data itself is very different between a polygon model file and a CAD model file.

- Michael

Thanks Michael,

I'm not too concerned with that, as a mesh to a simple solid is fine with me. I have things like Star Trek saucers (geek alert) in stl and obj formats that I'd like to import into Alibre and MOI and manipulate but can't. Losing parametric data on a 1/1000th scale Trek model, for example, isn't too concerning as long as the converted file results in something that I can then work from, build off of, and so on. Does that make sense?

Robert

Hi Robert,

re:
> Losing parametric data on a 1/1000th scale Trek model, for example, isn't too concerning as long as the
> converted file results in something that I can then work from, build off of, and so on. Does that make sense?

Sorry no it's not just that you've lost parametric data, it's that the CAD environment is not set up to work on models made up of 100,000 little tiny triangle pieces.

CAD modelers expect for there to be a smaller quantity of larger smooth surfaces. Trying to make a CAD model where there is a separate trimmed plane for each little triangle does not work very well, it results in an extremely heavy file and you cannot really work with data in that form, it is not suitable for the CAD environment.

They explain it in detail in the link that it is not recommended or expected to work:
https://cadexchanger.com/blog/the-challenge-of-the-polygonal-to-brep-conversion/

- Michael

JT format inside future Moi?

https://en.wikipedia.org/wiki/JT_(visualization_format)

Hi PIlou,

re:
> JT format inside future Moi?

What would it help you with?

- Michael

Not for me :)
For the iso norm in industry

Hi PIlou, well it's pretty "Enterprise"-y , it would probably fit with MoI if I raised the price to $3000 and started talking a lot about "PLM".

If you need it, it is supported by CAD Exchanger, I would recommend using that. It's probably not too likely to be added in directly to MoI because of low demand.

- Michael