Exporting a UG/NX6 File to Autocad. 2

[SDETERS]

I have a spline in UG/nx6 I need to get into Autocad or Dxf that goes through Many points. The data in Nx6 looks great. But the Data after I export it out to Autocad does not match the points. The Spline that is supposed to go through all of the points does not once the data is translated into Autocad. Is there a way to get better accuracy when translating into Autocad from NX6. This part we are having cut from the CAD data geometry. The points come in just fine when translated but the spline is really a mess. The mismatch is about .001

 

[JohnRBaker]

I suspect that you're seeing the limitations of DXF.

Not sure if they support IGES or STEP, but that might be a more appropriate way to go if they do support either of these. Also note that AutoCAD often represents freeform curves as 'polylines', which are not smooth curves, but rather an object made of a series of short linear segments which for 2D drafting purposes is often good enough, but not something you're want to machine or reference when creating additional complex geometry.

John R. Baker, P.E.
Product 'Evangelist'
Product Design Solutions
Siemens PLM Software Inc.
Industry Sector
Cypress, CA

http://www.siemens.com/plm

http://www.plmworld.com/museum/

To an Engineer, the glass is twice as big as it needs to be.

 

[cowski]

The mismatch is about .001

How accurate does it need to be?

You might try 'simplify curve' before you export. This will break the spline up into a series of arcs, but introduces its own approximation errors.

 

[SDETERS]

Needs to be within a profile of at least .0005 or so. I will try this. Good information thanks for the feedback

 

[SDETERS]

After I tried simplify curves the profile looks like the curves I get after the translation into Autocad. Thanks for the feedback once again.

 

[JohnRBaker]

What truly amazes me is that there's something in AutoCAD where being able to hold a tolerance of 0.0005 versus 0.001 would actually be critical to performing some task.

John R. Baker, P.E.
Product 'Evangelist'
Product Design Solutions
Siemens PLM Software Inc.
Industry Sector
Cypress, CA

http://www.siemens.com/plm

http://www.plmworld.com/museum/

To an Engineer, the glass is twice as big as it needs to be.

 

[SDETERS]

This part we are having it machined from the cad geometry to get a highly machined precision part to create a tooling member. If the tooling company needs to scale up and or down the profile to accomodate shrinkage this will magnify the error in the profile.

thanks for the comments and suggestions.

 

[JohnRBaker]

If you're NOT machining these parts in-house using the NX models, may I suggest that you find a supplier using something OTHER than AutoCAD if you're going to consistently need to have parts machined to these tolerances. AutoCAD was designed as a DRAFTING tool and as such, the way it handles spline data is adequate, but I would think twice before depending on it to feed manufacturing processes where you expect tolerances in the 0.0005 range to be maintained. Sorry, but that's just the way things are.

John R. Baker, P.E.
Product 'Evangelist'
Product Design Solutions
Siemens PLM Software Inc.
Industry Sector
Cypress, CA

http://www.siemens.com/plm

http://www.plmworld.com/museum/

To an Engineer, the glass is twice as big as it needs to be.

 

[SDETERS]

I tried exporting out a 2D IGES file and the profile is perfect when imported into Autocad.

Thanks for all the help and feedback

Shane