3D Print STL Export incorrect scale - ALWAYS

[ENTERteacher]

Hi All,

This has been an ongoing issue for years now and I am finally entering the conversation.

Dating back to Inventor exports and now continuing with Fusion 360, when STLs were/are exported and then imported into 3D printing software, the scale was never 1:1.  NEVER! 

We have used Cura, Makerware/Makerdesktop, Tinerine Suite 1.0 and 2.0, and the software with Printrbots.  I work in a school district on Vancouver Island and the few of us here have worked together here to find work-arounds (such as scaling to 1000% from Inventor imports).

Now, that I am working in Fusion 360, it is even more tricky to manage as an educator since we use different software/machines from school to school and students are "learning" (which means loads of mistakes).  It is getting to a point where these bugs are difficult to explain and solve on an individual basis for every learner.

My current frustration is a very simple cylinder.  I just modeled a 1" ID circle with .125" thickness using circle and offset in Sketch mode.  Then, I extruded it 1".  I then hit the 3D Print button.  I just want the STL so I did not send it to a printer or anything like that and it is on Medium refinement.

When I bring the model into Makerdesktop or Tinkerine Suite 2.0 (the printers I have access to right now), the come in at around 2000% less scale (closer to 2032%!).

I can switch to mm and get a better output, but is still out by a few mm.

Can anyone explain this?  Can anyone suggest a solid pathway that is guaranteed to work for students (age 10-14) every time?

Yay 21st century problems!

Thanks for the support!

Roger

[HughesTooling]

I work in mm for fusion and simplify 3d and the scale is always correct. I've used cura and slic3r and had no problems either so don't know why you're having problems. I try something in inches and see what happens.

Mark

[HughesTooling]

Just tried exporting a 1" cube and it comes out as 25.4 units in the STL so it looks like you need your slicer set to mm as Fusion is scaling the stl to mm. STL files have no unit info so you need to know how it was exported and set the units to match in whatever program you open the stl with.

Mark

[etfrench]

There may have been some changes with the latest update.  Models are now the correct size in Slic3r when I have the units in Fusion 360 set to either inches or millimeters.  Previously, STLs created with inches were not correct and I had to make sure to set the units to mm. I also only use millimeters in Slic3r.

If your models are off a millimeter or more, then the problem is most likely in the printer.  Do you have a calibration model that gets run regularly?

[ENTERteacher]

Solved!

Thanks for the thoughts and ideas!

After playing around a bit, yes, exports designed in millimeters should import into slicers at a 1:1 scale (great!).  It's when modelling in inches that some slicers won't convert or prompt the user when importing the STL.

If this is the case for you, do a quick test with a 1" cube, then export it as and STL and import it into your slicer to see what happens.  If it comes in as a 1mm cube (which is most likely the case since it appears STLs take any units as single units and assumes mms), then the solve is simply to scale the entire model by 2540%!

Thanks again team awesome!

[Anonymous]

i created a model in fusion 360 in mm, when i exported to slic3r PE the model seemed to be double scale, this is a new issue for me, all of my previously exported models have been very precise.   this seems to be a scaling issue rather than a calibration issue.   has anyone else encountered this?  solutions?  thoughts?

[laughingcreek]

-Are you using "send to 3d print utility", or are you exporting to a .STL first? (I personally prefer to save as a .STL first.)

-have you opened the .STL in another program to check the size there?

-Does slicer have a setting for what units to assume on import?

-have you compared exact measurements between two points in fusion and in slicer?

[Anonymous]

user error, i'm such a dummy, you can take down my post....

😖