.step .stp - export with groups and blocks //extra: CATIA data exchange

hello dear community,

I wanted to ask if there is a trick to export a rhino file to step with blocks and groups.
whenever I export my file and import it back into rhino I have solids but no group/block definitions whatsoever.

In addition I ask I someone of you is experienced in data exchange with CATIA - when I get a step from catia it seems I get a lot of conflicts with blocks and only some parts are shown correctly.
when I get a allcatparts-step it works fine but no blocks…

Hope someone can help me or lead me in the right (if there is one) direction.

best regards,
sebowim

Hi Sebastian -

When you make blocks from your Rhino objects, exporting those to STEP and then importing them back into Rhino will keep the blocks. A new top-level block will be created that you can get rid of by using the Explode command on that top-level block.
HTH,
-wim

ok, thank you! - I tought so aswell, but I have a different behaviour… Ill post a file when I am home or tomorrow - maybe its a bug!

best regards,
sebowim

Depends a bit on the Catia version and the Step versions. But blocks and instances on rhino will be converted to parts and assemblies in STEP. Coming from STEP parts and assemblies will become blocks and instances.

There are settings on the Rhino import to defeat this behavior if blocks are not wanted, but then an export back out will not include separate parts.

This is a model with a few parts and assemblies in it to see how the Catia imports it:
carbody.stp (4.1 MB)

hmm very strange, all of a sudden it works as it should - I swear I tried it with all the step formats and it didnt…

sorry for wasting your time… but thank you very much!

best regards,
sebowim

thank you for the file - and yes that should be the expected behaviour I want - and it also works with your file:

I found the ONE culprit - when opening the step I need to use “replace with imported block” rather than “keep both blocks” which gives me more geometry

BUT there is still stuff missing compared to the allcatpart file which then is only single parts and no blocks.

may I send you the files private for investigation?

best regards,
sebowim

Sure, send me the file.

Catia will be looking for closed NURBS solids. This is a different issue then parts and assemblies.

Repairing solids in Rhino so Catia will accept them can take some work. Catia has a hard coded tolerance and can be quite selective what it imports.

If there are certain parts that are not transferring, normally I would isolate those and see if they transfer by themselves.

perfect, thank you - Ill send you the files in a DM.

do you perhaps know the tolerance? maybe when I setup my file in rhino to the same tolerance it works better?

in addition do you know of a way to transport meshes in “engineering”-formats? bc. when I want to export them in step or igs it says you can’t export meshes - there is no universal format for this?

best regards,
sebowim

Meshes are much more troubling as they are not reallya solid geometry type.

DXF is probably the best for meshes, although not every program will import them.

Most of the time in an engineering situation the meshes must be converted to NURBs. This is especially challenging if the object is supposed to be smooth, but the mesh only represents.a bunch of flat faces.

hmm ok thanks alot for the time - this once again shows me how universal rhino in regards to data formats!