Why won’t Fusion 360 save STL files correctly?

[tmbespalko]

Greetings… Why won’t Fusion 360 save STL files correctly?

This is a 3fm file generated by some submeshes of a #3DBenchy.  Please note that the shown screen captured dimension is correct:

All I have done is export (since Autodesk blocks Save As) this file into a STL file.  Then I directly opened that STL file in Fusion 360.  Here is the same measurement:

Please note that the measurement is now ten times larger (10x) than the correct measurement in the 3fm file.

I also exported a OBJ file from the same 3fm file:

Although this has the correct measurement, it doesn’t work in Cura in that Cura shows the file to be one tenth (1/10) of the length.

How do I get Fusion 360 to correctly export STL & OBJ meshes that are correct and usable in slicer software?

As a side note these mesh pieces were downloaded from the Creative Tools 3dBenchy site on github.  I got the same results from the same meshes downloaded from the Creative Tools 3dBenchy site on Thingiverse.

Also, I am still working the issue that Cura thinks the imported meshes are not air tight yet Fusion 360 is not flagging any issues with them.

Thanks,

[TheCADWhisperer]

STL files are unitless.

You have to set the correct units on save and on open.

Right click directly on the Body ...

Most slicers also have a unit conversion setting to correct the scale for you.

[tmbespalko]

This has nothing to do with a slicer. I loaded a 3fm file into Fusion 360, exported it as a STL file then opened that file in Fusion 360 and the STL file measured 10x longer than it should have been. There was no slicer operation. This is entirely due to Fusion 360.

Please remain focused on a probable Fusion 360 cause since no other software package was used... It was 3fm from disk --> Fusion 360 with correct answer --> disk as STL --> back into Fusion 360 now showing with wrong answer. There is some wrong translation occurring with Fusion 360.

Thanks

[TrippyLighting]

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@tmbespalko wrote:
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Please remain focused on a probable Fusion 360 cause since no other software package was used....

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Please remain focused on what @TheCADWhisperer is trying to tell you. It isn't that complicated.

When you save an object as a triangulated mesh, the default unit is mm. However .stl is unitless. YOU have to know what units you exported it as.

Then it depends on how you opened the mesh file in Fusion. If you use file->open, the mesh imports with cm as the default, hence the difference.
If you use Insert-> mesh, you are given a choice to select the appropriate unit as, again, that isn't provided by the .stl file.

Then it should have the dimensions you expert. 

[TheCADWhisperer]

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@TheCADWhisperer wrote:

STL files are unitless.

You have to set the correct units on save and on open.

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Perhaps I should have used the word Import rather than Open.

Sometimes I forget the hidden stuff that beginners are not aware of.

This is the same in several different CAD softwares that I use. (SolidWorks, Autodesk Inventor Professional, Creo...)