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Old 01-12-2012, 03:29 AM
iffen iffen is offline
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[help!] Conversion from Solidworks to OSD

HI ALL:

Could some one help me?
I try to convert the design model from Solidworks to OSD in stp format. Our ME needs it to be 10 e-4 as its model resolution. But if I load the stp with 10 e-4, the model corrupts.

This is very frustrating because I am quite used to Solidworks and modifying the design. So could some one help me on this? How to convert without corrupting and yet keep the right resolution?

Thanks!!
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Old 01-12-2012, 06:30 AM
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Mike Swartz Mike Swartz is offline
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Re: [help!] Conversion from Solidworks to OSD

Probably not going to happen. The Solidworks file in question has a geometric resolution lower than your desired goal. What this means is that there are gaps or overlaps between adjacent edges of the part that exceed the resolution. The healing function built into the translator cannot resolve the issues.

You might want to try exporting the file as IGES. The CoCreate IGES translator has a better healer and it may be able to fix your part.

Ultimately, you cannot make a silk purse out of a sow's ear.
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Old 01-12-2012, 06:52 AM
iffen iffen is offline
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Smile Re: [help!] Conversion from Solidworks to OSD

hi Mike:
thanks for your reply.

So you mean solidworks has internal geometric resolution? How can we see this or change this when building it?

And OSD iges translator is something already embedded or extra add-on?
Thanks
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Old 01-13-2012, 09:28 AM
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Mike Swartz Mike Swartz is offline
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Re: [help!] Conversion from Solidworks to OSD

SolidWorks and CoCreate both support import and export of data through STEP IGES and SAT. This is built into the base product of both packages.

All CAD systems work to some specified geometric resolution. According to SolidWorks this is 1e-8 (Meters). Geometric resolution is (to greatly simplify a complex thing) the maximum allowed gap, overlap or misalignment between adjacent edges in a part.

Certain types of geometry require little computational effort to determine an exact solution, such as the geometry of a plane, cylinder, or cone. Other types of geometry, such as the intersection of two blended spline surfaces, require much more complex mathematical calculations to determine a solution. In these cases, Accuracy affects the calculations of geometry in order to achieve an acceptable level of approximation of the exact solution.

From working with many data translations, I have found that if you have a part with a lot of complex b-spline faces that join together, the actual geometric resolution is much lower. I do not know if the problem is with the native model, or if it becomes lowered when translated to a neutral data format. (Like STEP, IGES or SAT)

In either case, the resolution of the parts cannot usually be forced to be much better than they are.

Why does your ME require a geometric resolution of 1e -4 (mm)
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Old 01-13-2012, 01:34 PM
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BMaverick BMaverick is offline
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Re: [help!] Conversion from Solidworks to OSD

We have had better success moving 3D CAD models to/from SolidWorks to CoCreate using the SAT (ASIC) file format than with the STEP neutral format.

As for resolution, on geometry blends, the SAT holds the values tighter. Not sure if either of these will reach your 10 e-4. But the SAT format will be closer than STEP.


IGES is the worse for accuracy. It's been typically called I-GUESS file translation. When you zoom up on 3D geometry from an IGES file, intersections do not even connect or will be off plane.

Like Mike is hinting at, b-spline surfaces are difficult between CAD systems due to logarithms based on what solver is used and the science mathematics from various well known scholars. The problem is, just like there are many CAD systems, there are many different scholars dealing with surface formulations. Many of the higher ended CAD systems are now using NURB surfaces, therefore translation is identical between each with a high end accuracy as well.


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Old 01-14-2012, 04:59 AM
iffen iffen is offline
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Cool Re: [help!] Conversion from Solidworks to OSD

Hi Mike:
Our ME requires 1e-4 because according to him this is a standard for injection molding as a tradition of our company.

I can not argue too much about that.

What I still don't understand is where do I see or adjust geometry resolution in Solidworks. Could you tell me where to find it?

Something else is that I am an industrial designer, I am quite used to the way parametric CAD software(actually Solidworks in this case) and I personally think it is an ideal tool for Industrial designer. But the frustrating thing is none of my model can be translated into OSD in 1e-4 without corrupting.

I don't know some else share same experience, I really need some tips before getting tired of my job
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Old 01-14-2012, 05:01 AM
iffen iffen is offline
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Unhappy Re: [help!] Conversion from Solidworks to OSD

Quote:
Originally Posted by BMaverick View Post
We have had better success moving 3D CAD models to/from SolidWorks to CoCreate using the SAT (ASIC) file format than with the STEP neutral format.

As for resolution, on geometry blends, the SAT holds the values tighter. Not sure if either of these will reach your 10 e-4. But the SAT format will be closer than STEP.


IGES is the worse for accuracy. It's been typically called I-GUESS file translation. When you zoom up on 3D geometry from an IGES file, intersections do not even connect or will be off plane.

Like Mike is hinting at, b-spline surfaces are difficult between CAD systems due to logarithms based on what solver is used and the science mathematics from various well known scholars. The problem is, just like there are many CAD systems, there are many different scholars dealing with surface formulations. Many of the higher ended CAD systems are now using NURB surfaces, therefore translation is identical between each with a high end accuracy as well.

One another day I tried SAT. But I didnt find the SAT file, instead a error log which didn't say the cause of error. That meant the solidworks model was not successfully saved as a SAT file.
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Old 02-03-2012, 12:40 PM
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gmatelich gmatelich is offline
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Re: [help!] Conversion from Solidworks to OSD

I have found rare cases where I am not able to at least get a part's resolution to 1e-4 in Modeling (where remotely possible I strive for 1e-6) - though at times it takes a great amount of hassle to achieve this. Sometimes I'll get lucky on the first attempt and by lucky I mean that the model comes in as a face part, but I am able to use Surfacing commands to either Grow Part or Reintersect (using Show Gaps to show me what needs Reintersected).

If I'm not able to get there on the first round, it usually involves loading the step or sat model into Modeling using variable import resolution. Once I get a model that imports at least well enough to Grow Part or Reintersect (or maybe even Insert Face into a gap that I can't get to heal), then I check part, and save part back out as another step or sat file, then try loading that file as a something closer to desired resolution.

I don't think this helps you directly, but it may help the ME, if he's not already familiar with these techniques.
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  #9  
Old 02-06-2012, 04:58 AM
mrstero mrstero is offline
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Re: [help!] Conversion from Solidworks to OSD

in part due to PTC's desire to consolidate onto a single direct modeling tool (namely CREO DIRECT), PTC has invested $$ to improve the ability of CoCreate / Elements Direct V18 to open and handle models from other CAD systems.

If you are still paying maintenance and aren't yet working in V18 you might want to get your hands on the new version to experiment and see if V18 can load the model in question without the "face part" nonsense result....

good luck...
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