Hole error importing .step file

Eduart

Hi all,

I've got an strange problem during import of a .step file. STPviewer shows 5 though holes in my .step file (as designed) but when I import this file in Mecway one hole is not through. Some layer is created at one side of the part.

I've tried to export te file in .iges and .step files and imported it in Mecway (didn't work), did some save-as-stepfile in fusion360, imported that step file in fusion and saved it again with a different name and then imported it in Mecway (didn't work either). I also editted the part and made the holes a bit bigger and then saved the part as step, but no luck. A mirrored version of this part has the same issue. An totally different part with holes of the same diameter and position has no problems.

I then desided to destroy my part and cut huge holes in it. Saved it as .step and after importing it into Mecway two holes are no longer through.... Huh?

Anybody an idea of what's happening?

Chears,
Eduart

Victor

Sometimes a single large complex surface can cause problems. Maybe the conical(?) surface with the holes is like that. If you can split it into several, that might help.

You can try turning on Tools -> Labs -> Smooth geometry preview (slower). If there's no Labs menu, turn it on in Tools -> Options -> Labs. It only affects the display and increases the number of triangles used in the preview. If it helps then it sounds like a problem of too-complex a shape. Even if it doesn't help, it might make details of the problem easier to see.

Does the problem appear in the mesh too? Or does a solid mesh fail while a surface mesh succeeds?

disla

Could you attach the step file if it is not confidential or similar.?

Eduart

@Victor Tried the smooth geometry preview option. Unfortunately it didn't solve my problem (although it looks a bit nicer now ). I meshed the part and even in the mesh the hole isn't trough. The solid mesh (volume mesh?) failed so it had to be a surface mesh.

@Disla The step file is confidential, but I've created a version which has modified dimensions and geometry, see file atached. This file shows 2 not through holes as you can see (which of course should be through). Also this part gives errors while trying to do a volume mesh and works only with surface mesh. And in the mesh the 2 holes are not through....

Maybe you can try to open the step file and let me know if you get the same problems?

disla

I have found two issues.

As far as I know Iges is a surface oriented objects format.
No volume will be meshed with an iges file because there is no solid “below the surface”.

I have inspected your step file. One of the holes , the one in the positive Y axis y not closed so the face is not properly build.
It is the one that is giving you problems. Rebuild that hole. See pdf’s comparing a healthy one with the one that shows error.

Other point is that your flange is not at centered at the origin. You will not be able to benefit from symmetries in case you want to reduce your model

Victor

It's a strange one that I can't solve, sorry. Gmsh (option in Meshing parameters) works OK though. Here's a solid mesh I got.

If you don't want to install Gmsh, another way is to export as an stl file and mesh it in Mecway with Mesh tools -> Automesh 3D.

Eduart

@Disla Thanks for your help. Sounds like a plausible cause of the error. However I don't understand why it is a problem in Mecway and not in STPviewer. But probabely we will never know why....

@Victor Gmsh seems to work indeed. I'll use that one instead. Thanks!