Issues while save from .DWG to .STP HELP Please

[thomas.byrnes]

I've run across a biig problem that I can find no solution to anywhere. I've drawn myself a (detailed) object in 3d in AutoCAD. Now I want to get it printed as a 3D prototype. Problem is that I need to create either a .STP .STL or .IGS for the company to be able to see my creation and print it. Here are my issues. When I open my DWG in inventor fusion it will allow me to save in any of the required formats. However. .STL will save as a certified trust list. .IGS fails and when I open the file my object is gone. This leaves me with a .STP. It is the most successful. However, When I re-open this file, my object has grown by 10 times. Where a specific line is supposed to me 20mm it becomes 200mm. No good. Ive tried saving this save object scaled down to 10% in AutoCAD (the 20mm line is now 2mm) then do the same thing. But when I open the .STP file again, the line is once again 200mm. Something isn't working. I need a resolution. (So there is no confusion, the line I speak of is a specific line on my object that I use as a base measurment, a sort of control.) Any and all help will be greatly appreciated.

-Tom

[jeffrey.sun]

I can reproduce it with the workflow below.
1. Open AutoCAD 2012.
2. New a dwg based on template acad.dwt.
3. Change Insert scale to be Centimeters in the Drawing Units dialog. (Use the command "units" to open the dialog)
4. Create a box with the size 1x1x1.
5. Save the dwg as cm.dwg
6. Open the cm.dwg in Inventor Fusion 2012 and save it as cmFusionCopy.stp.
7. Open the cmFusionCopy.stp in Inventor 2012.
8. Measure the box edge. It is 10 mm. 10 times larger than the number in AutoCAD.

In AutoCAD, the gemoetries are unitless. When Fusion open the AutoCAD dwg, it uses the Insert Scale as the gemoetry unit. So it treat the box size as 1cm X 1cm X 1cm. When it saves the file as stp, the box size is changed to be 1cm X 1cm X 1cm. When the stp is opened in Inventor, it loads the stp body as 10mm x 10mm x 10mm. So the measurement is becomes 10mm.

If you have the same Insert scale setting with me, please have a try to chagne it to be Millimeters in step#3.

I'm not the expert in this domain. I just have encountered this kind of unit issues before. Just for your information, hope it helps.

[Wendy.Chen_Autodesk]

Hi Tom,

Many thanks for bring out the issue. As I know, the STL(including the OBJ) file only contains the FACET objects, and there's no Surfaces/Solids available for export. Thus any exporting operations from STL file without performing reverse engineering will be invalid.For detailed information about STL, please refer to http://en.wikipedia.org/wiki/STL_(file_format).

Hope this helps.and if you have any further problem, please let us know. Thanks!

Wendy

[JDMather]

@thomas.byrnes wrote:

I've run across a biig problem that I can find no solution to anywhere. I've drawn myself a (detailed) object in 3d in AutoCAD. Now I want to get it printed as a 3D prototype. Problem is that I need to create either a .STL  .STL will save as a certified trust list.  

-Tom

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I'm surprised Autodesk folks have so much trouble answering your simple question.

You don't need Inventor Fusion.

In AutoCAD set facetres = 10

In AutoCAD issue the stlout command.
The file is an stl file for 3D printing (it is not a certified trust list as you have stated - do not try to open the file by using Windows Explorer or double clicking the file - you must use software capable of reading an stl file to view the file. 

How did you try to view the contents of the file?  What made you think it was not valid for the purpose?