DXF Export - Arc and Circle Smoothness (not splines)

[marklaforest]

Inventor Pro 2014.

We are having problems with one of our aluminium CNC router suppliers where arc and circle profiles are being cut as facets and not true curves.

The supplier has suggested that the arc circle smoothness value is not set sufficiently high enough when translating to the DXF format.

He demonstrated this to me by opening the DXF file that was exported from IV in AutoCAD then going into Options>Display>Display Resolution and arc and circle smoothness was set at 100. He then changed to 20000 and saved and used this dxf file to produce a smooth true arc cut profile.

I wasn't convinced prior to him demonstrating this to me as my understanding was that this was just a display resolution from within the AutoCAD application and had nothing to do the geometry translation to the dxf format.

I have done some investigation into the issue and it seems that if you export a flat pattern as a dxf from IV then open in AutoCAD the arc and circle smoothness value (VIEWRES) defaults to a setting of 100. If you produce a dxf from the drawing idw environment (save copy as) then open that file in AutoCAD the VIEWRES value is 1000.

My question is this: Is there some way to make IV export dxfs that increase the VIEWRES value from 100 which seems to be the default that IV uses?

The only work around I can find so far is having to open each dxf file in AutoCAD and changing the VIEWRES and saving. this is very time consuming when dealing with many dxf files.

[johnsonshiue · Accepted solution]

Hi! I am not sure what your supplier said was true. A circle in Inventor is exported as a circle in DXF. This has nothing to do with VIEWRES. Only spline would be exported as faceted segments. There are configuration files you can use to smooth the segments. Could you provide an example exhibiting the problem? I would like to try and see if it helps.

Many thanks!

[marklaforest]

Thanks for the reply. My thoughts too!
Attached is the file in question.

[johnsonshiue]

Hi Mark,

Could you reattach the file?

Many thanks!

[marklaforest]

Please find attached

[johnsonshiue]

Hi Mark,

Could you attach the Inventor file also? I would like to try using a configuration file to see if I can make it smoother.

Many thanks!

[marklaforest]

Hi John,

IV file attached

[johnsonshiue]

Hi! I tried various ways to export DXF from Inventor using Weir Plate.ipt. I cannot seem to reproduce the faceted circle behavior (see attached). Could you tell me the exact workflow you used to export to DXF?

Many thanks!