Problem with file exporting (loosing elements from my 3d design)

Dear all,

lately I designed a structure in rhino which I will send to a company for a 3D stainless steel printing. They have asked me for a .step file and x_t file of my drawing. I exported to STEP and sended to them.
They followed up with issues:

I opened the .stp file with Solidworks and I even face many problems -> see below. And some elements are missing.
Could you please check your design again and make sure that you have only one structure without space between the elements.
Could you please send then a .step again and a x_t file.

As you can see in the picture that they have forwarded to me they get a broken modell with missing elements + they have asked me to have a single element.

Does anybody have and Idea of who can I get this export right? and who can I connect all the elements in my structure, and making them a single element?

In attachment you will find my 3dm file, the picture of the company with the issues and a screenshot of mine with who should look like the geometry.

Thank you all for your time
Best regards
Redon S.

geometry_try.3dm (4.8 MB)

Hi Redon - the parts are all capped off as individual solids - the straights and arcs - you need to get rid of the end caps on all the parts and join the ‘tubes’ up. This will take some work at the vertex on each end. But the result should be, presumably, one solid object, not a collection of closed solids.


Yes you don’t have a single element.

To get a single element you will need to use the surface modeling tools.

The biggest problem is the elbows in your file are degenerate surfaces. You need to allow more room for the elbow. to make the bend.
You also have a huge number of extra surfaces that are not needed.

The ends where 4 pipes come together will need to be handled in a special way in order to get the trim boundaries correct so that edges will join properly.

The first step is to explode everything, In the enclosed file I fixed the ends by using the two red splitting lines In a right side view. I selected everything and split with the 2 red lines. Then joined the parts that were useful and window selected and deleted all the useless pieces. The elbows on the end are also degenerate surfaces but running ShrinkTrimmedSrf after they are trimmed will get rid of the degenerate parts.

The remaining elbows could be fixed by cutting back the pipes a little way (use SplitSrf) and then make a new elbow with blendSrf. I did one elbow.

In the end you should be able to join it all into a single closed polysurface and export as STEPfile . Don’t bother trying to export as XT that’s unlikely to work.

geometry_X.3dm (316.1 KB)

First of all thank you for your answer and for your help. I didn’t really understant how you fixed the ends by using the two red splitting lines; what is the function of the splitting lines and what did it fix?

What do you mean by saying that they are degenerated surfaces? By the way I started using the splitsrf command and recreating the the curve with blendsrf, but I would like to understand why it was wrong in my version

What does the shrinktrimmedsrf do?

Thank you for your help! I wish I could give you a friendly handshake


Thank you Pascal for your help I working on recreating the join now



As I explained, I used the 2 lines to split all the surfaces (looking from a side view) and then joined the parts that were useful and deleted the rest. The idea is this will give you clean and accurate trim boundaries which can make the difference between success and failure when exporting to other CAD programs.

In mathematics degenerate cases are those where the usual functions that are supposed to work don’t work.
There are different ways geometry can become degenerate, Your surfaces are degenerate because they have stacked control points.
That will make it likely functions in both Rhino and Solidworks will not
work properly.

To prevent the elbow from collapsing to a point on one side you would need to make the bends a little larger.

Its a command that shrinks the surface to or nearly to its trim boundaries. This removes the area with stacked control points so that what is left is no longer degenerate.