Is there a way to define accuracy for STEP export?

[pimm]

I have my part files set up to have a default absolute accuracy of .0012.

When I import a STEP model the properties show an accuracy of .0012 and the model is almost sealed.

I exported this same model as a STEP model file (because I wanted to import the model to a different DCS location).

When I import this model it comes in at an accuracy of .007 instead of my default .0012, and the model registers numerous bad vertice errors that it didn't have before.

During the export process I noticed a callout of step_config.pro when I click on options. It doesn't tell you what that is supposed to do, but perhaps somehow this is how the STEP options can be modified to match the part model defaults.

Any idea in how to modify the accuracy of STEP exports? I'd like to be able to round trip a STEP as clean as what originally comes in.

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[ptc-2753269]

hi Paul,

I have the same question, maybe changeing the accuracy of STEP exports depend on the Pro/E software.

wish you get the answer earily.

thanks.

will

[Patriot_1776]

I don't know, but maybe try exporting the files at an absolute accuracy of .0001 or smaller.

There might be a setting somewhere for use in the config.pro file. Call PTC and post up.

[pimm · Accepted solution]

I did as you suggested and called PTC support. This time around we actually connected with someone with 5 minutes.

The issue I was having ended up being a setting's problem.

Even though I have absolute accuracy enabled and absolute accuracy was set to .0012 I had one thing out of place.

When I set up the template file I didn't modify the template model's accuracy. This is why the imported model was at my required .0012 accuracy and after it was saved and imported in again the accuracy changed from that value to .0072.

All I had to do was re-save my template model to the .0012 absolute accuracy and now my models come in at this exact value.

The person I talked with also told me how I could bring the model in with exact accuracy as the model was exported from the customer. I'll attach this document that helps you determine this accuracy even though it may be common knowledge.

Description
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When importing a STEP file into Pro/ENGINEER, it is recommended to set the accuracy in Pro/ENGINEER the same as the accuracy in the STEP file. To do this, the accuracy of the STEP file must first be determined.

Alternate Technique
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See resolution.

Resolution
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First, open the STEP file in a text editor. The accuracy can be found by searching for the text string
"UNCERTAINTY_MEASURE_WITH_UNIT". This will bring you to a line similar to the following:

#160=UNCERTAINTY_MEASURE_WITH_UNIT(LENGTH_MEASURE(2.34E-2),#154,'closure',

The accuracy is the number in parentheses next to "LENGTH_MEASURE". In this case, the accuracy is 2.34E-2, or 0.0234.

[Patriot_1776]

Awesome info, I would never have known that. I'm going to try it, thanks!

[pimm]

Good deal; glad I could help a little.

I do know that this forum has been extremely helpful to me. Many times I've had questions that completely had me stumped where someone here has pointed me in the right direction.

I am very glad that Creo does not determine it's own loose accuracy that can not be changed. For a while I was afraid this was a no win situation.

[Inoram]

ah thanks for the info. I was going to say, in hundreds of imports I do not remember ever seeing the accuracy change by itself.

And I think most people know this but get Notepad++ if you plan on doing this, regular notepad will grind to a halt with a large file.

[Inoram]

I am not sure a STEP file contains accuracy?

Which version STEP are you exporting?

I know when I switched to 214_is it has more options.

[pimm]

It is possible that a STEP export doesn't contain accuracy but when I bring the model back in the properties show the accuracy value changed from .0012 to .007.

If I bring the model in direct from the customer the accuracy value is .0012.

AP203_is would be the STEP version we are using by default. I tried the AP214 but didn't see any option for tolerance.

Seems something does happen with the accuracy at export, this should be controllable.

[DavorGranic]

There is option about accurasy when you open step file which affects this i think. I had problem that my step file when i open it got reltive accurasy instead of absolute that original part had.