Bug? Save as STL is always in mm...

[HenryPootel]

In system settings, units are set to inches and drawing units show as "Inches | deg | oz" on the lower status bar. When I save as STL, it saves in mm. My CAM program, which expects inches, thinks my 1 inch part is 25.4 inches. How do I get it to save the STL file in inches? Thanks!

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[hkramer · Accepted solution]

Hello,

indeed the unit of such a STL file is based on mm.

STL files do not have any header or similar which would maintain units information to be translated.

The basic unit of Creo Elements/Modeling PE is metric, no matter what you select your current units to be.

STL files are created from the faceted model, (The faceted model is what is displayed on your screen) not

from the mathmatical model, so any settings such as units have no effect on the faceted model.

There is no way to output STL in units other than mm.

In such cases it is needed to specify the unit when importing the file into the target application.

[HenryPootel]

Thank you Horst, for confirming this behavior is by design. This answers my question.

It is helpful to have the entire production chain (raw materials, measurement devices like dial indicators and rulers, CAD, CAM, CNC mill ends, etc) all interchange the same units of measure (regardless of their internal basic unit of measure). Unfortunately, I am stuck with imperial measures for other parts of my production chain. It turns our that my CAM program has similar a weakness: if I import as mm then it only generates gcode in mm, if I import as inches it only generates gcode in inches. The workaround. I suppose, is to import into the CAM program as inches (even though it is in mm) and then scale the imported object in the CAM program (multiply by 0.039...) and then generate the tool path.

Thanks again for your help.