Exporting to step, accuracy problem

[adrianos_filinisC9K3S]

Hello,

I am trying to export a model to step file and increase the accuracy as much as possible because it will be machined in CNC and I need high accuracy.

When exporting I choose options and increase the spline fit accuracy to the maximum which is 0.00001cm. 

When the file is imported to Creo ProE the accuracy goes down to 0.01mm, and checking as well the UNCERTAINTY_MEASURE_WITH_UNIT(LENGTH_MEASURE(0.01),#88060, it is 0.01 even though I increased the accuracy.

Do you know how I could solve the accuracy problem I am facing?

Thanks,
Adrianos

[CGBenner]

@adrianos_filinisC9K3S 

Welcome to the forum.  Could you possibly share one of your exported STEP files (something safe to share), so experts in this forum can look at this?  I wonder if the issue is on the CREO side... but we would need to look at the STEP file itself before pointing fingers.  🙂

[adrianos_filinisC9K3S]

Hello,

Thanks for the response.

I have updated my post with the model in stp format.

Best regards,

Adrianos

[johnsonshiue]

Hi! If I understand how STEP format works correctly, the UNCERTAINTY_MEASURE_WITH_UNIT setting in the STEP file is about the maximum tolerance allowed (not exceeding) in the exported file. The Spline Fit Tolerance when the STEP file is exported from Inventor is about the minimum tolerance of fitting a spline curve. These two are not the same.

Many thanks!

[adrianos_filinisC9K3S]

Thanks, though I still dont know how to increase the UNCERTAINTY_MEASURE_WITH_UNIT.

That is my goal. Do you have any advice?

[johnsonshiue]

Hi! I don't think Inventor allows that value to change. The maximum tolerance of 0.1mm is quite loose already. What do you want to change it to? Any bigger value could lead to bad geometry and modeling failure.

Many thanks!

[adrianos_filinisC9K3S]

So their no way to increase the accuracy of the exported file by decreasing that number? 

My part is going to be machined and it comes out faceted when imported from the engineer in their system.

[johnsonshiue]

Hi! Indeed, I don't believe there is a way to tighten up the tolerance other than Spline Fit Accuracy setting on STEP Export. I am working with the project team to understand the behavior better. In the meantime, please share the Inventor files with me directly johnson.shiue@autodesk.com.

Many thanks!