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Converting Surfaces to Solids

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Myndex

Electrical
Jan 14, 2005
75
I'm working on a project where there's an ID person using Alias, a surface modeler. As the design has grown in complexity, I don't seem to be able to use her surfaces to crate a solid body. She is giving me IGES files.

She could give me STEP instead, though I don't know if this would help.

My thought is that I should have her simplify her models to just the basic shape (with none of the details like the hole for a cable or button), and then I can use that to create the base body, and do the additional detailing from there.

2001+


Thank you for your thoughts.


A
 
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I recommend eliminating holes--and in some cases fillets--then kniting literally every surface with the Surface Knit feature. Within the Surface Knit feature, chose the "try to form solid" option before completing the operation.

You should then have a valid solid from which to work.

There are complications related to this if your geometry is not this straight-forward. Repost if necessary.

From the solid, you can add your fillets and then apply a nominal wall thicknes with the shell feature. Add holes.


Jeff Mowry
Reality is no respecter of good intentions.
 
When you import the IGES or STEP file, make sure you have selected "Try forming solids" under the "Options" button. If a solid body does not form, it is most likely because of import errors.
 
Well, she's a very talented ID person with a European design background, so that means lots of continuous curvature, and tons of surfaces.

Attempting to "make solid body" on import fails. I'm also having issues knitting, and having issues with "filled surface" to patch holes, etc.


I'm going to get her to simplify to just the base body, and use her "full featured" surfaces as references for sketches to recreate her more complex features, I think.

Thanks again


Andy

 
I also failed in knitting surfaces (iges surface bodies imported) to create a solid body. Here is the error message from SW.

Surface-Knit1: Failure to knit faces.

How do I diagnose areas where this failure occurs?

Thanks,

Alex
P.S. I am using SW 2004, sp4.0 in WinXP sp1.0
 
"Try forming solids" during import rarely works because miscellaneous surfaces are often exported into IGES or parasolid (or whatever format) files and therefore cannot be part of a solid. If only enclosed bodies are exported, however, this will be the quickest method and it should work.

Sometimes you can knit surfaces in increments--such as all surfaces above a planned parting line. See if those will knit. If so, see if another section of the model will knit. Sooner or later you will find the problem. Often the problem is a super-small surface that was not selected or surfaces that separate or cross one another. In those cases, you should ask for an improved exported file to work with or you will have hours of tedious work trying to repair the sloppy surface file.

When you are doing these partial knits, do not select the "try to form solid" option yet. Get some knits accomplished, then hide the original imported surfaces so you can see what you've got, then knit the knitted surfaces together and try to form a solid during that operation.

The best thing to do is to eliminate super small surfaces and fillets when exporting the original file. This will save lots of headache, and allow you to add-in the features after you have a valid knit or solid.


Jeff Mowry
Reality is no respecter of good intentions.
 
Thanks for the advice.


By the way, when using:

Insert -> Surface -> Imported...

There seems to be no way of importing only specific surfaces from the IGES file, and it attempts to pre-knit them, and these pre-knit surfaces are pretty much useless.... Is there a setting to turn this off?


A
 
Not that I know of. Some surfaces are truly knit to begin with, so if you have some surfaces that are not needed, I'd recommend you direct your ID person to save the part without the additional surface data--perhaps as an export copy specifically for that purpose.

I've done some extensive work with Pro-E file exports and normally need to come up with my own work-arounds for files like this. If possible, obtain new IGES (or other) files and work with those.


Jeff Mowry
Reality is no respecter of good intentions.
 
That's what I figured.

Dang, when do we get the software that just does what I'm thinking in my head?


heh

Thanks for the help...
A

 
Getting rid of fillets will save you a lot of trouble. If you are using 2005 it should have C2 continuity fillets. I am not sure if 2001 fillets will do for her design intent. C2 does look visibly better especially for high polish parts.

Make sure that her Alias tolerances are high. A lot of issues with surfaces not knitting stem from loose tolerances in Alias. Have previous models from her come in as solids or as separate surfaces?
 
PlasticFantastic: thanks for the input. What are C2 fillets? (not played with 2005 yet). And how are they better?

So far, they've all come in as surfaces, and I've had mixed results converting them to solids (using extrude to surface or cut to surface, etc.)

Andy
 
C2 or curvature continuous fillets are just smoother fillets. Instead of an arc based surface defining the join of two surfaces, it is a spline based surface
 
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