Faces do not map to proper surfaces

protontim

I have an imported STEP part which has been meshed. When I select the faces of the geometry part and add them to a surface, the resulting faces selected on the meshed part do not correspond 1:1 to the faces originally selected on the geometry.



In the picture I have selected 6 screw holes and added the surface. But the surfaces that are selected in the mesh are 5 of the 6 screw holes and a fileted edge (red arrow). How can I fix this? Thanks.

ehoule

Had this issue in the past... the step was created frow solidworks... the issue was solved by importing the step file to freecad and re-export the step from freecad...


https://mecway.com/forum/discussion/942/pinned-support-not-assigned-to-the-right-surface#latest

Victor

@protontim, which version of Mecway is this? I've changed how that works in 15. Hopefully it's more reliable, but might also go wrong in some cases that were OK in 14.

If you could send me the STEP file, that would really help in the long term since I currently have only one example to test on.

protontim

@ehoule my STEP file was indeed exported from SolidWorks. I will try your "fix". Thanks for the quick response.

Victor, I am using V14.0 and I have attached the STEP file.

protontim

Well it appears it may be a Mecway issue. I opened the STEP in Freecad and exported it. Now when it comes into MECWAY there are some holes that are "filled". I have attached this new STEP file. I will give V15 a try.

protontim

I imported the STEP part that originate from SW and was imported/exported from Freecad into V15. Unfortunately there are still "filled holes" on the part.

protontim

I also tried step 203 format. Same issue. Not sure if this has any bearing on the issue, but Netgen takes a very long time to load when meshing this part.

protontim

I exported from SW in an ACIS format. I imported/exported to STEP with both Freecad and SW and in all cases it was still whacked. Can't seem to get a model I can read with this part. I am going to try parasolid and then quit if that doesn't work.

JohnM

Strange. Mecway 14, I downloaded your STEP, meshed, selected the bolt holes in geometry, worked fine.

A workaround for now is to do direct selection on the mesh.

protontim

I tried a large number of different import and export options with various CAD tools. Most of the paths ended with a part that imported and looked like this. The part does mesh but the top face (the dark one) does not map from the model to the mesh. This part was generated by exporting parasolid from SW, importing into Alibre, exporting ACIS, importing to Alibre, exporting STEP... yikes. Nothing seems to work. Gotta move on for now.

protontim

@JohnM Thanks for looking into that. Strange that it worked for you. Try as I might it is messed up. What meshing tool were you using? Could you post your liml file so I can try and replicate on my end?

protontim

@JohnM created a new liml in MW14 and loaded the STEP. Same result. Really curious how yours could be different. The only think I can figure is the mesher.

JohnM

turns out it worked in 13.1, not 14

protontim

@JohnM well that explains it! Might be a good data point for Victor as he digs into this. I was finally able to get something working by changing the export options on Solidworks. If I check all the boxes shown below it looks like I can read it in OK and keep the faces and surfaces where they belong.

disla

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protontim

The original geometry is solid. And as you can see from the mesh it meshes solid as well. The STEP should be solid as well. I think splitting the periodic faces when exporting (or perhaps one of the other options checked above) got it to import into V14 correctly. as @JohnM noted it imports into 13 just fine without the changes.

Sebastianmaklary

@protontim I've also had issues with meshing gears exported as step files from solidworks where the solution was to check "split periodic faces". I haven't figured out what caused the issue as some gears had issues while others hadn't even though they were made from the same template but just with different parameters. Solidworks themselves say that the "split periodic faces" option is to improve the quality of the export so I thought that it was just another thing where Solidworks does a shitty job of being general purpose CAD software.

protontim

@Sebastianmaklary thanks for the confirmation. And I find some small comfort in the fact that others have battled with SolidQuirks... frustrating for sure. From now on I export with the "split periodic faces" checked. Only cost me 3 hours of messing around to get to that point.