Possible bug: .stp file export problem

Rhino
#1

Hi all,

I’m trying to use .stp files exported from Rhino 5 for subsequent import into the Quickfield finite element analysis package. This tends to work correctly for files containing incredibly simple geometry (eg a couple of rectangular extrusions), but anything more complex than this causes the Quickfield import to fail. Quickfield technical support have analysed the issue and believe that the .stp files generated by Rhino are faulty.

Does anybody have any knowledge of the issue of faulty .stp file generation and/or any fixes or workarounds?

Also, does anybody know whether any such issue may have been fixed in either Rhino 6 or 7?

Thanks in advance.

#2

And another thing…

Quickfield only accepts .stp files as its geometrical input so unfortunately there is no option to export an alternative format from Rhino.

Unless…

An intermediate software package is used which will generate a robust .stp file from some other format of exported file from Rhino (.dwg/.dxf/.stl…).

Any thoughts for a robust and “cost-effective” intermediate package anybody (I don’t really want to start installing another full CAD package just to make use of its import and export abilities)?
Ta.

#3

Maybe your geometry is full of details, which Quickfield mentions is not ideal…

3D import --QuickField FEA Software

Can you post your file?

#4

Thanks Martin Siegrist for your reply.

The problem models are very simple - 3 cylindrical extrusions touching on their flat faces. Rhino file attached.Rhino 3 cylinders for forum.3dm (51.8 KB)

So, as you see, very few details. Quickfield is able to cope with geometry which is much more complex.

I have just had further communication from Quickfield tech support as follows:

  1. This is a problem they have encountered with other users of Rhino/Quickfield.
  2. They have just generated this same geometry themselves using Rhino 7 and Quickfield import fails.
  3. When this problem has occurred before, if the Rhino .stp file is opened with Solidworks and then re-saved as a .stp file, the Solidworks file imports successfully into Quickfield.
#5

Perhaps you could get the Quickfield folks to to send you the before and after Solidworks .stp files to forward to McNeel?

#6

Thanks AIW: The before and after Solidworks .stp file fix is one which has been reported to them by a number of clients as an approach that has worked for them. I’m fairly confident that they don’t have example files which demonstrate this (unfortunately).

#7

Quickfield tech support is actively looking into the problem (all credit to them - they have been impressively responsive) and they have suggested that the version of ST-Developer (from STEP Tools inc) apparently used by Rhino in the generation .stp files may be a factor here (this is simply a suggested possibility). The problematic .stp files were generated using ST-Developer V15 (visible in the text of the file header). Files generated using Quickfield tech support with Rhino 7 seem to use ST-Developer V16.5 (again from the header text). The latest version of ST-Developer (from their website) seems to be V18.

Does anybody know if there is any way to upgrade this aspect of Rhino 5 to the latest ST-Developer as a possible fix?

Also, this old thread is discussing a very issue relating to problematic .stp file generation similar to the problem I’m seeing. Once again a Solidworks import/export dance seems to have been a workaround.

#8

Anybody out there with any expert pearls of wisdom on this problem?

I’m extremely keen to find a solution to this issue and any useful input would be most gratefully received.

#9

Hello - does QuickField support trimmed surfaces? Can you try the attached version?
Rhino 3 cylinders for forum_Untrimmed.3dm (114.9 KB)

-Pascal

#10

Hello Pascal,
Thanks for your input.
Could I trouble you to post this file Rhino 5 format please? I’m stuck in the dark ages with Windows 7 so a move to a more recent Rhino is impossible at the moment.

#11

Hi -

Here is Pascal’s file in the Rhino 5 format and in the STEP file format.
Rhino 3 cylinders for forum_Untrimmed.stp (37.7 KB)
Rhino 3 cylinders for forum_Untrimmed-RH5.3dm (1.8 MB)
-wim