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Active Contributor
LeonMF
Posts: 34
Registered: ‎02-14-2013

Is STL export broken?

626 Views, 13 Replies
07-10-2013 01:32 PM

When I export via STL, it appears that units don't get properly exported.  The file shows up in ReplicatorG as smaller than actual size by a large margin.  I have to export to IGS, import into FreeCAD, export as STL for sizing to be preserved.

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Valued Contributor
tdtwohy
Posts: 105
Registered: ‎03-29-2013

Re: Is STL export broken?

07-10-2013 01:48 PM in reply to: LeonMF

 

 

Yeah, they're having issues with files being reduced to 10% of original.

But the more complaints, the faster it gets fixed... we hope :smileyhappy:

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Product Support
innovatenate
Posts: 1,040
Registered: ‎11-22-2011

Re: Is STL export broken?

07-10-2013 05:50 PM in reply to: tdtwohy

I was curious if changing the default units in F360 to cm may be a work-around? I don't currently have Replicator G installed, but that may change soon :smileyhappy:

 

Thanks!

 

 



Nathan Chandler


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Valued Contributor
tdtwohy
Posts: 105
Registered: ‎03-29-2013

Re: Is STL export broken?

07-10-2013 06:15 PM in reply to: innovatenate


Are you sure there isn't an old "send to print" code from 123D in there?

I remember 123D used to be a centimeter based interface and there could be a lot of old code from 123D still remaining in F360.


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Product Support
innovatenate
Posts: 1,040
Registered: ‎11-22-2011

Re: Is STL export broken?

07-10-2013 06:40 PM in reply to: tdtwohy

The geometry kernel in F360 works behind the scene in cm's. The STL format is unitless (I believe - please correct me if I'm off base here). I think this may be where the issue is.

 

Here's what I've found so far:

 

-I created a 100 x 100 x 100 cm cube in F360. Next, I imported into Inventor where I can specify the units of my choice and the size is correct. 100x100x100 in, cm, mm, palms (just kidding), etc... 

-If I import the STL file into Alias (where the default is mm), I seem to get a similar results (100x100x100mm).

 

I was noticing that RepG gives two options for units, mm or in.  I just noticed that if I export the F360 cube into RepG, it looks like it comes in as 100x100x100 mm  (instead of 1000x1000x1000 mm). Does this like a possible explanation to what is happening? 

 

Thanks,

 

 



Nathan Chandler


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Active Contributor
LeonMF
Posts: 34
Registered: ‎02-14-2013

Re: Is STL export broken?

07-10-2013 07:26 PM in reply to: innovatenate
It does appear that STL is unitless. However, it also appears that the defacto standard is that the implicit unit is 1mm based on a quick google search. If Fusion 360 is using a different standard of cm, then that would exactly explain the problem.

FWIW, unitless or not, it would make sense for the software to support the defacto standard.
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Product Support
innovatenate
Posts: 1,040
Registered: ‎11-22-2011

Re: Is STL export broken?

07-10-2013 08:28 PM in reply to: LeonMF

 

Thanks for the quick feedback!

 

I'm hoping to clarify that if the default units are changed to mm (or to match the destination program's units) prior to exporting the STL file from Fusion 360, that the scale is correct once opened in the destination program. It's not that exporting a file that everything is shrinking by a scale of 1/10.

 

I'm hoping the above suggestion is a useable work-around for users importing into RepG, for now. The ultimate enhancement would be to have the ability to scale the exported STL during export; however, the above suggestion of matching units manually may be the best available option for the short term. Hope this is helpful!

 

Please keep the feedback coming, it is very much appreciated!

 

Thanks,

 

 



Nathan Chandler


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Board Manager
schneik
Posts: 758
Registered: ‎04-05-2003

Re: Is STL export broken?

07-10-2013 10:39 PM in reply to: innovatenate
are the wrong scale exports coming from when you are selecting/looking at the design in Fusion or from when you use the export tool built into the dashboard?

Kevin Schneider


13" Macbook Pro Retina - OSX 10.9 in Portland, Oregon


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tom
Member
tom
Posts: 6
Registered: ‎04-29-2013

Re: Is STL export broken?

07-11-2013 03:21 AM in reply to: LeonMF

STL is truly unitless - it's just numbers in the file.  For makerbot they assume everything is mm, although if you exported it in inches they will try to detect this and automatically correct.

 

I've seen a few 3d programs that export STL, and the most common way to export is to just use the native unit of the file you're exporting.  But I've seen one program handle this by asking you during STL export whether you'd like to export with native, mm, or inches as the unit.

 

Or, I bet if you switched the default units of fusion documents to mm it would fix the issue for most users.

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Active Contributor
LeonMF
Posts: 34
Registered: ‎02-14-2013

Re: Is STL export broken?

07-11-2013 05:21 AM in reply to: schneik
Kevin,

The problem is only with the exported file. I'm not aware of any problems with viewing the files in Fusion.
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