STEP vs Parasolid for Export/Import

matthew_stacy

What are the relative merits of STEP and Parasolids for export from and import to Onshape?  For parts?  For assemblies?

Neither file format seems to carry any attributes other than appearance through the export/import process.

S1mon

Parasolid is best if the other package uses Parasolid (eg Solidworks, SolidEdge, NX, Microstation, Ansys, Abaqus, etc). Parasolid is the native kernel of Onshape so you shouldn’t lose any geometry when going back and forth. Sometimes other packages will be on older versions of Parasolid, so you may have to research/experiment to get that right. 

STEP is much more universal, but you might have some things that don’t translate correctly. You didn’t ask, but I would only use IGES if Parasolid and STEP don’t work. IGES is a much older standard with more weird implementation differences between platforms. 

Also, if you happen to be working with people using Rhino, the 3DM (Rhino) import/export options in Onshape have worked well for me. 

GregBrown

What is the target system for the exported file?

In general, for importing to Onshape, the Parasolid format will be the preference... but it does depend on the source CAD system's method of writing the x_t (are they using native tools, 3rd party tools etc)

matthew_stacy

S1mon said:

Parasolid is best if the other package uses Parasolid (eg Solidworks, SolidEdge, NX, Microstation, Ansys, Abaqus, etc). Parasolid is the native kernel of Onshape so you shouldn’t lose any geometry when going back and forth.

@S1mon, for the case of two platforms built on the Parasolids kernel can you provide any examples of geometry that a Parasolids file can deliver that STEP would miss?  Have you actually encountered limitations with STEP or is this theoretical?

matthew_stacy

GregBrown said:

What is the target system for the exported file?

@GregBrown, in this case Onshape is the target destination for parts and assemblies coming from Solid Edge.  I believe that both of these platforms are built on the Parasolids kernel.

For preliminary testing purposes I exported a simple assembly from Onshape ... and then imported that back into Onshape.  I could not detect any difference between STEP and Parasolid file formats.  In both cases the imported part or assembly is comprised of "dumb" solids (non-parametric, non-feature-based, no mates, no attribute data other than color).  Would you anticipate differences using these two file formats?  What might those be and under what circumstances might these differences likely to occur?

Can you point me to any examples of export/import gone awry?