topic Re: STL Export Scaling Issue in Inventor Forum

STL Export Scaling Issue

sozoroski — Tue, 25 Aug 2020 10:30:47 GMT

When I export a model to an STL file it seems to change the units from inches to centimeters. Then when I go to open up the STL file the units display inches (like it should) but scaled as if it were converted to centimeters first. For example, a part with a 10in diameter would show 25.4in diameter on the exported file. I have checked my document settings and export settings to ensure both are set to inches (they are). Does anyone have any idea why this is happening?

I am running Inventor Professional 2021

Re: STL Export Scaling Issue

TheCADWhisperer — Tue, 25 Aug 2020 11:30:14 GMT

Can you Attach *.ipt and resulting *.stl file here?

Re: STL Export Scaling Issue

mcgyvr — Tue, 25 Aug 2020 12:06:56 GMT

Where are you opening this STL file?

What units is that program expecting?

My first guess is that you are modeling in inches and may have your stl options (options button next to the save button while exporting) but your program (maybe 3d printer program) is expecting different units..

You need to have your export options set to the units your opening program is expecting or set that program to open the file in the same units you exported with..

I model in inches.. set my export options to mm as my 3d printer software expects mm.

A stl file is unitless so it doesn't pass the desired units in the actual file..

Re: STL Export Scaling Issue

sozoroski — Tue, 25 Aug 2020 12:38:34 GMT

I am opening the stl file in Inventor and it still shows the scaled up dimensions (even with document units set to inches). Does inventor expect different units than what is set in the document settings when opening an stl file?

Re: STL Export Scaling Issue

mcgyvr — Tue, 25 Aug 2020 12:45:50 GMT

@sozoroski wrote:

I am opening the stl file in Inventor and it still shows the scaled up dimensions (even with document units set to inches). Does inventor expect different units than what is set in the document settings when opening an stl file?

Just like when exporting you have the "options" button right next to the open button.. Press that and select the proper units.

Do not confuse that with the document units.

Re: STL Export Scaling Issue

sozoroski — Tue, 25 Aug 2020 12:50:44 GMT

I cant upload the file I was working on but I did a test with a 1" diameter cylinder and got the same results. I attached the stl and ipt files. Very clearly shows that it converts to centimeters and just slaps on inches as the unit.

Re: STL Export Scaling Issue

sozoroski — Tue, 25 Aug 2020 12:57:01 GMT

I have the proper units set for the export settings as well. That is why I am stumped. The document settings are in inches, when I export and hit options the units are set to inches there as well.

Re: STL Export Scaling Issue

mcgyvr — Tue, 25 Aug 2020 12:58:27 GMT

@sozoroski wrote:

I have the proper units set for the export settings as well. That is why I am stumped. The document settings are in inches, when I export and hit options the units are set to inches there as well.

You need to set the correct units when you Open.. In the open dialog there is an options button just like when you export that you need to press and set the correct units.

Re: STL Export Scaling Issue

sozoroski — Tue, 25 Aug 2020 13:04:16 GMT

When I go to the open options, the units are set to "template units" which is inches. I switched it to "inch" just to be sure and it still opens at 2.54x the expected dimensions

Re: STL Export Scaling Issue

sozoroski — Tue, 25 Aug 2020 13:40:17 GMT

I've been using a work around by just direct editing the entire part and scaling it to 0.3937 the original size so when it exports it, it is at the correct dimensions. I would love to learn why it's doing that or what I am doing wrong but I have gone through every setting that I think could apply to the export but still no change in the final result. It seems that when I export the part it automatically scales it to centimeters despite what I have set in the export/document/opening settings.

Re: STL Export Scaling Issue

mcgyvr — Tue, 25 Aug 2020 14:01:15 GMT

You don't seem to be setting the correct units on export.

I have no problems opening your ipt file, doing an export (ensuring to set the options units to inch) and opening it back up (setting options units to inch).. It retains the proper scale..

If you are positive you are doing this please post a screencast of the entire process..

https://knowledge.autodesk.com/community/screencast

Re: STL Export Scaling Issue

sozoroski — Tue, 25 Aug 2020 14:34:31 GMT

Let me know if I'm doing something wrong!

https://autode.sk/3lkkulR

0475ccdc-341e-4456-a73c-6b09026ffb76,640,620

Re: STL Export Scaling Issue

mcgyvr — Tue, 25 Aug 2020 14:47:37 GMT

You've got it right from what I saw.. But Inventor isn't working properly for you there..

What version of Inventor are you using? including updates..

Please open the stl file I attached above.. Does that open up to be a 1" circle?

Re: STL Export Scaling Issue

sozoroski — Tue, 25 Aug 2020 15:13:09 GMT

The file you attached opened fine and displayed the correct units.

I am using inventor professional 2021 64 bit edition. Build 183. I do see that there is an update and hotfix released a month ago. I'll download those and see if the issue was resolved with the update. If not I'll send in a bug report.

Thanks for the help mcgyvr!

Re: STL Export Scaling Issue

mcgyvr — Tue, 25 Aug 2020 15:49:09 GMT

You may want to try the Inventor Reset Utility to reset your user profile..

(Export your application options first)

I have build 183 too installed now and have no problems exporting to the correct size..

Re: STL Export Scaling Issue

sozoroski — Tue, 25 Aug 2020 16:02:07 GMT

Are you using inventor 2021? The file you attached had 2020 in the name.

Re: STL Export Scaling Issue

sozoroski — Tue, 25 Aug 2020 16:46:43 GMT

I updated my inventor and installed the hotfix and it seemed to have solved the issue. Thanks for the help!