Size of export differs from model

Hey there,

first of all, thanks a lot for providing this amazing app :slight_smile:

I got one problem though.
The model, once exported, is 10x smaller than i modelled it, when i import it into the slicer for 3d-printing.

It doesn’t matter if i model it on a cm or mm grid. If i make it 5 cm wide, it’s 5mm in the STL file.
If i scale it up by the factor 10 beforehand, making it 50cm wide in shapr, it is 5cm in the slicer.

I can fix it by scaling it up later too, but it would be more convenient if the actual measures were correct to begin with.

Do you have a tip what i’m doing wrong or is there a bug in the export format?

Thanks in advance,

SOLUTION: Why did my STL file change units? – Shapr3D Help Desk


STL does not contain unit information. That means if your workspace is set to inches, and you create a 1x1x1 inch cube, if you load it to your slicer, it will interpret it as a 1x1x1 mm cube. Because STL format is crap. Never meant to be an input format. Really sad that 3d printing does not have a decent mesh format. So the solution is to scale your model once you loaded it to the slicer. Or set the units to mm in Shapr.

Can you please try to export to 3MF instead of STL?

Thanks for replying so quick Istvan. Think I’ve sorted it.

However, would there be a reason why an OBJ file exported from the same project would be much smaller than a STL of the same model? Still learning the best workflow from 3d printing at the moment. Thanks.

STL and OBJ formats do not contain any unit information, thus it’s almost arbitrary how the units will be interpreted by another software. 3MF format is the best choice for 3D printing.


Because it holds unit information? As in if I make a model in mm and bring it into a slicer set to inches the model will keep its scale? Is there a reason why so many models available online are STL’s for printing?

Yes. 3MF format is the modern replacement of STL. It holds unit information and a ton of other information. This is a pretty good summary on the topic: 3MF vs STL: Which File Type Should Designers Use? - GrabCAD Blog

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Thank you! Still getting to grips with it. I’ll be back I’m sure. Thanks for the hasty response.

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I’m having the same problem with exporting stl with shapr3d but when I used to use Fusion 3d to export stl I never had a problem with the scale changing. it seem like it’s a shaper 3d issue, and I’d like to know before I commit to a subscription that I can use stl exporting without issues.

Hello! For sure there is a way, please visit the Advanced Options of the STL export window where you’ll find a Unit setting. It basically scales the file according to the units you have used in the modeling space.

STL files do not have units, they are just pure geometry. Some slicers (Cura for example) expect all the imported models in mm but if you designed in different units there may be some scale issues. The unit setting that I mentioned above solves this issue by scaling up the file. This scaling may be done automatically in Fusion.

Units are the main reason why we highlight the 3MF format over STL. 3MF transfers units also, it does not have to be scaled during the export.